JP2012065757A - Cardiac potential sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a cardiac potential sensor which can accurately remove a myoelectric signal containing cardiac potential signals.SOLUTION: The cardiac potential sensor includes: a first electrode 3 arranged in a site adjacent to muscle fiber group 2 dominated by one motor neuron; a second electrode 5 arranged in a site adjacent to the muscle fiber group 2 while separating an interval of the first electrode 3 and an innervation band 4 from the innervation band 4 of the muscle fiber group 2; and a signal processing part 6 to which the signals detected by the first electrode 3 and the second electrode 5 input respectively. The signal processing part 6 calculates the difference between the signal detected by the first electrode 3 and the signal detected by the second electrode 5.

Description

  The present invention relates to a cardiac potential sensor that detects a cardiac potential of, for example, a human body or an animal.

  A conventional electrocardiographic sensor will be described with reference to FIGS. In FIG. 10, a cardiac potential detection electrode 31 a and a common electrode 31 b for detecting cardiac potential are connected to the filter circuit 32. For example, as shown in FIG. 11, the electrocardiogram detection electrode 31a is fixed to the head of the human body, particularly the forehead, by a hair band 33 or the like, and the common electrode 31b is fixed to the arm, particularly the wrist, like a wristwatch. used. As described above, an electrocardiographic signal is detected between both electrodes fixed to the head and the arm. The cardiac potential signal detected by the cardiac potential detection electrode 31a and the common electrode 31b is input to the arithmetic circuit 35 after the commercial power source and high frequency noise are removed by the filter circuit 32 and amplified by the amplifier circuit 34. .

  On the other hand, as shown in FIG. 10, the myoelectric potential detection electrode 31 c for detecting myoelectric potential and the common electrode 31 b are connected to the filter circuit 36. The myoelectric potential detection electrode 31c is a belt, an adhesive tape, or the like at a portion between the cardiac potential detection electrode 31a and the common electrode 31b, for example, at the elbow or the base of the arm as in the example of FIG. Fixed. The myoelectric potential detection electrode 31c and the common electrode 31b detect the myoelectric potential waveform signal associated with the movement of the arm to which the myoelectric potential detection electrode 31c and the common electrode 31b are fixed.

  The myoelectric potential waveform signal detected by the myoelectric potential detection electrode 31c and the common electrode 31b is removed from the commercial power supply, high frequency noise, and the like by the filter circuit 36 in the same manner as the waveform signal of the previous cardiac potential. And then input to the arithmetic circuit 35.

  In the arithmetic circuit 35, in-phase components of the cardiac potential signal detected by the cardiac potential detection electrode 31a and the common electrode 31b and the myoelectric potential signal detected by the myoelectric potential detection electrode 31c and the common electrode 31b are removed.

JP-A-62-213728

  In the conventional electrocardiographic sensor described above, the myoelectric potential signal superimposed on the electrocardiographic signal detected by the electrocardiographic electrode 31a and the common electrode 31b is the muscle of the head to which the electrocardiographic electrode 31a is fixed. It is a time change of a potential difference between the potential of the fiber and the potential of the muscle fiber portion of the wrist to which the common electrode 31b is fixed. On the other hand, the myoelectric potential signal detected by the myoelectric potential detection electrode 31c and the common electrode 31b is the electric potential of the muscle fiber of the elbow to which the myoelectric potential detection electrode 31c is fixed and the wrist of the wrist to which the common electrode 31b is fixed. It is a time change of a potential difference with the potential of a muscle fiber. Therefore, the myoelectric potential signal superimposed on the cardiac potential signal detected by the cardiac potential detection electrode 31a and the common electrode 31b and the myoelectric potential signal detected by the myoelectric potential detection electrode 31c and the common electrode 31b are detected. Because the target muscle fibers are different, they are different.

  As a result, the arithmetic circuit 35 has a problem that the myoelectric potential signal included in the electrocardiographic signal cannot be accurately removed.

  Therefore, an object of the electrocardiographic sensor of the present invention is to accurately remove a myoelectric potential signal contained in an electrocardiographic signal.

  In order to achieve this object, the electrocardiographic sensor of the present invention includes a first electrode disposed in a region close to the muscle fiber group A controlled by one motor neuron, and the innervation zone of the muscle fiber group A. To the second electrode disposed in the region close to the muscle fiber group A separated by the distance between the first electrode and the innervation zone, and the signals detected by the first electrode and the second electrode, respectively. A signal processing unit, and the signal processing unit calculates a difference between the signal detected by the first electrode and the signal detected by the second electrode.

  In the electrocardiographic sensor of the present invention, both the first electrode and the second electrode are arranged close to the same muscle fiber group, and the signal detected by the first electrode and the second electrode are detected by the signal processing unit. The electrocardiographic signal is obtained by calculating the difference between the signals to be transmitted. On the other hand, after the signal transmitted from the motor neuron reaches the innervation zone, the myoelectric signal propagates from the innervation zone that exists in the middle of the length direction of the muscle fiber group toward both ends of the muscle fiber. It occurs based on depolarization. Therefore, the myoelectric potential generated at the same distance from the innervation zone is almost the same potential. Since the first electrode and the second electrode of the electrocardiographic sensor of the present invention are arranged so that the distance from the innervation zone is equal, the myoelectric potential detected at each electrode is approximated. Of value. Therefore, the myoelectric potential signal is difficult to be superimposed on the electrocardiographic signal obtained by calculating the difference between the signal detected at the first electrode and the signal detected at the second electrode, and a highly accurate electrocardiographic signal is It becomes possible to detect. Furthermore, since a highly accurate electrocardiographic signal can be detected using only two electrodes, the burden on the subject can be reduced.

Block diagram of an electrocardiographic sensor according to the present invention Diagram showing cardiac potential signal Block diagram of an electrocardiographic sensor according to the present invention Block diagram of an electrocardiographic sensor according to the present invention Block diagram of an electrocardiographic sensor according to the present invention The figure which shows the electrocardiogram signal on which the myoelectric signal was superimposed Diagram showing myoelectric signal Diagram showing an electrocardiogram signal from which the myoelectric signal is deleted Block diagram of an electrocardiographic sensor according to the present invention Block diagram of an electrocardiographic sensor according to the present invention Block diagram of a conventional electrocardiographic sensor Schematic layout of conventional electrocardiographic sensor

(Embodiment 1)
Hereinafter, the electrocardiographic sensor according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an electrocardiographic sensor according to the first embodiment.

  In FIG. 1, the electrocardiographic sensor 10 according to the first embodiment of the present invention is arranged on the surface of the skin 7 close to the muscle fiber group 2 controlled by one motor neuron 1 in the spinal cord 8. The first electrode 3 and the surface of the skin 7 close to the muscle fiber group 2 away from the innervation zone 4 by the distance between the first electrode 3 and the innervation zone 4 of the muscle fiber group 2 and the first electrode 2, the second electrode 5 disposed at a position other than the portion where 3 is disposed, the ground electrode 9 serving as a reference for the potential detected by the first electrode 3 and the second electrode 5, and the first electrode 3 and the second electrode 5. And a signal processing unit 6 to which the signals detected in the above are input.

  A method for detecting the cardiac potential signal by the cardiac potential sensor 10 will be described below. The cardiac potential generated by the heartbeat is transmitted through the body, and is detected by the first electrode 3 disposed closer to the heart than the second electrode 5 with the ground electrode 9 as a reference potential. Next, this cardiac potential is similarly detected by the second electrode 5 disposed at a position farther from the heart than the first electrode 3 with the ground electrode 9 as a reference potential. During this period, the cardiac potential is attenuated, and by calculating the difference between the cardiac potential signal detected by the first electrode 3 and the cardiac potential signal detected by the second electrode 5, for example, the cardiac potential as shown in FIG. Obtaining a potential signal. Conversely, even if the second electrode 5 is disposed closer to the heart than the first electrode 3, an electrocardiographic signal as shown in FIG.

  On the other hand, when the myofiber group 2 in which the electrocardiographic sensor 10 is disposed is activated, the myoelectric potential with the ground electrode 9 as a reference potential is detected by the first electrode 3 and the second electrode 5. After the signal transmitted from the motor neuron 1 reaches the innervation zone 4, the myoelectric signal is transferred from the innervation zone 4 that exists in the middle of the length direction of the muscle fiber group 2 to both ends of the muscle fiber. Propagation is caused by depolarization. Therefore, the myoelectric potentials generated at the same distance from the innervation zone 4 are almost the same.

  Since the first electrode 3 and the second electrode 5 of the electrocardiographic sensor 10 of the present invention are arranged so that the distance from the innervation zone 4 is equal, the muscles detected at the respective electrodes The potential is an approximate value. Therefore, the myoelectric potential signal is difficult to be superimposed on the electrocardiographic signal obtained by calculating the difference between the signal detected by the first electrode 3 and the signal detected by the second electrode 5 even during exercise. It is possible to detect a high electrocardiographic signal. Furthermore, since a highly accurate electrocardiographic signal can be detected using only two electrodes, the burden on the subject can be reduced. In addition, since all the electrodes are arranged in the same muscle fiber group 2, the wiring is not lengthened unlike the conventional electrocardiographic sensor shown in FIG. 11, and the size and cost can be reduced.

  Since the ground electrode 9 is for determining a reference potential, the ground electrode 9 does not need to be disposed on the same muscle fiber group 2 as the first electrode 3 and the second electrode 5, and touches a part of the body. It should be. The amplitude of at least one of the myoelectric potential signals detected from the first electrode 3 or the second electrode 5 may be adjusted by the signal processing unit 6. As a result, the amplitudes of the myoelectric potential signals detected from both electrodes can be made equal, and the myoelectric signal waveform is less likely to be superimposed after the difference between these two signals is calculated in the signal processing unit 6, resulting in higher accuracy. It is possible to detect a high electrocardiographic signal.

(Embodiment 2)
Hereinafter, the electrocardiographic sensor of the present invention according to Embodiment 2 will be described with reference to FIG.

  FIG. 3 is a block diagram of the electrocardiographic sensor according to the second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The first a electrode 11 and the second electrode 5 and the first b electrode 12 and the second electrode 5 are arranged on the surface of the skin 7 in the state of being close to the same muscle fiber group 2 as shown in FIG. The The ground electrode 9 is in contact with a part of the body. Thereby, the electrocardiographic signal is detected from each of the first a electrode 11 and the second electrode 5 and the first b electrode 12 and the second electrode 5 according to the principle described in the first embodiment. At the same time, a myoelectric potential signal is detected during the activity of the muscle fiber group 2 in which the electrodes are arranged close to each other. The signal processing unit 6 calculates the difference between the signals from the respective electrodes, thereby obtaining a waveform in which the myoelectric potential signal is superimposed on the cardiac potential signal. Here, a signal obtained by calculating a difference between signals detected by the first a electrode 11 and the second electrode 5 is referred to as a first signal, and a signal detected by the first b electrode 12 and the second electrode 5 A signal obtained by calculating the difference is referred to as a second signal. At this time, by comparing the signal levels of the myoelectric potential signal of the first signal and the myoelectric potential signal of the second signal and selecting a signal having a smaller signal level, a highly accurate electrocardiographic signal is detected. Is possible. For example, when comparing the signal levels of the myoelectric potential signal superimposed on the first signal and the myoelectric potential signal superimposed on the second signal, if the myoelectric potential signal of the first signal is smaller, It can be said that the interval between the innervation zone 4 and the first a electrode 11 was closer to the interval between the innervation zone 4 and the second electrode 5 than the interval between the innervation zone 4 and the first b electrode 12.

  Here, the signal level is the magnitude of the signal, and refers to the amplitude value or power value of the signal, the integral value for a certain time, the average value, or the like. When it is difficult to extract a myoelectric potential signal from the first signal or the second signal, the average value of the amplitude value or power value of the first signal itself over a certain period of time and the amplitude value or power of the second signal itself The smaller signal level may be selected by comparing the average value over a certain period of time. In general, since the amplitude value of the myoelectric potential signal is larger than that of the electrocardiographic signal, even if attention is paid to the first signal and the second signal in which the myoelectric potential signal is superimposed on the electrocardiographic signal, An electrode with a small myoelectric potential signal superimposed as a noise component with high accuracy can be selected.

  With such a configuration, the subject or the like is conscious so that the distance from the innervation zone is approximately the same in the case of the first electrode 3 and the second electrode 5 as in the electrocardiographic sensor of the first embodiment. And since it becomes unnecessary to arrange | position these electrodes 3 and 5, the attachment ease of a cardiac potential sensor can be improved. Further, even when the electrodes 5, 11, and 12 are displaced due to the subject exercising or the like, a highly accurate electrocardiographic signal is detected by selecting again the one with a lower signal level of the myoelectric signal waveform. It becomes possible. In addition, since all the electrodes are arranged in the same muscle fiber group 2, the wiring is not lengthened unlike the conventional electrocardiographic sensor shown in FIG. 11, and the size and cost can be reduced.

  In addition, the signal processing unit 6 compares the signal levels of the first signal and the second signal, and stops calculating the second signal for a predetermined period when the level of the first signal is low. Also good. In this case, the myoelectric potential signal superimposed on the first signal is more than the myoelectric potential signal superimposed on the second signal unless the attachment positions of the electrodes 5, 11, 12 are changed by the movement of the subject. Therefore, it is not necessary to calculate the second signal during a predetermined interval during which the attachment positions of the electrodes 5, 11, and 12 are expected not to change. Thereby, the power consumption of the electrocardiogram sensor can be reduced. Similarly, the signal processing unit 6 compares the signal levels of the first signal and the second signal, and stops calculating the first signal for a predetermined period when the level of the second signal is small. It is good. Thereby, it is possible to suppress an increase in power consumption of the electrocardiographic sensor.

  In the second embodiment, the first electrode 3 in the first embodiment is replaced with two electrodes, ie, the first a electrode 11 and the first b electrode 12, but the second electrode 5 side or both are provided. Two or more electrodes may be used. Thereby, a test subject etc. can arrange | position each electrode, without being conscious of the distance of each electrode from an innervation zone more.

(Embodiment 3)
Hereinafter, the electrocardiographic sensor of the present invention according to Embodiment 3 will be described with reference to FIG.

  FIG. 4 is a block diagram of the electrocardiographic sensor according to the third embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The first electrode 3 and the second electrode 5 are disposed on the surface of the skin 7 adjacent to the same muscle fiber group 2 as shown in FIG. The ground electrode 9 is in contact with a part of the body.

  According to the operation principle described in the first embodiment, an electrocardiogram signal is detected from the first electrode 3 and the second electrode 5, and at the same time, an electromyogram signal is generated during the activity of the muscle fiber group 2 arranged close to the electrodes 3 and 5. Detected. The cardiac potential signal is obtained by calculating a difference between signals from the respective electrodes in the signal processing unit 6. On the other hand, the myoelectric potential signal detected from the first electrode 3 and the second electrode 5 has either phase due to a difference in the distance from the innervation zone 4 between the first electrode 3 and the second electrode 5. May be late.

  Here, the signal processing unit 6 of the electrocardiographic sensor according to Embodiment 3 adjusts the phase of at least one of the signal detected by the first electrode 3 and the signal detected by the second electrode 3. have. By aligning the phases of both myoelectric potential signals by the phase adjusting unit 13, the both myoelectric potential signals become approximate myoelectric potential signals. By calculating the difference between them by the signal processing unit 6, it is difficult to superimpose myoelectric potential signals even during exercise, and it is possible to detect highly accurate electrocardiographic signals.

  With such a configuration, it is not necessary to accurately position the first electrode 3 and the second electrode 5 from the innervation zone 4, so that convenience is improved when the electrocardiographic sensor is attached. Further, even when the electrodes 3 and 5 are displaced, it is possible to detect the electrocardiographic signal with high accuracy by adjusting the phase of the myoelectric potential signal again by the phase adjusting unit 13. Moreover, since all the electrodes 3 and 5 are arrange | positioned in the same muscle fiber group 2, wiring is not lengthened like the conventional cardiac potential sensor shown in FIG. 11, and size reduction and cost reduction are attained. . In addition, the amplitude value of at least one of the myoelectric potential signals detected from the first electrode 3 or the second electrode 5 is adjusted in the signal processing unit 6 so that the amplitudes of the myoelectric potential signals detected from both the electrodes are approximately the same. By aligning, it becomes difficult to superimpose myoelectric potential signals after the difference is calculated, and it becomes possible to detect a more accurate electrocardiographic signal.

(Embodiment 4)
Hereinafter, the electrocardiographic sensor of the present invention according to Embodiment 4 will be described with reference to FIG.

  FIG. 5 is a block diagram of the electrocardiographic sensor according to the fourth embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. The first electrode 3 and the second electrode 5 are arranged on the surface of the skin 7 in the vicinity of the same muscle fiber group 2 as shown in FIG. The third electrode 14 is arranged on the surface of the skin 7 close to the muscle fiber group 2 and at a position away from the innervation zone 4 by the interval between the first electrode 3 and the innervation zone 4. The electrodes 3, 5, 14 are arranged on the surface of the skin 7 so that the distance between the first electrode 3 and the second electrode 5 is longer than the distance between the second electrode 5 and the third electrode 14. Yes.

  The ground electrode 9 is in contact with a part on the body. The signal processing unit 6 includes a first signal processing unit 15 and a second signal processing unit 16. The first electrode 3 and the second electrode 5 are connected to the first signal processing unit 15, and the third electrode 14 and the second signal processing unit 16 are connected. The electrode 5 is connected to the second signal processing unit 16.

  The first signal processing unit 15 calculates a difference between signals detected from the first electrode 3 and the second electrode 5 to obtain a third signal. The second signal processing unit 16 calculates a difference between signals detected from the third electrode 14 and the second electrode 5 to obtain a fourth signal.

  First, regarding the third signal, the first signal processing unit 15 detects the cardiac potential signal from the first electrode 3 and the second electrode 5 according to the principle described in the first embodiment, and at the same time, the arrangement of the electrodes 3 and 5 is arranged. It is obtained by detecting the myoelectric potential signal superimposed on the electrocardiographic signal when the myofiber group 2 is activated. Specifically, the third signal is obtained by calculating the difference between the signals obtained at the electrodes 3 and 5 in the first signal processing unit 15, and the third signal includes an electrocardiographic signal and Superimposed myoelectric signal is included. An example of the waveform of the third signal in which the myoelectric potential signal is superimposed on the cardiac potential signal is shown in FIG.

  Next, with respect to the fourth signal as well as the first signal processing unit 15, the second signal processing unit 16 uses the detection signal at the third electrode 14 and the second electrode 5 according to the principle described in the first embodiment. It is obtained by calculating the difference from the detection signal. However, since the distance between the third electrode 14 and the second electrode 5 is arranged to be narrower than the distance between the first electrode 3 and the second electrode 5, the electrocardiogram potential between the electrodes 5 and 14. The attenuation of the signal is smaller than the attenuation of the electrocardiographic signal between the electrodes 3 and 5. As a result, the level of the electrocardiogram signal included in the fourth signal is lower than the level of the electrocardiogram signal included in the third signal.

  On the other hand, during the activity of the muscle fiber group 2 in which the third electrode 14 and the second electrode 5 are arranged close to each other, myoelectric potential is detected from each of the third electrode 14 and the second electrode 5, and the second signal processing unit 16 By calculating the difference between the detection signals of the electrodes 5 and 14, the myoelectric potential signal is superimposed on the fourth signal. The myoelectric potential signal obtained from the second signal processing unit 16 has a first distance because the distance from the third electrode 14 to the innervation zone 4 is substantially equal to the distance from the first electrode 3 to the innervation zone 4. This is approximately approximate to the myoelectric potential signal in the third signal calculated by the signal processing unit 15. Therefore, an example of the fourth signal obtained by the second signal processing unit 16 is as shown in FIG. Here, the signal processing unit 6 further calculates the difference between the third signal and the fourth signal, thereby obtaining an electrocardiographic signal in which the myoelectric potential signal is attenuated as shown in FIG. In this way, myoelectric potential signals are not easily superimposed even during exercise, and it is possible to detect a highly accurate electrocardiographic signal. Furthermore, since all the electrodes 3, 5, 14 are arranged in the same muscle fiber group 2, the wiring is not lengthened, and downsizing and cost reduction are possible. In addition, since the distance between the 1st electrode 3 and the 2nd electrode 5 is made longer than the distance between the 2nd electrode 5 and the 3rd electrode 14, the distance between electrodes which detect a cardiac potential waveform can be expanded. Thus, the detectable electrocardiographic signal can be increased.

  In FIG. 5, the distance between the first electrode 3 and the second electrode 5 is longer than the distance between the third electrode 14 and the second electrode 5, but the present invention is not limited to this. If the interval between the second electrode 5 and the interval between the third electrode 14 and the second electrode 5 are different, an electrocardiographic signal in which the superimposed myoelectric potential signal is attenuated can be obtained. If the distance between the first electrode 3 and the second electrode 5 and the distance between the third electrode 14 and the second electrode 5 are different, the electrocardiographic signal between the first electrode 3 and the second electrode 5 This is because the attenuation amount and the attenuation amount of the electrocardiographic signal between the third electrode 14 and the second electrode 5 are different.

  In addition, since all the electrodes 3, 5, and 14 are arranged in the same muscle fiber group 2, the wiring is not long like the conventional electrocardiographic sensor shown in FIG. 11, and the size and cost can be reduced. It becomes. Further, the amplitude value of at least one of the myoelectric potential signals detected from the first electrode 3, the second electrode 5, or the third electrode 14 is adjusted by the signal processing unit 6, and the electrodes 3, 5, 14 By aligning the amplitudes of the detected myoelectric potential signals to the same extent, it becomes difficult to superimpose myoelectric potential signals after the difference is calculated, and it becomes possible to detect a more accurate electrocardiographic signal.

(Embodiment 5)
Hereinafter, the electrocardiographic sensor of the present invention according to Embodiment 5 will be described with reference to FIG.

  FIG. 8 is a block diagram of the electrocardiographic sensor according to the fifth embodiment. The same parts as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The first electrode 3, the second electrode 5, the 3a electrode 17, and the 3b electrode 18 are disposed on the surface of the skin 7 in the vicinity of the same muscle fiber group 2 as shown in FIG. The distance between the first electrode 3 and the second electrode 5 is longer than the distance between the second electrode 5 and the third a electrode 17 and the distance between the second electrode 5 and the third b electrode 18.

  The ground electrode 9 is in contact with a part of the body. The first electrode 3 and the second electrode 5 are connected to the first signal processing unit 15, and the third a electrode 17, the third b electrode 18, and the second electrode 5 are connected to the second signal processing unit 16.

  The first signal processing unit 15 calculates a difference between signals detected by the first electrode 3 and the second electrode 5 to obtain a third signal. The second signal processing unit 16 calculates the difference between the signals detected by the 3a electrode 17 and the second electrode 5 to obtain the 4a signal, and the signal detected by the 3b electrode 18 and the second electrode 5 The difference is calculated to obtain the 4b signal.

  In the activity of the myofiber group 2 in which the first electrode 3 and the second electrode 5 are arranged close to each other, the third signal is obtained by superimposing the myoelectric potential signal on the cardiac potential signal according to the principle described in the first embodiment. It becomes.

  Similarly, regarding the 4a signal and the 4b signal, the myoelectric potential signal is superimposed on the cardiac potential signal according to the principle described in the first embodiment. However, since the distance between the 3a electrode 17 and the second electrode 5 and the distance between the 3b electrode 18 and the second electrode 5 are narrower than the distance between the first electrode 3 and the second electrode 5, the electrodes 5, 17 And the attenuation of the electrocardiographic signal between the electrodes 5 and 18 are smaller than the attenuation of the electrocardiographic signal between the electrodes 3 and 5. Therefore, the level of the cardiac potential signal in the 4a signal and the 4th signal is lower than the level of the cardiac potential signal in the third signal.

  On the other hand, during the activity of the muscle fiber group 2 in which the electrodes 3, 5, 17, and 18 are closely arranged, myoelectric potentials are detected from the 3 a electrode 17, the 3 b electrode 18, and the second electrode 5, respectively, and second signal processing is performed. By calculating the difference between the electrodes 5 and 17 and the electrodes 5 and 18 by the unit 16, the myoelectric potential signal between the electrodes 5 and 17 and the myoelectric potential signal between the electrodes 5 and 18 are obtained.

  Here, for example, either the distance from the 3a electrode 17 to the innervation zone 4 or the distance from the third b electrode 18 to the innervation zone 4 is the distance from the first electrode 3 to the innervation zone 4. When the distance is equal, the level of the myoelectric potential signal in the third signal is approximately approximate to the level of the myoelectric potential signal in the 4a signal or the 4b signal. That is, by selecting the one closer to the distance from the first electrode 3 to the innervation zone 4 out of the distance from the third a electrode 17 to the innervation zone 4 or the distance from the third b electrode 18 to the innervation zone 4. The level of the myoelectric potential signal obtained by the first signal processing unit 15 and the level of the myoelectric potential signal obtained by the second signal processing unit 16 can be brought close to each other.

  Next, the signal processor 6 calculates the difference between the third signal and the 4a signal to obtain the 5a signal in which the myoelectric potential signal is attenuated, and similarly calculates the difference between the third signal and the 4b signal. As a result, the 5b signal in which the myoelectric potential signal is attenuated is obtained. At this time, the myoelectric potential signal of the 5a signal and the myogenic potential signal of the 5b signal are compared, and a signal having a smaller signal level is selected to detect a highly accurate electrocardiographic signal. Is possible. In this work, the distance closer to the distance from the first electrode 3 to the innervation zone 4 out of the distance from the third electrode 17 to the innervation band 4 or the distance from the third b electrode 18 to the innervation band 4 is selected. It is equivalent to the work to select.

  Here, the signal level is the magnitude of the signal, and indicates an amplitude value or power value of the signal, an integral value for a certain time, an average value, or the like. With such a configuration, it is necessary to arrange the first electrode 3 and the third electrode 14 so that the distances from the innervation zone 4 are substantially the same as in the electrocardiographic sensor of the fourth embodiment shown in FIG. This eliminates the convenience of attaching the electrocardiographic sensor. Further, even when the electrodes 3, 5, 17, and 18 are displaced, a highly accurate electrocardiogram is selected by selecting the one with the smaller signal level of the myoelectric signal superimposed on the 5a signal and the 5b signal again. A signal can be detected. Further, since all the electrodes are arranged in the same muscle fiber group 2, the wiring is not lengthened, and it is possible to reduce the size and cost. Further, when the signal processing unit 6 compares the 5a signal with the 5b signal and the level of the 5a signal is low, the calculation of the 5b signal may be stopped for a predetermined period. . In this case, the myoelectric potential signal superimposed on the 5a signal is the myoelectric potential signal superimposed on the second signal, as long as the attachment position of the electrodes 3, 5, 17, 18 is not changed by the subject's movement or the like. Therefore, it is not necessary to calculate the 5b signal during a predetermined period during which the attachment positions of the electrodes 3, 5, 17, and 18 are expected not to change. Thereby, the power consumption of the electrocardiogram sensor can be reduced. Similarly, the signal processing unit 6 compares the signal levels of the 5a signal and the 5b signal, and stops calculating the 5a signal for a predetermined period when the level of the 5b signal is small. It is good. Thereby, it is possible to suppress an increase in power consumption of the electrocardiographic sensor.

  In FIG. 8, the distance between the first electrode 3 and the second electrode 5 is longer than the distance between the third a electrode 17 and the second electrode 5 and the distance between the third b electrode 18 and the second electrode 5. However, the present invention is not limited to this. The distance between the first electrode 3 and the second electrode 5, the distance between the third a electrode 17 and the second electrode 5, and the distance between the third b electrode 18 and the second electrode 5 are as follows. If they are different, as a result, an electrocardiogram signal in which the superimposed myoelectric signal is attenuated can be obtained. If the distance between the first electrode 3 and the second electrode 5, the distance between the third a electrode 17 and the second electrode 5, and the distance between the third b electrode 18 and the second electrode 5 are different, the first electrode Between the third electrode 2 and the second electrode 5, the attenuation of the cardiac potential signal between the third a electrode 17 and the second electrode 5, and the third b electrode 18 and the second electrode 5. This is because the amount of attenuation of the electrocardiographic signal is different.

  In addition, since all the electrodes 3, 5, 17, and 18 are arranged in the same muscle fiber group 2, the wiring is not long like the conventional electrocardiographic sensor shown in FIG. 11, and the size and cost are reduced. Is possible. Further, the amplitude value of at least one of the myoelectric potential signals detected from the first electrode 3, the second electrode 5, the 3a electrode 17, or the 3b electrode 18 is adjusted in the signal processing unit 6, and each electrode 3 By aligning the amplitudes of the myoelectric potential signals detected from 5, 17, and 18 to the same extent, it becomes difficult to superimpose myoelectric potential signals after the difference is calculated, and it is possible to detect a more accurate electrocardiographic signal. Become.

(Embodiment 6)
Hereinafter, the electrocardiographic sensor of the present invention according to Embodiment 6 will be described with reference to FIG.

  FIG. 9 is a block diagram of the electrocardiographic sensor according to the sixth embodiment. The same parts as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The first electrode 3, the second electrode 5, and the third electrode 14 are disposed on the surface of the skin 7 in the vicinity of the same muscle fiber group 2 as shown in FIG. The distance between the first electrode 3 and the second electrode 5 is longer than the distance between the second electrode 5 and the third electrode 14. The ground electrode 9 is in contact with a part of the body. The first electrode 3 and the second electrode 5 are connected to the first signal processing unit 15, and the third electrode 14 and the second electrode 5 are connected to the second signal processing unit 16. The first signal processing unit 15 adjusts the phase of at least one of the signals detected from the first electrode 3 and the second electrode 5 by the first phase adjustment unit, and then calculates a difference to obtain a third signal. The second signal processing unit 16 adjusts the phase of at least one of the signals detected from the third electrode 14 and the second electrode 5 by the second phase adjustment unit, and then calculates a difference to obtain a fourth signal.

  Based on the principle described in the first embodiment, the third signal becomes an electrocardiographic signal on which the myoelectric potential signal is superimposed when the myofiber group 2 in which the electrodes 3, 5, and 14 are arranged close to each other. Similarly, the fourth signal is also an electrocardiographic signal on which the myoelectric potential signal is superimposed. However, since the distance between the third electrode 14 and the second electrode 5 is narrower than the distance between the first electrode 3 and the second electrode 5, the attenuation amount of the electrocardiographic signal between the electrodes 5 and 14 is the electrode 3, 5 is smaller than the attenuation amount of the electrocardiogram signal between 5. As a result, the signal level of the electrocardiogram signal in the fourth signal is smaller than the signal level of the electrocardiogram signal in the third signal.

  On the other hand, myoelectric potential is detected from each of the third electrode 14 and the second electrode 5 during the activity of the myofiber group 2 in which the electrodes 3, 5, and 14 are closely arranged, and the difference is calculated by the second signal processing unit 16. Thus, a myoelectric potential signal is obtained. If the distance from the third electrode 14 to the innervation zone 4 is equal to the distance from the first electrode 3 to the innervation zone 4, the myoelectric potential signal obtained from the second signal processing unit 16 is equal to the first signal processing unit. 15 is approximated to a myoelectric signal obtained from 15. However, when the electrodes 3, 5, and 14 cannot be arranged so that the distance from the third electrode 14 to the innervation zone 4 and the distance from the first electrode 3 to the innervation zone 4 cannot be equal, 3 and 14 cause a phase difference between the myoelectric potentials detected by the first signal processing unit 15 and the second signal processing unit 16. Therefore, the electrocardiographic sensor according to the sixth embodiment includes the first phase adjustment unit 19 in the first signal processing unit 15 and the second phase adjustment unit 20 in the second signal processing unit 16, respectively. The phase of at least one of the third signal and the fourth signal can be aligned using at least one of the adjusting units 19 and 20. Thereafter, the signal processing unit 6 calculates the difference between the third signal and the fourth signal, whereby the myoelectric potential signal can be attenuated with high accuracy, and a high-quality cardiac potential signal can be obtained. With such a configuration, it is not necessary to consciously arrange the distance from the innervation zone 4 so that the first electrode 3 and the second electrode 5 coincide with each other. improves. Further, even when the sensor is displaced, a highly accurate electrocardiographic signal is detected by adjusting the phase of the myoelectric potential signal again by at least one of the first phase adjusting unit 19 and the second phase adjusting unit 20. Is possible.

  In FIG. 9, the distance between the first electrode 3 and the second electrode 5 is longer than the distance between the third electrode 14 and the second electrode 5, but the present invention is not limited to this. If the distance between the second electrode 5 and the distance between the third electrode 14 and the second electrode 5 are different, as a result, an electrocardiographic signal in which the superimposed myoelectric potential signal is attenuated can be obtained. If the distance between the first electrode 3 and the second electrode 5 and the distance between the third electrode 14 and the second electrode 5 are different, the electrocardiographic signal between the first electrode 3 and the second electrode 5 This is because the attenuation amount and the attenuation amount of the electrocardiographic signal between the third electrode 14 and the second electrode 5 are different.

  In addition, since all the electrodes 3, 5, and 14 are arranged in the same muscle fiber group 2, the wiring is not long like the conventional electrocardiographic sensor shown in FIG. 11, and the size and cost can be reduced. It becomes. Further, the amplitude value of at least one of the myoelectric potential signals detected from the first electrode 3, the second electrode 5, or the third electrode 14 is adjusted by the signal processing unit 6, and the electrodes 3, 5, 14 By aligning the amplitudes of the detected myoelectric potential signals to the same extent, it becomes difficult to superimpose myoelectric potential signals after the difference is calculated, and it becomes possible to detect a more accurate electrocardiographic signal.

  In the electrocardiographic sensor according to the present invention, the length of each signal line that electrically connects each electrode and the signal processing unit may be substantially the same. Thereby, the amount of phase shift in each signal line connecting each electrode and the signal processing unit can be made uniform, and a highly accurate electrocardiographic signal can be calculated.

  As described above, the electrocardiogram sensor of the present invention is optimal for a device that detects an electrocardiogram signal during a period in which the body is moving, such as during exercise, because the myoelectric signal is not superimposed on the electrocardiogram signal.

DESCRIPTION OF SYMBOLS 1 Motor neuron 2 Muscle fiber group 3 1st electrode 4 Innervation zone 5 2nd electrode 6 Signal processing part 7 Skin 8 Spinal cord 9 Ground electrode 10 Electrocardiographic sensor 11 1a electrode 12 1b electrode 13 Phase adjustment part 14 3rd electrode DESCRIPTION OF SYMBOLS 15 1st signal processing part 16 2nd signal processing part 17 3a electrode 18 3b electrode 19 1st phase adjustment part 20 2nd phase adjustment part

Claims (12)

A first electrode disposed at a site close to a group of muscle fibers controlled by one motor neuron;
A second electrode disposed at a site close to the muscle fiber group separated from the innervation band of the muscle fiber group by an interval between the first electrode and the innervation band;
A signal processing unit to which signals detected by the first electrode and the second electrode are respectively input;
The signal processing unit is a cardiac potential sensor that calculates a difference between a signal detected by the first electrode and a signal detected by the second electrode. A 1a electrode, a 1b electrode, spaced apart from each other at a site close to a group of muscle fibers controlled by one motor neuron;
And a second electrode disposed in a region where the muscle fiber group is close to the first a electrode and the first b electrode,
A signal processing unit to which signals detected by the first a electrode, the first b electrode, and the second electrode are input;
The signal processing unit calculates a difference between the signal detected at the first electrode and the signal detected at the second electrode, and is detected by the signal detected at the first electrode and the second electrode. An electrocardiographic sensor that calculates the difference from the measured signal. The signal processing unit
A first signal obtained by calculating a difference between the signal detected by the first electrode and the signal detected by the second electrode;
Comparing the magnitude of the signal level of the second signal obtained by calculating the difference between the signal detected by the first b electrode and the signal detected by the second electrode;
When the signal level of the first signal is lower, the calculation of the second signal is stopped for a predetermined period,
The electrocardiographic sensor according to claim 2, wherein when the signal level of the second signal is smaller, the calculation of the first signal is stopped for a predetermined period. A first electrode disposed at a site close to a group of muscle fibers controlled by one motor neuron;
A second electrode disposed in a region close to the muscle fiber group and not disposed in the first electrode;
A signal processing unit to which signals detected by the first electrode and the second electrode are respectively input;
The signal processing unit adjusts the phase of at least one of the signal detected by the first electrode and the signal detected by the second electrode, and then adjusts the signal detected by the first electrode and the first signal. An electrocardiographic sensor that calculates a difference from a signal detected by two electrodes. The signal processing unit adjusts the amplitude of at least one of the signal detected by the first electrode and the signal detected by the second electrode, and then adjusts the signal detected by the first electrode and the first signal. The electrocardiographic sensor according to claim 1 or 4, wherein a difference from a signal detected by two electrodes is calculated. A first electrode disposed at a site close to a group of muscle fibers controlled by one motor neuron;
A second electrode disposed in proximity to the muscle fiber group;
A portion close to the muscle fiber group that is separated from the innervation zone of the muscle fiber group by an interval between the first electrode and the innervation zone, and the distance from the second electrode is the first electrode. And a third electrode disposed different from the interval between the second electrodes,
A signal processing unit to which signals detected by the first electrode, the second electrode, and the third electrode are respectively input;
The signal processing unit
Calculating the difference between the signal detected at the first electrode and the signal detected at the second electrode to obtain a third signal;
Calculating the difference between the signal detected at the second electrode and the signal detected at the third electrode to obtain a fourth signal;
An electrocardiographic sensor that calculates a difference between the third signal and the fourth signal. The electrocardiographic sensor according to claim 6, wherein a distance between the first electrode and the second electrode is longer than a distance between the second electrode and the third electrode. A first electrode, a second electrode, a 3a electrode, and a 3b electrode that are spaced apart from each other in a region close to a group of muscle fibers controlled by one motor neuron;
A signal processing unit to which signals detected at the first electrode, the second electrode, the 3a electrode, and the 3b electrode are input,
The signal processing unit
Calculating the difference between the signal detected at the first electrode and the signal detected at the second electrode to obtain a third signal;
Calculating the difference between the signal detected at the second electrode and the signal detected at the 3a electrode to obtain a 4a signal;
Calculating the difference between the signal detected at the second electrode and the signal detected at the 3b electrode to obtain a 4b signal;
An electrocardiographic sensor that calculates a difference between the third signal and the 4a signal and a difference between the third signal and the 4b signal. The signal processing unit
A 5a signal obtained by calculating a difference between the 3rd signal and the 4a signal;
Comparing the magnitude of the signal level with the 5b signal obtained by calculating the difference between the third signal and the 4b signal;
When the signal level of the 5a signal is lower, the calculation of the 5b signal is stopped for a predetermined period, and
9. The electrocardiographic sensor according to claim 8, wherein when the signal level of the 5b signal is lower, the calculation of the 5a signal is stopped for a predetermined period. A first electrode and a second electrode that are spaced apart from each other at a site close to a group of muscle fibers controlled by one motor neuron;
A third electrode disposed close to the muscle fiber group and disposed such that a distance from the second electrode is different from a distance between the first electrode and the second electrode;
A signal processing unit to which signals detected by the first electrode, the second electrode, and the third electrode are respectively input;
The signal processing unit
After adjusting the phase of at least one of the signal detected at the first electrode and the signal detected at the second electrode, the signal detected at the first electrode and the signal detected at the second electrode Calculating the difference from the signal to obtain a third signal,
After adjusting the phase of at least one of the signal detected by the second electrode and the signal detected by the third electrode, the signal detected by the second electrode and the signal detected by the third electrode Calculate the difference from the signal to obtain the fourth signal,
An electrocardiographic sensor that calculates a difference between the third signal and the fourth signal. The signal processing unit adjusts the amplitude of at least one of the signal detected by the first electrode, the signal detected by the second electrode, and the signal detected by the third electrode,
The electrocardiographic sensor according to claim 7 or 10, wherein the third signal and the fourth signal are calculated. Having a ground electrode placed on the body,
The signal detected by the ground electrode is used as a ground potential of the signal processing unit, according to any one of claims 1, 2, 4, 6, 8, and 10. The described electrocardiographic sensor.

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