Biological signal processing device, biological signal inspection device, and biological signal processing method

Abstract

To select an appropriate filter corresponding to noise to be mixed.SOLUTION: A biological signal processing device performs signal processing of a biological signal. The biological signal processing device includes: a calculation section for calculating a mixture degree of noise to be mixed with a biological signal; a determination section for determining whether the strength of a filter for removing noise to be mixed with a biological signal is to be changed in response to the calculated mixture degree; and a removal section for removing noise to be mixed with a biological signal with the use of the filter by changing the strength of the filter when the determination section determines that the strength of the filter is to be changed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a biological signal processing device, a biological signal inspection device, and a biological signal processing method for performing signal processing on measured biological signals.

Background Art

[0002] In order to grasp the health state of a living body such as a human, a biological signal inspection device that measures and inspects the biological signals of the living body, for example, an electrocardiograph, is known.

[0003] For example, an electrocardiograph is a device that measures and inspects an electrocardiogram waveform (electrocardiogram), which is a biological signal indicating the electrical activity of the heart of a living body, with electrodes attached to the skin of the living body. By analyzing the electrocardiogram, information regarding the activity of the heart can be obtained. In the electrocardiogram measured in this way, for example, electromyographic noise due to muscle tension in the hands and feet, AC noise caused by commercial power supply, etc. may be mixed in.

[0004] Since noise may be mixed in the electrocardiogram, the user of the electrocardiograph measures an electrocardiogram for visually determining the presence or absence of noise mixing. When it is determined that there is noise mixing in the measured electrocardiogram, an operation of setting a necessary filter is performed. Then, after setting the filter, an electrocardiogram is measured and noise processing is performed. Alternatively, the user of the electrocardiograph measures the electrocardiogram with a filter necessary for noise processing set in advance, and performs noise processing using the filter set in advance when the electrocardiogram is measured (see, for example, Patent Document 1).

[0005] Professional clinical laboratory technicians who are familiar with setting the filter of the electrocardiograph can often judge the presence or absence of noise mixing by themselves. Therefore, professional clinical laboratory technicians and the like can select an appropriate filter for noise processing for the measured electrocardiogram and perform noise processing. In addition, professional clinical laboratory technicians and the like can optimize the skin treatment of the living body before measurement and the measurement environment, etc. Therefore, when measuring the electrocardiogram, it is also possible to suppress the mixing of noise caused by these.

[0006] On the other hand, for medical personnel other than full-time clinical laboratory technicians, it is possible to set the filters necessary for noise processing in the electrocardiograph in advance, as described above, in order to provide electrocardiograms with as little noise as possible. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-143911 Summary of the Invention [Problem to be solved by the invention]

[0008] When biological signals such as electrocardiograms are contaminated with noise, it can be difficult to obtain appropriate measurement values or analytical findings through automated analysis. On the other hand, when noise processing of biological signals is performed using a filter, excessive noise processing can occur, causing distortion in the waveform and preventing appropriate measurement values or analytical findings from automated analysis.

[0009] For example, in electrocardiograms, excessive noise processing by filters can cause the R waves, which are made up of high-frequency components, to decrease in height (the height of the R waves decreases), the shape of the J waves to change from a notch type to a slur type, or even disappear.

[0010] Therefore, it is necessary to perform noise processing using a filter according to the mixed noise, but in order to perform noise processing using a filter appropriately, the skills of a dedicated clinical laboratory technician are required. Therefore, there is a demand for a device that can perform appropriate noise processing according to the mixed noise, regardless of whether it is used by a dedicated clinical laboratory technician or any medical professional.

[0011] An object of the present invention is to provide a biological signal processing device, a biological signal inspection device, and a biological signal processing method capable of appropriately performing noise processing according to the noise to be mixed in.

Means for Solving the Problems

[0012] The biological signal processing device according to the present invention is a biological signal processing device that performs signal processing on a measured biological signal, a calculation unit that calculates the degree of noise mixing in the biological signal, a determination unit that determines whether to change the strength of a filter that removes the noise mixed in the biological signal according to the calculated degree of mixing, when it is determined by the determination unit that the strength of the filter is to be changed, a removal unit that changes the strength of the filter and uses the filter to remove the noise mixed in the biological signal, When it is determined by the determination unit that the strength of the filter is to be changed, a notification unit that notifies the user of the determination; and includes.

[0013] The biological signal inspection device according to the present invention is an acquisition unit that acquires a biological signal of a living body, the above biological signal processing device, and includes.

[0014] The biological signal processing method according to the present invention is a biological signal processing method that performs signal processing on a measured biological signal, calculating the degree of noise mixing in the biological signal, determining whether to change the strength of a filter that removes the noise mixed in the biological signal according to the calculated degree of mixing, when it is determined that the strength of the filter is to be changed, Notify the user of the determination; changing the strength of the filter and using the filter to remove the noise mixed in the biological signal.

Effects of the Invention

[0015] According to the present invention, noise processing can be appropriately performed according to the noise that is mixed in.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

[0018] [Biological Signal Inspection Device] FIG. 1 is a block diagram showing an electrocardiograph 10 which is an example of a biological signal inspection device according to the present embodiment. Here, the electrocardiograph 10 is illustrated, but the present invention is applicable to any device that measures and inspects biological signals.

[0019] The electrocardiograph 10 is a device that measures and examines an electrocardiogram waveform (electrocardiogram), which is the electrical activity of the heart of a living body (for example, a human body), as a biological signal.

[0020] The electrocardiograph 10 includes an electrode group 11, an A / D conversion unit 12, a calculation unit 13, a determination unit 14, a removal unit 15, an operation display unit 16, a memory unit 17, a communication unit 18, a control unit 19, and the like.

[0021] The electrode group 11 functions as an acquisition unit that acquires the biological signal of the living body. In this embodiment, it is attached to the skin of the living body, detects the electrical signal that becomes the electrocardiogram of the living body, and inputs it to the A / D conversion unit 12. The electrode group 11 has a plurality of electrodes in order to acquire an electrocardiogram composed of multiple types of leads. For example, in order to acquire a standard 12-lead electrocardiogram, it has limb electrodes (4) and chest electrodes (6).

[0022] For example, in a standard 12-lead electrocardiogram, as shown in FIG. 3 to be described later, as the electrocardiogram detected by the limb electrodes, there are bipolar limb leads (lead I, lead II, lead III), unipolar limb leads (lead aVF, lead aVR, lead aVL). Also, as the electrocardiogram detected by the chest electrodes, there are chest leads (V1 - V6 leads).

[0023] Note that the type and number of electrodes included in the electrode group 11 are changed according to the type and number of electrocardiograms measured by the electrocardiograph 10. Also, when detecting the electrical signal of a living body at a location far from the electrocardiograph 10 with the electrode group 11, the detected electrical signal may be transmitted to the electrocardiograph 10 using a device such as a telemeter transmitter. In this case, if the detected electrical signal (analog signal) is converted into a digital signal and transmitted to the electrocardiograph 10, it may be input to the calculation unit 13 without passing through the following A / D conversion unit 12.

[0024] The A / D conversion unit 12 converts the electrical signal, which is an analog signal input from each electrode of the electrode group 11, into a digital signal and outputs it to the calculation unit 13 as an electrocardiogram.

[0025] The calculation unit 13 calculates the degree of noise contamination in the electrocardiogram input from the A / D conversion unit 12. Specifically, the calculation unit 13 calculates the degree of noise contamination for each lead. Examples of noise include electromyogram noise, AC noise, and drift noise, and the degree of contamination is calculated for each type of noise.

[0026] Electromyogram noise is, for example, noise generated by muscle tension in the hands and feet. The degree of electromyogram noise contamination is calculated, for example, by the method described below. First, in the electrocardiogram, an interval other than the QRS complex, for example, the interval from the end point of the S wave to the start point of the next Q wave, is extracted. Then, frequency analysis of the extracted interval is performed using, for example, the fast Fourier transform to calculate the power in the frequency range of electromyogram noise (25 - 75 Hz), thereby calculating the degree of electromyogram noise contamination. At this time, it is desirable to calculate the power in the frequency range of electromyogram noise excluding the frequency range of the commercial power supply (50 Hz or 60 Hz) described below.

[0027] AC noise is, for example, noise caused by the commercial power supply. The degree of AC noise contamination is calculated, for example, by the method described below. First, in the electrocardiogram, an interval other than the QRS complex, for example, the interval from the end point of the S wave to the start point of the next Q wave, is extracted. Then, frequency analysis of the extracted interval is performed using, for example, the fast Fourier transform to calculate the power in the frequency range of the commercial power supply (50 Hz or 60 Hz), thereby calculating the degree of AC noise contamination.

[0028] Drift noise is, for example, noise caused by the baseline of the electrocardiogram fluctuating with respiration. The degree of drift noise contamination is calculated, for example, by the method described below. First, for a predetermined segmentation point of the electrocardiogram, for example, the start point of the Q wave, the values (potentials) of the start points of two consecutive Q waves are obtained. Then, the difference (potential difference) between the values of the start points of two consecutive Q waves is calculated, thereby calculating the degree of drift noise contamination.

[0029] The calculation unit 13 calculates, for example, the degree of contamination of the above-described myoelectric noise, AC noise, and drift noise at each predetermined time period, and outputs the result to the determination unit 14.

[0030] The calculation unit 13 not only calculates the degree of contamination of the noise mixed in the electrocardiogram input from the A / D conversion unit 12, but also calculates the degree of contamination of the noise mixed in the electrocardiogram after the noise removal process by the removal unit 15 described later.

[0031] The determination unit 14 determines whether to change the strength of the filter for removing the noise mixed in the electrocardiogram according to the degree of contamination of the myoelectric noise, AC noise, and drift noise calculated for the electrocardiogram input from the A / D conversion unit 12. Further, the determination unit 14 determines whether to change the strength of the filter for removing the noise mixed in the electrocardiogram according to the degree of contamination of the myoelectric noise, AC noise, and drift noise calculated for the electrocardiogram after the noise removal process by the removal unit 15 described later.

[0032] Thresholds for determining whether to change the strength of the filter are set in the determination unit 14 for the degree of contamination of the myoelectric noise, AC noise, and drift noise, respectively. For example, when the degree of contamination of the myoelectric noise is equal to or greater than the threshold, it is determined that the strength of the filter is to be changed. Further, in order to improve the reliability of the determination, when the degree of contamination of the myoelectric noise is continuously equal to or greater than the threshold for a predetermined number of consecutive times, it may be determined that the strength of the filter is to be changed. The same applies to the degree of contamination of the AC noise and the drift noise.

[0033] Note that the above-described thresholds and the predetermined number of consecutive times may be made changeable by the user of the electrocardiograph 10 or the like according to the measurement environment or the like.

[0034] The determination unit 14 outputs the determination result determined for the degree of contamination of the myoelectric noise, AC noise, and drift noise to the removal unit 15.

[0035] When the determination unit 14 determines that the strength of the filter needs to be changed for the electrocardiogram input from the A / D conversion unit 12, the removal unit 15 changes the strength of the filter and uses the filter to remove the interfering noise. Also, when the determination unit 14 determines that the strength of the filter needs to be changed for the electrocardiogram after the noise removal process was performed by the removal unit 15 last time, the removal unit 15 changes the strength of the filter and uses the filter to remove the interfering noise.

[0036] The removal unit 15 has filters with multiple levels of strength, including the case where no filter is applied, for each of the electromyogram noise, AC noise, and drift noise. As an example, the removal unit 15 is assumed to have filters with three levels of strength: "OFF" where no filter is applied, "weak" where the strength of the filter is weak, and "strong" where the strength of the filter is strong, for each of the electromyogram noise, AC noise, and drift noise. Here, for the sake of simplicity, it is described as having three levels of strength, but it may have even more levels.

[0037] As an example, the strength of the filter corresponding to the electromyogram noise is changed by changing the bandwidth (region width) of the frequency to be cut. For example, when the strength of the filter corresponding to the electromyogram noise is "strong" rather than "weak", the bandwidth of the frequency to be cut is widened. Similarly, as an example, the strength of the filter corresponding to the drift noise is changed by changing the bandwidth of the frequency to be cut. For example, when the strength of the filter corresponding to the drift noise is "strong" rather than "weak", the bandwidth of the frequency to be cut is widened.

[0038] The strength of the filter corresponding to the AC noise is changed, for example, by changing the presence or absence of preprocessing. For example, when the strength of the filter corresponding to the AC noise is "weak", no preprocessing is performed, and the frequency bands other than the power frequency band are passed through a band-pass filter. On the other hand, when it is "strong", preprocessing is performed to remove high-frequency components with a high-cut filter having a predetermined cut-off frequency, and then the frequency bands other than the power frequency band are passed through a band-pass filter. Note that the strength of the filter corresponding to the AC noise may be changed by changing the content of the preprocessing, for example, changing the above-mentioned cut-off frequency.

[0039] In the initial state of the measurement and inspection of the electrocardiogram by the electrocardiograph 10, the strength of the filter for each of the electromyogram noise, AC noise, and drift noise is "OFF". When it is determined by the determination unit 14 that the strength of the filter is to be changed, the removal unit 15 changes the strength of the filter to "weak" so that the strength of the filter is stronger than when the strength of the filter is not changed (for example, when the degree of noise mixing described above is less than the threshold). Even after that, when it is determined by the determination unit 14 that the strength of the filter is to be changed, the removal unit 15 changes the strength of the filter to "strong" so that the strength of the filter is stronger than when the strength of the filter is not changed.

[0040] When the removal unit 15 changes the strength of the filter, it is desirable to increase the strength of the filter step by step. This is because, for example, when the strength of the filter is changed from "OFF" to "strong", there is a possibility that the degree of noise mixing described above may become less than the threshold as a result of excessive noise processing.

[0041] On the other hand, when it is determined by the determination unit 14 that the strength of the filter is not to be changed, if the current strength of the filter is "OFF", it remains "OFF" and the filter is not used. If the current strength of the filter is "weak", it remains "weak", and the filter is used to remove the mixed noise. The same applies when the current strength of the filter is "strong".

[0042] As described above, the above-described calculation unit 13, determination unit 14, and removal unit 15 determine whether to change the strength of the filter according to the degree of noise mixing of the above-described electrocardiogram input from the A / D conversion unit 12 and the electrocardiogram after noise removal processing by the removal unit 15. When it is determined that the strength of the filter is to be changed, the strength of the filter is changed. When it is determined that the strength of the filter is not to be changed, the current strength of the filter is used to remove the noise mixed in the above-described electrocardiogram using the filter. In this way, the above-described calculation unit 13, determination unit 14, and removal unit 15 perform signal processing of the electrocardiogram, which corresponds to the biological signal processing device in the present invention.

[0043] The above-described calculation unit 13, determination unit 14, and removal unit 15 are configured as, for example, independent electronic circuits. Note that the above-described calculation unit 13, determination unit 14, and removal unit 15 may be configured to program their functions and execute them by the control unit 19.

[0044] The operation display unit 16 is configured by, for example, a liquid crystal display with a touch panel, and functions as a display unit and an operation unit. The display unit displays various information such as electrocardiograms and analysis reports, and various operation screens according to the display control signal input from the control unit 19. The operation unit includes various operation keys such as numeric keys and start keys, receives input operations for inputting various settings and instructions by the user, and outputs an operation signal to the control unit 19. The operation unit may include input devices such as a keyboard, a pointing device (mouse, trackball, etc.), and a voice input device.

[0045] The storage unit 17 is a storage device for storing measured electrocardiogram data and the like. The storage device may use a removable recording medium such as a non-volatile memory card, may be non-removable such as a built-in non-volatile memory or a built-in hard disk drive, or may include both.

[0046] Although not shown in the figure, the communication unit 18 performs communication processing for transmitting and receiving various types of information such as electrocardiograms between an external computer, server, etc. via a network such as a telephone line, LAN (Local Area Network), or WAN (Wide Area Network). The communication unit 18 may perform wireless communication as well as wired communication.

[0047] The control unit 19 controls the above-described calculation unit 13, determination unit 14, removal unit 15, operation display unit 16, storage unit 17, communication unit 18, etc., to control the operation of the entire electrocardiograph 10. The control unit 19 is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc. The CPU of the control unit 19 reads out various programs such as the processing program stored in the ROM and expands it in the RAM, and executes various processes according to the expanded program.

[0048] The printer 20 prints, for example, an electrocardiogram and an analysis report according to the control of the control unit 19. When noise is mixed in the electrocardiogram, the type and degree of the mixed noise are printed together with the electrocardiogram and the analysis report.

[0049] [Biological Signal Processing Method] FIG. 2 is a flowchart for explaining the biological signal processing method implemented by the electrocardiograph 10 shown in FIG. 1. The biological signal processing method of the present embodiment will be described with reference to FIGS. 1 and 2 and also FIGS. 3 to 8. In FIGS. 3 to 8, as an example, the case where electromyographic noise occurs in the V3 lead is shown (refer to the portion indicated by the thick black arrow).

[0050] (Step S11) In the electrocardiograph 10, when the user makes an operation input for starting the electrocardiogram examination from the operation display unit 16, the control unit 19 detects an electrical signal that becomes the electrocardiogram of the living body with the electrode group 11 attached to the skin of the living body, converts it into a digital signal by the A / D conversion unit 12, and measures the electrocardiogram.

[0051] When the control unit 19 acquires an electrocardiogram from the A / D conversion unit 12, it displays an inspection screen D1 shown in FIG. 3 on the operation display unit 16. FIG. 3 is an electrocardiogram measured by the electrocardiograph 10 and shows an inspection screen D1 that displays the electrocardiogram before signal processing.

[0052] Note that the filter display area A1 is an area for displaying the type, state of the filter, and the level of noise contamination. "MF" indicates the state of the filter for myoelectric noise, "AC" indicates the state of the filter for AC noise, and "DF" indicates the state of the filter for drift noise. In "MF", "AC", and "DF", white characters indicate that the filter is off, and black characters indicate that the filter is on (see FIG. 5 described later). Although not shown, in the state where the filter is on, the area surrounding the black characters may be set to different colors for "weak" and "strong". For example, in the case of "strong", in order to make it more prominent on the screen than in the case of "weak", the area surrounding the black characters is set to red. Also, the numerical values shown next to each of "MF", "AC", and "DF" indicate the level of noise contamination. Regarding the level of noise contamination, although it will be described later, here, assuming that the maximum level of myoelectric noise is occurring, the level "5" is displayed. Also, assuming that the minimum levels of AC noise and drift noise are occurring, the levels "1" are displayed for them.

[0053] (Step S12) When the control unit 19 acquires an electrocardiogram from the A / D conversion unit 12, the calculation unit 13 calculates the degree of contamination of the noise (myoelectric noise, AC noise, and drift noise) mixed in the electrocardiogram. The degree of contamination of myoelectric noise is calculated for each lead, and in the standard 12-lead electrocardiogram shown in FIG. 3, it is calculated for each of the I lead, II lead, and V1 - V6 leads. The degree of contamination of AC noise is calculated by summing up all the leads, and the degree of contamination of drift noise is also calculated by summing up all the leads.

[0054] The method for calculating the degree of contamination of EMG noise, AC noise, and drift noise is as described above. Therefore, although the explanation is omitted here, the calculation unit 13 calculates the degree of contamination of EMG noise, AC noise, and drift noise every predetermined time period, for example, every 4 seconds.

[0055] (Step S13) The control unit 19 determines in the determination unit 14 whether to change the strength of the filter, so it determines whether the degree of contamination of EMG noise, AC noise, and drift noise is equal to or greater than a threshold value. If the degree of contamination of any one of the EMG noise, AC noise, and drift noise is equal to or greater than the threshold value (YES), it proceeds to step S14. If all are less than the threshold value (NO), it returns to step S11.

[0056] Note that in order to improve the reliability of the determination, when the degree of contamination of any one of the EMG noise, AC noise, and drift noise becomes equal to or greater than the threshold value for a predetermined number of consecutive times or more, it may be configured to proceed to step S14. In this case, for any of the EMG noise, AC noise, and drift noise, if the number of consecutive times that the degree of contamination becomes equal to or greater than the threshold value is less than the predetermined number of consecutive times, it returns to step S11.

[0057] The above-mentioned threshold value and the predetermined number of consecutive times can be changed by the user of the electrocardiograph 10 or the like according to the measurement environment and the like. For example, for the threshold value, a plurality of threshold values for classifying the degree of contamination of the above-mentioned noise into a plurality of levels (for example, 5 levels) are set in advance, and the user can select an appropriate threshold value according to the measurement environment and the like. The level is indicated by an integer from 1 to 5, for example, and the smaller the numerical value of the level, the smaller the degree of contamination of the noise.

[0058] Also, for the predetermined number of consecutive times, it can be changed to, for example, a shorter, normal, or longer number of consecutive times. In the case of shorter, the number of consecutive times is set to 3 times, in the normal case, the number of consecutive times is set to 4 times, and in the longer case, the number of consecutive times is set to 5 times, etc.

[0059] (Step S14) The control unit 19 checks the current filter strength. If the filter strength is "strong" (YES), it returns to step S11. If the filter strength is not "strong" (NO), it proceeds to step S15. As described above, as an example, the removal unit 15 has filters with three levels of strength: "OFF" where no filter is applied to each of the myoelectric noise, AC noise, and drift noise, "weak" where the filter strength is weak, and "strong" where the filter strength is strong. When the filter strength is "strong", since there is no filter with a stronger strength, the control unit 19 returns to step S11 and measures the electrocardiogram while maintaining the filter strength at "strong".

[0060] (Step S15) The control unit 19 determines whether to display an operation window. If it is to display the operation window (YES), it proceeds to step S17. If it is not to display the operation window (NO), it proceeds to step S16. Whether to display the operation window is set in advance by the user, and the control unit 19 determines whether to display the operation window by checking this setting.

[0061] (Step S16) When the control unit 19 determines not to display the operation window in step S15, it displays on the operation display unit 16 an inspection screen D2 including the message M1 shown in FIG. 4. FIG. 4 is a diagram showing the inspection screen D2 including the message M1 displayed when noise is detected in the electrocardiogram.

[0062] When the user selects the setting not to display the operation window, if the control unit 19 detects the noise described above in the electrocardiogram, it notifies the user that the noise has been detected and that the filter strength will be changed by displaying the message M1 (notification unit) on the inspection screen D2. In this case, the filter strength is automatically changed without any operation by the user. Here, as an example, it is the case where electromyogram noise of level "5" occurs in the V3 lead, so the message M1 "Noise has been detected. The filter will be turned on. (MF)" is displayed on the inspection screen D2 shown in FIG. 4. The same message is displayed for AC noise and drift noise as well.

[0063] (Step S17) On the other hand, when the control unit 19 determines in step S15 to display the operation window, it displays on the operation display unit 16 the inspection screen D3 including the operation window W1 shown in FIG. 5. FIG. 5 is a diagram showing the inspection screen D3 including the operation window W1 displayed when noise is detected in the electrocardiogram.

[0064] When the user selects the setting to display the operation window, if the control unit 19 detects the noise described above in the electrocardiogram, it displays the operation window W1 (notification unit and input unit) on the inspection screen D3. By displaying the operation window W1, it notifies the user that the noise has been detected and requests the user to input permission or non - permission regarding changing the filter strength.

[0065] Here, as an example, it is the case where electromyogram noise of level "5" occurs in the V3 lead, so the message "Noise has been detected. The filter will be turned on. (MF)" is displayed on the operation window W1. Also, on the operation window W1, the filter setting for the electromyogram noise when it is changed is displayed. Regarding AC noise and drift noise, since no noise is occurring, it is displayed that the filter settings for AC noise and drift noise are "OFF".

[0066] In addition, the operation window W1 displays a back button B11, a cross button B12, and a detailed settings button B13, which accept operation inputs from the user. When the user presses any of the back button B11, the cross button B12, and the detailed settings button B13, the control unit 19 determines whether or not to permit the filter change.

[0067] (Step S18) When the user presses the back button B11 or the cross button B12 displayed in the operation window W1, the control unit 19 determines that this is an operation to permit the filter change (YES) and proceeds to step S19. On the other hand, when the user presses the advanced settings button B13 displayed in the operation window W1, the control unit 19 determines that this is an operation to prohibit the filter change (NO) and proceeds to step S20.

[0068] (Step S19) When the control unit 19 determines that the filter strength should be changed for the electrocardiogram input from the A / D conversion unit 12, the removal unit 15 increases the filter strength by one step and uses the filter to remove any noise that has been mixed in.

[0069] 6 shows the test screen D4 that displays the electrocardiogram after noise removal processing. In this case, myoelectric noise occurs in lead V3, so "MF" is displayed in black in the filter display area A1, and the level displayed next to it is displayed as "3," indicating that the level of myoelectric noise has been reduced.

[0070] After the noise removal process is performed in step S19, the electrocardiogram after the noise removal process is also subjected to the processes of steps S12 to S18 described above to check whether the noise removal process is sufficient.

[0071] That is, in step S12, the calculation unit 13 calculates the degree of noise mixing in the electrocardiogram after the noise removal process in step S19. Then, in step S13, the determination unit 14 determines whether to change the strength of the filter that removes the noise mixed in the electrocardiogram according to the degree of noise mixing calculated for the electrocardiogram after the noise removal process in step S19.

[0072] Then, the control unit 19 performs the processes of steps S14 to S18 described above. Regarding steps S14 to S16, basically, as described above, so here, duplicate explanations are omitted.

[0073] Then, in steps S17 to S18, the control unit 19 displays an inspection screen D5 including the operation window W2 shown in FIG. 7 on the operation display unit 16. FIG. 7 is a diagram showing the inspection screen D5 including the operation window W2 displayed when noise is detected in the electrocardiogram after the noise removal process.

[0074] Then, when the control unit 19 detects the above-mentioned noise in the electrocardiogram after the noise removal process, it displays an operation window W2 (notification unit and input unit) on the inspection screen D5. By displaying the operation window W2, the user is notified that noise has been detected, and the user is requested to input permission or non-permission regarding changing the strength of the filter.

[0075] Here, as an example, a case where myoelectric noise of level "4" occurs in lead V3. In other words, in the electrocardiogram after the previous noise removal process, myoelectric noise of level "4" remains in lead V3 without being removed. In this case, the operation window W2 also displays a message saying "Noise has been detected. The filter will now be turned on. (MF)". The operation window W2 also displays the filter settings for myoelectric noise when they are changed. Since no noise is occurring for AC noise and drift noise, the filter settings for AC noise and drift noise are displayed as "OFF". The operation window W2 also displays a back button B21, a cross button B22, and a detailed settings button B23, which are the same as those in the operation window W1.

[0076] Then, in step S18, when the user presses the back button B21 or the cross button B22 displayed in the operation window W2, the control unit 19 determines that this is an operation to permit the filter change (YES), and proceeds to step S19. On the other hand, when the user presses the advanced settings button B23 displayed in the operation window W2, the control unit 19 determines that this is an operation to prohibit the filter change (NO), and proceeds to step S20.

[0077] Then, in step S19, if the judgment unit 14 judges that the filter strength should be changed for the electrocardiogram after the previous noise removal process by the removal unit 15, the removal unit 15 increases the filter strength by one step and uses the filter to remove any mixed noise.

[0078] 8 is a diagram showing an examination screen D6 that displays an electrocardiogram after further noise removal processing. In this case, myoelectric noise occurs in lead V3, so "MF" is displayed in black in the filter display area A1, and the level displayed next to it is displayed as "2," indicating that the level of myoelectric noise has been reduced.

[0079] (Step S20) In step S18, when the detailed setting button B13 displayed on the operation window W1 is pressed by the user, the control unit 19 stops the autofilter function, that is, stops the function of automatically setting the filter strength described above. The same applies when the detailed setting button B23 displayed on the operation window W2 is pressed by the user. This is to give priority to the settings made by the user regarding the filter settings. Thereafter, the electrocardiograph 10 will perform electrocardiogram measurement using the filter set by the user (including the case where the filter is set to off).

[0080] As described above, the electrocardiograph 10 of the present embodiment changes the filter strength according to the degree of noise mixing in the measured electrocardiogram, and also changes the filter strength according to the degree of noise mixing in the electrocardiogram after the noise removal process.

[0081] Therefore, the electrocardiograph 10 automatically sets a filter with an appropriate strength according to the degree of noise mixing. By setting a filter with an appropriate strength, noise processing can be appropriately performed, and electrocardiogram measurement and inspection can be carried out.

[0082] In addition, since a filter with an appropriate strength is automatically set, the labor of the user's operation can be reduced, the individual differences in filter settings by the user can be eliminated, and the quality of electrocardiogram measurement and inspection can be improved.

[0083] Also, at the start of the inspection, since the filter of the electrocardiograph 10 is off, when there is no noise mixing, electrocardiogram measurement and inspection with less distortion can be performed.

[0084] It should be noted that the above embodiments are merely examples of specific implementations when implementing the present invention, and the technical scope of the present invention should not be limitedly interpreted by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

Explanation of Reference Numerals

[0085] 10 Electrocardiograph 11 Electrode group 12 A / D conversion unit 13 Calculation unit 14 Judgment unit 15 Removal unit 16 Operation display unit 17 Memory unit 18 Communication unit 19 Control unit 20 Printer

Claims

1. A biological signal processing device that performs signal processing on biological signals, a calculation unit that calculates the degree of noise contamination in the biological signal, a determination unit that determines whether to change the strength of a filter that removes the noise contaminating the biological signal according to the calculated degree of contamination, a removal unit that, when it is determined by the determination unit that the strength of the filter is to be changed, changes the strength of the filter and uses the filter to remove the noise contaminating the biological signal, a notification unit that, when it is determined by the determination unit that the strength of the filter is to be changed, notifies the user of the determination, comprising: a biological signal processing device.

2. When the calculation unit changes the strength of the filter to remove the noise contaminating the biological signal, the calculation unit calculates the degree of noise contamination in the biological signal after the noise has been removed, The determination unit determines whether to change the strength of a filter that removes the noise contaminating the biological signal after the noise has been removed according to the degree of contamination calculated from the biological signal after the noise has been removed, The biological signal processing device according to claim 1.

3. When the degree of contamination is equal to or greater than a predetermined threshold, the determination unit changes the strength of the filter so that it is stronger than when the degree of contamination is less than the predetermined threshold, The biological signal processing device according to claim 1 or 2.

4. The filter has multiple levels of strength including the case where the filter is not applied, When the degree of contamination is equal to or greater than a predetermined threshold, the determination unit changes the strength of the filter so that it is one level stronger than when the degree of contamination is less than the predetermined threshold, The biological signal processing device according to any one of claims 1 to 3.

5. The notification unit has an input unit for the user to input permission or non - permission for the change in the strength of the filter, When permission is input to the input unit, the removal unit changes the strength of the filter and removes the noise contaminating the biological signal, The biological signal processing device according to any one of claims 1 to 4.

6. An acquisition unit that acquires a biological signal of a living body, comprising the biological signal processing device according to any one of claims 1 to 5, a biological signal inspection device.

7. A biological signal processing method for performing signal processing on biological signals, comprising: calculating the degree of noise contamination in the biological signal, Determine whether to change the strength of a filter that removes noise mixed into the biological signal according to the calculated degree of mixing, If it is determined to change the strength of the filter, notify the user of the determination, change the strength of the filter, and use the filter to remove noise mixed into the biological signal. Biological signal processing method.

Images