Electrocardiogram measuring equipment

Abstract

An electrocardiogram measuring device includes: a first electrode and a second electrode, which respectively receive a first electrocardiogram voltage and a second electrocardiogram voltage of a first body part and a second body part in contact with the first electrode and the second electrode; two amplifiers for receiving the first and second electrocardiogram voltages from the first and second electrodes; an electrode driver, which outputs a driving voltage; a third electrode, which contacts a third human body part and transmits the third electrocardiogram voltage to an input end of the electrode driver; a fourth electrode, which is located near one of the three electrodes and transmits the output of the electrode driver to the contacted human body part; wherein each of the two amplifiers simultaneously receives and amplifies an electrocardiogram voltage, and the four electrodes are in contact with the right hand, the left hand and the left leg, respectively, and the device obtains six electrocardiogram limb lead (Lead) signals. The obtained six electrocardiogram limb lead (Lead) signals are displayed in a smart phone.

Description

Technical Field

[0001] An electrocardiograph provides an electrical signal waveform that can be easily acquired and used to analyze a patient's heart condition, namely an electrocardiogram, which contains very useful information about the patient's heart condition. An electrocardiograph can be composed of an electrocardiogram measuring device (measuring sensor) and a computer. In recent years, almost everyone uses a smartphone. A smartphone can be regarded as a computer with a wireless communication function and an excellent display effect. Therefore, the combination of an electrocardiogram measuring device (measuring sensor) and a smartphone can constitute an excellent electrocardiograph. The present invention relates to an electrocardiogram measuring device (measuring sensor) that an individual can use in conjunction with a smartphone. The present invention is classified as a device for measuring an electrocardiogram according to the International Patent Classification (IPC) as A61B5 / 04 for detecting, measuring or recording bioelectric signals of the human body. Background Art

[0002] An electrocardiograph is a useful device that can conveniently diagnose a patient's heart condition. Depending on the purpose of use, electrocardiographs can be divided into several types. In order to obtain as much information as possible, a 12-channel electrocardiograph using 10 wet electrodes is used as the standard for hospital electrocardiographs. A patient sensory device is used to continuously measure a patient's heart condition through a small number of wet electrodes attached to the patient. Holter recorders and event recorders that users can move and use by themselves have the following basic functions. These functions include a compact, battery-powered storage device that stores measurement data and a communication device that can transmit data. Holter recorders mainly use 4 to 6 wet electrodes and cables connected to these electrodes and provide multi-channel ECG. However, the disadvantage of a Holter recorder is that it makes the user feel uncomfortable because the wet electrodes connected to the cable are attached to the human body. Patch-type electrocardiographs also require the electrodes to be continuously attached to the body.

[0003] On the other hand, the event recorder can be carried so that the user can measure ECG in time when feeling abnormal heart. Therefore, the event recorder is small, and mainly has no cable for connecting electrodes, and has dry electrodes on the surface of the event recorder. The event recorder according to the prior art is a 1-channel electrocardiograph, which mainly measures one ECG signal by making two hands touch two electrodes respectively.

[0004] The electrocardiogram measuring device, which is the object of the present invention, should be convenient for personal use, should provide accurate and rich electrocardiogram measurement results, and should be compact and easy to carry. The device required for convenient personal use must be able to transmit data by wireless communication with a smartphone. The device required for this must be powered by a battery. The device, which needs to increase battery life and reduce size, should not include a display screen, and the ECG should be displayed on the smartphone.

[0005] In order to provide accurate and rich ECG measurements, two limb leads are directly measured in the present invention. As described later, in the present invention, four leads can be calculated and provided based on the two limb lead measurements measured simultaneously. Generally, with respect to ECG, "channel" and "lead" are used interchangeably to represent an ECG signal or ECG voltage. With respect to the ECG, the word "simultaneously" should be used very carefully at the same time. The meaning of the word "simultaneously" is not "sequential". That is, measuring two leads at the same time actually means measuring two ECG voltages at any time. Specifically, if Lead II is sampled while Lead I voltage is sampled during regular sampling, the time for sampling Lead II each time must be less than the sampling time since Lead I was sampled. It should also be noted that the word "measurement" is used. Only when the physical quantity is actually measured, the word "measurement" should be referred to as measurement. In digital measurement, one measurement should represent an AD conversion. As will be described later, for example, by measuring Lead I and Lead III in ECG measurement, Lead II can be calculated according to Kirchhoff's voltage law. In this case, Lead II must be stated as “calculated”; stating it as “measured” would be confusing.

[0006] One of the most difficult problems in electrocardiogram measurement is to eliminate the power line interference contained in the ECG signal. A well-known method for eliminating power line interference is the driven right leg (DRL) method. In fact, all electrocardiograms have eliminated power line interference by the DRL method. The disadvantage of the DRL method is that one DRL electrode should be attached to the right foot or the lower right part of the trunk. Therefore, in order to measure two limb leads using the DRL method, in the prior art, four electrodes including the DRL electrode must be brought into contact with the body. However, an important problem at this time is that the DRL electrode must be brought into contact with the right lower abdomen, so a cable must be used or the size of the device must be increased. That is, it is difficult to manufacture an electrocardiogram device that uses a DRL electrode to measure two leads to the size of a credit card. Moreover, it is important that if the DRL electrode is brought into contact with the human body adjacent to another electrode, the voltage of the adjacent electrode will be distorted because the voltage of the DRL electrode includes an electrocardiogram signal component. It is very difficult to eliminate power line interference without using DRL electrodes, and special circuits must be used (In-Duk Hwang and Jhon G. Webster, Direct Interference Cancellation of a Two-Electrode Biopotential Amplifier, IEEE Transactions on Biomedical Engineering, Vol. 55, No. 11, pp. 2620-2627, 2008). To eliminate power line interference, multiple filters with very high quality factors (Q) may be required, however, multiple filters may be difficult to manufacture and calibrate.

[0007] Dry electrodes have large electrode impedance, and dry electrodes generate greater power line interference. However, in ECG measurement, for the convenience of the user, it is necessary to use dry electrodes attached to the housing surface of the electrocardiogram measuring device instead of wet electrodes connected to the cable. In addition, for the convenience of the user, it is necessary to reduce the number of dry electrodes. It is also required not to make the DRL electrode contact with the right foot or the lower right part of the body. However, it is difficult to provide an electrocardiogram measuring device that does not use a cable, uses a minimum number of electrodes, and eliminates power line interference in the prior art.

[0008] In order to solve the above problems and necessities, the present invention uses dry electrodes instead of cables for the convenience of users, and uses two amplifiers and three electrodes connected to one electrode driving unit for the simultaneous measurement of two limb leads. For the convenience of users, the electrocardiogram device according to the present invention provides a plate-shaped electrocardiogram device having two dry electrodes separated from each other on one surface and one dry electrode on the other surface. In addition, the present invention provides a method for eliminating power line interference without using DRL electrodes.

[0009] As described later, the present invention discloses an electrocardiogram measuring device, characterized in that three electrodes are included, and a power line interference current flows intensively through one electrode connected to an electrode driving unit, and two amplifiers are used that are connected to two electrodes other than the electrode among the three electrodes, and the two amplifiers amplify one electrocardiogram signal respectively, and two electrocardiogram signals are measured simultaneously. At this time, one amplifier means that a signal is amplified, and in an actual configuration, one amplifier may mean a plurality of amplifier stages connected in series or a set composed of active filters.

[0010] As described below, the prior art does not provide the technical solution provided by the present invention.

[0011] Righter (US Pat. No. 5,191,891, 1993) equipped the phenotypic device with three electrodes and obtained only one ECG signal.

[0012] Amluck (DE20119965, 2002) discloses an electrocardiogram with two electrodes on the top and one electrode on the bottom, but only one lead is measured. Moreover, unlike the present invention, Amluck has a display and input / output buttons.

[0013] Wei et al. (US Pat. No. 6,721,591, 2004) used a total of six electrodes, including a ground electrode and an RL electrode, and published a method of measuring four leads and calculating the remaining eight leads.

[0014] Kazuhiro (JP2007195690, 2007) equips a device including a display with four electrodes including a ground electrode.

[0015] Tso (U.S. Publication No. 2008 / 0114221, 2008) discloses a meter that includes three electrodes. However, Tso touches two electrodes with one hand at the same time to measure a limb lead, such as Lead I. Only one lead can be measured at a time, so three measurements must be performed sequentially to obtain three limb leads. In addition, Tso directly measures the enhanced limb lead that does not need to be measured directly, and uses a separate platform for this measurement.

[0016] Chan et al. (U.S. Publication No. 2010 / 0076331, 2010) disclose a watch including three electrodes. However, Cho et al. measured three leads using three differential amplifiers. In addition, Chan et al. used three filters connected to the respective amplifiers to reduce signal noise.

[0017] Bojovic et al. (U.S. Pat. No. 7,647,093, 2010) describe a method for calculating a 12-lead signal by measuring three special (non-standard) leads. However, to measure three leads including one limb lead (Lead I) and two special (non-standard) leads from the chest, five electrodes with a ground electrode on both sides of a plate-shaped device and three amplifiers are used.

[0018] Saldivar (U.S. Publication No. 2011 / 0306859, 2011) discloses a cellular communication cradle. Saldivar has three electrodes on one side of the communication cradle. However, Saldivar uses a lead selector to connect two of the three electrodes to a differential amplifier 68 to measure one lead ( Figure 4 C and

[0054] paragraph), that is, Saldivar is 3 and the leads are measured one by one.

[0019] Berkner et al. (U.S. Pat. No. 8,903,477, 2014) use three or four electrodes placed on both sides of the housing to calculate a 12-lead signal through sequential measurements performed when the device is moved sequentially. However, the detailed structure and shape of the device including the connection method of the electrodes inside has not been provided. Most importantly, Berkner uses one amplifier 316 and one filter module 304. For example, if one amplifier 316 and one filter module 304 are used to measure two leads, two measurements are performed sequentially. Berkner said: "In a three-electrode system, the reference electrode is different and will shift in each lead measurement. This can be done by designated software or hardware including optionally a switch." (... Therefore, in a system including only 3 electrodes, the reference electrode is different and will change each lead measurement. This can be done by designated software and hardware / or hardware including optionally a switch.) The above technology shows that Berkner uses one amplifier 316 and one filter 304 to measure one lead at a time and perform multiple measurements sequentially. That is, compared with the method of measuring two leads simultaneously using three electrodes and two amplifiers proposed by the present invention, the method of Berkner et al. has many disadvantages.

[0020] Amital (US Publication No. 2014 / 0163349, 2014) generates a common mode cancellation signal from three electrodes in a device equipped with four electrodes, and the common mode cancellation signal is another electrode coupled (see claim 1) to remove the common mode signal. This is an existing DRL method well known before Amital.

[0021] Thomson et al. (U.S. Publication No. 2015 / 0018660, 2015) discloses a smartphone case with three electrodes. Thomson's smartphone case has a hole in the front through which the smartphone screen can be seen. However, no method of using two amplifiers to measure two leads simultaneously is proposed. In addition, because Thomson's device uses ultrasonic communication, there is a disadvantage that communication problems may occur even if the smartphone and the device are slightly separated (approximately 1 foot). In addition, if the user changes the smartphone, Thomson's smartphone case may not be able to use the existing smartphone case.

[0022] Drake (U.S. Publication No. 2016 / 0135701, 2016) has three electrodes on one side of the mobile device, which can provide 6 leads. However, Drake is "composed of one or more amplifiers for amplifying analog signals received from the three electrodes" (paragraph

[0025] and claim 4, "including one or more amplifiers configured to amplify analog signals received from the three electrodes"). Therefore, Drake is vague about the essential part of the invention, that is, how many amplifiers to use and how to connect the amplifiers to the three electrodes. Drake also said: "The ECG device 102 includes a signal processor 116 that can be configured to perform one or more signal processing operations on signals received from the right arm electrode 108, the left arm electrode 110, and the left leg electrode 112" (paragraph

[0025] ). Therefore, Drake receives three signals. And it is unclear whether Drake receives the three signals simultaneously or sequentially. In addition, Drake also describes that "various embodiments disclosed herein may relate to a handheld electrocardiogram device for simultaneously acquiring six leads" (paragraph

[0019] ). At this point, Drake incorrectly, inappropriately, and unclearly uses the word "simultaneously". The structure of the Drake device is similar to that of the Thomson device. Drake places three electrodes on one side of the device. Therefore, similar to the Thomson, it is difficult to make the three electrodes contact both hands and the body at the same time.

[0024] The Saldivar (WO2017 / 066040, 2017) device uses a lead selection stage 250 to connect three electrodes to one amplifier 210. In addition, Saldivar performs six measurements one by one to obtain six leads. That is, Saldivar cannot measure multiple leads simultaneously. Saldivar can also directly measure three enhanced limb leads in sequence. Summary of the invention

[0025] Technical issues to be solved

[0026] The present invention is proposed in view of the above-mentioned problems, and its purpose is to provide an electrocardiogram device with three electrodes that uses two amplifiers associated with two limb Leads to simultaneously measure the Leads of two limbs. It is medically important to measure the Leads of two limbs at the same time. This is because it is time-consuming and inconvenient to measure the two Leads sequentially. More importantly, the two limb Leads measured at different times may not be correlated with each other, and may confuse the detailed arrhythmia distinction. For the convenience of users, the electrocardiogram device according to the present invention includes a plate-shaped electrocardiogram device, which has two dry electrodes separated from each other on one surface and one dry electrode on the other surface. In addition, the present invention will provide a method for eliminating power line interference without using DRL electrodes. In the present invention, a convenient electrocardiogram measurement method of contacting two hands with two electrodes and contacting one electrode on the body, and an electrocardiogram measurement device having a suitable structure are disclosed.

[0027] Technical Solution

[0028] The appearance, operation principle, structure and use method of the electrocardiogram device according to the present invention for solving the above problems are as follows: The present invention solves the above problems through systematic analysis circuit design and software production.

[0029] An electrocardiogram measuring device according to an embodiment of the present invention includes:

[0030] The first electrode and the second electrode respectively receive two electrocardiogram voltages of the part in contact with the human body;

[0031] two amplifiers, receiving the two ECG voltages from the first electrode and the second electrode respectively;

[0032] an electrode driving unit for outputting a driving voltage;

[0033] a third electrode, receiving the output of the electrode driving unit and transmitting the output of the electrode driving unit to the contacted body part;

[0034] An AD converter connected to the respective output terminals of the two amplifiers and converting the output signals of the two amplifiers into two digital signals;

[0035] A microcontroller receives two digital signals from the AD converter;

[0036] a communication device for transmitting the two digital signals,

[0037] The microcontroller receives power from the battery,

[0038] The microcontroller controls the AD converter and the communication device,

[0039] The two amplifiers respectively receive an ECG voltage for amplification at the same time, and the output impedance of the electrode driving unit is smaller than the input impedance of each of the two amplifiers.

[0040] Figure 1 An electrocardiogram measuring device 100 according to the present invention is shown. The electrocardiogram measuring device 100 includes three electrodes 111, 112, 113 on its surface. Two electrodes 111, 112 spaced at a predetermined interval are mounted on one surface of the electrocardiogram measuring device 100, and one electrode 113 is mounted on the other surface.

[0041] Figure 2 The method of measuring an electrocardiogram in a six-channel mode using the electrocardiogram measuring device 100 according to the present invention is shown. The user touches the electrodes 111 and 112 provided on one side of the electrocardiogram measuring device 100 with two hands, and touches the electrode 113 installed on the other side to the user's left lower abdomen (or left leg). When the three electrodes are in contact with the human body in this way, two limb Leads can be measured, and four additional Leads can be calculated as described below. Figure 2 The measurement method provided by the present invention is the most convenient method for obtaining 6-channel ECG. In addition, the present invention provides the most suitable Figure 2 The principle of the measuring method is as follows.

[0042] The existing 12-lead ECG is described in ANSI / AAMI / IEC60601-2-25:2011, Medical Electrical Equipment Part 2-25: Particular Requirements for Basic Safety and Basic Performance of Electrocardiographs. In the existing 12-lead ECG, the three limb leads are defined as follows. LeadI=LA-RA, LeadII=LL-RA, LeadIII=LL-LA. In the above formula, RA, LA, and LL are the voltages of the right arm, left arm, left leg, or parts of the body close to these limbs, respectively. At this time, in order to eliminate power line interference, the right leg (DRL) electrode is generally used in the prior art. According to the relationship, a limb lead can be obtained from the other two limb leads. For example, LeadIII=LeadII-LeadI. The three enhanced limb leads are defined as follows. aVR=RA-(LA+LL / 2,aVL=LA-(RA+LL / 2,aVF=LL-(RA+LA / 2。Therefore,three enhanced limb leads can be obtained from two limb leads。For example,aVR=-(I+II / 2。Therefore,if two limb leads are measured,the remaining four leads can be calculated and obtained。Therefore,the present invention discloses a device for simultaneously measuring two leads using three electrodes and two amplifiers to provide six leads。At this time,one amplifier means that the signal is amplified,and in the actual configuration,one amplifier can be composed of a plurality of amplification ends or a collection of active filters connected in series。A standard 12-lead electrocardiogram consists of 6 leads from V1 to V6 and 6 pre-recorded leads。

[0043] The modified chest lead (MCL) is similar to the precoded lead and is very useful in medicine. On the other hand, in the principle of the present invention, the voltage of one electrode of the three electrodes that is not connected to the amplifier is substantially equal to the common circuit in the signal band. Therefore, the electrocardiogram measurement device 100 according to the present invention is suitable for measuring one MCL among six MCLs from MCL1 to MCL6. This is because the respective MCLs are based on the voltage of the body part connected to the left hand at the corresponding recorded lead position.

[0044] Figure 3 1 shows a method for a user to measure MCL1 using the electrocardiogram device according to the present invention in the MCL mode. For example, using the electrocardiogram device according to the present invention, in order to measure MCL1, as Figure 3 As shown, the user touches the electrodes 111 and 112 provided on one side of the electrocardiogram measuring device 100 with both hands, and touches the electrode 113 provided on the other surface with the MCL position (for example, the V1 position when measuring MCL1). In the present invention, in order for the user to measure MCLn, the user needs to touch the electrode 113 to the MCLn position of the user's body, that is, the Vn position.

[0045] Now, refer to Figure 4 and Figure 5 An embodiment of the electrocardiogram measuring apparatus according to the present invention is described. Figure 4 It is an equivalent circuit model for explaining the principle and embodiment of eliminating power line interference in the electrocardiogram measuring device according to the present invention. Figure 5 1 is an equivalent circuit model of an embodiment of simultaneously measuring two channels of an electrocardiogram using two single-ended input amplifiers and one electrode driver in an electrocardiogram measuring apparatus according to the present invention.

[0046] Reference Figure 4 , current source 450 is used to model power line disturbances. Figure 4 In FIG. 4 , the human body is marked as 430 and is modeled by three electrode resistors 431 , 432 , 433 connected to each other at one point. Figure 5 In the present invention, an ECG signal is modeled as a voltage source 461 and 462 existing between two electrode resistors. In the present invention, since three electrodes are used, Figure 5 In FIG. 4 , two ECG voltage sources 461 and 462 are simulated in the human body. This is because there are three ECG voltages on the three electrodes (this is because there are three when two electrodes are selected from the three electrodes), but only two ECG voltages are independent. Figure 4 Power line disturbance modeling and Figure 5 The electrocardiogram signal in is modeled. However, the model is suitable for illustrating the problem to be solved. In addition, the above model clearly suggests the content that the present invention should be designed. In addition, by using the above model, the present invention can be easily understood. The present invention is designed based on the above model. Since the prior art does not use the above model, the prior art cannot accurately propose a solution to the problem.

[0047] As will be described later, the present invention can be expressed in various embodiments. However, the various embodiments of the present invention are generally based on the following principles of the present invention. The principles of the present invention are designed for the present invention in the present invention. Compared with the DRL used in the prior art, the principles of the present invention have the difference of not using DRL electrodes.

[0048] An unresolved problem that has not been solved by existing ECG measurement devices that do not use DRL electrodes is to eliminate or reduce power line interference. Figure 4 As shown, the power line interference in the electrocardiogram measuring device is generated by a current source with essentially infinite output impedance due to the relatively large output impedance. Figure 4, the power line interference current source is represented as 450. ) Therefore, in order to eliminate the power line interference, it is necessary to minimize the impedance from the power line interference current source to the human body. The impedance from the power line interference current source to the human body is the sum of the impedance of the human body itself and the impedance of the electrocardiogram measuring device. As a result, it is necessary to minimize the impedance of the electrocardiogram measuring device seen through the three electrodes. On the other hand, there is an impedance called electrode impedance or electrode resistance between the electrodes for measuring the electrocardiogram and the human body ( Figure 4 431, 432, 433 in FIG. 4). Therefore, in order to minimize the influence of electrode impedance and measure the ECG voltage, the ECG measuring device must have a high impedance. Therefore, the ECG measuring device must meet two opposite conditions, namely, it must have a low impedance to eliminate power line interference and it must have a high impedance to measure the ECG voltage.

[0049] In order to meet two opposite conditions, for example, when three electrodes are used, three resistors with larger values ​​are connected to the three electrodes respectively, the other ends of the three resistors are connected together as points, and the common mode signal of the three electrodes is negatively fed back to a point connecting the three resistors. However, this method is actually difficult to use. This is because the impedance of the power line interference current source is large, so the magnitude of the power line interference current will not decrease. Therefore, in this case, the power line interference voltage induced in the three resistors is still large. Otherwise, the amplifier may be saturated. In addition, since the magnitude of the power line interference current is not reduced and the impedance of each electrode can be different, different power line interference voltages are induced at a high level for each electrode. Therefore, even if a differential amplifier is used, it is difficult to eliminate the power line interference caused to each electrode. This is a difficulty in the prior art.

[0050] Therefore, in the present invention, the power line interference current is concentrated and flows only to one of the electrodes installed in the electrocardiogram measuring device. For this reason, while the three electrodes are connected to the human body, the power line interference current source minimizes the impedance entering the electrocardiogram measuring device through one electrode. Then, the power line interference voltage (at Figure 4Then, since the power line interference voltage induced to the human body is minimized, the input impedance of the other electrodes of the electrocardiogram measuring device can be increased, and the electrocardiogram voltage can be accurately measured. At this time, it is important that in one electrode where the power line interference current is concentrated, the power line interference voltage is induced higher, and therefore, the electrode should not be used for measurement. Therefore, in the present invention, when three electrodes are used, two electrodes and two amplifiers receiving ECG signals from the two electrodes are used for measurement. In particular, it should be noted that since only two electrodes must be used for measurement in an electrocardiogram measuring device using three electrodes, two differential amplifiers cannot be used. Moreover, when negative feedback is used, when negative feedback is performed on all frequency bands, the electrocardiogram signal is generated on the electrode side and fed back and mixed with the power line interference voltage, so the negative feedback should be performed only at the power line interference frequency. Hereinafter, a detailed description of the present invention will be described with reference to the accompanying drawings.

[0051] exist Figure 4 In the following figures, for the sake of convenience, the electrocardiogram measuring device 100 according to the present invention only shows a part of the device according to the present invention. Figure 4 In the embodiment of the present invention, the electrocardiogram measuring device 100 includes three electrodes 111, 112, 113, two amplifiers 411, 412, and an electrode driver (specifically, a bandpass filter) 413. Figure 4 and Figure 5 , the two amplifiers 411 and 412 used in the present invention are not differential amplifiers but single-ended input amplifiers.

[0052] The present invention Figure 4 An important feature of the illustrated embodiment is that the electrocardiogram measuring device 100 according to the invention comprises an electrode driver 413 represented by a bandpass filter. Figure 4 In the present invention, the electrode driver 413 may have a bandpass frequency characteristic. Therefore, in the present invention, the electrode driver 413 may be described as a bandpass filter. The input of the electrode driver 413 is connected to one electrode 112. The output of the electrode driver 413 drives the electrode 113 through the resistor 423 (feeds back to the electrode 113). The resonant frequency or peak frequency of the electrode driving unit (i.e., the bandpass filter 413) is the same as the frequency of the power line interference. In addition, the bandpass filter 413 has a large Q. In Figure 4 In the embodiment, the input impedance of the bandpass filter 413 is large, while the output impedance is small. The element value of the resistor 423 is represented by RO. In the present invention, for the sake of convenience, the resistor 423 is regarded as the output impedance of the electrode driver 413.

[0053] In the present invention, two of the three electrodes are connected to the analog circuit via resistors 421 and 422, with a resistance value of RI. The resistors 421 and 422 are considered as input impedances of the amplifiers 411 and 412.

[0054] exist Figure 4 In , 430 is the human body model. There is contact resistance between the human body and the electrode, which is usually called electrode impedance. Figure 4 In FIG. 4 , the electrode impedance (electrode resistance) between the human body 430 and the three electrodes 111, 112, 113 is represented by resistors 431, 432, 433. The device values ​​of the electrode resistors 431, 432, 433 are represented by Re1, Re2, Re3, respectively.

[0055] Figure 4 450 is a power line interference current source for modeling power line interference. The current in of the power line interference current source 450 flows through the circuit of the electrocardiogram device 100 according to the present invention through the human body 430 and the three electrodes 111, 112, 113. When the power line interference currents flowing through the three electrodes 111, 112, 113 are represented by in1, in2, in3, respectively, according to Kirchhoff's current law, the following situation holds.

[0056] in=in1+in2+in3·····················(Formula 1)

[0057] For circuit analysis purposes, the power line disturbance induced in the human body 430 is represented by νbody. Figure 4 In Equation 1, νn1, νn2, νn3 represent the power line interference voltages of the electrodes 111, 112, 113, respectively. In Equation 1, the currents are as follows.

[0058]

[0059] at this time

[0060]

[0061] In the above, the transfer function of the bandpass filter 413 is represented by -H(f). Using the above equation, the following equation is obtained:

[0062]

[0063] In the present invention, use Figure 4 The device values ​​of the circuit are used to realize the following approximation (Equations 7 and 8). Equations 7 and 8 are important components of the present invention.

[0064] Ri>>Re1, Re2, orRe3······················(Formula 7)

[0065] Ri>>Ro·······················(Formula 8)

[0066] Then, the following approximation is established.

[0067]

[0068] The following equation is obtained from the above equation 9.

[0069]

[0070] In Equation 10, if there is no feedback, ie, H(f) = 0, the following holds.

[0071] vbody≈(Ro+Re3)inifH(f)=0··········(Formula 11)

[0072] By comparing equation 10 and equation 11, we can see that the effect of the present invention is to reduce the influence of the power line interference current in to the feedback amount, that is, (1+H(f)), so at the resonant frequency of the bandpass filter, when the gain size |H(fo)|>1, vbody≈0. This proves the principle of eliminating power line interference in the present invention.

[0073] The following equation is confirmed by using Equation 2 and Equation 10.

[0074]

[0075] The following results are obtained for vn3. From the above results, we can use vbody≈0 and in3≈in

[0076] vn3≈vbody-in3Re3≈-inRe3············(Formula 13)

[0077] From Equation 12 and Equation 13, we can confirm the following equation:

[0078] |vn3|>>|vn1|············(Formula 14)

[0079] This is a result of the feedback |H(f)| being large, almost all of the power line interference current flows through the feedback electrode ( Figure 4 113 in the embodiment of the present invention), so the feedback electrode is contaminated by the power line interference rather than the feedback electrode ( Figure 4The electrodes 111 and 112 in the ECG are power lines. This means that there is little influence of interference. This means that for ECG measurement, feedback electrodes should not be used, but only non-feedback electrodes should be used. Therefore, the influence of power line interference cannot be eliminated by using a differential amplifier with inputs connected to electrodes 111 and 113 or a differential amplifier with inputs connected to electrodes 112 and 113. This is one of the important problems of the prior art.

[0080] Next, the principle of obtaining two ECG channel signals using three electrodes according to the present invention will be described. Figure 5 is an equivalent circuit when an electrocardiogram is measured using the electrocardiogram apparatus according to the present invention.

[0081] exist Figure 5 In , ν1, ν2, ν3 represent the ECG signal voltages of electrodes 111, 112, 113, respectively. The voltage v2 of electrode 112 is obtained by analyzing the equivalent circuit using the following superposition principle.

[0082]

[0083] In the equation 15, the symbol || represents the value of the parallel resistance. As described above, the conditions of equations 7 and 8 can be assumed in equation 15. Then, the voltage ν2 is approximated as follows.

[0084]

[0085] Therefore, under the conditions of Equation 7 and Equation 8, the voltage ν1 is as follows.

[0086]

[0087] From the above baseband signal, we can confirm that |H(f)| < 1 when v2≈vb

[0088] Figure 6 FIG. 2 shows the frequency response of the bandpass filter used in the electrocardiogram measuring device according to the present invention. Figure 6 In FIG. 1 , the resonant frequency of the bandpass filter is 60 Hz, the gain at the resonant frequency is 20, and Q=120. Figure 7 Show when using Figure 6 When the bandpass filter is used, νb can be obtained with an accuracy of 98% at frequencies below 40 Hz.

[0089] Similarly, the voltage ν1 of electrode 1 is obtained as follows.

[0090]

[0091] When the conditions of Equation 7 and Equation 8 are used, the voltage ν1 is approximated as follows.

[0092] v1≈+va+vb-v2H(f)

[0093] ≈va+v2·····················(Formula i9)

[0094] The above equation is obtained using equation 16. The following equation 20 is obtained from the above equation, and νa can be obtained by this equation. As can be seen from equation 20, νa can be obtained without the influence of the bandpass filter.

[0095] v1-v2≈+va···························(Formula 20)

[0096] Thus, according to the present invention, the principle of using two single-ended amplifiers to obtain the signals of two ECG channels has been described.

[0097] Figure 8 832 is an equivalent circuit model showing the principle and embodiment of eliminating power line interference using a common mode signal of two electrodes in an electrocardiogram measuring device according to the present invention. Naturally, even when a common mode signal is used, the power line interference current is concentrated and flows through electrode 832, the output of electrode driver 813 is fed back to electrode 832, and the power line interference voltage exists in electrode 832. Fig. 9 When using Figure 8 The equivalent circuit model of an embodiment of the method, i.e., when using a common mode signal to remove power line interference, simultaneously measures two channels of an electrocardiogram using a differential amplifier 811 and a single-ended input amplifier 812. Like the previous two single-ended input amplifiers, two ECG voltages can be obtained.

[0098] For convenience, the Figure 8 and 9 Circuit analysis. Figure 8 and Fig. 9 In the embodiment, Figure 4 and Figure 5 As in the embodiment of the present invention, the electrode driving unit, i.e., the bandpass filter 813, is applied by applying a driving voltage to a human body part to which the electrode 112 contacts through an output impedance Ro and an electrode 112. That is, the electrode 112 is not connected to an amplifier for measuring the ECG voltage, but is connected to the electrode driver 813 through an output impedance 823. That is, the electrode 112 is not used to measure the ECG voltage. When the peak value of the bandpass filter is large, in order to achieve |H(f)|<<1 in the signal frequency band, the transfer function H(f) of the bandpass filter can be corrected or compensated.

[0099] exist Figure 8 In the example, a bandpass filter 813 is used as an electrode driver, but in Fig.10In the method, a constant voltage source 1013 is used as an electrode driver. The constant voltage source 1013 applies a driving voltage to a part of the human body in contact with the electrode 112 through a resistor 1023 having a small resistance value R0 and the electrode 112. Most of the power line interference current flows through the electrode 112. In order to further concentrate the power line interference current, the output impedance 1023 of the electrode driver 1013 can be reduced. Compared with the previous method using a bandpass filter, this method has a smaller effect in eliminating power line interference. Fig.10 In the embodiment of the present invention, in addition to the electrodes where the power line interference current is concentrated and flows, two ECG voltages are simultaneously amplified by using two amplifiers connected to the two electrodes. Fig.10 In the embodiment of the present invention, a differential amplifier 1011 and a single-ended input amplifier 1012 are used. The output of the single-ended input amplifier 1012 may include small power line interference, and a band pass filter 1033 may be used to further reduce the power line interference.

[0100] exist Figure 5 , Fig. 9 and Fig.10 In the present invention, an electrode driver with a small output impedance is usually used to drive one electrode in order to reduce power line interference. The output of the electrode driver is transmitted to the part of the human body that the electrode contacts. Once the power line noise is reduced, two single-ended input amplifiers can be used to amplify the two ECG voltages received from the two electrodes, and one single-ended input amplifier and one differential amplifier can be used.

[0101] The principle of the present invention is summarized as follows. The condition that the power line interference current source should reduce the input impedance entering the electrocardiogram measuring device is met by reducing the output impedance of the electrode driver connected to one electrode, and the condition that the ECG signal voltage must increase the input impedance entering the electrocardiogram measuring device is met by increasing the input impedance entering from two different electrodes. Through the above method, the electrocardiogram measuring device according to the present invention can accurately measure the ECG signal voltage while reducing power line interference. Therefore, the output impedance of the electrode driver of the electrocardiogram measuring device according to the present invention is less than the respective input impedances of the two amplifiers.

[0102] As described above, according to the present invention, the present invention uses two amplifiers with large input impedance to receive two ECG voltages from two electrodes while eliminating power line interference by applying the output of one electrode driver to one electrode, thereby simultaneously measuring an example of the two ECG voltages.

[0103] Beneficial Effects

[0104] The electrocardiogram measuring device according to the present invention provides six ECG leads obtained simultaneously using the minimum number of electrodes (specifically, three electrodes). When the electrocardiogram measuring device according to the present invention is used in the MCL mode, a limb lead (specifically, LeadI) and a MCL can be measured.

[0105] Since the portable electrocardiogram measuring device according to the present invention is the size of a credit card, it is easy to carry, so it is most convenient to obtain multiple electrocardiograms regardless of time and place, and since it wirelessly communicates with a smartphone, it can be conveniently used without any substantial limitation on the distance between the electrocardiogram measuring device according to the present invention and the smartphone.

[0106] In addition, according to the electrocardiogram measuring device of the present invention, when not in use, all circuits except the current sensor are disconnected and only the microcontroller enters the sleep mode, and when in use, only the required circuits are powered and the microcontroller enters the activation mode, so that the power consumption of the built-in battery of the electrocardiogram measuring device can be minimized.

[0107] In addition, the electrocardiogram measuring device according to the present invention does not include a mechanical power switch or a selection switch to achieve miniaturization and thinness, and the user does not need to trouble using the switch, which will not cause the possibility of switch failure, limited life, and increased manufacturing price.

[0108] In addition, since the electrocardiogram measuring apparatus according to the present invention does not include a display such as an LCD, it can be manufactured in a compact size and can be easily carried without causing malfunction and degradation of the display and an increase in manufacturing price. BRIEF DESCRIPTION OF THE DRAWINGS

[0109] Figure 1 is a perspective view of an electrocardiogram measuring device having three electrodes according to the present invention.

[0110] Figure 2 A method for measuring an electrocardiogram in a 6-channel mode using an electrocardiogram measuring device according to the present invention

[0111] Figure 3 The present invention provides a method for measuring an electrocardiogram in an MCL mode using the electrocardiogram measuring device according to the present invention.

[0112] Figure 4 It is an equivalent circuit model for explaining the principle and embodiment of eliminating power line interference in the electrocardiogram measuring device according to the present invention.

[0113] Figure 5 This is an equivalent circuit model of an embodiment of simultaneously measuring two channels of an electrocardiogram using two single-ended input amplifiers and one bandpass filter (electrode driving section) in the electrocardiogram measuring apparatus according to the present invention.

[0114] Figure 6 is the frequency response of a bandpass filter used as an electrode driving section in the electrocardiogram measuring apparatus according to the present invention.

[0115] Figure 7 is the frequency response of one signal path when a bandpass filter is used as the electrode driving section in the electrocardiogram measuring apparatus according to the present invention.

[0116] Figure 8 It is an equivalent circuit model for explaining the principle and embodiment of eliminating power line interference using a common mode signal in an electrocardiogram measurement device according to the present invention.

[0117] Fig. 9 The equivalent circuit model of an embodiment of the electrocardiogram measuring device according to the present invention, which uses a differential amplifier and a single-ended input amplifier and a bandpass filter (electrode driving section) to simultaneously measure two channels of electrocardiogram when a common mode signal is used to eliminate power line interference.

[0118] Fig.10 Another embodiment of simultaneously measuring two channels of an electrocardiogram by using a differential amplifier and a single-ended input amplifier and a constant voltage generator (electrode driving section) in the electrocardiogram measuring device according to the present invention.

[0119] Fig.11 is a block diagram of a circuit embedded in an electrocardiogram measuring device according to the present invention.

[0120] Fig.12 is an operation flow chart of the electrocardiogram measuring device according to the present invention.

[0121] Fig.13 is an initial screen of a smartphone when a smartphone application is executed to use the electrocardiogram measurement device according to the present invention.

[0122] Fig.14 This is a flowchart of a smartphone application when using the electrocardiogram measuring device of the present invention.

[0123] Fig.15 The present invention is an electrocardiogram measuring device provided with a blood test strip insertion port.

[0124] Fig.16 is an example of implementing the electrocardiogram measuring device according to the present invention in the shape of a smart watch.

[0125] Fig.17 This is an example in which the electrocardiogram measuring device of the present invention is implemented in a ring shape.

[0126] Fig.18 and Fig.19is an example of the electrocardiogram measuring device according to the present invention when measuring an electrocardiogram by being connected to trousers.

[0127] Fig. 20 and Fig.21 It is a shape that can be connected to a watchband of a wristwatch by using two or one sliding guide of the electrocardiogram measuring device serving as an electrode according to the present invention.

[0128] Fig. 22 is a perspective view of an electrocardiogram measuring device having four electrodes according to the present invention.

[0129] Fig.23 It is the prior art.

[0130] Fig.24 This is an embodiment of the electrocardiogram measuring device of the present invention.

[0131] Fig.25 For analysis Fig.24 An electrical equivalent circuit model of an embodiment of the present invention is shown.

[0132] Fig.26 This is another embodiment of the electrocardiogram measuring device of the present invention.

[0133] Fig. 27 Table 1 shows examples of Group A of the present invention.

[0134] Fig.28 This is another embodiment of the electrocardiogram measuring device of the present invention.

[0135] Fig.29 Table 2 shows examples of Group B of the present invention.

[0136] Fig.30 This is another embodiment of the electrocardiogram measuring device of the present invention.

[0137] Fig.31 It is used for analysis Fig.30 The electrical equivalent circuit model of the embodiment of the present invention is shown.

[0138] Fig.32 Table 3 of Group C examples of the present invention.

[0139] Fig.33 This is another embodiment of the electrocardiogram measuring device of the present invention.

[0140] Fig.34 Table 4 is a group D example of the present invention.

[0141] Fig.35 for Fig.24 and Fig.25Equivalent circuit model for motion artifacts analysis in the illustrated embodiment.

[0142] Fig.36 This is another embodiment of the electrocardiogram measuring device of the present invention.

[0143] Fig.37 for Fig.36 Equivalent circuit model for motion artifacts analysis in the illustrated embodiment.

[0144] Fig.38 This is an embodiment of the present invention in which the electrocardiogram measuring device including four electrocardiogram electrodes is implemented in a ring shape.

[0145] Fig.39 Another embodiment of the present invention is that the electrocardiogram measuring device including four electrocardiogram electrodes is implemented in a ring shape.

[0146] Fig.40 Another embodiment of the present invention is that the electrocardiogram measuring device including four electrocardiogram electrodes is implemented in the form of a wristwatch.

[0147] Fig.41 This is another embodiment of the electrocardiogram measuring device of the present invention.

[0148] Fig.42 It is used for analysis Fig.41 An electrical equivalent circuit model for analyzing motion artifacts in an embodiment of the present invention is shown.

[0149] Fig.43 Table 5 shows examples of Group F of the present invention.

[0150] Fig.44 Shows the same watch worn on the left and right hands.

[0151] Fig.45 Table 6 is shown, which shows an embodiment in which the connection and configuration of electrodes and an internal measurement circuit are symmetrical to each other and correspond to one watch.

[0152] Fig.46 is a flow chart of electrocardiogram measurement, in which parameters representing the arm to be worn are preset and stored.

[0153] Fig.47 Table 7 is shown, which shows the errors in the calculated ECG lead signals due to the errors in the measured ECG lead signals. DETAILED DESCRIPTION

[0154] Hereinafter, an embodiment according to the present invention will be described with reference to the accompanying drawings. In this embodiment, an electrocardiogram (ECG) measuring device is described as including three electrodes, but it is not limited thereto, and the electrocardiogram measuring device may be a device including more than three electrodes. Figures 4 to 10 Important embodiments of the present invention are described to explain the principles of the present invention.

[0155] In order to increase portability, the portable electrocardiogram measuring device according to the present invention is preferably in the shape of a credit card and has a thickness of 6 mm or less. Since the portable electrocardiogram measuring device according to the present invention is portable, it uses a battery, and when a CR2032 type battery is used, it can be used for about 2 years.

[0156] In addition, a mechanical power switch or a selection switch may not be provided to miniaturize the portable ECG measuring device, and a display may not be used to reduce power consumption.

[0157] In the portable electrocardiogram measuring device according to the present invention, it is characterized in that a current sensor can be used so as not to use a mechanical power switch or a selector switch. The current sensor is always provided with the power required for operation, and waits for the generation of an output signal when an event occurs. When a user touches a plurality of electrodes to a human body to measure an electrocardiogram, a circuit through which a tiny current flows passes through the human body. Therefore, when the human body is electrically connected to the current sensor, the current sensor causes the microcurrent to flow through the human body, and the current sensor senses the microcurrent and generates an output signal. In order to increase the battery life, when the portable electrocardiogram measuring device is not used, only the current sensor works, the remaining circuits are powered off, and the microcontroller waits in sleep mode. At this time, when an event occurs in which two hands touch two electrodes and the current sensor generates an output signal, the microcontroller is activated to turn on the power supply of the electrocardiogram circuit and perform electrocardiogram measurement. The current sensed by the current sensor is provided by a battery provided in the portable ECG measuring device and is direct current.

[0158] The electrocardiogram measuring device 100 according to the present invention may further include a function of measuring blood characteristics such as blood sugar level, ketone level or international normalized ratio (INR). Therefore, in the present embodiment, the electrocardiogram measuring device 100 will be taken as an example, and the electrocardiogram and blood characteristics will be measured together as an example. The blood sugar level or ketone level can be measured using the amperometric method. The INR is a measure of coagulation trend, and the electrical impedance method, amperometric method or mechanical method of capillary blood can be used to measure. The blood test strip for the blood characteristic test is inserted into a blood test strip insertion port, and the blood test strip insertion port is arranged on the housing of the electrocardiogram measuring device according to the present invention.

[0159] In an embodiment of the electrocardiogram measuring device 100 according to the present invention, a thermometer function may be included. In order to include the thermometer function in the electrocardiogram measuring device 100 according to the present invention, a suitable shape is a contact type, and a suitable temperature sensor is a thermistor. In order to measure body temperature by using the electrocardiogram measuring device 100 according to the present invention including the thermometer function, the user contacts the user's forehead or armpit through a portion of the ECG measuring device 100 to which the temperature sensor is attached. In order to accurately measure body temperature, the temperature of the skin should not be changed by the portion on the electrocardiogram measuring device 100 to which the temperature sensor is mounted.

[0160] Fig.11 FIG. 1 is a block diagram showing a circuit built into the electrocardiogram measuring device 100 according to the present invention. Fig.11 , but the electrocardiogram measuring device according to the present invention may include a blood test circuit, a blood test strip insertion port, etc. Fig.11 The functions and operations of the respective blocks in are as follows. When the user touches a pair of electrodes 111, 112 with two hands, the electrocardiogram current sensor 1140 allows a tiny current to flow through the two hands and detects the tiny current flowing through the two hands. The current sensor 1140 generates a signal to change the microcontroller 1180 from a sleep mode to an active mode. Then, the microcontroller 1180 powers on the ECG measurement circuit 1160 and the AD converter 1170. The ECG measurement circuit 1160 amplifies the two ECG signals from the two amplifiers and generates two outputs. The AD converter 1170 receives the two outputs of the ECG measurement circuit 1160, and the output of the AD converter 1170 is sent to the smartphone 210 through the wireless communication device 1190 and the antenna 1192. The smartphone 210 receiving the data displays a plurality of ECG waveforms. After the measurement within a certain period of time, the microcontroller 1180 enters a sleep mode and waits for the next touch of both hands.

[0161] If the ECG measuring device of the present invention is touched with both hands and the lower left abdomen, six Leads can be displayed at a time, but when it is inconvenient to touch the ECG measuring device with the lower left abdomen or only one Lead is measured, the electrocardiogram measuring device automatically grasps whether the user measures only one Lead or intends to measure six Leads. When the user touches the electrocardiogram measuring device with both hands to measure only one Lead, the current sensor 1140 senses only one current. Then, only Lead I is displayed on the smartphone. When the user touches the ECG measuring device with both hands and the lower left abdomen to measure six Leads, the current sensor 1140 and the current sensor 1150 sense the current together. Then, six Leads will be displayed on the smartphone. Fig.11The respective blocks shown in can be implemented in the prior art using commercially available components.

[0162] Fig.12 12 is an operation flow chart of the electrocardiogram measuring device 100 according to the present invention when measuring the electrocardiogram. In order for the user to measure the electrocardiogram, the pair of electrodes 111 and 112 of the electrocardiogram measuring device 100 are respectively touched 1210 with two hands. Then, the current sensor that senses the tiny current flowing through the human body between the two hands generates an output signal 1215. The output signal generates an interrupt of the microcontroller 1180 to activate the microcontroller 1180 (1220). The activated microcontroller 1180 activates the wireless communication device 1190. In the following, a case where the wireless communication device 1190 is a Bluetooth low energy device will be described. The wireless communication device 1190 of the electrocardiogram measuring device 100 is advertised as a Bluetooth low energy peripheral device 1225. At this time, the smartphone scanning as a Bluetooth low energy central device discovers the electrocardiogram measuring device 100 and attempts to connect. At this time, if the electrocardiogram measurement device 100 approves the connection, the smartphone and the electrocardiogram measurement device 100 are connected to Bluetooth low energy 1230. At this time, the electrocardiogram measurement device 100 may determine whether the user has actually touched the electrocardiogram measurement button of the smartphone to measure the electrocardiogram 1235.

[0163] When it is confirmed that the ECG measurement is requested, the microcontroller 1180 turns on the power supply 1240 of the ECG measurement circuit 1160. This can be performed by connecting the output pin of the microcontroller 1180 to the ECG measurement circuit 1160 and setting the voltage of the output pin to High. Next, the current sensor 1245 is used to check whether the pair of electrodes 111, 112 are touched by two hands. This step is to determine when the microcontroller 1180 starts measuring ECG, that is, when AD conversion starts. That is, it is used to check whether the two hands are in continuous contact with the electrodes 111, 112.

[0164] After the above process, the microcontroller 1180 starts ECG measurement 1250. That is, the microcontroller 1180 performs AD conversion according to a preset AD conversion cycle and brings an AD conversion result. In the present invention, two ECG signals are measured. The measured electrocardiogram data is sent to the smart collection 210 (1255), and when the preset measurement time, for example, 30 seconds, passes, the microcontroller 1180 enters a sleep mode 1260.

[0165] Fig.11 All circuits are driven by a battery built into the electrocardiogram measuring device 100. Fig.11There may be no mechanical power switch, mechanical selector switch, or display. Fig.11 In the embodiment, when the electrocardiogram measurement device 100 is not measuring, the electrocardiogram current sensor and the microcontroller 1180 each consume approximately 1 uA, and all other modules are completely powered off.

[0166] The electrocardiogram measuring device 100 according to the present invention is used together with a smartphone 210 . Fig.13 The initial screen of the smartphone when executing the smartphone application according to the present invention is shown. When the smartphone application is executed, touch buttons 1331, 1332, 1334, 1336, 1342, 1344, 1346, 1350 are displayed on the display 1320 of the smartphone 210. Buttons 1331, 1332, 1334, 1336 related to electrocardiogram are configured in the electrocardiogram box 1330. When the electrocardiogram measurement device 100 according to the present invention includes a function of measuring blood characteristics, buttons 1342, 1344, 1346 related to blood characteristics are configured in the blood glucose box 1340. The user selects and touches one of the ECG measurement mode buttons 1331, 1332 to be measured in order to measure ECG. When the user measures ECG in 6-channel mode, touch button 1331. When the user measures electrocardiogram in MCL mode, touch button 1332. Then, when the user touches the pair of electrodes 111, 112 of the ECG measurement device 100 with both hands, the ECG measurement device 100 measures ECG as described above. The data is displayed in a graph on the smartphone display 1320 and stored in the smartphone 210. To view the electrocardiogram measurement data stored in the past in a graph, touch the open button 1334. To send the data to a doctor or hospital, touch the send button 1336. The setting button 1350 is used to record the user's name, date of birth, gender, address, etc., or set options.

[0167] Fig.14 FIG. 1 shows a flow chart of a smartphone application according to the present invention. For the sake of convenience, only the process of measuring an electrocardiogram will be described. Fig.14 As shown, the process when measuring ECG consists of two trunks of central trunks 1422, 1424, 1426, 1428, 1430, 1432 and Bluetooth Low Energy (BLE) trunks 1452, 1454. After launching the application, various buttons 1410 appear on the smartphone display 1320, and then the BLE trunks 1452, 1454 for performing Bluetooth Low Energy communication are launched. A user who wants to measure an electrocardiogram touches one 1422 of the ECG measurement buttons 1331, 1332.

[0168] When the user touches one of the ECG measurement buttons 1331 or 1332, 1422, an ECG measurement request signal is sent to the BLE stems 1452, 1454 (1424). In addition, according to the ECG measurement mode, a message 1424 to the contact electrodes according to the ECG measurement mode is displayed on the smartphone display 1320. The BLE stems 1452, 1454 send the ECG measurement request signal 1454 to the ECG measurement device 100.

[0169] The electrocardiogram measurement device 100 that receives the electrocardiogram measurement request signal executes Fig.12 , to resend the electrocardiogram data measured by the BLE stems 1452, 1454. The BLE stems 1452, 1454 transmit the ECG data received from the electrocardiogram measurement device 100 to the central stems 1422, 1424, 1426, 1428, 1430, 1432. The central stems 1422, 1424, 1426, 1428, 1430, 1432 receive the ECG data 1426. The received ECG data is displayed in the central stems 1422, 1424, 1426, 1428, 1430, 1432 of the smartphone display 1320 in a chart shape 1428. After all electrocardiogram measurements are completed, the measured electrocardiogram data is stored in a smartphone storage device in a file format 1430. While the measured ECG data is displayed in a graph on the smartphone display 1320 , the smartphone application waits for the user to end the application by pressing an application exit button 1432 .

[0170] According to the present invention, the user uses the electrocardiogram measuring device 100 without mechanical switches or selection switches, a display, and uses a simplified smartphone application, and the user can get the expected results without any abnormalities in all possible operation sequences.

[0171] As described above, the present invention has been described in detail regarding the case of measuring an electrocardiogram using the single electrocardiogram measurement device 100 and the smartphone application, but the electrocardiogram measurement device 100 according to the present invention is not limited thereto and various measurement items may be additionally measured.

[0172] As described above, the electrocardiogram measuring device 100 according to the present invention may further include a function of measuring blood characteristics. In this case, an embodiment of the electrocardiogram measuring device 1500 having the function of measuring blood characteristics according to the present invention added thereto includes a blood characteristics test strip insertion port 1510 into which a blood characteristics test strip 1520 can be inserted, which may be configured, and one of its shapes may be as follows: Fig.15 shown.

[0173] So far, it has been described that the electrocardiogram measuring device 100 according to the present invention is implemented in a plate shape. However, the electrocardiogram measuring device according to the present invention uses a minimum filter in principle, and the circuit structure is simple, so it can be manufactured in a small size. Therefore, the electrocardiogram measuring device according to the present invention has the characteristic of low power consumption of the battery. Therefore, the electrocardiogram measuring device according to the present invention is suitable for being implemented in the shape of a watch or a ring. In particular, when the electrocardiogram measuring device according to the present invention is implemented as a watch type or a ring, it is suitable for the user to wear it all the time and has the advantage that it can be used in combination with a photoplethysmograph (PPG).

[0174] A photoplethysmograph uses an LED to emit light to the skin and measures the reflected or transmitted light. Recently, a photoplethysmograph built into a smartwatch can provide heart rate, heart rate variability (HRV), and respiratory rate (BR). HRV provides a lot of information about a person's health. HRV is used for sleep analysis or stress analysis, and is also used to detect arrhythmias such as atrial fibrillation. Usually, HRV analysis is performed using an ECG, but recently, it has also been analyzed using a photoplethysmograph. The photoplethysmograph contained in the patient monitoring equipment used in hospitals measures oxygen saturation and issues an alarm when the oxygen saturation is low. Recently, a light quantity signal has been obtained using a camera installed in a smartphone, and the signal can be used to detect the occurrence of arrhythmia symptoms. Therefore, by installing a photoplethysmograph on a watch or ring, the occurrence of arrhythmia symptoms can be conveniently detected. Therefore, when a photoplethysmograph and an electrocardiogram measuring device according to the present invention are mounted together on a watch or a ring, the photoplethysmograph generates an alarm signal when the occurrence of arrhythmia symptoms is detected, and the user who receives the alarm signal uses the electrocardiogram measuring device according to the present invention to measure an electrocardiogram.

[0175] For user convenience and accuracy of ECG measurements, the location of the ECG electrodes is important. Fig.16 A number of examples of implementing the electrocardiogram measuring device according to the present invention in a wristwatch are described.

[0176] In a first example, three ECG electrodes may be mounted on both sides of the strap. Fig.16 In the embodiment, one ECG electrode 111 is mounted on the inner surface of the strap, i.e., the surface of the strap in contact with the wrist, and two electrodes 112, 113 are located on the outer surface of the strap, i.e., the surface of the strap not in contact with the wrist. In this example, when the user wears the watch on the left hand, the electrode 111 contacts the left wrist, the electrode 112 is touched on the left lower abdomen or chest, and the right hand finger is touched on the electrode 113 to measure ECG.

[0177] In a second example, an ECG electrode 1610 can be mounted on the bottom of the watch. In this case, electrode 1610 is always in contact with the wrist of the watch, and in order for the user to measure ECG, electrode 112 is in contact with the left lower abdomen or chest, and electrode 113 is in contact with one finger of the hand without the watch.

[0178] In the third example, another part of the table body, such as 1640, may be used instead. Fig.16 Electrode 113.

[0179] In the case where the electrodes are mounted on a watch or a watchband, in order for the user to conveniently and accurately measure ECG, in all the above cases, if the electrodes are mounted on a watch or a watchband, an electrode 112 is mounted on the outer surface of the watchband on the inner side of the wrist (not on the back of the hand, but on the palm), that is, the watchband does not contact the surface of the wrist. This is to allow the electrode 112 to comfortably contact the user's left lower abdomen or chest area. In addition, in the case where all the above electrodes are mounted on a watch or a watchband, the capacitive volume recorder 1630 mounted on the bottom of the watch can analyze the optical volume signal and generate an alarm to the user.

[0180] Electrocardiogram measuring device according to the present invention can be realized in the shape of a ring. At this moment, the ring is worn on the thumb or little finger to facilitate ECG measurement. Fig.17 This is an example of implementing the electrocardiogram measuring device of the present invention in a ring shape. Fig.17 In the embodiment, one of the three electrodes 111 contacts the finger being worn, and electrodes 112 and 113 do not contact the finger, that is, are located outside the thumb or little finger, and electrodes 112 and 113 are separated from each other. When the ring is worn on the thumb of the left hand, electrode 111 contacts the thumb of the left hand, electrode 112 contacts the left lower abdomen, and electrode 113 can contact the second finger of the right hand. The photoplethysmograph 1730 installed on the surface in contact with the ring and the skin can analyze the light quantity signal and generate an alarm to the user.

[0181] In order to always wear the electrocardiogram measuring device according to the present invention, it can be implemented in a shape that is easy to attach to other objects. Fig.18 and Fig.19 An example of an electrocardiogram measuring device according to the present invention is shown, and when an electrocardiogram is measured by connecting to pants, an electrocardiogram can be measured immediately. Fig.18In the embodiment, two clips 111 and 112 used as two electrodes are used to attach the ECG measuring device 100 according to the present invention to the inside of the pants, that is, between the pants and the user's body. When in use, the ECG measuring device 100 is attached to the position of the left lower abdomen of the pants using the clips 111 and 112, and the electrode 113 and the photoplethysmograph 1830 automatically contact the left lower abdomen of the user. When the photoplethysmograph 1830 sends an alarm or wants to measure ECG, the user touches the fingers of the left hand to the clip 111, and the fingers of the right hand to the clip 112.

[0182] Fig.19 The electrocardiogram measuring device 100 according to the present invention is attached to the outside of the trousers. The ECG measuring device 100 and the clip 113 inside the trousers squeeze the trousers, and the ECG measuring device 100 is fixed to the trousers. When measuring the electrocardiogram, the clip 113 automatically contacts the user's lower left abdomen, and the user touches the left hand finger to the electrode 111, and the right hand finger to the electrode 112.

[0183] Fig. 20 and Fig.21 It is possible to couple the electrocardiogram measuring device according to the present invention to the shape of a watch strap using two or one sliding guide used as electrodes. Fig. 20 In the embodiment, when the watchband is inserted between the electrocardiogram measurement device 100 according to the present invention and the sliding guides 112 and 113 used as electrodes, the electrocardiogram measurement device 100 is fixed to the watchband. When the watch is worn on the left hand, the electrode 111 and the photoplethysmograph 2030 automatically come into contact with the left wrist. When the photoplethysmograph 2030 sends an alarm or wants to measure ECG, the user touches the sliding guide 113 with the left lower abdomen and touches the sliding guide 112 with the fingers of the right hand.

[0184] exist Fig.21 In the embodiment, when the watchband is inserted between the electrocardiogram measurement device 100 according to the present invention and the sliding guide 111, the electrocardiogram measurement device 100 is fixed to the watchband. When the watch is worn on the left hand, the electrode 111 automatically contacts the left wrist. To measure ECG, the user touches the left lower abdomen to the electrode 113 and the fingers of the right hand to the electrode 112.

[0185] As mentioned above, adding Fig.18 and Fig. 20 The electrocardiogram measuring device according to the present invention of the photoplethysmograph 1830 and 2030 has the advantage of always monitoring the heart rhythm of the user. For the sake of convenience, no separate picture is added, but the ECG measuring device according to the present invention can be used by using Fig.18 or Fig.19 The clip shown instead of Fig. 20 and Fig.21The sliding guide shown is connected to the strap of the watch.

[0186] In an embodiment of the electrocardiogram measuring device according to the present invention, the electrocardiogram measuring device 100 is described as including three electrodes, but according to the present invention, other examples of electrocardiogram measuring devices include four electrodes. The operating principle of the electrocardiogram measuring device including the four electrodes according to the present invention is the same as the previous description for the case including three electrodes. It is important that the electrocardiogram measuring device including the four electrodes according to the present invention is composed of three amplifiers that receive electrocardiogram signals from the three electrodes, and the three amplifiers amplify one electrocardiogram signal, so the device actually measures three ECG signals simultaneously.

[0187] The electrocardiogram measuring device including four electrodes can be easily implemented by the foregoing description. The method of using the electrocardiogram measuring device including four electrodes according to the present invention is almost the same as the method of using the electrocardiogram measuring device 100 including three electrodes according to the present invention. The three ECG signals measured by the electrocardiogram measuring device including four electrodes according to the present invention include, for example, two limb Leads and one MCL. Alternatively, the three ECG signals may be one limb Lead and two MCLs. Fig. 22 An embodiment of an electrocardiogram measuring device including the four electrodes according to the present invention is shown. Fig. 22 In the embodiment, four electrodes 111 , 112 , 113 , 114 are arranged two on each of two wide faces of a plate-shaped wide face.

[0188] As described above, the electrocardiogram measuring apparatus according to the present invention has been described in detail, but the present invention is not limited thereto and the present invention can be changed in various shapes according to the purpose of the present invention.

[0189] The embodiments described from now on are based on HWANG (Application No.: KR10-2023-0003099, Filing Date: Jan. 09, 2023) filed with the Korean Intellectual Property Office and HWANG (Provisional Application No.: 63 / 444,228, Filing Date: Feb. 09, 2023) filed with the United States Patent and Trademark Office. In addition, some of the embodiments described below are based on designs registered with the European Patent Office and the United States Patent and Trademark Office. The prior art related to the embodiments described below is as follows.

[0190] Chan et al. (US Patent No.: US 7,894,888 B2, Date of Patent: Feb. 22, 2011, H. Chan, et al.) used three differential amplifiers in a wristwatch electrocardiograph for measuring Lead I, Lead II, and Lead III. Chan et al. used three electrodes for this purpose.

[0191] For a handheld device using four electrodes, Amitai et al. (US Patent No.: US10,092,202B2, Date of Patent: Oct. 9, 2018, D. Amitai, et al.) measured three differential voltages. That is, Amitai used three differential amplifiers. In addition, Amitai used a Wilson Central Terminal.

[0192] The configuration for generating the Wilson center terminal voltage is as follows Figure 3 As shown in B by VAJDIC et al. (US Pub. No.: US2022 / 0125363A1, Pub. Data: Apr. 28, 2022, B. VAJDIC, ​​et al.), in order to generate the Wilson center terminal voltage, three buffer amplifiers and three matching resistors are used to equally receive the three electrocardiogram voltages sensed from the three electrodes contacting the right hand, left hand, and left leg.

[0193] The summary of the above prior art is as follows Fig.23 shown. Fig.23 The conventional technology of the measuring device for acquiring six electrocardiogram Lead signals is shown. The Wilson center terminal is realized by three matching resistors connected to the outputs of three buffer amplifiers. The voltage of the Wilson center terminal is applied to the input terminal of an electrode driver 2340, and the output of the electrode driver 2340 is applied to the right leg electrode (RL: right leg) contacting the right leg. Lead I (Lead I), Lead II (Lead II), Lead III (Lead III) are obtained by three differential amplifiers respectively amplifying the three differential voltages between the right arm (RA: Right Arm), the left arm (LA: Left Arm), the left leg (LL: Left Leg) or the left lower abdomen. For convenience, the left lower abdomen is omitted in the description. From now on, the left leg refers to the left leg or the left lower abdomen.

[0194] Fig.23A representative prior art is shown. However, there is also a conventional technique using two differential amplifiers. Charkravarthi et al. (US Pub. No.: US2021 / 0113108 A1, Pub. Date: Apr. 22, 2021, VS Charkravarthi, et al.) disclosed a device using a small number of probes (i.e., electrodes). Charkravarthi et al. used a Wilson center end and two differential amplifiers. However, Charkravarthi et al. applied the signal of the Wilson center end to the right leg (RL).

[0195] RFA Santala et al. (US Patent No.: US10,405,765B2, Date of Patent: Sep. 10, 2019, RFA Santala, et al.) disclose two differential amplifiers connected to three electrodes contacting the right hand, left hand, and left leg, respectively, and a right leg driver (RLD), whose output is applied to the electrode contacting the right leg. Therefore, Santala et al. used four electrodes, two differential amplifiers, and one electrode driver. The differential voltage is measured by connecting the right arm (RA) electrode to the negative input terminal of each differential amplifier. On the other hand, Santala et al. did not use the Wilson center terminal. Santala et al. receive the input of the right leg driver (RLD) from the right hand (RA) electrode and apply the output of the right leg driver to the right leg (RL) electrode.

[0196] The embodiments described below are based on the previous invention of the present invention (WO2019 / 108044A1, International Publication Date: June 6, 2019, International Application No.: PCT / KR2018 / 015193, International Application Date: December 3, 2018) and can be regarded as further embodiments using further concepts.

[0197] In the present invention, from now on, the above-mentioned previous invention will be referred to as the three-electrode embodiment for ease of description. In the present invention, from now on, the differences from the above-mentioned previous invention will be mainly described. Therefore, matters not described in the present invention described below can be applied to the contents described in the three-electrode embodiment (i.e., the contents described in the previous part of this application). Therefore, the present invention described below includes the above contents.

[0198] The most notable feature of the three-electrode embodiment is the use of at least one single-ended input amplifier to sense the two electrocardiogram lead signals sensed on the first and second electrodes of the three electrodes. In addition, the output of an electrode driver is applied to the third electrode of the three electrodes. This is to reduce the effect of power line interference by connecting the electrode driver output terminal with low output impedance to the third electrode so that almost all the current of the power line interference current source flows through the third electrode.

[0199] After measuring two electrocardiogram Lead signals simultaneously, four additional electrocardiogram Lead signals are calculated and obtained. The additional four electrocardiogram Lead signals can be displayed on a smart phone. From now on, the embodiments described will focus on measuring two electrocardiogram Lead signals simultaneously.

[0200] The features of the above three-electrode embodiment are also applicable to an electrocardiogram measuring device using four electrodes. The device in the following embodiment is an embodiment in which one electrode is added to the device of the three-electrode embodiment. All other required components and methods of use are the same. The device is suitable for being implemented as a wearable device such as a watch, a ring, a patch or a chest strap.

[0201] In order to reduce power line interference in the three-electrode embodiment, the input impedance of the power line interference current source entering the electrocardiograph through the human body must be reduced, so the electrode driver output terminal with low output impedance is connected to one electrode. The four-electrode embodiment described below also has the same common features.

[0202] The goal of the present invention is to achieve a device that complies with the international standard for electrocardiographs [ANSI / AAMI / IEC 60601-2-25:2011, Medical electrical equipment-part 2-25: Particular requirements for the basic safety and essential performance of electrocardiographs]. The goal is to obtain the electrocardiogram voltage defined by the standard, but to achieve a simple and convenient device. The purpose of the present invention is to achieve a wearable device that is small, light and has low power consumption.

[0203] The embodiments described below use four electrodes but contact three parts of the human body. When the device has four electrodes, it can contact four parts of the human body, but for convenience, the wearable device usually contacts the right hand, left hand, and left leg. It is very inconvenient to contact four parts of the human body with one wearable device.

[0204] Furthermore, in all the embodiments described below, one electrode driver is used for negative feedback. The frequency band of the electrode driver used in all the embodiments includes the power line interference frequency and the frequency band of the electrocardiogram signal according to ANSI / AAMI / IEC 60601-2-47:2012, i.e., at least from 0.67 Hz to 40 Hz. If the frequency band of the electrode driver includes 0.67 Hz or lower, ST segment measurement or recording of the electrocardiogram of an infant can be performed. In addition, an additional effect of reducing baseline drift can be obtained.

[0205] Briefly describe the invention: A wearable electrocardiograph using four electrocardiogram electrodes, each electrode contacts one of three body parts. The wearable electrocardiograph includes two electrodes connected to two amplifiers, one electrode connected to an electrode driver input terminal, and one electrode connected to an electrode driver output terminal.

[0206] Compared with the above-described embodiment using three electrodes, the features of the embodiment using four electrodes described below are briefly summarized as follows.

[0207] i) Measure two ECG Lead signals induced on two electrodes.

[0208] ii) Applying the output of one electrode driver to the third electrode.

[0209] iii) Obtain six ECG Lead signals.

[0210] iv) The difference from the three-electrode electrocardiograph is that an additional electrode is added.

[0211] v) Connecting the added electrodes to the input terminals of the electrode driver to better reduce power line interference.

[0212] Compared with the prior art, the advantages and differences of the embodiments described below are as follows.

[0213] i) The present invention includes embodiments that use two single-ended input amplifiers instead of two differential amplifiers. Differential amplifiers used in electrocardiogram measurements in the prior art are as follows: Fig.23 As shown, it is an instrumentation amplifier. An instrumentation amplifier is a differential amplifier with high input impedance and low output impedance. An instrumentation amplifier is usually implemented using three operational amplifiers and four matching resistors. In contrast, the single-ended input amplifier used in the present invention is implemented using one operational amplifier. Therefore, Fig.23 The differential amplifier in is much more complex, larger, more expensive, and consumes more power than the single-ended input amplifier used in the present invention.

[0214] As is known, a single-ended input amplifier used in the present invention is implemented using an operational amplifier. At the same time, when one of the two input terminals of the differential amplifier is connected to the circuit common terminal (i.e., signal ground), the differential amplifier operates as a single-ended input amplifier. Therefore, a single-ended input amplifier in the present invention includes a differential amplifier or an instrument amplifier, in which one input terminal is connected to the circuit common terminal. Connecting one input terminal of the differential amplifier to the circuit common terminal includes connecting the input terminal of the differential amplifier to the circuit common terminal through a high impedance element.

[0215] In addition, it will be described later that the voltage of the electrode connected to the electrode driver input is almost zero, that is, it becomes a virtual ground. Therefore, a differential amplifier whose input terminal is connected to the electrode driver input can be regarded as a single-ended input amplifier. Therefore, in the present invention, a single-ended input amplifier includes a differential amplifier whose input terminal is connected to the electrode driver input. Here, a differential amplifier includes an instrument amplifier.

[0216] In the prior art, using three differential amplifiers to measure the three electrocardiogram Lead signals of Lead I, Lead II and Lead III is a redundant implementation. This is because if two of the three electrocardiogram Lead signals are known, the other one can be calculated. Therefore, using three differential amplifiers is less efficient than using two differential amplifiers. Therefore, using two single-ended input amplifiers in the present invention is more efficient than using three differential amplifiers.

[0217] As will be described later, even when using a differential amplifier, the induced motion artifacts are the same as when using a single-ended input amplifier. This is another reason for using a single-ended input amplifier in the present invention.

[0218] ii) The conventional Wilson center terminal is not used in the present invention. In an embodiment of the present invention, the input signal of the electrode driver is received from one electrode. Alternatively, in other embodiments of the present invention, in order to simplify the conventional Wilson center terminal, a buffer amplifier is not used and only two or three resistors are used to implement it.

[0219] In the prior art, in order to use the Wilson center terminal, in an environment where power line interference is very strong (such as a hospital operating room), the output of the electrode driver is applied to the right leg (RL) to measure the chest Lead as well as the limb Lead. From the perspective of the embodiments of the present invention, the prior art is very inefficient because the embodiments of the present invention place the RL electrode in a different position suitable for a wearable electrocardiograph device. Therefore, the prior art of using the Wilson center terminal and applying the output of the electrode driver to the RL simply adds a practically unnecessary element, although it may have some benefits in the prior art. Therefore, when implementing a wearable electrocardiograph, the prior art is less efficient than the present invention.

[0220] iii) In the present invention, the output of the electrode driver is not applied to the right leg. In the present invention, the output of the electrode driver is applied to one of the body parts of the right hand, left hand or left leg as needed. Not applying the output of the electrode driver to the right leg is an absolute prerequisite for the miniaturization of the wearable device. If the electrode of the wearable device is to contact the right leg, a cable and an electrode connected to one end of the cable must be used. This is very inconvenient in use and unnecessarily increases the size of the wearable device. In this embodiment, the output of the electrode driver can be applied to RA, LA or LL according to the embodiment. This embodiment discloses all possible embodiments of obtaining six electrocardiogram Leads using four electrodes.

[0221] iv) Santala et al. receive inputs to the electrode driver from RA. In this embodiment, the inputs to the electrode driver may be received from LA or LL instead of RA. In this embodiment, the inputs to the electrode driver may be received from one of RA, LA, or LL, depending on the embodiment, and all possible embodiments of acquiring six ECG Leads using four electrodes are disclosed.

[0222] v) Santala et al. connected the inputs of two differential amplifiers to RA while receiving the input of the electrode driver from RA. That is, the input of the electrode driver is connected to the two inputs of the two differential amplifiers. That is, the input of the electrode driver is connected to the two amplifiers. However, in this embodiment, the input and output of the electrode driver are not used to measure the ECG Lead signal. That is, the two electrodes connected to the input and output of the electrode driver are not connected to the input of the amplifier for measurement. Among the four electrodes, only two electrodes that are not connected to the input or output of the electrode driver are connected to the two amplifiers to measure the two ECG Lead signals.

[0223] vi) The present invention is directed to various types of wearable devices, such as plate-shaped, watch-shaped, ring-shaped, patch-shaped, etc. Therefore, in the present invention, the arrangement of the four electrodes is suitable for the structure, manufacturing method, and use method of each wearable device. To this end, an electrode arrangement rule according to the present invention is provided. This is described in more detail below.

[0224] vii) Motion artifacts also need to be considered when placing ECG electrodes. Motion artifacts are noises that occur when the relative position and pressure of one electrode to the skin contacting the electrode changes. Motion artifacts are a particularly troublesome problem in wearable devices because they are difficult to remove once they occur. Compared to hospital electrocardiographs that use wet electrodes to measure ECGs while the user is lying comfortably and resting, dry electrodes in wearable devices that must contact preset body parts in unfixed positions according to the user's wishes are prone to motion artifacts. However, reducing motion artifacts is very important for accurate and comfortable ECG readings.

[0225] The four electrodes mounted on the wearable device are inevitably affected by motion artifacts. Motion artifacts are the main cause of baseline drift. Human body motion may cause baseline drift noise in the electrocardiogram. Baseline drift noise is as easy to occur in wearable devices as motion artifacts. Although it is also difficult to remove baseline drift noise in wearable devices, it is important to reduce baseline drift noise. In the present invention, a rule for reducing motion artifacts is prepared, and an embodiment is disclosed based on the rule.

[0226] So far, the present invention has been described as being implemented using a single-ended input amplifier. In the present invention, the use of a single-ended input amplifier is more advantageous than the use of a differential amplifier in terms of size, price, and power consumption. However, it is possible to implement the present invention using a differential amplifier instead of a single-ended input amplifier. In the present invention, all embodiments using a single-ended input amplifier can be replaced with embodiments using a differential amplifier without additional requirements. Therefore, even if a differential amplifier is not specifically mentioned or described, the present invention also includes embodiments using a differential amplifier.

[0227] The differences between using a differential amplifier and using a single-ended input amplifier in the present invention are further considered below.

[0228] In order to sense a differential voltage, a differential amplifier must be used. In a differential amplifier, two signals are input to the + input terminal and the - input terminal, respectively. That is, two ECG electrodes must be connected to one differential amplifier. Therefore, at least three ECG electrodes must be connected to two differential amplifiers. Therefore, one of the three ECG electrodes is connected to the two input terminals of the two differential amplifiers. Now, the input and output of the electrode driver must be connected to the two electrodes.

[0229] Taking Santala et al. as an example, the inputs of the two differential amplifiers are connected to the RA electrode in common. When the electrode driver is working, the input of the electrode driver becomes a virtual ground. This will be described later in the embodiments of the present invention. That is, when the input of the electrode driver is connected to the RA electrode, the voltage of the RA electrode is almost zero volts. Therefore, the two inputs of the two differential amplifiers connected to the RA electrode in common are actually zero volts. Therefore, the use of differential amplifiers is not much different from the use of single-ended input amplifiers.

[0230] On the other hand, in the above-mentioned embodiment, the case where the input and output of the electrode driver are changed is considered. That is, consider the case where the output of the electrode driver is applied to the right-hand electrode (referred to as DRA to distinguish it from RA) and the input of the electrode driver is received from the other right-hand electrode (referred to as RA). However, in this case, since the power line interference voltage output by the electrode driver is very high, strong power line interference is applied to the DRA electrode connected to the output of the electrode driver and the input terminal of the differential amplifier. That is, the signal-to-noise ratio of the electrocardiogram signal output from the differential amplifier is greatly reduced. Therefore, in this case, if two differential amplifiers are used, instead of obtaining a good electrocardiogram signal with the power line interference removed, a rather poor result will inevitably be obtained. Therefore, the input of the differential amplifier must be connected to the input of the electrode driver, rather than the output of the electrode driver.

[0231] The purpose of the embodiments described below is to simplify and optimize Fig.23 The prior art shown is suitable for wearable devices. From now on, the embodiments of the present invention will be divided into several groups for description. One group has common points, and there are differences between different groups.

[0232] The embodiments from now on will be referred to as embodiment group A. In embodiment group A, the input and output electrodes of the electrode driver contact the same body part.

[0233] In the electrocardiogram measuring device including four electrocardiogram electrodes described below and the electrocardiogram measuring device including three electrocardiogram electrodes described above, the three electrodes usually contact the right hand, the left hand and the left leg. The electrocardiogram measuring device including four electrocardiogram electrodes has one more electrode than the electrocardiogram measuring device including three electrocardiogram electrodes described above.

[0234] An electrode to be added is connected to the input of an electrode driver. Since the present invention pursues a wearable device, the added electrode should also contact one of the right hand, left hand or left leg. Since the four electrocardiogram (ECG) electrodes contact three body parts, two electrodes contact one of the right hand, left hand or left leg. The contact position of the two electrodes is selected according to the application (i.e., the device). That is, the position of the electrode connected to the electrode driver input varies according to the embodiment. The position of the electrode connected to the electrode driver input should be selected as a position with less noise in the ECG signal.

[0235] Assume that three electrodes are installed before adding an additional electrode. Two amplifier inputs and one electrode driver output are connected to three parts of the human body. That is, one device has been connected to each body part. Now an additional electrode must be selected as the electrode driver input. Therefore, it is conceivable that an additional electrode can be installed at any of the three body parts and the electrode driver input is connected to the additional electrode. However, this is not the case. The reason is as follows.

[0236] The electrode arrangement rules start with understanding the following. In the case of the present invention using four electrodes, an electrode driver is an amplifier with a relatively high input impedance. As described later, the input of the electrode driver becomes a virtual ground electrically. That is, the voltage at the input of the electrode driver is close to zero.

[0237] Since the electrode driver input has a high impedance, the voltage of the electrode driver input is the same as the voltage of the body part contacted by the electrode connected to the electrode driver input. That is, the electrocardiogram voltage of the body part contacted by the electrode connected to the electrode driver input becomes zero. Therefore, if another electrode contacts the body part connected to the electrode driver input electrode, and the amplifier input is connected to the electrode contacting the body part, the electrocardiogram voltage input to the amplifier becomes zero. Therefore, an important conclusion is drawn.

[0238] Electrode placement rule 1: Electrodes connected to the ECG measurement amplifier input must not be mounted or placed in the same location as electrodes at the electrode driver input.

[0239] Electrode placement rule 2: Taking into account the above electrode placement rule 1, the electrodes connected to the electrode driver input must be placed on the same body part that contacts the electrodes connected to the electrode driver output.

[0240] Therefore, the input electrode and the output electrode of the electrode driver are installed on the same body part. However, there is no restriction on the installation position of the electrode driver input and output. Therefore, the two electrodes connected to the input and output of the electrode driver can be installed at any position of the right hand, left hand or left leg. That is, there are three methods of installing the two electrodes connected to the input and output of the electrode driver. Therefore, the position of the electrode for sensing the two ECG signals must also be changed. This is a new concept and cannot be inferred from the method of Santala et al.

[0241] An embodiment according to the present invention will now be described with reference to the accompanying drawings. In this embodiment, the electrocardiogram measurement device is described as including four electrodes, but is not limited thereto, and the electrocardiogram measurement device may include five or more electrodes.

[0242] All the figures used in the embodiments of the present invention can show the measurement circuit of the electrocardiogram measurement device according to the present invention implemented as a wearable device. The importance of electrical equivalent circuit modeling cannot be overemphasized. The development of the electrocardiogram measurement device starts with electrical equivalent circuit modeling, and the content to be improved must also be based on this.

[0243] Fig.24 An embodiment of the present invention is shown. Fig.24 In the embodiment of the present invention, two ECG Lead signals, Lead I and Lead III, are sensed by single-ended input amplifiers. The output of the electrode driver 2430 is applied to the electrode DLA. The difference between the present invention and the three-electrode invention is that an electrode is added and the added electrode is connected to the input of the electrode driver. Fig.24 In the embodiment, an LA electrode is added and the LA electrode is connected to the input of the electrode driver 2430.

[0244] It can be seen that Fig.24 The embodiment relative to Fig.23 It is very simple compared with the existing technology. Fig.24 In the following figures, 4990 indicates that when two connecting wires are used to contact two electrodes with the human body to realize the present invention as a Holter type electrocardiograph or an electrocardiograph using a cable, one cable can be bundled for use. This provides convenience and avoids confusion about the cable. At the same time, when the device according to the present invention is realized as a wearable device, it means that it can be placed on a body part. For example, when Fig.24 When the device is implemented as a device included in a watch, two electrodes may be placed at the bottom of the watch in contact with the wrist of the person wearing the watch. As another example, when Fig.24 When the device is implemented as a device included in a ring, the two electrodes can be placed on the inner surface of the ring that contacts the finger wearing the ring. Fig.24 The embodiments are suitable for implementation as a single watch or ring.

[0245] Fig.25 Shown for analysis Fig.24 The electrical equivalent circuit of the electrical operation of the embodiment. Fig.25In the figure, for convenience, the RA electrode is shown above the figure and the LL electrode is shown below the figure. The power line interference is caused by the power line interference current source 2530. The power line interference current source 2530 applies the power line interference current to the electrocardiogram measuring device 2400 according to the present invention through the user's body 2500. The device 2400 according to the present invention includes four electrodes RA, LA, DLA and LL. The voltage of each electrode is represented by v1, v4, v3 and v2 respectively. Two single-ended input amplifiers 2410 and 2420 are connected to two ECG sensing electrodes RA and LL respectively. The input of an electrode driver 2430 is connected to the electrode LA, and the output is connected to the electrode DLA. The transfer function of the electrode driver 2430 is represented by -H(f), and the amplitude of the transfer function is quite large in the power line interference frequency and the ECG Lead signal frequency band.

[0246] The input impedance of two amplifiers and one electrode driver is represented by Rin. Four electrodes are in contact with the human body 2500, and there is an electrode impedance Rel between the skin and the electrode. Usually Rin is large, that is, Rin>>Rel. The impedance value of each electrode may be different. The difference between the electrode impedance 2541 and the electrode impedance 2542 is represented by ΔR. Generally speaking, since the output impedance of the electrode driver is much smaller than the electrode impedance Rel, it is considered to be zero in many cases. The electrocardiogram voltage of electrode LA relative to electrode RA is represented by va, that is, va is Lead I. The electrocardiogram voltage of electrode LL relative to electrode LA is represented by vb, that is, vb is LeadIII.

[0247] The analysis of the electrical equivalent circuit yields the following results. The voltage vbody induced by the power line interference current source 2530 on the human body becomes very small due to the influence of the electrode driver 2430. vbody = in*Rel / (H(f)+1) In the present invention, substantially all of the power line interference current flows through an electrode connected to the output of the electrode driver. This is the same as the above three-electrode embodiment. Fig.25 In the embodiment, substantially all the power line interference current flows through one electrode DLA. Due to the influence of the electrode driver 2430, v4 becomes very small. In fact, v4 is zero volts. That is, v4 is a virtual ground. It should be noted here that the virtual ground is for AC signals, and v4 may contain a DC voltage component. A constant voltage source that supplies a constant DC voltage is considered to be grounded in an AC circuit.

[0248] Therefore, v1 = -va = -Lead I. In addition, v2 = vb = Lead III. That is, the power line interference is eliminated, and two ECG Lead signals, Lead I and Lead III, are measured. In one embodiment of the present invention, -Lead I is an inverted Lead I. In a wearable measurement device using one battery, the analog signal is referenced to a common AC signal ground provided at approximately the middle value of the battery. The signal referenced to the AC signal ground is AD converted to the approximate middle value of the AD conversion range. Negative signals only vary up and down with a reference to the middle of the AD conversion range. Therefore, the negative value of -Lead detected or measured is not important.

[0249] This is the main difference between an electrocardiogram measuring device that uses a common ground in an electronic circuit of positive and negative power supplies and performs AD conversion based on a circuit common end, i.e., zero DC voltage, and a wearable electrocardiogram measuring device that uses a single battery. This difference is obvious. Due to this difference, various embodiments of the present invention are possible. In this embodiment, an inverted signal, such as -Lead I instead of Lead I, can be measured, so that various embodiments can be easily implemented.

[0250] Fig.26 Another embodiment of the present invention is shown. The input and output of the electrode driver 2630 are connected to the left leg. The signal sensed by the right hand electrode RA is -Lead II. The signal sensed by the left electrode LA is -Lead III. Fig.26 The embodiment is conducive to achieving Fig.18 The electrocardiogram device shown is fixed to the trousers by two clips. When wearing the electrocardiogram measuring device fixed to the trousers by two clips, even if the electrocardiogram is not measured, the two electrodes LL and the electrode DLL are kept in contact with the left lower abdomen. When measuring the electrocardiogram, the two hands are Fig.18 The two clips 111 and 112 are in contact.

[0251] The ones described so far include Fig.24 and Fig.26 The embodiments of the embodiment group A will be referred to as embodiment group A. There are three embodiments in embodiment group A, which are summarized in Fig. 27 In Table 1 of Example Group A, two electrocardiogram measurement electrodes are respectively arranged at two body parts that are not contacted by the input electrode and the output electrode of the electrode driver. The embodiments described below will be referred to as Example Group B. In the embodiments of Example Group B, the input electrode and the output electrode of the electrode driver are installed to contact different body parts. Example Group B is feasible because of the following electrode placement rule 3.

[0252] Electrode placement rule 3: The electrodes connected to the output of the electrode driver can be placed anywhere on the three parts of the human body.

[0253] Thus, the electrode driver output electrode can be placed on a body part in contact with another electrode connected to an electrocardiogram measuring amplifier. Surprisingly, this is possible. Fig.28 An example of this is shown in . This is a new concept that is difficult to infer from the method of Santala et al. Before actually implementing electrode placement rule 3, the following electrode placement rule 4 can be used.

[0254] Electrode placement rule 4: Assign the electrode driver input electrode to the third body part where the two ECG measurement electrodes are not installed. The electrode driver output electrode can now be freely assigned to the desired position among the three body parts.

[0255] Electrode placement rules 3 and 4 can be expressed as follows. Three electrodes are arranged on the right hand, left hand, and left leg, respectively, and the inputs of three amplifiers are connected to the three electrodes. One of the three amplifiers is set as an electrode driver. The output of the electrode driver is connected to the fourth electrode, and the fourth electrode is assigned to the same human body part where one of the three electrodes has been placed.

[0256] Using the above electrode placement rules, we get the following results. In the final stage of electrode placement, the following electrode placement rules5 need to be checked.

[0257] Electrode placement rule 5: Install another electrode on the body part where an electrode driver output electrode is installed. That is, the two electrodes are installed on the same body part. This can be expressed as when two electrodes are in contact with a body part, one of the two electrodes must be the electrode driver output electrode.

[0258] Fig.28 One embodiment of the present invention is shown. Fig.28 The device in the embodiment senses the ECG signals sensed by the right hand and the left hand. Fig.28 In the embodiment of the present invention, the ECG signals measured at the right hand and the left hand are Fig.26 The electrode driver 2830 receives the input signal from the left leg and applies the output signal of the electrode driver 2830 to the left hand. Then the ECG signal sensed from the right hand is -Lead II. The ECG signal sensed from the left hand is -Lead III. In the embodiment of the present invention, Fig.28 It can be seen from the embodiments that the input electrode and the output electrode of an electrode driver can be connected to different parts of the human body respectively. Fig.28 An embodiment of the invention is characterized by two electrodes in contact with the left hand.

[0259] Compared with the embodiment group C or the embodiment group D using the additional matching resistor, Fig.28The embodiment has advantages in manufacturing. The electrical equivalent circuit model analysis is omitted. So far, it has been found that the contact positions of the electrodes connected to the input and output of the electrode driver can have various changes. As can be seen from the above figure, the position of the electrode used in this embodiment is limited to the right hand, left hand, left leg or left lower abdomen or chest. Apart from this, there is no restriction on the position of the electrode. Therefore, the number of embodiments is six in total, as shown in detail. Fig.29 As shown in Table 2 in FIG. Although these six embodiments may differ in mechanical form, they all have in common that they all acquire two ECG Lead signals. Fig.29 In the embodiment and the position of the electrodes, each electrode has a different impedance Rel and motion artifacts, which will be further described later. In order to simply call the electrodes connected to the input and output ends of the electrode driver respectively, they can be referred to as electrode driver input electrodes and electrode driver output electrodes.

[0260] Reviewing the embodiments of embodiment group B, the following advantages are provided.

[0261] i) It can be decided where on the body the two electrodes are to be placed.

[0262] ii) It can be decided which embodiment to choose to reduce motion artifacts, as described below.

[0263] iii) It can be reviewed what possible embodiments exist.

[0264] In embodiment group B, one electrocardiogram measuring electrode is located at the same position as the electrode driver output electrode, and the other electrocardiogram measuring electrode is located at a position where the electrode driver input and output electrodes are not placed.

[0265] So far, the present invention has been implemented using a single-ended input amplifier. However, as previously described, the present invention includes the use of a differential amplifier instead of a single-ended input amplifier. As described above, it is not necessary to use a differential amplifier in the present invention. Using a single-ended input amplifier is more advantageous than using a differential amplifier in terms of size, cost, and power consumption.

[0266] However, the present invention can be implemented using a differential amplifier instead of a single-ended input amplifier. In the present invention, all embodiments using a single-ended input amplifier can be replaced intactly with embodiments using a differential amplifier. Therefore, even if a differential amplifier is not specifically mentioned or described, the present invention also includes embodiments using a differential amplifier. For embodiment group B, a differential amplifier can be used instead of a single-ended input amplifier. The method of using the differential amplifier in the present invention will be described later.

[0267] The examples from now on belong to example group C. In example C, a voltage divider is configured using two matched resistors, and an input signal of the electrode driver can be received at the intersection of the voltage divider. Fig.30 An embodiment belonging to embodiment group C of the present invention is shown. Fig.30 In an embodiment of the present invention, two matched resistors are placed between the right-hand electrode and the left-hand electrode. The two resistors act as a voltage divider. The junction of the two resistors is connected to the input of the electrode driver. Fig.30 This is the case where the output of the electrode driver is applied to the left hand. In another embodiment, a voltage divider may be formed between two electrodes contacting different body parts.

[0268] Fig.31 Shown for analysis Fig.30 The electrical equivalent circuit model of the operation of the embodiment of the present invention is shown in FIG. - Lead I / 2 is sensed from the right hand electrode. Lead I / 2+Lead III=aVF is sensed from the left leg electrode. Lead I and Lead III are calculated based on the two sensed Lead signals. The calculation can be performed after the two sensed Lead signals are AD converted. Detailed description is omitted.

[0269] Fig.30 The embodiment has the advantage of being able to directly measure aVF without calculation. In the embodiment group C of the practical example, a differential amplifier can be used to replace a single-ended input amplifier in the three-electrode embodiment. For example, in Fig.31 In the embodiment of the present invention, a single differential amplifier receiving inputs from RA and LA can be used to replace the single-ended input amplifier 3010. Embodiment Group C has nine embodiments, such as Fig.32 As shown in Table 3. Detailed description is omitted.

[0270] The embodiment hereinafter will be referred to as embodiment group D. The resistors used in embodiment groups C and D have a high resistance value of at least 10 MOhm or more. Compared with the past, commercially available small chip resistors or thin film resistors of 10 MOhm or more are now easily available. Fig.23 The matching resistor used in the prior art can generally use a resistor of the order of 10 kOhm.

[0271] Fig.33 Another embodiment of the present invention is shown which uses three matching resistors to obtain the Wilson center terminal voltage. Fig.33 The embodiment achieves Fig.23 The Wilson center terminal shown in the prior art is a simpler Wilson center terminal. Fig.33In the embodiment of , the obtained Wilson center terminal voltage is applied to the LA electrode of the left hand. In this case, -2 / 3*Lead I–1 / 3*Lead III is detected in the right amplifier 3310. 1 / 3*Lead I+2 / 3*Lead III is detected on the left leg amplifier. Lead I and Lead III are calculated based on the two sensed values.

[0272] exist Fig.33 In the embodiment, the output electrode of the electrode driver can contact any position of the right hand, left hand or left leg. Therefore, embodiment group D has three embodiments, such as Fig.34 As shown in Table 4. In the embodiment of digitally implementing the Wilson center terminal, the use of three matching resistors can be avoided. Instead of using three resistors, two ECG voltages measured at two electrodes are used to obtain an additional ECG voltage, and then the Wilson center terminal voltage can be obtained by calculation.

[0273] The embodiments hereinafter will be referred to as embodiment group E. In embodiment group E, among the various embodiments described above, a superior embodiment for reducing motion artifacts is described. As described above, for the convenience of the user and the accuracy of electrocardiogram measurement, the position and shape of the electrocardiogram electrodes installed in the electrocardiogram measurement device are important.

[0274] In the embodiment using four electrodes, an additional ECG electrode connected to the electrode driver input is added compared to the above embodiment using three electrodes. From now on, in the various embodiments described above, the preferred embodiment is selected to reduce motion artifacts. However, the following embodiments can be modified according to the purpose and method of use. Therefore, it is also within the scope of the present invention to change the embodiment groups A to D to embodiments similar to the following embodiments.

[0275] Among the further considerations when arranging ECG electrodes, motion artifacts can be considered. Motion artifacts are noise generated when the relative position and pressure of an electrode to the skin in contact with the electrode changes. As we all know, motion artifacts are a particularly troublesome problem in wearable devices because they are difficult to eliminate once they appear (H. Halvaei, L. Sornmo, and M. Stridh, Signal quality assessment of a novel ECG electrode for motion artifact reduction, Sensors, 2021, 21, 5548.).

[0276] Hospital-grade electrocardiographs are used to measure ECG by attaching and fixing wet electrodes to your skin while you lie down comfortably and rest. Wearable electrocardiographs, on the other hand, must use dry electrodes that contact preset body parts in an unfixed, moving posture. Therefore, motion artifact noise is more likely to occur in wearable devices. Reducing motion artifacts is very important for accurate and comfortable ECG readings. However, the four electrodes installed in wearable devices are inevitably affected by motion artifacts.

[0277] Motion artifacts are an important cause of baseline drift (L. Zhong, Pub. No.: US2014 / 0023134A1, Pub. Date: Jan. 23, 2014). Baseline drift in electrocardiograms may be caused by human motion. The probability of baseline drift noise on wearable devices is as high as that of motion artifacts. Baseline drift noise in wearable devices is also difficult to eliminate, so it is very important to reduce baseline drift noise.

[0278] The motion artifacts are analyzed in order to develop a criterion for determining which of the various embodiments described thus far is advantageous for a wearable device. Fig.35 is to insert the motion artifact voltage source into Fig.25 The electrical equivalent circuit model of the electrical equivalent circuit model of the . Each independent motion artifact voltage source is connected to an electrode. The motion artifact voltage source is connected in series with the electrode resistance or electrode impedance. Generally speaking, the higher the electrode resistance, the stronger the motion artifact. Analysis Fig.35 , and the following results are obtained. For convenience, power line interference is omitted.

[0279] v1=-va+vm1-vm4…………………………………………(Formula 21)

[0280] v2=vb+vm2-vm4…………………………………………(Formula 22)

[0281] Of course, each motion artifact is applied to each electrode. Thus, VM1 is applied to V1 and VM2 is applied to V2. However, it should be noted that -VM4 generated from the input electrode of the electrode driver is applied jointly to both measured ECG voltages V1 and V2.

[0282] These results occur because the voltage at the electrode driver input electrode is effectively zero even if there is motion artifact or baseline drift. That is, this is because the electrode driver input electrode becomes a virtual ground. This result means that motion artifacts generated from the electrode driver input electrode are sensed to the ECG measurement electrode.

[0283] The above results are important. In particular, considering that the electrode driver input electrode is a virtual ground, it is very surprising that the motion artifacts generated from the virtual ground electrode are transferred to all measurement electrodes. The above expression means the following. The following will be referred to as the considerations or rules regarding motion artifacts.

[0284] i) Motion artifacts generated from the electrode driver input electrodes are transmitted to all ECG measurement electrodes. When four electrodes are used, it propagates to two measurement amplifiers, and when additional chest electrodes are used, it propagates to the chest electrodes as well. Therefore, it is very important to reduce motion artifacts generated from the electrode driver input electrodes. It is a natural and well-known fact that the electrodes measuring the ECG Lead should be installed at locations where motion artifacts or baseline fluctuations are less likely to occur. However, it is even more necessary to consider installing not only the ECG Lead measurement electrodes but also the input electrodes of the electrode driver at locations where motion artifacts or baseline fluctuations are weak.

[0285] ii) Another surprising result is that VM3 does not co-occur in V1 and V2. Motion artifacts generated from the electrode driver output electrodes do not propagate to any ECG measurement electrodes. Therefore, it can be concluded that it is advantageous to place the electrode driver output electrodes in locations where motion artifacts are expected to be higher or stronger.

[0286] iii) From i) above, it can be seen that two motion artifacts are applied to an ECG Lead signal amplifier. The first motion artifact is generated from the electrode connected to measure the ECG signal. The second motion artifact is generated at the electrode to which the electrode drive input is connected. This is a very important consideration that must be taken into account in implementing embodiments of the present invention.

[0287] iv) According to the present invention, after measuring and obtaining two ECG Lead signals, four ECG Lead signals are calculated and obtained. The motion artifacts contained in the two ECG Lead signals are also mixed with the calculated four ECG Lead signals. Therefore, it is very important to measure the two ECG Lead signals so that the motion artifacts do not occur.

[0288] v) As described many times before, the embodiments of the present invention use a single-ended input amplifier. As a reference, the case of using a differential amplifier will be analyzed. Fig.37 When the voltage between the electrode RA and the electrode LA is amplified using a differential amplifier, the following results are obtained.

[0289] V(RA)-V(LA)=-va+vm1-vm4=v1………………………………(Formula 23)

[0290] In other words, even if a differential amplifier is used, the result of motion artifacts is the same as when a single-ended input amplifier is used. Therefore, a single-ended input amplifier is also required in the present invention.

[0291] This provides us with an important consideration or rule about how to deal with motion artifacts. When installing ECG electrodes, it is important to consider which function to assign to each ECG electrode. In each of the above-mentioned embodiment groups A to D, it is very important to carefully consider the electrode arrangement that is favorable to motion artifacts and baseline fluctuations, and select the embodiment accordingly. That is, in order to achieve an electrocardiogram measurement device with less noise, in addition to the above-mentioned considerations about the electrode arrangement of the electrode driver, the above-mentioned considerations about motion artifacts must also be applied.

[0292] In order to realize a low-noise ECG measuring device, the shape and installation position of each ECG electrode should be considered. In addition, which component is to be connected to each ECG electrode should also be considered. To this end, a shape suitable for a wearable device should be designed. In the present invention described so far, when the human body part contacted by the electrode driver input electrode is determined, the electrode for ECG measurement will be automatically assigned to the remaining two human body parts. Therefore, it is convenient to give priority to the electrode driver input electrode in the electrode allocation. From now on, when introducing preferred embodiments of specific shapes (such as rings, watches, clip shapes, etc.) in sequence, the electrode driver input electrode will be given priority.

[0293] Use the above Fig.24 etc., it has been described that an electrocardiogram measuring device having four electrodes can be implemented in the form of a ring worn on one finger. A preferred first embodiment for reducing motion artifacts in an electrocardiogram having four electrodes contained in a ring will now be described. In the first embodiment, two electrodes can be placed on the inner surface of the ring. The skin of the finger in contact with the inner surface of the ring is soft, the electrode resistance is low, and it contains moisture. Therefore, the electrode in contact with the skin generates less motion artifacts. Electrodes that generate less motion artifacts should be selected as electrode driver input electrodes.

[0294] The two electrodes mounted on the inner surface of the ring are respectively set as the electrode driver input electrode and output electrode. This corresponds to Fig.24 In order to reduce motion artifacts, the two electrodes mounted on the inner surface of the ring need to be Fig.17 The electrodes 111 and 114 shown in FIG.

[0295] The remaining two electrodes are connected to two amplifiers for ECG measurement. The remaining two electrodes are mounted on the outer surface of the ring, touching the fingers of the other hand and the left leg respectively. Fig.17 The electrodes 112 and 113 mounted on the outer surface are wider, which is also helpful in reducing motion artifacts.

[0296] In addition to the above-described embodiments, an embodiment in which two electrodes are mounted on the inner surface of the ring and each electrode is used as an output of an electrode driver and an electrocardiogram sensing electrode may be adopted. In this case, the two electrodes mounted on the upper and lower surfaces of the ring are used as input electrodes of the electrode driver and another sensing electrode for ECG signals. These correspond to Embodiment B3 and Embodiment B4, respectively. In the case of the ring, these embodiments are generally considered not to be superior to Embodiment A2 described above from the perspective of motion artifacts. However, these embodiments may be implemented depending on the design of the ring.

[0297] On the other hand, it is necessary to install a photoplethysmograph and an electrocardiograph in the ring. As mentioned above, the photoplethysmograph can alert the user when arrhythmia occurs by analyzing the photoplethysmograph signal. The photoplethysmograph should be installed on the inner surface of the ring to contact the finger. Therefore, there may not be enough space on the inner surface of the ring to install two ECG electrodes. In addition, installing an electrode with a larger area on the inner surface of the ring and using this electrode as the input electrode of the electrode driver is beneficial to reduce motion artifacts.

[0298] In this case, three electrodes may be placed on the outer surface of the ring. Fig.36 The electrical connections are shown for an embodiment where three electrodes are placed on the outer surface of the ring. Fig.36 A second preferred embodiment for the ring is shown. For the embodiment, when Fig.36 When the embodiment is implemented as a ring, the electrode driver input electrode LA can be set on the inner surface of the ring worn on the left hand finger, and three electrodes can be set on the outer surface of the ring.

[0299] Fig.37 yes Fig.36 The electrical equivalent circuit model of the embodiment of FIG. Analyzing the model, the following results can be obtained. For convenience, the power line interference is omitted.

[0300] v1=-va+vm1-vm4…………………………………………(Formula 24)

[0301] v2=vb+vm2-vm4…………………………………………(Formula 25)

[0302] The above formula and Fig.35 against Fig.24 The analysis results are the same. This is because the positions of the electrode driver input electrodes are the same. In this embodiment, since the area of ​​the electrode driver input electrodes is increased, the motion artifact of the electrode driver input electrodes of the ECG voltage v1 and the ECG voltage v2 applied to the right hand electrode and the left leg electrode can be reduced -vm4.

[0303] In the above embodiment, when the ring is worn on the fingers of the left hand, the fingers of the right hand contact the two electrodes RA and DRA, and one electrode LL contacts the left leg. Fig.38 Two electrodes are mounted on the upper surface of the ring as shown. -

[0304] In the present invention, four electrodes are in contact with three human body parts. If the user wears a ring or a watch on the left hand, the user places the left hand on the left leg when taking an electrocardiogram. Therefore, in this case, the most unstable part of the three body parts is the right hand. Therefore, if the right hand can be stabilized, the motion artifacts generated by the right hand can be reduced. Fig.38 In the case of the electrocardiograph included in the ring, if the right hand is placed on the left hand or left leg and one right finger is placed on the two electrodes 3810 and 3820, the right hand can be stabilized and motion artifacts can be reduced.

[0305] at the same time, Fig.39 Another embodiment is shown in which one electrode is mounted on the inner surface of the ring. In this embodiment, the ring is implemented so that the fingers of the right hand contact one electrode 3910 (RA electrode) and the left leg contacts two electrodes 3920 and 3930 (LL electrode and DLL electrode). In this embodiment, the electrodes 3940 and 3950 in the ring are connected as one and are designated as electrode driver input electrodes. When measuring an electrocardiogram, the two electrodes 3920 and 3930 are also conducive to stably contacting the left leg. In addition, the area of ​​the right hand electrode 3910 can be increased. Therefore, this embodiment is conducive to reducing motion artifacts. In this case, the lower part of the ring can be made thicker, wider, and more mechanically strong than a traditional ring.

[0306] The above-described preferred embodiments for reducing motion artifacts in an electrocardiogram contained in a ring have in common that the electrode driver input electrodes are mounted on the inner surface of the ring.

[0307] So far, the present invention has been described as being implemented using a single-ended input amplifier. However, as previously mentioned, the present invention relates to using a differential amplifier instead of a single-ended input amplifier. As described above, it is not necessary to use a differential amplifier in the present invention. In terms of size, cost, and power consumption, it is more advantageous to use a single-ended input amplifier than to use a differential amplifier. However, the present invention may be implemented using a differential amplifier instead of a single-ended input amplifier. In the present invention, all embodiments using a single-ended input amplifier may be replaced as is with embodiments using a differential amplifier. Therefore, even if a differential amplifier is not specifically mentioned or described, the present invention also includes embodiments using a differential amplifier.

[0308] The method of using the differential amplifier of the present invention is as follows.

[0309] i) Two differential amplifiers are used in the present invention to replace two single-ended input amplifiers.

[0310] ii) One of the two input terminals of the differential amplifier is connected to the input terminal of the single-ended input amplifier, and the other is connected to the input terminal of the electrode driver. Since two single-ended input amplifiers are used in the present invention, the connection method of the two differential amplifiers is determined. The polarity of the input terminal of the differential amplifier is not important. This is because the measured value can be processed according to the polarity of the measured value.

[0311] iii) The present invention uses one electrode driver and does not use a Wilson center terminal. Even if a differential amplifier is used, matters related to the electrode driver are the same as when a single-ended input amplifier is used. The input of the electrode driver is connected to one electrode.

[0312] iv) The output of the electrode driver is connected to an electrode.

[0313] v) Since the present invention is directed to a wearable device and six limb leads are obtained, four electrodes contacting three body parts are used. These statements do not change when a differential amplifier is used instead of a single-ended input amplifier.

[0314] Therefore, in the case of using differential amplifiers in the present embodiment, the two differential amplifiers have one input terminal in common, which is connected to the electrode mounted on the inner surface of the ring.

[0315] Circuit analysis shows that even with a differential amplifier, the motion artifacts are the same as when a single-ended input amplifier is used. This is another reason for using a single-ended input amplifier in the present invention.

[0316] In the previous three electrode embodiment, it was described that depending on the situation or need, it may be necessary to measure only Lead I. Fig.24 and Fig.38 In the embodiment of the present invention, only Lead I can be measured without contacting the left leg electrode. Fig.24 and Fig.38 In the embodiment of the present invention, power line interference can be reduced without contacting the left leg electrode. When only Lead I is to be measured, Fig.26 and Fig.39 Unless the left leg electrode is in contact with the left leg, Fig.26 and Fig.39 There is no way to reduce power line interference.

[0317] The photoplethysmograph installed on the inner surface of the ring in contact with the finger analyzes the photoplethysmograph signal and issues an alarm command when it is determined that there is an abnormality. The ring can send the command signal for issuing the alarm to a smart device or smartphone wirelessly connected to the ring.

[0318] Now, an embodiment in which four electrocardiogram electrodes are installed on the watch body and the watch band will be described. In this case, there are three preferred embodiments.

[0319] The first preferred embodiment is as follows. The optimal mounting position of the electrode driver input electrode is the bottom surface of the watch body. This is because the bottom surface of the watch is always in contact with the user's wrist and provides the widest space for placing the ECG electrode. In addition, since the skin on the wrist that the bottom of the watch contacts is soft and moist, there are fewer motion artifacts. Therefore, in Fig.16 In the embodiment, the two electrodes of electrode 1610 and electrode 1620 installed at the bottom of the meter body are respectively designated as the input electrode and the output electrode of the electrode driver. This corresponds to Fig.24 The electrical connections of embodiment A2 shown in . This embodiment is very similar to the first preferred embodiment of the ring described above.

[0320] The remaining two electrodes are connected to two amplifiers for ECG measurement. Fig.16 One of the electrodes 1640 is mounted on the watch body and contacts a finger of the other hand. Fig.16 Another electrode 112 is mounted on the outer surface of the strap and contacts the left leg.

[0321] Consider another embodiment in which two electrodes are mounted on the bottom of the watch body. Fig.16 The electrode 1640 in the watch is selected as the electrode driver input, and the electrode 1610 or 1620 installed on the bottom of the watch is selected as the electrode driver input. However, in this embodiment, due to the unstable right-hand contact Fig.16 The small electrode 1640 has relatively large motion artifacts. Therefore, this embodiment is not a good embodiment.

[0322] On the other hand, in the first embodiment which is preferred when realizing the electrocardiograph included in the above-mentioned wristwatch, the right hand electrode (RA) having the smallest electrode size and in contact with the right hand which is an unstable part of the body is used as the ECG measurement electrode. Therefore, motion artifacts may occur in the RA electrode of this embodiment. Therefore, in this embodiment, we design a method of stabilizing the watch worn on one hand with one hand to reduce motion artifacts.

[0323] use Fig.16An embodiment of stabilizing a watch worn on one hand with the other hand to reduce motion artifacts is described. The watch is stabilized by holding one side of the watchband and electrode 113 simultaneously with the thumb and finger of the other hand. Electrode 113 is connected to the electrode driver input. Electrode 1610 at the bottom of the watch body is connected to the electrode driver output. When the watch is worn on the left hand, another electrode 1620 at the bottom of the watch body is connected to an electrocardiogram measuring amplifier to measure Lead I. The electrocardiogram measured by electrode 1620 at the bottom of the watch body has the advantage of being less affected by motion artifacts. Electrode 112 mounted on the outer surface of the watchband contacts the left leg. This corresponds to embodiment B3. This embodiment is one of the preferred embodiments of installing an electrocardiograph included in a watch. In this embodiment, an additional electrode facing electrode 113 can be installed opposite to the watchband on which electrode 113 is installed. The above-mentioned electrodes and electrode 113 can be held with the other hand.

[0324] The above two embodiments can be expressed as follows: the input of the electrode driver is connected to an electrode mounted on the bottom of the watch body or the outer surface of the watch band, and another electrode mounted on the watch band is in contact with the left leg of the electrocardiogram measuring device.

[0325] Another watch structure suitable for reducing the motion artifacts produced by the right-hand electrode is as follows Fig.40 shown. Fig.40 The embodiment is a third preferred embodiment of the electrocardiograph installed in a wristwatch. Fig.40 When the watch is worn on the left hand, if the two electrodes 4010 and 4020 are respectively held with the thumb and index finger of the right hand, the watch is fixed on the right hand, thereby reducing motion artifacts.

[0326] The two electrodes 4010 and 4020 held by the thumb and index finger of the right hand are respectively designated as electrode drive output electrodes and electrocardiogram measurement electrodes. Fig.36 The embodiment of is electrically corresponding to that of embodiment B1. In this embodiment, since the electrode driving input electrode is installed at the bottom of the meter body, less motion artifacts are generated. This embodiment may be preferred.

[0327] In this embodiment, the Fig.40 The electrode 4030 is in contact with the left hand wearing the watch, and the electrode 4050 installed on the outer surface 4080 of the watchband is in contact with the left leg. In order to reduce motion artifacts, this embodiment meets the electrode use rule of using the right hand electrode (DRA) with the smallest size and the most unstable body part in contact with the electrode as the electrode drive output.

[0328] Other embodiments may be applicable to Fig.40The two electrodes 4010 and 4020 held by the thumb and index finger of the right hand are electrically connected and assigned to the electrode drive input. Of the two electrodes at the bottom of the watch body, one is assigned to the electrode drive output electrode and the other is assigned to the ECG measurement electrode. The electrode mounted on the outer surface of the watch band becomes the ECG measurement electrode in contact with the left leg. Lead I and Lead II are then measured at each ECG Lead measurement electrode. This embodiment is also a good embodiment for motion artifacts.

[0329] use Fig.40 Two embodiments of the watch can be expressed as follows. An electrocardiogram measuring device, wherein an input electrode of an electrode driver is assigned to at least one of two electrodes mounted on a watch body so that the watch can be stabilized with the other hand not wearing the watch, and the other electrode mounted on the outer surface of the watch band contacts the left leg.

[0330] Therefore, the superiority of the embodiments can be judged by motion artifact analysis. Embodiments A2 and B1 of the electrocardiograph for use in a watch are preferred embodiments for reducing motion artifacts, and they have in common that the electrode driver input electrodes are mounted at the bottom of the watch body.

[0331] The following thoughts above regarding an electrocardiograph included in a ring also apply to an electrocardiograph included in a watch. It has been described above that it may be necessary, depending on the circumstances or necessity, to measure only Lead I. Fig.24 Embodiments A2, B3 and Fig.36 Embodiment B1 in the embodiment is advantageous when only Lead I is measured without contacting the left leg. In the above three embodiments, A2, B3 and B1 can reduce power line interference without contacting the left leg. For reference, Fig.26 and Fig.28 The embodiment of is disadvantageous when only Lead I is measured. Fig.26 and Fig.28 In the embodiment, power line interference cannot be reduced unless the left leg electrode is in contact with the left leg.

[0332] A photoplethysmogram device mounted on the bottom of the watch can analyze the photoplethysmogram signals and issue alerts to the user.

[0333] As above combined Fig.18 and Fig.26As described, the electrocardiogram measuring device can be implemented by coupling with the pants so that the electrocardiogram can be measured immediately when the electrocardiogram needs to be measured. Using two clips as two electrodes, the electrocardiogram measuring device is fixed inside the pants, that is, between the pants and the left lower abdomen of the user. When the electrocardiogram measuring device is fixed to the left lower abdomen of the pants using the two clips, the two electrodes and the photoplethysmograph automatically contact the left lower abdomen of the user. When the photoplethysmograph sounds an alarm or the user wants to measure the electrocardiogram, the user touches the first clip with the fingers of the left hand and touches the second clip with the fingers of the right hand.

[0334] The electrocardiogram measuring device corresponds to embodiment A3, wherein two electrodes are in contact with the left lower abdomen. Since the two electrodes in contact with the left lower abdomen are in contact with soft and moist skin, it is suitable to designate one of the electrodes as an electrode drive input electrode; since the two electrodes are adjacent and in contact with the same body part, the other electrode is designated as an electrode drive output electrode.

[0335] Figure 1 The electrocardiogram measuring device shown is in the shape of a flat plate, and its length is greater than its width. Any one of the three electrodes installed in the electrocardiogram measuring device can be divided into two, so that the device has four electrodes. That is, one of the three electrodes can be made smaller and an electrode can be added nearby. Figure 1 The electrode 113 in is preferably divided into two electrodes and the two electrodes are contacted with the left leg or the left lower abdomen to reduce motion artifacts.

[0336] Nanoelectrodes can be used to reduce motion artifacts. Nanoelectrodes have low electrode impedance and are made of materials other than conventional metals (S. Yao, and Y. Zhu, Nanomaterial-Enabled Electrodes for Electrophysiological Sensing: A Review, The Journal of The Minerals, Metals & Materials Society, Vol. 68, pp. 1145-1155, 2016)

[0337] In order to reduce the electrical contact resistance of the nanoelectrode, prevent it from breaking, and enhance the mechanical strength, the nanoelectrode can be used in combination with a metal electrode. In this embodiment, the nanoelectrode is well combined with the metal electrode, and the two are bonded together using a bonding material with low resistance.

[0338] Digital signal processing can be used in all embodiments of the present invention. That is, after the voltage amplified by the amplifier is converted into a digital signal, the microcontroller performs necessary operations and outputs the operation results through a DA converter. The output of the DA converter can be applied to the input of the electrode driver. That is, in the embodiments of the present invention, the input of the electrode driver can come from the DA converter.

[0339] However, since the ECG signal is weak, to apply digital signal processing, an amplifier must be used for voltage amplification. Only after the ECG signal is amplified can AD conversion with appropriate resolution be performed. The ECG signal received from one electrode is amplified, AD converted, digitally processed, and the output of the DA converter is applied to the electrode driver input.

[0340] In the analysis of all embodiments, it is assumed that the output impedance of the electrode driver is low. However, a series resistor may be inserted at the output end of the electrode driver to prevent the electrode driver from applying excessive current to the human body.

[0341] As described in the three-electrode embodiment, when the electrode contacts the human body part, the electrocardiogram measuring device can be automatically powered on by the current sensor. The user can also start recording the electrocardiogram with the current sensor. Therefore, if the current sensor is used, the mechanical switch can be omitted. See the three-electrode embodiment for details.

[0342] The present invention discloses a device for obtaining a multi-channel ECG Lead signal and reducing noise such as power line interference, motion artifacts, baseline drift, etc. The present invention includes a method for reducing power line interference, motion artifacts, baseline drift, and high-frequency noise through deep learning. In particular, since power line interference is a signal with a constant frequency, it is easy to generate training data, and training is also easy, and the results are effective. In addition, by creating and training training data using a deep learning method, motion artifacts, baseline drift, and high-frequency noise can be eliminated.

[0343] The above describes an embodiment of measuring MCL in a three-electrode embodiment. Even in an embodiment using four electrodes, Fig.24 Embodiment A2 in Fig.36 Embodiment B1 and embodiment B6 in are also applicable to measuring the thoracic Lead with MCL based on LA voltage. Alternatively, the thoracic Lead can be measured relative to the Wilson central terminal using five electrodes.

[0344] Although in the above embodiment of the electrocardiogram measuring device, it has been described that the electrocardiogram measuring device includes four electrodes, another embodiment of the electrocardiogram measuring device according to the present invention may include five electrodes. The working principle of the electrocardiogram measuring device including five electrodes according to the present invention is the same as the above description of the embodiment including four electrodes. The important point is that the electrocardiogram measuring device including five electrodes according to the present invention includes three amplifiers, which receive three electrocardiogram signals from three electrodes respectively, and each of the three amplifiers amplifies one electrocardiogram signal, so that the device amplifies three electrocardiogram signals at the same time. Therefore, three electrocardiogram signals are actually measured at the same time.

[0345] As described above, an electrocardiogram measuring device including five electrodes can be easily implemented. The method of using the electrocardiogram measuring device including five electrodes according to the present invention is almost the same as the method of using the electrocardiogram measuring device including four electrodes according to the present invention. The three electrocardiogram signals measured by the five-electrode electrocardiogram measuring device of the present invention, in an embodiment, include two limb Leads and one chest Lead. Alternatively, the three electrocardiogram signals may also be one limb Lead and two chest Leads. The five-electrode electrocardiogram measuring device of the present invention can be implemented in a form suitable for the method of use and function.

[0346] The above four-electrode ECG measuring device or the five-electrode ECG measuring device described so far can obtain a standard 12-lead ECG by calculating two limb Leads and one chest Lead. To this end, a method similar to that of Dower et al. (patent number: US4,850,370, patent date: July 25, 1989) or a deep learning method can be used.

[0347] An electrocardiogram measurement device mounted on a chest strap includes at least four electrodes that can be used to obtain seven or more electrocardiogram lead signals. The electrocardiogram measurement device mounted on the chest strap can be used in parallel with the electrocardiograph included in the watch, and one embodiment can use Hwang (Hwang, WO2023 / 018318A1, publication date: February 16, 2023). In this case, a method similar to Dower et al. or a deep learning method can be used to generate a standard 12-lead electrocardiogram.

[0348] The following embodiments will be referred to as embodiment group F. Embodiment group F belongs to the above-mentioned embodiments using three electrodes. One embodiment of embodiment group F is as follows.

[0349] An electrocardiogram measuring device, comprising:

[0350] A first electrode and a second electrode configured to receive a first electrocardiogram voltage of a first body part and a second electrocardiogram voltage of a second body part through contact, respectively;

[0351] a first amplifier configured to receive a first electrocardiogram voltage from a first electrode;

[0352] an electrode driver configured to receive a second electrocardiogram voltage from the second electrode and transmit it to a third electrode and a second amplifier;

[0353] a third electrode configured to receive a second electrocardiogram voltage from the electrode driver and transmit it to a contacted third body part;

[0354] a second amplifier configured to receive a second electrocardiogram voltage from the electrode driver;

[0355] An AD converter is connected to respective output terminals of the two amplifiers and converts the output signals of the two amplifiers into two digital signals.

[0356] Here, two amplifiers each receive and amplify an ECG voltage simultaneously.

[0357] So far, embodiments have been disclosed for obtaining six limb Lead signals using four electrodes. Using four electrodes and an electrode driver is advantageous in reducing power line interference. However, when there is insufficient space to install four electrodes, an embodiment using three electrodes is necessary. That is, when trying to make a small-sized wearable electrocardiograph, installing four electrodes may be troublesome. For a wearable electrocardiograph, power line interference is generally less than that of an electrocardiograph used in a hospital operating room, etc., so reduced power line interference can be obtained while using three electrodes.

[0358] Fig.41 An embodiment of obtaining six ECG limb Lead signals using three electrodes is shown. In embodiment group F, the output of an electrode driver connected to an electrode in contact with a human body part is connected to the input of a single-ended input amplifier. Fig.41 The embodiment can be regarded as Fig.36 The two electrodes RA and DRA of the embodiment are combined into one electrode. Embodiment group F has the feature that the output voltage of the electrode driver is an electrocardiogram Lead signal. The output of the electrode driver is an electrocardiogram Lead signal, which is a significant feature. Another electrocardiogram Lead signal is received from an electrode not connected to the input or output of the electrode driver and amplified by another amplifier 4120.

[0359] Embodiment Group F measures two ECG signals simultaneously, as in the above embodiment using three electrodes. Figure 4The embodiment using three electrodes and a bandpass filter described in . However, the frequency band of the electrode driver used in embodiment group F includes the power line interference frequency and the frequency band of the electrocardiogram signal according to ANSI 60601-2-47, that is, from 0.67 Hz to 40 Hz. If the frequency band of the electrode driver includes 0.67 Hz or lower, an additional effect of reducing baseline drift can be obtained.

[0360] Fig.42 It is used for analysis Fig.42 Electrical Characteristics Fig.41 The input voltage v1 of the single-ended input amplifier 4110 and the input voltage v2 of the single-ended input amplifier 4120 are expressed as follows.

[0361] v1=-va+vm1-vm3–inRe1…………………………………………(Formula 26)

[0362] v2=vb+vm2-vm3+in*Re1 / (H(f)+1)…………………………………………(Formula 27)Looking at the above two analysis results, the following conclusions can be drawn.

[0363] i) Both measured ECG voltages include motion artifact vm3 of the electrode connected to the electrode driver input. This result is the same as the embodiment using four electrodes. It is common for the electrodes connected to the electrode driver input to contain motion artifacts. Therefore, when measuring two ECG Lead signals using three ECG electrodes and negative feedback of one electrode driver, it is necessary to reduce the motion artifacts generated by the electrodes connected to the electrode driver input. In addition, in this embodiment, two motion artifacts are mixed with one ECG Lead signal.

[0364] ii) Fig.42 The power line interference of v2 in is reduced to 1 / (H(f)+1). This is because, Fig.42 As shown, almost all the power line interference current flows to the output end of the electrode driver 4130, and the output impedance of the electrode driver 4130 is very small. The effect of removing power line interference is the same as that of the above-mentioned embodiment using three electrodes plus a bandpass filter. However, this embodiment is easier to implement than the embodiment using a bandpass filter. The effect of removing power line interference in this embodiment is the same as that when four electrodes are used. However, it should be noted that the power line interference in v1 is not reduced.

[0365] iii) Note that v1 contains the unamplified ECG voltage va. This is because amplifier 4130 acts as a negative feedback amplifier. Therefore, amplifier 4110 must be included to obtain the amplified va. In order to sense the ECG voltage in an ECG measurement device, amplification is essential. This is because the voltage of a normal ECG signal is very small. The amplitude of the R wave (i.e., the maximum peak in the ECG signal) is usually very small, about 1mV.

[0366] iv) Since amplifier 4130 outputs v1 to electrode RA, it is appropriate to call amplifier 4130 an electrode driver. The input of amplifier 4130 is the ECG voltage induced at electrode LA. Therefore, amplifier 4110 receives the ECG voltage induced at electrode LA.

[0367] Another consideration of this embodiment is as follows. Fig.37 A motion artifact analysis was performed. Looking closely at the results of this analysis, Fig.37 An electrode driver is used in the , but it does not help to reduce motion artifacts. The electrode driver is used to reduce power line interference.

[0368] Therefore, using three electrodes may be advantageous for reducing motion artifacts. Fig.38 In FIG. 3 , when electrode 3810 and electrode 3820 are combined to form one electrode, the area of ​​the combined electrode becomes wider. Therefore, the area in contact with the right hand finger can be expanded, and then the motion artifact can be reduced. This may be an important conclusion.

[0369] Embodiment group F has Fig.43 The six embodiments shown in Table 5 are omitted. To select one of the embodiments in Group F for a wearable electrocardiograph, it should be considered that the electrode driver input should be connected to an electrode with low motion artifacts. This is the same as the teaching in the embodiment using four electrodes. Fig.41 In an embodiment, the electrode driver input electrode is in contact with the left hand. Fig.41 The embodiment is suitable for being implemented as a watch or a ring. As in the embodiment using four ECG electrodes described above, the input of the electrode driver can be connected to the electrodes mounted on the bottom of the watch body or the inner surface of the ring. In the embodiment of the device using two clips, the electrode driver input is connected to the left leg electrode LL.

[0370] The embodiments of the above-mentioned electrocardiogram measuring device may include three or four electrocardiogram measuring electrodes. However, the common goal pursued by all the above-mentioned embodiments is to obtain six electrocardiogram Lead signals from the electrocardiogram measuring device. It has been described that the number of electrocardiogram Lead signals that need to be measured and obtained in order to achieve this purpose is two. In all the above-mentioned embodiments including three or four electrocardiogram measuring electrodes, if two electrocardiogram Lead signals are measured and obtained, four additional electrocardiogram Lead signals can be obtained. That is to say, measuring and obtaining three electrocardiogram Lead signals is an unnecessary, inefficient and redundant method, and falls within the scope of the present invention. In all the above-mentioned embodiments, since a single-ended input amplifier is used, one amplifier output is characterized by one electrocardiogram Lead signal.

[0371] Compared with the embodiment including three ECG electrodes, in the above embodiment including four ECG electrodes, an additional ECG electrode is connected to the input of an electrode driver. Other than that, the embodiment including four ECG electrodes and the embodiment including three ECG electrodes are the same in many aspects.

[0372] The above embodiments are all electrocardiogram measuring devices, including at least three electrocardiogram electrodes, which are in contact with three body parts: right arm (RA), left arm (LA), and left leg (LL).

[0373] Generally speaking, in ECG, "channel" and "Lead" can be used interchangeably, and they refer to an ECG signal or an ECG voltage. In addition, various expressions can be used according to the situation and needs, such as ECG channel, ECG Lead, ECG Lead signal, ECG signal voltage, etc.

[0374] In order to obtain four additional ECG Lead signals, the requirements for two ECG Lead signals must be clarified. In other words, the requirements for an ECG measuring device for measuring two ECG Lead signals must be clarified. The following will describe the requirements for an ECG measuring device including three or four ECG measuring electrodes in order to measure at least two ECG Lead signals.

[0375] Part of the contents of the embodiments described below is based on WO2023 / 018318A1 (International Application Date: August 16, 2022, Inventor: HWANG, In-Duk). In addition, the embodiments described from now on can apply the contents of the above application without repeated description.

[0376] Electrocardiogram measuring device with preset parameters representing the arm being worn

[0377] For an electrocardiogram measuring device including three or four electrocardiogram measuring electrodes, one of the requirements is as follows: First, it is necessary to determine what the two measured electrocardiogram Lead signals are, which is explained below through an example.

[0378] exist Fig.16 In the embodiment of the watch shown, when the watch is worn on the left hand, electrodes 1610 and 1620 installed on the bottom of the watch body contact the left wrist. Electrode 1640 installed on the right side of the watch body contacts a finger of the right hand. Electrode 112 installed on the strap contacts the left leg. According to the connection configuration of the four electrodes installed inside the watch and the electrocardiogram measurement circuit, the watch can be implemented as Fig.24 A2 in Fig.28 B4 and B3 in Fig.30 C4, C5, C6 in Fig.33 Of course, the two ECG Lead signals measured in the above seven embodiments are different from each other.

[0379] Fig.44 A watch worn on the left hand and a watch worn on the right hand are shown. When the watch is worn on the left hand, the electrode 1640 is mounted on the right side of the watch body. When the watch is worn on the right hand, the electrode 1640 appears to be mounted on the left side of the watch body. This is because the watch worn on the right hand has rotated the same watch worn on the left hand counterclockwise about an axis perpendicular to the figure by approximately 150 degrees. Fig.44 The two watches in the diagram are the same watch. However, the display or screen shown on the watch worn on the right hand is the display shown on the watch worn on the left hand, with the display rotated perpendicular to the Fig.44 The axis of is rotated 180 degrees. Similarly, Fig.44 The two watches in the video are the same watch. More on that later.

[0380] When the watch is worn on the right hand, electrodes 1610 and 1620 installed on the bottom of the watch body contact the right wrist, and electrode 1640 contacts the fingers of the left hand. Electrode 112 contacting the left leg contacts the left leg regardless of whether the watch is worn on the right or left hand. The connection and configuration of the four electrodes installed inside the watch and the electrocardiogram measurement circuit are the same as those of the watch worn on the left hand. When the watch is worn on the right hand, the watch can correspond to Fig.36 There are seven embodiments of the invention: A1, B1, B2, C1, C2, C3, and D1.

[0381] The seven embodiments of the watch worn on the left hand and the seven embodiments of the watch worn on the right hand have a symmetrical relationship, such as Fig.45 As shown in Table 6. In Table 6, the left and right embodiments are for wearing the same electrocardiogram measuring device, such as a watch, on alternate hands. For example, A1 and A2 are for wearing on alternate hands. Fig.24It should be noted that even if the watch is worn on the other hand, the left leg electrode 112 is still in contact with the left leg.

[0382] When the watch is worn on the left hand to measure the ECG, e.g. Fig.24 In the embodiment A2 of the embodiment A1, the measured ECG Lead signals are Lead I and Lead III. However, when the watch is worn on the right hand, the ECG Lead signals measured in the embodiment A1 are Lead I and Lead II. That is, when the same watch is worn on the other hand, the two ECG Lead signals measured by the watch will change. Therefore, in order to know what the two ECG Lead signals measured by the watch are, it is necessary to know which hand the watch is worn on.

[0383] This problem does not occur when the watch is worn on only one hand. Therefore, the present embodiment includes the following to solve this problem: two types of watches: a watch worn only on the left hand and a watch worn only on the right hand. The present embodiment includes: a ring worn only on the left hand or a ring worn only on the right hand. The above problem does not occur unless the above-mentioned long and flat stick-shaped electrocardiogram measuring device is used interchangeably with the left and right hands.

[0384] An embodiment of the above-mentioned watch worn only on the left hand includes: a watch, including: an electrode in contact with the left hand; an electrode driver having an input end connected to the electrode; and two amplifiers, one of the two amplifiers amplifies Lead III sensed in the electrode in contact with the left leg, wherein Lead II is calculated and obtained.

[0385] For a watch that measures only one electrocardiogram Lead signal (Lead I), Dusan disclosed how the software analyzes the electrocardiogram Lead signal measured by the watch and automatically determines on which hand the watch is worn to measure the electrocardiogram. (Sorin V. Dusan, Pat. No.: US10,045,708B2, Aug. 14, 2018) However, it is believed that the reliability of the method disclosed by Dusan is not high enough. This method may not be very reliable.

[0386] Dusan's method may be unreliable for the following reasons. First, Dusan assumes that Figure 3 A, 3B, and 3C are due to Lead inversion, i.e., the ECG measured by changing hands while wearing a watch. However, while this assumption is correct in many cases, it may not be correct in some cases. A representative incorrect case is when one of the ECGs has right axis deviation (RAD). When the ECG shows RAD, the R wave appears inverted. The cause of RAD may be right ventricular hypertrophy. The following three references can be used to show that Dusan's assumption may be incorrect.

[0387] Reference 1: Thomas B. Garcia, "12-Lead ECG,The Art of Interpretation", 2ndEd., Jones&Bartlett Learning, 2015, pp.359-360.

[0388] Reference 2: Keith Wesley, "ECG AND 12-LEAD INTERPRETATION", 5th Ed., Elsevier, 2017, p. 215.

[0389] Reference 3: James H. OKeefe, et al., "The Complete Guide to ECGs", 4th Ed., Jones&Bartlett Learning, 2017, p.578and p.581.

[0390] Second, Dusan compared the measured ECG with the ECG measured during the registration phase of the watch. However, it may be difficult to compare the ECG measured during an arrhythmia with the ECG measured during the registration phase.

[0391] Third, some users show that the change in the signal amplitude of Lead I relative to time is too small, that is, the ECG waveform is flat and difficult to analyze. The case where the amplitude change of Lead I is too small is when the direction of the heart's electrical axis is in the aVF direction, that is, downward.

[0392] In this case, the aVF Lead has the largest change in amplitude over time among the six limb Leads. In this case, the waveform of Lead I is flat. This phenomenon is a representative reason why an ECG Lead other than Lead I is needed. This is a well-known fact in cardiology.

[0393] Therefore, the method disclosed by Dusan may be effective in many cases, but may be wrong in some cases. In medical diagnosis, it is more important not to make a wrong diagnosis than to make a correct diagnosis. Therefore, Dusan's method loses its effectiveness. Dusan's method may present wrong results to users, which may cause confusion and danger.

[0394] As described above, in the present invention, Dusan's method is incomplete. Therefore, in order to eliminate the incompleteness, the present invention discloses the following method which is different from Dusan's method.

[0395] In addition to measuring Lead I, the present invention also measures an additional electrocardiogram Lead. That is, Lead III or Lead II is additionally measured according to the type of hand on which the watch is worn. However, if the user's cardiac electrical axis is aVF, it is difficult to determine whether the additionally measured ECG Lead is Lead III or Lead II by only observing the two ECG waveforms. In addition, it has been explained that it is difficult to determine the hand on which the watch is worn using only Lead I and adopting Dusan's method. Therefore, although Lead III or Lead II is further measured in the present invention, if the user's cardiac electrical axis is in the aVF direction, it is difficult to determine on which hand the electrocardiogram measuring device is worn and what the two ECG Lead signals measured are when the hand on which the device is worn changes.

[0396] Based on the above judgment, an embodiment of the present invention includes the following method. In this method, the user predetermines the hand on which the wearable device (usually a watch or ring) is to be worn. When the user uses the watch or ring for the first time, the device may be registered in a smartphone application.

[0397] The user stores the user's information on the watch or smartphone. In the registration step, two buttons for selecting the wearing hand are displayed on the screen of the smartphone or smart watch, and the user selects one button. The two buttons represent the left hand and the right hand, respectively. When the user selects one button, the hand to be worn is set. When the hand to be worn is set, the parameters indicating the hand to be worn are stored in the memory of the watch or smartphone.

[0398] The parameters representing the hand to be worn must be used to specify which two ECG Leads are measured by performing ECG measurement. For example, it should be determined whether the two ECG Leads measured are (Lead I and Lead II) or (Lead I and Lead III). The above parameters are also used to select the calculation formula for obtaining the additional ECG Lead signal.

[0399] As described above Fig.44 The two watches shown are identical. One display or image of one watch can be obtained by rotating another display or image of another watch by 180 degrees. The display direction is selected or changed by the user using a watch or smartphone application software. The selection of the display direction is equivalent to selecting the hand on which the watch is worn. Therefore, if the display direction is set, there is no need to set the hand on which the watch is worn to measure the electrocardiogram. That is, the above-mentioned step of selecting the hand on which the watch is worn using two buttons is not required. This is because the display direction setting parameter can be used as a setting parameter for the hand on which the watch is worn in the watch application. Therefore, selecting the display direction of the watch in the following embodiments is regarded as setting the hand on which the watch is worn.

[0400] While the hand on which it is to be worn can be pre-set when the watch or ring is manufactured in the factory, the user must be able to ultimately check and change the hand on which it is to be worn.

[0401] After setting the wearing hand once, you do not need to set the wearing hand each time you measure the ECG Lead signal. The user may wear the watch on another hand for ECG measurement without changing the setting. To check if this has happened, you can compare the measured ECG Lead with the previously measured ECG Lead to determine if the Lead has changed. If the wearing hand has been changed, a pop-up window may be displayed asking the user to confirm the wearing hand. ECG Lead signals calculated using different calculation formulas may be modified based on the user's confirmation.

[0402] The embodiment described above includes: a watch for measuring at least two electrocardiogram Lead signals, comprising: at least three electrocardiogram electrodes; and a button displayed on a screen of the watch for selecting a wearing hand.

[0403] Alternatively, an embodiment includes: a watch or smartphone storing in a memory parameters representing a hand on which the watch is worn.

[0404] Alternatively, an embodiment includes: an electrocardiogram measuring device that calculates and obtains an additional electrocardiogram Lead signal by selecting a calculation formula according to a selection of a button displayed on a watch display screen. The button is a button for selecting a hand to wear the watch or setting a display direction of the watch.

[0405] Alternatively, an embodiment includes: an electrocardiogram measuring device that calculates and obtains an additional electrocardiogram Lead signal by selecting a calculation formula according to a selection of a button displayed on a smartphone screen. The button is used to select a hand to wear the electrocardiogram measuring device.

[0406] Optionally, an embodiment includes: an electrocardiogram measurement device, which calculates an additional electrocardiogram Lead signal by setting a hand to be worn and selecting a calculation formula according to preset parameters.

[0407] One embodiment includes the following.

[0408] An electrocardiogram measuring device comprises:

[0409] One electrode in contact with one hand;

[0410] an electrode driver having an input connected to the electrode;

[0411] an amplifier from the Lead II or Lead III that amplifies the sensory input from the electrode in contact with the left leg; and

[0412] A smartphone that selects a calculation formula using a parameter representing the hand on which the device is worn and calculates and obtains Lead III or Lead II based on the parameter.

[0413] If the electrocardiogram measuring wearable device does not include a sufficiently wide display screen, a button for selecting a hand to be worn is displayed on the smartphone display screen, and a calculation formula for additionally obtaining an electrocardiogram Lead signal can be selected according to the selected button. The electrocardiogram measuring wearable device that does not include a wide display screen includes the above-described devices together with the previously shown devices, such as a ring and a device including two clips.

[0414] According to the above, one embodiment includes: displaying two buttons for selecting a hand to wear a ring on a smartphone screen, and selecting a smartphone for obtaining a calculation formula for an additional electrocardiogram Lead signal according to the selected buttons.

[0415] What has been described so far can be found in Fig.46 The steps of the flowchart are implemented in the following. Hereinafter, the electrocardiogram measurement step of presetting the parameters representing the arm to be worn will be described. For convenience, the electrocardiogram measurement device can be represented as a watch or a ring. As described above, in the present embodiment, the parameters representing the arm to be worn are pre-set. This is done in step 461 of registering the watch or ring to the smartphone. In this step, the user registers the watch or ring to the smartphone, including the user's personal information.

[0416] As described above, you can set the arm to wear by selecting the button displayed on the watch or smartphone screen or setting the display direction of the watch. When you select the arm to wear, the parameters of the arm to wear are stored in the memory of the watch, ring or smartphone. This ends the setting of the arm to wear.

[0417] The measurement of the ECG Lead signals starts at step 463. In step 463, the user selects the number of ECG Lead signals to be measured. This selection can be made by the user directly on the screen of the watch or smartphone, or by determining the number of body parts that the current sensor contacts. If only Lead 1 is measured, the number of ECG Lead signals to be measured is 1. To obtain six ECG Lead signals, the number of ECG Lead signals to be measured is 2. Depending on the number of ECG Lead signals to be measured, the watch or ring starts taking ECG measurements.

[0418] What the measured ECG Lead signal is is determined by the parameters representing the arm on which the watch or ring is worn. Fig.46 The electrocardiogram Lead signals measured in the four measurement steps shown in step 465 are all different. It is worth recalling that Fig.46 Four types of ECG measurements that can be performed in a watch or a ring are shown. When measuring ECG Lead signals, the watch can present at least one ECG Lead signal on the screen of the watch.

[0419] The ECG data measured in one of the four cases of step 465 can be transmitted to the smartphone. The ECG data transmitted by the watch or ring is a value obtained by sampling one or two ECG Lead signals. The ECG data to be transmitted may include the parameters of the arm to be worn and the number of ECG Leads measured. The watch or ring can communicate with the smartphone via low-power Bluetooth.

[0420] In step 467, the smartphone receives at least one measured ECG Lead signal. The smartphone can determine what the received ECG is. The parameters of the worn arm can be stored in the memory of the smartphone or included in the received ECG data. And, the received ECG data can include quantity information of the measured ECG Lead signals. Therefore, in step 467, the smartphone determines the received ECG data and performs subsequent operations based on the determined content. When Lead I is measured, the sign of Lead I can be determined. When two ECG Leads are measured, the smartphone selects the calculation formula to be used, and calculates, obtains and displays each ECG Lead signal.

[0421] The smartphone can store the measured data in the cloud server before finishing the electrocardiogram measurement. The measured electrocardiogram data can be automatically diagnosed on the smartphone or the cloud server. The automatic diagnosis result can be sent to the medical staff as well as the user.

[0422] Example of measuring Lead I only

[0423] Although all the above embodiments relate to an electrocardiogram measuring device that obtains six electrocardiogram Lead signals, it has been described that in the above embodiment including three electrocardiogram electrodes, only Lead I can be measured for convenience. In addition, an electrocardiogram measuring device provided with a hand for wearing has just been described. Next, conditions, devices, and methods required for an embodiment in which only Lead I is measured according to a user's selection for convenience will be described.

[0424] For convenience, it may be necessary to measure only the ECG Lead signal between both hands. This includes situations where some users can obtain sufficient information with only Lead I, and it is inconvenient for the user to touch the ECG measurement device to the left leg or the user's clothing is not suitable.

[0425] Many embodiments using four ECG electrodes are described above. In these embodiments, in order to measure only Lead I, the electrode connected to the input of the electrode driver or the electrode connected to the output of the electrode driver should not touch the left leg. This is because in the above-mentioned embodiment using four ECG electrodes, the electrode driver must form a feedback loop. If the left leg does not contact the ECG measurement device and only Lead I is measured, the feedback loop of the electrode driver is disconnected. Therefore, in order to measure only Lead I, the electrode connected to the input of the electrode driver and the electrode connected to the output of the electrode driver must be touched with one hand, or the two electrodes must be touched with both hands.

[0426] In all of the above embodiments, one electrode contacts the same part of the human body as the electrode connected to the output of the electrode driver. Therefore, in order to measure only Lead I, three electrodes must be in contact with the right hand (RA) and the left hand (LA). That is, two electrodes contact one hand and one electrode contact the other hand. That is, the electrode that is not used to measure Lead I but should contact the left leg must be connected to the input of one amplifier.

[0427] For convenience, Table 6 is used to describe an embodiment of measuring only Lead I. Among the 7 symmetrical pairs shown in Table 6, there are 3 pairs of electrodes connected to the input terminal of the electrode driver and the electrodes connected to the output terminal of the electrode driver that do not contact the left leg, namely, the embodiment pairs of A1 and A2, B1 and B3, and C1 and C4. Since these symmetrical pairs correspond to the situation of wearing the watch on the other hand, it can be said that A2, B3, and C4 actually have different physical structures or configurations, that is, only these three are suitable for measuring only Lead I. These three physical configurations have a common feature, that is, the electrode connected to the input terminal of the electrode driver and the electrode connected to the output terminal of the electrode driver are in contact with one hand respectively, or the two electrodes are in contact with two hands respectively.

[0428] In an ECG measurement device having a ring shape or the like, the ring may not include a display, and the ring may also need to initiate ECG measurement without a mechanical activation switch. In particular, the ring needs to accommodate the user's intention to measure only Lead I. In this case, if the contact of the left leg electrode with the left leg is not detected within a certain period of time after the current detector detects contact of both hands, only Lead I can be measured.

[0429] As described above, measurement of only one ECG Lead signal (Lead I) may be performed before or after determining on which hand the ECG measurement device is worn.

[0430] So far, for the sake of convenience, the necessity and method of measuring only Lead I have been described. In a case where the user's cardiac electrical axis is in the aVF direction, a warning message may be generated stating that only Lead I should not be measured. When the user measures Lead I, if the signal strength of Lead I is not strong enough, a warning message may be generated on a smartphone or smartwatch saying "Because the signal strength of Lead I is not strong enough, only Lead I should not be measured." Alternatively, a warning message may be displayed saying "Touch the device with your left leg."

[0431] In all embodiments described so far or in all embodiments described below, the electrode driver can be implemented to include digital signal processing. The ECG Lead signal sensed on an electrode is amplified by an amplifier, the output of the amplifier is AD converted, digital signal processing is performed, and the output of the DA converter is amplified as the electrode driver output. This implementation can accurately control the output of the electrode driver.

[0432] An embodiment according to the above conditions includes: an electrocardiogram measuring device, wherein an electrode connected to an electrode driver input and an electrode connected to an electrode driver output are in contact with one arm or both arms.

[0433] One embodiment includes:

[0434] An electrocardiogram measuring device, which measures only an electrocardiogram Lead signal between two hands according to a user's selection, comprises:

[0435] an electrode connected to an output of an electrode driver;

[0436] An electrode connected to the input of an amplifier, which amplifies the ECG Lead signal between the two hands;

[0437] These electrodes are in contact with the same hand.

[0438] Alternatively, another embodiment includes the following:

[0439] An electrocardiogram measuring device, in which a current sensor detects contact between two hands to start electrocardiogram measurement, and measures only an electrocardiogram Lead signal between the two hands when one electrode is not detected to be in contact with the left leg.

[0440] Tolerance requirements

[0441] Now, it is known on which hand the wearable ECG measuring device (such as a watch or ring) is worn, based on which the two measured ECG Lead signals can be determined. Now, an embodiment of calculating and obtaining four ECG voltages or ECG Lead signals by using two measured ECG voltages will be described. The following part has been published in the application of the same inventor (Publication No.: WO 2023 / 018318A1, Feb. 16, 2023, Application No.: PCT / KR2022 / 012211, Aug. 16, 2022).

[0442] First, let's summarize the equations for the six common electrocardiogram limb leads. The following equations 28 to 33 describe ANSI / AAMI / IEC 60601-2-25:2011, Medical electrical equipment-part 2-25: Particular requirements for the basic safety and essential performance of electrocardiographs, which is an international medical equipment standard. These six equations apply to the six limb leads out of the twelve leads. RA, LA, and LL are the voltages of the right arm, left arm, left leg, or body parts close to these limbs, respectively, measured by the electrocardiograph.

[0443] I = LA - RA (Formula 28)

[0444] II=LL-RA(Formula 29)

[0445] III=LL-LA (Formula 30)

[0446] aVR=RA-(LA+LL) / 2 (Formula 31)

[0447] aVL=LA-(RA+LL) / 2 (Formula 32)

[0448] aVF=LL-(RA+LA) / 2 (Formula 33)

[0449] As described above, according to the present invention, after determining the two measured ECG Lead signals, four ECG Lead signals are calculated and obtained. There are two following cases for the formula or equation for obtaining the four ECG Lead signals. It should be noted that the calculation formula and the result are different according to the two measured ECG Lead signals. Now, in this embodiment, an electrocardiogram measuring device and a method for selecting and using an additional calculation formula for obtaining four ECG Lead signals according to the two ECG Lead signals measured by the electrocardiogram measuring device will be disclosed.

[0450] When the electrocardiogram measurement device according to this embodiment measures Lead I and Lead II, the following equations are used to obtain four electrocardiogram Leads. Fig.24 When the device in is worn on the right hand, Fig.44 As shown on the right, Lead I and Lead II are measured, so the following equation is used.

[0451] III=-I+II(Formula 34)

[0452] aVR=-(I+II) / 2 (Formula 35)

[0453] aVL=I-II / 2 (Formula 36)

[0454] aVF=-I / 2+II (Formula 37)

[0455] The use of the above formulas 34 to 37 in this embodiment is original. Thomson et al. disclosed formulas 35 to 37. (US Patent Application Publication, Pub. No.: US2015 / 0018660A1, Pub. Date: Jan. 15, 2015, Appl. No.; 14 / 328,962, Claim 28.) However, in order to use the above three formulas, Thomson et al. measured three voltages of RA, LA and LL. On the other hand, in this embodiment, only two ECG Lead signals, i.e., ECG voltages, are measured. Therefore, this embodiment is more effective than Thomson et al. In addition, Thomson et al. used formula 30, III=LL-LA. That is, Thomson et al. did not use formula 34. It is described above that Thomson et al. only used formulas 35 to 37. In addition to formulas 34 to 37, the present invention also discloses the following formulas 38 to 41. Therefore, this embodiment is different from Thomson et al.

[0456] When the electrocardiogram measurement device according to this embodiment measures Lead I and Lead III, the following formula is used to obtain four electrocardiogram Leads. Fig.24When the device is worn on the left hand, Fig.44 When measuring Lead I and Lead III as shown on the left, use the following formula.

[0457] II=I+III(Formula 38)

[0458] aVR=-I-III / 2 (Formula 39)

[0459] aVL=(I-III) / 2(Formula 40)

[0460] aVF=I / 2+III (Formula 41)

[0461] When the electrocardiogram measuring device of this embodiment measures Lead II and Lead III, a formula different from the above formula may be used to obtain four electrocardiogram Leads. For the sake of convenience, this embodiment may be omitted.

[0462] In order to implement the above embodiment, there are several points to note: The terms of formula 38 are expressed as time functions as follows.

[0463] Lead II(to+nT)=Lead I(to+nT)+Lead III(to+nT)(Formula 42)

[0464] The above formula 42 means that in order to obtain another ECG Lead from two measured ECG Leads, the two measured ECG Leads must be sampled at the same time point. In formula 42, T represents the sampling period and n represents the number of samples. Assume that the ECG measurement start command occurs at t=0. Then to represents the time (t=to) until the first (n=0) sampling is performed. When the total number of samples is N+1, NT represents the total time of the measurement. In one embodiment, if the sampling rate is 300sps (samples / second), T=3.333ms. If the measurement is 30 seconds, N=30s / 3.333ms=9,000.

[0465] Formula 42 indicates that two ECG Lead signals, Lead I and Lead III, are sampled at the same sampling rate. Therefore, in order to use Formulas 34 to 41 in this embodiment, the ECG measurement device must sample the two ECG Lead signals at the same sampling rate. Of course, when the sampling rates are different, interpolation can be used to convert the sampling rates to be the same. However, using the same sampling rate is much more effective.

[0466] After obtaining additional ECG leads through calculation, the six ECG leads can be displayed on the display of the smartphone. It can also be stored on the cloud server, and the doctor can analyze the six ECG leads in the office. The smartphone or cloud server can automatically diagnose the six ECG leads and provide the diagnosis results to the doctor. When the automatic diagnosis results indicate an emergency, the doctor can be alerted.

[0467] According to the above description, one embodiment includes: an electrocardiogram measuring device, including at least three electrocardiogram electrodes, wherein the electrocardiogram measuring device selects an equation for calculating and obtaining an electrocardiogram Lead signal according to parameters representing a wearing arm.

[0468] From now on, in order to use Equations 34 to 37 or Equations 38 to 41, additional conditions required for an electrocardiogram measuring apparatus including two amplifiers and two electrocardiogram Lead signals measured using the apparatus are described.

[0469] The wearable device according to this embodiment is a medical device. The electrocardiogram measuring device implemented in this embodiment must comply with the medical device certification standards. The international standard ANSI / AAMI / IEC 60601-2-47:2012, Medical electrical equipment-part 2-47: Particular requirements for the basic safety and essential performance of ambulatory electrocardiographic systems that can be applied in this embodiment.

[0470] In order to implement this embodiment, the following conditions need to be met: the gains of the two amplifiers used in this embodiment must be the same.

[0471] When two ECG Lead signals measured using two amplifiers with unequal gains are applied to any of the above formulas 34 to 37, inappropriate results will be obtained. Here, the gain includes the gain of the amplifier contained in the electrocardiogram measuring device. The gain may refer to the final gain obtained after digital signal processing after AD conversion. In all embodiments of the present disclosure, the gain refers to the final gain after digital signal processing including a digital frequency filter. Therefore, the meaning of the gain may include frequency response characteristics. Digital signal processing does not have to be performed in the same wearable device that performs AD conversion. Digital signal processing can be performed by a smartphone application software connected to the electrocardiogram measuring device via wireless communication.

[0472] Before using the two measured ECG Lead signals to obtain four ECG Lead signals, the two measured ECG Lead signals may be subjected to digital signal processing. For example, digital signal processing must be performed to eliminate noise such as the above-mentioned power line interference or motion artifacts. Otherwise, noise will also appear on the calculated four ECG Leads. Once the two measured ECG Lead signals are subjected to noise elimination, there is no need to perform noise elimination on the calculated four ECG Leads. By performing digital signal processing on the two measured ECG Leads to eliminate noise, noise can be eliminated from all six ECG Leads (including the calculated four ECG Leads). For the four Leads obtained using the above formula, digital signal processing is not required to eliminate noise.

[0473] In addition to noise elimination, the digital signal processing of the two measured ECG Lead signals mentioned above also includes scaling conversion for displaying the ECG Lead waveform. For example, the digital value after AD conversion and the number of pixels on the display screen corresponding to 1mV are determined. Therefore, the digital signal processing includes standardization to display and store the ECG Lead signal in mV. This signal processing can generally be called scaling or standardization. In this way, gain correction can also be performed in digital signal processing.

[0474] In this embodiment, the measured and calculated ECG Lead signals, a total of 6 ECG Lead signals, are displayed on the smartphone. When the ECG Lead signals obtained in this embodiment are displayed on the smartphone, the same gain of the ECG measurement device means that when the same input signal is input to the two amplifiers, the two ECG waveforms displayed on the smartphone display are equal within the tolerance range. The detailed grids of the horizontal and vertical axes of the smartphone screen can be used to obtain accurate information about the ECG signal waveform displayed on the smartphone display.

[0475] In this embodiment, when the ECG Lead signal is measured using a watch without a smartphone, one or two ECG Lead signals may be displayed on the watch screen. In this case, the ECG Lead signal displayed on the watch screen may include the most important Lead II in medicine.

[0476] One embodiment includes a watch including at least three electrocardiogram electrodes and displaying Lead II on a watch display.

[0477] When the smartphone and the watch are wirelessly connected, the ECG data obtained from the watch can be automatically transmitted to the smartphone. The smartphone can display six ECG Lead signals using the transmitted ECG data.

[0478] In the above, same or identical means that the magnitude of the difference between the two values ​​is less than the tolerance or tolerable error. According to the above international standard, the gain accuracy must be within + / -10% of the maximum magnitude error. The compliance test for the above requirement in the international standard is performed as follows: "Apply a 5Hz, 2mV pv sinusoidal signal to all ECG input channels."

[0479] Therefore, all of the present embodiments have the feature of using the same two amplifiers to simultaneously amplify two electrocardiogram Lead signals. In order to obtain an additional electrocardiogram Lead signal using the above formulas 34 to 37 or formulas 38 to 41, it is necessary to use the same two amplifiers to simultaneously measure the two electrocardiogram Lead signals.

[0480] So far, we have understood the situation and introduced the concepts, but now we will describe the above more strictly. Although the term accuracy is used in the above standards, tolerance may be more appropriate than precision. Therefore, in the following, the term tolerance or tolerance range may be used depending on the situation.

[0481] Furthermore, the term tolerance or tolerance range will be used by distinguishing two purposes. That is, the terms "tolerance required for the device" or "tolerance range required for the device" and "tolerance required for the amplifier" or "tolerance range required for the amplifier" will be used. The reasons and meanings of using these terms will become more apparent in the following embodiments. The tolerance required for the device or the tolerance range required for the device refers to the tolerance required by the above-mentioned international standards or the performance target required for the electrocardiogram measuring device to be manufactured by the company. On the other hand, the tolerance required for the amplifier or the tolerance range required for the amplifier refers to the permissible error of the measured electrocardiogram lead signal displayed on the screen of the smartphone after amplifying the electrocardiogram lead signal induced at the electrocardiogram electrode.

[0482] Will use Fig.47 Table 7 in describes an example. Table 7 shows an example of an error in the calculated ECG Lead signal caused by an error in the measured ECG Lead signal. In the example of Table 7, when 0.60mV is applied to Lead I and 1.00mV to Lead II as a test signal, the measurement results are Lead I = 0.54mV and Lead II = 1.10 due to the gain error of the two amplifiers used. In this example, the accuracy of the two measurements is within the range allowed by the above international standards.

[0483] However, using these measured values, calculating aVF using Equation 37 yields 0.83mV, which is 119% of the error-free value of 0.70mV. In this case, a 19% error has occurred. This error exceeds the international standard tolerance of + / -10%. If the measurement tolerance of Lead I and Lead II is 5%, we can derive aVF = 0.765mV from Equation 37. Then, the resulting error is 9%, which meets the requirements of the international standard.

[0484] Therefore, when implementing, the gain accuracy of the two amplifiers is required to be better than the international standard. For example, the gain tolerance of the two amplifiers must be within + / -5%. In this case, the maximum measurement tolerance or the tolerance required by the amplifier is 5%.

[0485] From the example of Table 7, it can be concluded that the tolerance of the calculated ECG lead signal must meet the "device required tolerance" of the ECG measurement device, and for this purpose, the tolerance of the measured ECG lead signal must be smaller than the "device required tolerance". The tolerance of the measured ECG lead signal must meet the "amplifier required tolerance". Therefore, the "amplifier required tolerance" is smaller than the "device required tolerance" and is approximately half of it.

[0486] Table 7 shows what may happen when actually measuring an ECG lead signal. However, it may be difficult to draw a general conclusion because the amplitude of the ECG lead signal varies depending on the user in an actual measurement environment. Therefore, the error analysis shown in Table 7 can be expanded by using two identical inputs for two ECG electrodes. Even in this method, the same conclusion as in Table 7 can be drawn. That is, the error of the calculated ECG lead signal is always greater than the error of the measured ECG lead signal.

[0487] Therefore, the present embodiment includes: an electrocardiogram measuring device, comprising at least three electrocardiogram electrodes; and two amplifiers, wherein the amplifiers have the same gain, and the gain is within a tolerance range required by the amplifiers.

[0488] When the same input signal is applied to two amplifiers with the same gain, the waveforms of the two ECG lead signals displayed on the smartphone screen should be the same. Therefore, the present embodiment includes: an ECG measurement device, including: at least three electrocardiogram electrodes; and two amplifiers connected to two of the at least three electrocardiogram electrodes, wherein when the same input signal is applied to the two amplifiers, the amplitudes of the two measured electrocardiogram lead signals displayed on the smartphone screen are the same and have the tolerance required by the amplifiers.

[0489] In order to make the two amplifiers have the same characteristics, the two amplifiers need to have the same structure or components. Therefore, this embodiment includes: an electrocardiogram measuring device, which includes two amplifiers with the same components.

[0490] The amplifiers included in this embodiment are basically manufactured using operational amplifiers. In amplifiers using operational amplifiers, the errors in amplifier characteristics (such as gain and frequency response) are mainly caused by the component value errors of resistors and capacitors. However, the errors of these amplifiers can be controlled by computer simulation design and verification by considering the tolerance of the component values. For this reason, the resistors and capacitors can be high-precision, low-tolerance components. The tolerance of resistors and capacitors can be + / -1%. The operational amplifier can be a low-noise amplifier. The input impedance of both amplifiers must be greater than 10MOhm. Applying these considerations can manufacture the same two amplifiers required for this embodiment.

[0491] To implement this embodiment, the following conditions are required. The gain accuracy of the two amplifiers used must be better than the gain accuracy required by the international standard. For example, the maximum amplitude error of the two amplifiers must be within + / -5%. Otherwise, the accuracy of the ECG lead signal calculated using formulas 34 to 37 may have a maximum amplitude error greater than + / -10%. This can be understood from the example in Table 7.

[0492] It can be seen from the above example that in order to obtain a calculated ECG lead signal with the allowable error required by the device, the allowable error of the measured ECG lead signal must be less than the allowable error required by the device. In the following, the ECG lead signal obtained by the ECG measurement device of this embodiment is divided into a measured ECG lead signal and a calculated ECG lead signal.

[0493] It should be noted that the above situation will occur even if three ECG lead signals are measured and obtained by calculation. In addition, the above situation will occur regardless of whether the ECG lead signal to be measured is a limb lead or an enhanced limb lead. Therefore, this embodiment includes an embodiment for measuring three ECG lead signals and an embodiment for measuring an enhanced limb lead.

[0494] If the two ECG lead signals measured in the above embodiment are completely accurate, then the other four ECG lead signals obtained by calculation are also completely accurate. However, since the measuring device always has errors, the measured values ​​will have errors, and the other four ECG lead signals obtained by calculation will also have errors. The accuracy requirements of the ECG lead signals measured in the above embodiment are better than the required standards. In other words, in order to obtain the calculated ECG lead signals with the accuracy required by the device, the accuracy of the measured ECG lead signals must be higher.

[0495] The accuracy of the calculated ECG lead signal is always lower than the accuracy of the measured ECG lead signal. The accuracy of the measuring device is an important specification of the measuring device. Therefore, when indicating the specifications of the ECG measuring device, the accuracy of the calculated ECG lead signal must be indicated. Alternatively, the accuracy of the measured ECG lead signal and the accuracy of the calculated ECG lead signal should be recorded together.

[0496] Similarly, although the measured two ECG lead signals are actually measured, it is not an accurate expression to express the accuracy of the measured two ECG lead signals as the accuracy of ECG measurement. In order not to confuse the user, the final accurate result should be informed. The measured ECG lead signal is not the final result. The final result is the calculated ECG lead signal. Therefore, the accuracy of the calculated ECG lead signal should be informed and expressed as the accuracy of the ECG measurement device. The accuracy of the ECG measurement device should be expressed as the accuracy of the calculated ECG lead signal, whose error is large and the worst case. By distinguishing the measured ECG lead and the calculated ECG lead, the two accuracies can be known.

[0497] From now on, the required accuracy of the calculated ECG leads can inform the permissible error of the ECG measuring device. Therefore, the required tolerance of the calculated ECG leads is the same as the tolerance of the ECG measuring device. Therefore, the required tolerance of the measured ECG leads should be less than the tolerance of the ECG measuring device. The required tolerance of the measured ECG leads can be determined as half of the tolerance of the ECG measuring device.

[0498] The accuracy of the calculated ECG leads should be determined as the required accuracy of the ECG measuring device. When testing is performed by a medical device certification office or when test results are presented independently, the accuracy of the measured ECG leads shall not be presented. The accuracy of the calculated ECG leads shall be presented.

[0499] The accuracy of the calculated ECG leads as well as the accuracy of the measured ECG leads can be measured by viewing the smartphone screen. Alternatively, automated testing software can be used.

[0500] In order to improve the accuracy of the measured ECG leads, it may be necessary to consider the selection of components to be used from the design stage of the ECG measuring device. Even when the accuracy of the ECG measuring device is tested after the ECG measuring device is produced, it should be considered that the accuracy of the measured ECG leads should be higher than the accuracy of the calculated ECG leads.

[0501] According to the above, an embodiment includes: an electrocardiogram measurement device for obtaining calculated electrocardiogram leads having a predetermined tolerance and measured electrocardiogram leads having a tolerance less than the predetermined tolerance.

[0502] Additionally, one embodiment includes an electrocardiogram measurement apparatus for acquiring calculated electrocardiogram leads that meet a predetermined tolerance and measured electrocardiogram leads that meet a tolerance that is approximately half of the predetermined tolerance.

[0503] The error produced by the AD converter or the smartphone microprocessor performing the calculation is much smaller than the allowable error of the electrocardiogram measuring device. Therefore, one embodiment includes: an electrocardiogram measuring device including two equivalent amplifiers that meet a tolerance smaller than the tolerance of the electrocardiogram measuring device.

[0504] In addition, the present embodiment includes: an electrocardiogram measuring device including two amplifiers, wherein the gain accuracy is higher than the calculated electrocardiogram lead accuracy.

[0505] The present embodiment includes: an electrocardiogram measurement device, wherein a measured electrocardiogram lead and a calculated electrocardiogram lead are displayed on a smartphone screen, and a tolerance of the measured electrocardiogram lead is smaller than a tolerance of the calculated electrocardiogram lead.

[0506] Embodiments include an electrocardiogram measurement device wherein calculated electrocardiogram leads displayed on a smartphone display screen meet tolerances determined based on device requirements.

[0507] Embodiments include: an electrocardiogram measurement device including at least three electrocardiogram electrodes in contact with three body parts of a right arm, a left arm, and a left leg, wherein a calculated electrocardiogram lead signal calculated using the measured electrocardiogram lead signal has a tolerance that meets the device requirements.

[0508] To implement this embodiment, the following conditions need to be met: The frequency response characteristics of the two amplifiers must be the same within the "tolerance range required by the amplifier". If two ECG lead signals measured by two amplifiers with unequal frequency response characteristics are applied to any of the above formulas 34 to 37, inappropriate results will be obtained. According to the above international standards, the frequency response requirements for testing with a sine wave are as follows: The amplitude response in the frequency range of 0.67 Hz to 40 Hz should be between 140% and 70% of the amplitude response at 5 Hz. The test was performed at 0.67 Hz, 1 Hz, 2 Hz, 5 Hz, 10 Hz, 20 Hz and 40 Hz.

[0509] According to the above, embodiments include: an electrocardiogram measuring device including two amplifiers whose amplitude responses of frequency responses are the same within a "tolerance range required by the amplifiers".

[0510] When the input signal is applied to two amplifiers with the same frequency response, the two measured ECG voltage waveforms displayed on the smartphone screen must be identical within the tolerance range. This means that the two measured ECG voltage waveforms displayed on the smartphone screen must meet more stringent requirements for frequency response than those required by the above international standards.

[0511] Thus, embodiments include an electrocardiogram measurement device wherein, when an input signal is applied to two amplifiers, two frequency responses of two measured electrocardiogram voltages displayed on a smartphone screen are identical within a tolerance range required by the amplifiers.

[0512] In order to implement the embodiment, the following conditions are required: the frequency response characteristics of the two amplifiers used in the embodiment must have a smaller tolerance than the above international standard requirements. The reason is the same as the amplifiers required to have higher precision gain characteristics as described above. This is because the allowable error of the calculated ECG lead signal is greater than the allowable error of the measured ECG lead signal. For example, the amplitude response of the two amplifiers in the frequency range of 0.67Hz to 40Hz may be within 120% and 85% of the amplitude response at 5Hz.

[0513] One embodiment includes an electrocardiogram measurement device including two amplifiers, wherein a frequency response tolerance of the two amplifiers is smaller than a tolerance of the electrocardiogram measurement device.

[0514] In combination with the embodiments described so far, the present embodiment includes: an electrocardiogram measuring device including two amplifiers, the amplifiers having the same characteristics and a tolerance range smaller than the tolerance range required by international standards.

[0515] Furthermore, one embodiment includes an electrocardiogram measurement apparatus including a smartphone that performs an operation of calculating an additional electrocardiogram lead signal using a measured electrocardiogram lead signal and an operation of displaying six electrocardiogram lead signals on a screen thereof.

[0516] Arrhythmias may be intermittent and asymptomatic. Therefore, a photoplethysmogram (PPG) can be mounted on a watch or ring, and the pulse or heart activity can be continuously monitored using PPG. The advantage of PPG is that the photoplethysmogram can be measured by wearing it on one hand. If the PPG, which has been monitoring heart activity, detects abnormal heart activity, that is, detects the occurrence of arrhythmia, the PPG can generate an alarm. The alarm can be in the form of sound, vibration or light. After the alarm is detected, the user can measure the electrocardiogram. Specifically, this embodiment can obtain 6 ECG lead signals.

[0517] After sensing the alarm, the user touches the other hand wearing the watch or ring to the corresponding electrode of the watch or ring. Then, the current sensor installed in the ECG measurement device detects the contact of the other hand. The current sensor causes the microprocessor to prepare the ECG measurement of Lead I and try to establish a low-power Bluetooth connection with the smartphone. In addition, when the user touches the corresponding electrode to the left leg, the current from the current sensor flows between the left leg and the hand. Then, the current sensor detects the contact of the left leg and generates a corresponding output. The microcontroller performs the ECG measurement of Lead II or Lead III after preparing the ECG measurement.

[0518] As described above, embodiments of an apparatus and method for obtaining at least six electrocardiogram leads (Lead) by measuring at least two electrocardiogram leads (Lead) and calculating the measured at least two electrocardiogram leads (Lead) have been disclosed. To this end, in the above embodiments, at least three electrocardiogram electrodes contacting three human body parts are used.

[0519] As described above, the present invention can be implemented in various ways. According to the present invention, embodiments can be configured differently from the embodiments shown so far. An embodiment suitable for a specific design of a wearable device can be selected. The electrocardiogram measuring device according to the present invention is easy to carry and can be easily used anytime and anywhere, and can be used as a portable electrocardiogram measuring device capable of obtaining electrocardiogram information of multiple ECG signals.

Claims

1. An electrocardiogram measuring device, comprising: a first electrode and a second electrode for receiving first and second electrocardiogram voltages from first and second body parts in contact therewith, respectively; two amplifiers for receiving first and second electrocardiogram voltages from first and second electrodes; An electrode driver outputs a driving voltage; a third electrode that contacts a third human body part and transmits a third electrocardiogram voltage to an input terminal of the electrode driver; a fourth electrode, located near one of the three electrodes and transmitting the output of the electrode driver to the contacted human body part; an AD converter connected to an output terminal of each of the two amplifiers to convert output signals of the two amplifiers into two digital signals; A microcontroller for receiving two digital signals from the AD converter; as well as A communication device for transmitting two digital signals; wherein: The microcontroller receives power from the battery; The microcontroller controls the AD converter and the communication device; The two amplifiers respectively receive and amplify an electrocardiogram voltage simultaneously.

2. The electrocardiogram measuring device according to claim 1, wherein the electrode connected to the input terminal of the electrode driver and the electrode connected to the output terminal of the electrode driver contact the same body part of the user. 3 . The electrocardiogram measuring device of claim 1 , wherein the electrode connected to the input of the electrode driver and the electrode connected to the output of the electrode driver contact different body parts of the user.

4. The electrocardiogram measuring device according to claim 1, wherein: The input of the electrode driver comes from two electrodes among the first, second and third electrodes.

5. The electrocardiogram measuring device as claimed in claim 1, wherein the input of the electrode driver comes from the first, second and third electrodes.

6. The electrocardiogram measuring device according to claim 1, wherein at least one of the two amplifiers of the electrocardiogram measuring device is a single-ended input amplifier.

7. The electrocardiogram measuring device according to claim 1, wherein two amplifiers of the electrocardiogram measuring device are differential amplifiers, and one of two input terminals of the two differential amplifiers is connected to an input terminal of the electrode driver.

8. The electrocardiogram measuring device according to claim 1, wherein the electrocardiogram measuring device and its four electrodes are mounted on a watch body and a watch band.

9. The electrocardiogram measuring device according to claim 8, wherein the electrode connected to the electrode driver input terminal is installed on the bottom of the watch body, and one electrode is installed on the strap to contact the left leg.

10. The electrocardiogram measuring device according to claim 8, wherein the electrode connected to the output terminal of the electrode driver is installed on the bottom of the watch body, and one electrode is installed on the strap to contact the left leg.

11. The electrocardiogram measuring device according to claim 1, wherein the electrocardiogram measuring device and its four electrodes are mounted on a ring.

12. The electrocardiogram measuring device according to claim 11, wherein the electrode connected to the electrode driver input terminal is installed on the inner surface of the ring, and one electrode is installed on the outer surface of the ring to contact the left leg.

13. The electrocardiogram measuring device according to claim 11, wherein three electrodes are installed on the outer surface of the ring, and one electrode is installed on the outer surface of the ring to contact the left leg.

14. The electrocardiogram measuring device according to claim 1, wherein the memory stores parameters representing a wearing hand.

15. The electrocardiogram measuring device according to claim 1, wherein: An additional electrocardiogram lead signal is calculated by selecting a calculation formula based on parameters representing the hand on which the device is worn.

16. The electrocardiogram measuring device according to claim 1, wherein the electrode connected to the input terminal of the electrode driver and the electrode connected to the output terminal of the electrode driver contact the same arm together, or contact the left and right arms respectively.

17. The electrocardiogram measuring device according to claim 1, wherein the current sensor detects contact between both hands and initiates electrocardiogram measurement.

18. The electrocardiogram measuring apparatus according to claim 1, wherein the gain amplitudes of the two amplifiers are the same within a tolerance range required by the amplifiers.

19. The electrocardiogram measuring device of claim 1, wherein the measured electrocardiogram lead (Lead) and the calculated electrocardiogram lead (Lead) are displayed on a smartphone display, and a tolerance of the measured electrocardiogram lead is smaller than a tolerance of the calculated electrocardiogram lead.

20. An electrocardiogram measuring device, comprising: a first electrode, a second electrode, and a third electrode for receiving first, second, and third electrocardiogram voltages from first, second, and third body parts in contact therewith, respectively; three amplifiers for receiving first, second, and third electrocardiogram voltages from the first, second, and third electrodes; An electrode driver outputs a driving voltage; a fourth electrode, contacting a fourth human body part and transmitting a fourth electrocardiogram voltage to an input terminal of an electrode driver; a fifth electrode, located near one of the four electrodes and transmitting the output of the electrode driver to the contacted human body part; an AD converter connected to an output terminal of each of the three amplifiers to convert output signals of the three amplifiers into three digital signals; A microcontroller for receiving three digital signals from the AD converter; as well as A communication device for transmitting three digital signals; wherein: The microcontroller receives power from the battery; The microcontroller controls the AD converter and the communication device; The three amplifiers respectively receive and amplify an electrocardiogram voltage simultaneously.

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