Electrocardiographic measurement device and electrocardiographic measurement method

Abstract

To provide an electrocardiographic measuring device capable of sufficiently amplifying an electrocardiographic signal, reducing power consumption, and being miniaturized regardless of a material such as stainless steel in which the magnitude and variation of electrode static potential cannot be ignored.SOLUTION: An electrode group including a plurality of electrodes in contact with the skin of a person to be measured; a high-pass filter group including a plurality of high-pass filters to which potential signals output from the electrodes included in the electrode group are respectively input; and, An electrocardiographic measurement device comprising: a multiplexer that selects and outputs a processed signal output from a set of any two high-pass filters included in a high-pass filter group; an amplifier that differentially amplifies the processed signal output from the multiplexer; an AD converter that performs analog-to-digital conversion on an amplified signal output from the amplifier; and a storage unit that stores a converted signal output from the AD converter in time series.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electrocardiogram measuring device and an electrocardiogram measuring method. [Background technology]

[0002] BACKGROUND ART Up until now, upper arm electrocardiographs have been proposed that are worn on the upper arm of a subject to measure electrocardiographic waveforms (for example, Patent Documents 1 and 2).

[0003] In this type of upper arm electrocardiograph, the upper arm is The signal obtained through the electrodes that come into contact with the skin at the site is very weak, at only a few tenths of the normal level, so it is difficult to observe unless it is amplified by nearly 60 dB.

[0004] In addition, such upper arm electrocardiographs generally use reusable stainless steel electrodes to monitor electrocardiogram waveforms over long periods of time. Stainless steel electrodes have a large and highly variable resting electrode potential, which must be removed to achieve high amplification of the signal acquired through the electrodes. Furthermore, because stainless steel electrodes are not adhesive, contact conditions change with body movement, resulting in noise.

[0005] Furthermore, since the locations at which characteristics of an electrocardiogram waveform appear vary depending on the subject, measurements must be taken at multiple locations to obtain an electrocardiogram waveform.

[0006] Furthermore, since the device is to be worn for a long period of time, it is required to be lightweight, small, and easy to wear, thereby reducing the discomfort of wearing it. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-147582 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-147583 Summary of the Invention [Problem to be solved by the invention]

[0008] The upper arm electrocardiographs described in Patent Documents 1 and 2 are designed to be used at a level where the influence of the electrode resting potential can be ignored. In reality, the presence of the electrode resting potential causes the signal to saturate when highly amplified, making measurement impossible. Furthermore, if the contact of the reference electrode becomes unstable, noise may occur in all electrode signals. Furthermore, the upper arm electrocardiograph described in Patent Document 2 is provided with a circuit including an instrumentation amplifier, an LPF, and an A / D converter for each electrode, which increases the circuit size and power consumption.

[0009] The present invention aims to provide an electrocardiogram measuring device that can sufficiently amplify electrocardiogram signals, reduce power consumption, and be miniaturized, even when using materials such as stainless steel, where the magnitude and variation of the electrode resting potential cannot be ignored. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides: an electrode group including a plurality of electrodes that come into contact with the skin of the subject; a high-pass filter group including a plurality of high-pass filters to which potential signals output from the electrodes included in the electrode group are respectively input; The processed signal output from the high-pass filter included in the high-pass filter group is a multiplexer that selects and outputs the processed signals that are input and output from a set of any two of the high-pass filters included in the high-pass filter group; an amplifier that differentially amplifies the processed signals output from the multiplexer; an AD converter that converts the amplified signal output from the amplifier into an analog-to-digital signal; a storage unit that stores the converted signals output from the AD converter in time series; The electrocardiogram measuring device is characterized by comprising:

[0011] According to this, potential signals output from the electrodes included in the electrode group are each input to a high-pass filter to remove electrode rest potential components, enabling sufficient amplification in the downstream amplifier. Furthermore, the multiplexer selects processed signals output from any pair of high-pass filters included in the high-pass filter group, making it possible to measure electrocardiogram waveforms from a pair of electrodes that are less affected by body movement. Furthermore, the multiplexer selects processed signals output from any pair of high-pass filters included in the high-pass filter group, making it possible to measure electrocardiogram waveforms from a larger number of electrode pairs with a smaller number of electrodes. Furthermore, the multiplexer selects and outputs processed signals output from any pair of high-pass filters included in the high-pass filter group, so only one system of circuitry is required downstream from the differential amplifier, thereby enabling the electrocardiogram measuring device to be made smaller.

[0012] In addition, in the present invention, The multiplexer may be configured to switch the processed signal from any one of the sets included in the group of high-pass filters in a time division manner and output the processed signal to the amplifier.

[0013] According to this, the processed signals from any pair of high-pass filters included in the group of high-pass filters are switched in a time-division manner and output from the multiplexer, so that for all pairs of any two electrodes included in the group of electrodes, electrocardiographic waveforms based on the potential signals output from those pairs of electrodes can be obtained. As a result, electrocardiographic waveforms that satisfy appropriate conditions can be used from among the electrocardiographic waveforms obtained from the group of electrodes including multiple electrodes.

[0014] In addition, in the present invention, The image forming apparatus may further include a signal extracting unit that extracts the converted signals stored in the storage unit in time series for each group.

[0015] According to this, the signal extraction unit obtains information on the time change of the converted signal obtained from a specific set of electrodes included in the electrode group.

[0016] In addition, in the present invention, The plurality of electrodes included in the electrode group may be made of stainless steel.

[0017] In this way, even if the electrodes included in the electrode group are made of stainless steel, which has a large and variable resting electrode potential component, the potential signals output from the electrodes are input to the high-pass filter, which removes the resting electrode potential component, allowing for sufficient amplification in the downstream amplifier.Furthermore, the electrodes can be used repeatedly for a long period of time.

[0018] In addition, in the present invention, The electrode group may be arranged on the upper arm of the person being measured.

[0019] The present invention also provides An electrocardiogram measurement method for measuring an electrocardiogram waveform of a subject, comprising: A group of electrodes including a plurality of electrodes in contact with the skin of the subject, acquiring a signal; a step of outputting a processed signal obtained by removing the resting electrode potential component from the potential signal; outputting the processed signal based on the potential signals acquired from a pair of any two of the electrodes included in the electrode group by switching the pair in a time-division manner; a step of differentially amplifying the set of processed signals that are switched and output in a time division manner and outputting an amplified signal; a step of outputting a converted signal obtained by analog-to-digital converting the amplified signal; storing the converted signals in time series; extracting the converted signals stored in time series for each of the sets in time series; Includes.

[0020] This removes the electrode rest potential component from the potential signal output from the electrodes included in the electrode group, enabling sufficient amplification in the downstream amplifier. Furthermore, because the processed signal based on the potential signal acquired from a pair of any two electrodes included in the electrode group can be switched between pairs in a time-division manner, it becomes possible to measure electrocardiogram waveforms from a pair of electrodes that is less affected by body movement. Furthermore, because the processed signal based on the potential signal acquired from a pair of any two electrodes included in the electrode group can be switched between pairs in a time-division manner, it becomes possible to measure electrocardiogram waveforms from a larger number of electrode pairs with a smaller number of electrodes. Furthermore, because the processed signal based on the potential signal acquired from a pair of any two electrodes included in the electrode group is differentially amplified by switching between pairs in a time-division manner, only one system of circuitry is required from the differential amplifier onward, thereby enabling the device to be more compact. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide an electrocardiogram measuring device that can sufficiently amplify electrocardiogram signals, reduce power consumption, and be miniaturized, even when materials such as stainless steel are used, in which the magnitude and variation of the electrode resting potential cannot be ignored. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing the appearance of an electrocardiograph according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing a hardware configuration of the electrocardiograph according to the embodiment. [Figure 3] FIG. 3 is a flowchart illustrating a processing procedure of the electrocardiogram measuring method in the electrocardiograph according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing sampling in the electrocardiograph according to the embodiment. [Figure 5] FIG. 5 is a schematic diagram showing details of one sampling in the electrocardiograph according to the embodiment. [Figure 6] FIG. 6 is a diagram schematically illustrating the structure of data stored in the electrocardiograph according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] An example of an embodiment of the present invention will be described below. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this example are not intended to limit the scope of the present invention to those only.

[0024] The electrocardiograph 10 is worn around the outer circumference of the subject's upper arm and measures electrocardiographic waveforms. The electrocardiograph 10 may also have a function for detecting biological signals other than electrocardiographic waveforms. The electrocardiograph 10 corresponds to the electrocardiographic measuring device of the present invention.

[0025] FIG. 1 is a perspective view showing the appearance of an electrocardiograph 10. As shown in FIG. The electrocardiograph 10 mainly includes a band 11 and a main body 12 provided on the band 11. The band 11 is fixed to the main body 12.

[0026] Main body 12 has a frame 121, an operation unit 123 provided on frame 121, a display unit 124 (see FIG. 2) provided on frame 121, a pair of support units 121a and 121b provided on frame 121, a first electrode 21 provided on support unit 121a, and a second electrode 22 provided on support unit 121b. Operation unit 123 has operation buttons for inputting instructions such as turning on / off the power of main body 12, starting measurement, and stopping measurement. Display unit 124 is composed of a liquid crystal display or the like that displays various information such as electrocardiogram waveforms.

[0027] When the electrocardiograph 10 is attached to the upper arm of a user, the support parts 121a and 121b are on the living body side (back side) of the frame 121, the operation part 123 is in a position where it can be operated with the user's fingers, etc., and the display part 124 is in a position where it can be seen by the user, that is, on the opposite side from the living body (front side). The support parts 121a and 121b are members formed in a substantially wedge shape from a flexible material that can be elastically deformed.

[0028] A first electrode 21 is fixed to the support portion 121a. A second electrode 22 is fixed to the other support portion 121b. The first electrode 21 and the second electrode 22 are used as sensors or transducers that detect electric potential. The first electrode 21 and the second electrode 22 are formed into plate shapes, for example, from stainless steel plates, and are spaced apart from each other.

[0029] The band 11 has a first band portion 111 and a second band portion 112. The first band portion 111 and the second band portion 112 are strip-shaped and extend in the longitudinal direction. Two electrodes, a third electrode 23 and a fourth electrode 24, are fixed to the first band portion 111. Two electrodes, a fifth electrode 25 and a sixth electrode 26, are fixed to the second band portion 114. The third electrode 23, the fourth electrode 24, the fifth electrode 25, and the sixth electrode 26 are formed into a plate shape using stainless steel plates. Here, an example is described in which six electrodes, the first electrode 21 to the sixth electrode 26, are arranged along the extension direction of the band 11. However, the number of electrodes and the arrangement of the electrodes are not limited to this, and the band 11 may include electrodes arranged in a direction perpendicular to the extension direction of the band 11, i.e., offset along the longitudinal direction of the arm when worn.

[0030] The main body 12 is fixed to a desired position on the user's upper arm, for example, using the band 11. The lengths of the first band portion 111 and the second band portion 112 of the band 11 may be constant regardless of the intended user, or may be varied depending on the intended user. For example, a lineup of bands 11 with lengths intended for adults, children, men, women, etc. may be available.

[0031] The first band portion 111 has one end 111a, the other end 111b, and an elastic portion 111c. A hook-and-loop fastener is formed on the other end 111b side, and the length of the first band portion 111 can be adjusted by adjusting the position of a folded portion 111d that passes through a ring member 114b (described later) and folds back, and then connecting the hook-and-loop fasteners by abutting each other.

[0032] The second band portion 112 has a strip-shaped band main body 113 and a ring-shaped ring member 114 provided at a position that will become the band end along the longitudinal direction of the second band portion 112. The band main body 113 has one end 113a, the other end 113b, and a folded-back portion 113c. The one end 113a and the other end 113b of the band main body 113 are continuous. The one end 113a of the band main body 113 is supported by the main body portion 12.

[0033] Fig. 2 is a diagram showing the hardware configuration of the electrocardiograph 10. Fig. 3 is a flowchart showing the processing steps of an electrocardiographic measurement method (method of measuring an electrocardiographic waveform) by the electrocardiograph 10. The electrocardiograph 10 mainly comprises an electrode group 20, an electrode resting potential removal unit 30 including a high-pass filter group 320, a switching unit 40, an amplification conversion unit 50, a control unit 60, a storage device 70, an operation unit 123, and a display unit 124. Equipped with.

[0034] The electrode group 20 includes a first electrode 21, a second electrode 22, a third electrode 23, a fourth electrode 24, a fifth electrode 25, and a sixth electrode 26. The first electrode 21 to the sixth electrode 26 included in the electrode group 20 come into contact with the skin of the user's upper arm when the electrocardiograph 10 is worn. Potential signals S11 to S16 generated at the contact sites are acquired. As shown in FIG. 3 , it is determined whether or not it is sampling time (step St101). When the sampling time arrives, the potential signals S11 to S16 generated at the contact sites are acquired by the first electrode 21 to the sixth electrode 26. The potential signals S11 to S16 are input via buffers 311 to 316 to a high-pass filter group 320 consisting of high-pass filters 321 to 326. That is, the potential signal S11 acquired by the first electrode 21 is input to the buffer 311, and the signal S21 output from the buffer 311 is input to the high-pass filter 221. The potential signal S12 acquired by the second electrode 22 is input to the buffer 312, and the signal S22 output from the buffer 312 is input to the high-pass filter 322. Similarly, the potential signal S16 acquired by the sixth electrode 26 is input to the buffer 316. The buffers 311 to 316 are circuits that adjust the impedance between the first electrode 21 to the sixth electrode 26 and the high-pass filters 321 to 326, respectively. The high-pass filters 321 to 326 are circuits that attenuate signals below a predetermined frequency, and by passing the signals through the high-pass filters 321 to 326, the electrode resting potential components included in the potential signals from the first electrode 21 to the sixth electrode 26 are removed. The high-pass filters 321-326 remove the electrode resting potential components due to the first electrode 21 to the sixth electrode 26 from the signals S21-S26 input from the buffers 311-316, and output processed signals S31-S36 to the multiplexer 41 (step St103). In this way, by removing the electrode resting potential components included in the potential signals from the first electrode 21 to the sixth electrode 26 using the high-pass filters 321-326, clipping in the amplification at the subsequent stage can be avoided, and the electrocardiographic signals obtained from the first electrode 21 to the sixth electrode 26 can be sufficiently amplified.Furthermore, with this configuration, stainless steel, which has a large electrode resting potential and a large variation in it, can be used as the electrode material, and therefore an electrocardiograph 10 that can be used repeatedly for a long period of time can be provided.

[0035] Based on a control signal from the control unit 60, the multiplexer 41 switches between sets of two processed signals from the six processed signals S31 to S36 input from the high-pass filters 321 to 326 in a time-division manner, according to a method described below, and outputs the signals to the instrumentation amplifier 42 (step St104). In this way, the multiplexer 41 switches between sets of two processed signals from the processed signals S31 to S36 in a time-division manner and outputs the signals to the instrumentation amplifier 42, making it possible to acquire electrocardiographic waveforms that meet appropriate conditions, such as electrode sets that are less affected by body movement. Furthermore, this configuration makes it possible to acquire electrocardiographic waveforms from a greater number of electrode sets using a smaller number of electrodes.

[0036] The instrumentation amplifier 42 is an operational amplifier for differential amplification having a high input impedance. The instrumentation amplifier 42 is a circuit that amplifies the difference between the two processed signals S41 and S42 input from the multiplexer 41 with a constant gain. Here, the instrumentation amplifier 42, or the instrumentation amplifier 42 and the amplifier circuit 51, correspond to the amplifier of the present invention.

[0037] The signal S50 output from the instrumentation amplifier 42 is input to the amplifier circuit 51 and amplified to a level at which the required resolution can be obtained. The amplified signal S60 output from the amplifier circuit 51 is input to the AD converter 52 (step St105).

[0038] The AD converter 52 is a circuit that converts the analog signal amplified by the amplifier circuit 51 into a digital signal. The converted signal S70, which is a digital signal output from the AD converter 52, is input to the control unit 60 (step St106). In this way, the multiplexer 41 As a result, a set of two processed signals is switched in a time-division manner from the processed signals S31 to S36 and output to the instrumentation amplifier 42, the amplifier circuit 51, and the AD converter 52, so that only one system of circuits is required downstream from the instrumentation amplifier 42. This reduces electrode consumption, makes it possible to miniaturize the electrocardiograph 10, and reduces discomfort when wearing it.

[0039] The control unit 60 is a microcomputer equipped with a CPU 61, a ROM (Read Only Memory) 62, and a RAM (Random Access Memory) 63. The electrocardiogram measurement method described herein is performed by executing a program stored in the ROM. The converted signal S70 input from the AD converter 52 is stored in the RAM 62 by the CPU 61 of the control unit 60, and then undergoes predetermined processing before being stored in the storage device 70, which is made up of a non-volatile memory (steps St107 and St108).

[0040] Next, the electrocardiogram measuring method according to this embodiment will be described in detail. FIG. 4 is a graph showing the sampling timing of an electrocardiogram waveform, with time [ms] on the horizontal axis and voltage [mV] on the vertical axis. In reality, the first electrode 21 to the sixth electrode 26 constituting the electrode group 20 are in contact with different parts of the user's upper arm, so they do not measure a single electrocardiogram waveform. However, a single electrocardiogram waveform is shown here as a schematic diagram to explain the sampling timing. For example, the electrocardiogram waveform is sampled every 8 ms. The vertical dashed lines in FIG. 4 indicate the sampling timing every 8 ms.

[0041] 5 shows an enlarged view of the switching method of multiplexer 41 in one sampling cycle indicated by the dotted circle in FIG. 4. Multiplexer 41 switches between pairs of two signals to be output to instrumentation amplifier 42 from processed signals S31 to S36 input from six high-pass filters 321 to 326 in a time-division manner. There are 15 possible signal pairs created from the six processed signals S31 to S36, and these 15 types of signal pairs are sequentially switched in a time-division manner to be input to instrumentation amplifier 42 as processed signals S41 and S42. As shown in FIG. 5, in one sampling cycle, the signal pairs output from multiplexer 41 are switched in succession from pair 1 to pair 2 to pair 3, up to pair 15, in units of μs.

[0042] In this way, each pair of processed signals is input in time series to the instrumentation amplifier 42 and the amplifier circuit 51, and is AD converted in the AD converter 52. In this way, the AD converted converted signals S70 are stored in time series in the RAM 63 of the control unit 60 (step St107). The configuration of the data stored in this RAM 63 is schematically shown in the upper part of FIG. 6. In this way, data of each processed signal pair is stored in RAM 63 in order from pair 1 to pair 15, and further, data of each processed signal sampled at the next timing is similarly stored in order from pair 1 to pair 15. Here, the RAM 63 corresponds to the storage unit of the present invention.

[0043] As described above, the data stored in RAM 63 of the control unit 60 is sorted by pair by the control unit 60, and as shown in the lower part of Fig. 6, only the data of pair 1 is extracted and stored in the storage device 70. Similarly, for each of the signal pairs of pair 2, pair 3, and pair 15, only the data of each pair is extracted and stored in the storage device 70 (step St108). Here, the control unit 60 corresponds to the signal extraction unit of the present invention.

[0044] That is, the pair of processed signals S41 and S42 output from the multiplexer 41 is switched in a time-division manner, and at a certain timing, only one signal pair is subject to subsequent processing, but by switching the multiplexer 41, all signal pairs are sequentially subject to subsequent processing. Then, in the control unit 60, the data of each signal pair is arranged in chronological order. The data is stored in RAM 63 as extracted data. By sorting the data in which different signal pairs are arranged in time series as described above and extracting the signals of each pair, each signal pair, i.e., an electrocardiogram waveform of any two electrode pairs of first electrode 21 to sixth electrode 26 included in electrode group 20, is measured. [Explanation of symbols]

[0045] 10 Electrocardiograph 20 electrode groups 21~26 electrodes 41 Multiplexer 42 Instrumentation Amplifier 51 Amplification circuit 52 AD converter 63 RAM 320 High-pass filters 321~326 High-pass filter

Claims

1. an electrode group including a plurality of electrodes that come into contact with the skin of the subject; a high-pass filter group including a plurality of high-pass filters to which potential signals output from the electrodes included in the electrode group are respectively input; a multiplexer that receives the processed signals output from the high-pass filters included in the high-pass filter group, and selects and outputs the processed signals output from a set of any two of the high-pass filters included in the high-pass filter group; an amplifier that differentially amplifies the processed signals output from the multiplexer; an AD converter that converts the amplified signal output from the amplifier into an analog-to-digital signal; a storage unit that stores the converted signals output from the AD converter in time series; An electrocardiogram measuring device comprising:

2. 2. The electrocardiogram measuring device according to claim 1, wherein the multiplexer switches the processed signal from any one of the high-pass filter groups in a time-division manner and outputs the processed signal to the amplifier.

3. 3. The electrocardiogram measuring apparatus according to claim 2, further comprising a signal extracting unit that extracts the converted signals stored in the storage unit in time series for each group.

4. 2. The electrocardiogram measuring device according to claim 1, wherein the plurality of electrodes included in the electrode group are made of stainless steel.

5. 5. The electrocardiogram measuring device according to claim 1, wherein the electrode group is placed on the upper arm of the subject.

6. An electrocardiogram measurement method for measuring an electrocardiogram waveform of a subject, comprising: acquiring a potential signal from each of a group of electrodes including a plurality of electrodes in contact with the skin of the subject; a step of outputting a processed signal obtained by removing the electrode resting potential component from the potential signal; outputting the processed signal based on the potential signals acquired from a pair of any two of the electrodes included in the electrode group by switching the pair in a time-division manner; a step of differentially amplifying the set of processed signals that are switched and output in a time division manner and outputting an amplified signal; a step of outputting a converted signal obtained by analog-to-digital converting the amplified signal; storing the converted signals in time series; extracting the converted signals stored in time series for each of the sets in time series; An electrocardiogram measurement method comprising:

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