Biological signal processing device

Abstract

To select an appropriate filter corresponding to noise to be mixed.SOLUTION: A biological signal processing device includes: a removal section which changes the strength of a filter according to a mixture degree of noise mixed in a biological signal and removes the noise from the biological signal with the use of the filter; and a control section which displays a state of the filter corresponding to a type of the noise, on a screen of a display section.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a biological signal processing device that processes a measured biological signal. [Background technology]

[0002] 2. Description of the Related Art In order to grasp the health state of a living body such as a human being, there are known biosignal testing devices, such as electrocardiographs, that measure and test the biosignals of the living body.

[0003] For example, an electrocardiograph is a device that measures and tests electrocardiograms (electrocardiograms), which are biosignals that indicate the electrical activity of a living body's heart, using electrodes attached to the skin of the living body, and can obtain information about cardiac activity by analyzing the electrocardiogram. Electrocardiograms measured in this way may contain, for example, myoelectric noise caused by muscle tension in the limbs, or AC noise caused by commercial power sources.

[0004] Because noise may be present in an electrocardiogram, a user of an electrocardiograph measures an electrocardiogram to visually determine whether or not noise is present, and if it is determined that noise is present in the measured electrocardiogram, the user sets a necessary filter. After setting the filter, the user measures an electrocardiogram and performs noise processing. Alternatively, the user of an electrocardiograph measures an electrocardiogram with a filter necessary for noise processing set in advance, and performs noise processing using the preset filter when the electrocardiogram is measured (see, for example, Patent Document 1).

[0005] A dedicated clinical laboratory technician who is familiar with setting electrocardiograph filters can often determine for himself whether or not noise is present. Therefore, a dedicated clinical laboratory technician can select an appropriate filter for noise processing for the measured electrocardiogram and perform noise processing. In addition, a dedicated clinical laboratory technician can prepare the skin of a living subject before measurement and optimize the measurement environment, thereby suppressing noise contamination caused by these factors when measuring an electrocardiogram.

[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 a filter can cause the R waves, which are formed by high-frequency components, to decrease in height (the height of the R waves becomes lower), or the shape of the J waves can change from a notch type to a slur type, or they may even disappear.

[0010] Therefore, it is necessary to perform noise processing using a filter depending on the noise that is mixed in, but 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 depending on the noise that is mixed in, 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 that can appropriately perform noise processing in accordance with the mixed noise. [Means for solving the problem]

[0012] The biological signal processing device according to the present invention comprises: a removal unit that changes the strength of a filter according to the degree of noise contamination in the biological signal and removes noise from the biological signal using the filter; The device is provided with a control unit that displays the state of the filter corresponding to the type of noise on the screen of the display unit.

[0013] Furthermore, the biological signal processing device according to the present invention comprises: A biological signal processing device that processes a biological signal, a calculation unit that calculates the degree of noise mixed into the biological signal; a determination unit that determines whether or not to change the strength of a filter that removes noise mixed into the biological signal according to the calculated degree of mixing; a removal unit that, when the determination unit determines that the filter strength should be changed, changes the filter strength and removes noise mixed in the biological signal using the changed filter; The calculation unit calculates the degree of noise mixed into the biological signal after the noise has been removed by changing the filter strength, The determination unit determines whether to change the strength of the filter that removes noise mixed into the biological signal after the noise has been removed, depending on the degree of mixing calculated from the biological signal after the noise has been removed. [Effects of the Invention]

[0014] According to the present invention, noise processing can be performed appropriately depending on the noise that is mixed in. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing an example of a biological signal testing device according to an embodiment of the present invention; [Figure 2] 2 is a flowchart illustrating a biological signal processing method performed by the biological signal testing device shown in FIG. [Figure 3]2 is a diagram showing an examination screen that displays a biological signal measured by the biological signal examination device shown in FIG. 1 and before signal processing. FIG. [Figure 4] FIG. 10 is a diagram showing an examination screen including a message displayed when noise is detected in a biological signal. [Figure 5] FIG. 10 is a diagram showing an examination screen including an operation window that is displayed when noise is detected in a biological signal. [Figure 6] FIG. 10 is a diagram showing an examination screen that displays a biological signal after signal processing. [Figure 7] FIG. 10 is a diagram showing an examination screen including an operation window that is displayed when noise is detected in a biological signal after signal processing. [Figure 8] FIG. 10 is a diagram showing an examination screen that displays a biological signal after further signal processing. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0017] [Biological signal testing device] 1 is a block diagram showing an electrocardiograph 10, which is an example of a biological signal testing device according to the present embodiment. Although an electrocardiograph 10 is shown here as an example, the present invention is applicable to any device that measures and tests biological signals.

[0018] The electrocardiograph 10 is a device that measures and tests an electrocardiogram (electrocardiogram), which is the electrical activity of the heart of a living organism (for example, a human body), as a biological signal.

[0019] The electrocardiograph 10 includes an electrode group 11, an A / D converter 12, a calculator 13, a determiner 14, a remover 15, an operation display unit 16, a memory unit 17, a communicator 18, a controller 19, and the like.

[0020] The electrode group 11 functions as an acquisition unit that acquires biosignals of a living body, and in this embodiment, is attached to the skin of the living body to detect electrical signals that become an electrocardiogram of the living body and input them to the A / D conversion unit 12. The electrode group 11 has a plurality of electrodes in order to acquire an electrocardiogram consisting of multiple types of leads, and for example, has four limb electrodes and six chest electrodes in order to acquire a standard 12-lead electrocardiogram.

[0021] For example, in a standard 12-lead electrocardiogram, as shown in Fig. 3 described later, the electrocardiogram detected by the limb electrodes includes bipolar limb leads (leads I, II, and III) and unipolar limb leads (leads aVF, aVR, and aVL).In addition, the electrocardiogram detected by the chest electrodes includes chest leads (leads V1 to V6).

[0022] The type and number of electrodes included in the electrode group 11 are changed depending on the type and number of electrocardiograms measured by the electrocardiograph 10. When the electrode group 11 detects electrical signals from a living body located away from the electrocardiograph 10, the detected electrical signals may be transmitted to the electrocardiograph 10 using a device such as a telemeter transmitter. In this case, if the detected electrical signals (analog signals) are converted into digital signals and transmitted to the electrocardiograph 10, the signals may be input to the calculation unit 13 without going through the A / D conversion unit 12 described below.

[0023] The A / D converter 12 converts the analog electrical signals input from each electrode of the electrode group 11 into digital signals, and outputs them to the calculator 13 as an electrocardiogram.

[0024] The calculation unit 13 calculates the degree of noise mixed into the electrocardiogram input from the A / D conversion unit 12. Specifically, the calculation unit 13 calculates the degree of noise mixed into each lead. Examples of noise include myoelectric noise, AC noise, and drift noise, and the calculation unit 13 calculates the degree of noise mixed into each lead.

[0025] Myoelectric noise is noise that occurs, for example, due to muscle tension in the limbs. The degree of myoelectric noise contamination is calculated, for example, by the method described below. First, a section other than the QRS wave is extracted from the electrocardiogram, for example, a section from the end point of the S wave to the start point of the next Q wave. Then, frequency analysis of the extracted section is performed, for example, using a fast Fourier transform, to calculate the power in the frequency range of myoelectric noise (25 to 75 Hz), thereby calculating the degree of myoelectric noise contamination. At this time, it is desirable to calculate the power in the frequency range of myoelectric noise, excluding the frequency range of commercial power (50 Hz or 60 Hz) described below.

[0026] AC noise is noise caused by, for example, commercial power sources. The degree of AC noise contamination is calculated, for example, by the method described below. First, a section other than the QRS wave is extracted from an electrocardiogram, for example, a section from the end of an S wave to the start of the next Q wave. Then, a frequency analysis of the extracted section is performed, for example, using a fast Fourier transform, to calculate the power in the frequency domain (50 Hz or 60 Hz) of the commercial power source, thereby calculating the degree of AC noise contamination.

[0027] Drift noise is noise caused by, for example, fluctuations in the baseline of an electrocardiogram due to breathing. The degree of drift noise contamination is calculated, for example, by the method described below. First, for a predetermined division point of the electrocardiogram, for example, the start point of a 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 the two consecutive Q waves is calculated to calculate the degree of drift noise contamination.

[0028] The calculation unit 13 calculates the degree of mixing of the above-mentioned myoelectric noise, AC noise, and drift noise for each predetermined time period, and outputs the calculated degree of mixing to the determination unit 14.

[0029] The calculation unit 13 not only calculates the degree of noise mixed into the electrocardiogram input from the A / D conversion unit 12, but also calculates the degree of noise mixed into the electrocardiogram after noise removal processing by the removal unit 15 described later.

[0030] The determination unit 14 determines whether to change the strength of the filter that removes noise mixed into the electrocardiogram, depending on the degree of mixing of myoelectric noise, AC noise, and drift noise calculated for the electrocardiogram input from the A / D conversion unit 12. Furthermore, the determination unit 14 determines whether to change the strength of the filter that removes noise mixed into the electrocardiogram, depending on the degree of mixing of myoelectric noise, AC noise, and drift noise calculated for the electrocardiogram after noise removal processing by the removal unit 15, which will be described later.

[0031] The determination unit 14 has set therein thresholds for determining whether or not to change the filter strength for the degree of myoelectric noise, AC noise, and drift noise. For example, when the degree of myoelectric noise is equal to or greater than the threshold, it determines that the filter strength should be changed. In addition, to improve the reliability of the determination, it may determine that the filter strength should be changed when the degree of myoelectric noise is equal to or greater than the threshold a predetermined number of times in succession. The same applies to the degree of AC noise and drift noise.

[0032] The above-mentioned threshold value and the predetermined number of consecutive times may be changed by the user of the electrocardiograph 10 depending on the measurement environment and the like.

[0033] The determining unit 14 outputs the determination result regarding the degree of mixing of myoelectric noise, AC noise, and drift noise to the removing unit 15.

[0034] The removal unit 15 changes the filter strength and removes mixed noise using the filter when the determination unit 14 determines that the filter strength should be changed for the electrocardiogram input from the A / D conversion unit 12. Furthermore, when the determination unit 14 determines 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 changes the filter strength and removes mixed noise using the filter.

[0035] The removal unit 15 has filters with multiple levels of strength, including a case where no filter is applied, for each of myoelectric noise, AC noise, and drift noise. As an example, the removal unit 15 has filters with three levels of strength, for each of myoelectric noise, AC noise, and drift noise: "OFF" where no filter is applied, "weak" where the filter strength is weak, and "strong" where the filter strength is strong. Note that, for simplicity of explanation, three levels of strength are used here, but more levels may be used.

[0036] The strength of the filter corresponding to myoelectric noise is adjusted, for example, by changing the bandwidth (area width) of the frequencies to be cut. For example, when the strength of the filter corresponding to myoelectric noise is "strong" rather than "weak," the bandwidth of the frequencies to be cut is made wider. The strength of the filter corresponding to drift noise is also adjusted, for example, by changing the bandwidth of the frequencies to be cut. For example, when the strength of the filter corresponding to drift noise is "strong" rather than "weak," the bandwidth of the frequencies to be cut is made wider.

[0037] The strength of the filter that handles AC noise can be adjusted by, for example, changing whether or not preprocessing is performed. For example, when the strength of the filter that handles AC noise is "weak," no preprocessing is performed, and frequencies other than the power supply frequency band are passed through a band-pass filter. On the other hand, when the strength is "strong," preprocessing is performed to remove high-frequency components using a high-cut filter with a predetermined cutoff frequency, and then frequencies other than the power supply frequency band are passed through a band-pass filter. Note that the strength of the filter that handles AC noise can be adjusted by changing the content of the preprocessing, for example, the cutoff frequency.

[0038] In the initial state of electrocardiogram measurement and testing by the electrocardiograph 10, the filter strengths for each of myoelectric noise, AC noise, and drift noise are "OFF." When the determination unit 14 determines that the filter strength should be changed, the removal unit 15 changes the filter strength to "weak" so that the filter strength is stronger than when the filter strength is not changed (for example, when the degree of noise contamination described above is less than the threshold). Even after that, when the determination unit 14 determines that the filter strength should be changed, the removal unit 15 changes the filter strength to "strong" so that the filter strength is stronger than when the filter strength is not changed.

[0039] When changing the filter strength in the removal unit 15, it is desirable to increase the filter strength by one step at a time. This is because, for example, when the filter strength is changed from "OFF" to "Strong," excessive noise processing may be applied, resulting in the degree of noise contamination described above falling below the threshold.

[0040] On the other hand, if the determination unit 14 determines that the filter strength should not be changed, the removal unit 15 leaves the current filter strength "OFF" if it is "OFF" and does not use a filter. Also, if the current filter strength is "weak," the removal unit 15 leaves it "weak" and uses the filter to remove the mixed noise. The same applies when the current filter strength is "strong."

[0041] As described above, the calculation unit 13, determination unit 14, and removal unit 15 determine whether or not to change the filter strength based on the degree of noise contamination for the electrocardiogram input from the A / D conversion unit 12 or the electrocardiogram after noise removal processing by the removal unit 15. If it is determined that the filter strength should be changed, the filter strength is changed, and if it is determined that the filter strength should not be changed, the filter is used as the current filter strength to remove the noise contaminating the electrocardiogram. In this way, the calculation unit 13, determination unit 14, and removal unit 15 perform signal processing of the electrocardiogram and correspond to the biological signal processing device of the present invention.

[0042] The calculation unit 13, the determination unit 14, and the removal unit 15 are configured as independent electronic circuits, for example. Note that the calculation unit 13, the determination unit 14, and the removal unit 15 may be configured so that their functions are programmed and executed by the control unit 19.

[0043] The operation display unit 16 is composed of, 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, various operation screens, etc., in accordance with a display control signal input from the control unit 19. The operation unit has various operation keys such as a numeric keypad and a start key, accepts input operations by the user to input various settings and instructions, and outputs operation signals to the control unit 19. The operation unit may also have input devices such as a keyboard, a pointing device (such as a mouse or trackball), and a voice input device.

[0044] The storage unit 17 is a storage device for saving measured electrocardiogram data, etc. The storage device may be, for example, a removable recording medium such as a nonvolatile memory card, a non-removable one such as an internal nonvolatile memory or an internal hard disk drive, or both.

[0045] Although not shown, the communication unit 18 performs communication processing to transmit and receive various information such as electrocardiograms to and from external computers, servers, etc. via networks such as telephone lines, LANs (Local Area Networks), WANs (Wide Area Networks), etc. The communication unit 18 is not limited to wired communication and may also perform wireless communication.

[0046] The control unit 19 controls the above-mentioned calculation unit 13, determination unit 14, removal unit 15, operation display unit 16, storage unit 17, communication unit 18, etc., to control the overall operation of the electrocardiograph 10. The control unit 19 is configured with, 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 processing programs stored in the ROM, loads them into the RAM, and executes various processes according to the loaded programs.

[0047] The printer 20 prints, for example, an electrocardiogram and an analysis report under the control of the control unit 19. If noise is mixed into the electrocardiogram, the type and degree of the mixed noise are printed together with the electrocardiogram and the analysis report.

[0048] [Biological signal processing method] Fig. 2 is a flowchart illustrating a biological signal processing method performed by the electrocardiograph 10 shown in Fig. 1. The biological signal processing method of this embodiment will be described with reference to Figs. 3 to 8 as well as Figs. 1 and 2. Figs. 3 to 8 show, as an example, a case where myoelectric noise occurs in lead V3 (see the portion indicated by the thick black arrow).

[0049] (Step S11) In the electrocardiograph 10, when the user inputs an operation to start an electrocardiogram test from the operation display unit 16, the control unit 19 detects electrical signals that become the electrocardiogram of the living body using the electrode group 11 attached to the skin of the living body, converts them into digital signals using the A / D conversion unit 12, and measures the electrocardiogram.

[0050] When the control unit 19 acquires the electrocardiogram from the A / D conversion unit 12, it displays an examination screen D1 shown in Fig. 3 on the operation display unit 16. Fig. 3 is a diagram showing the examination screen D1 that displays the electrocardiogram measured by the electrocardiograph 10 before signal processing.

[0051] The filter display area A1 displays the type and status of the filter and the level of noise contamination. "MF" indicates the filter status against myoelectric noise, "AC" indicates the filter status against AC noise, and "DF" indicates the filter status against drift noise. For "MF," "AC," and "DF," white text indicates that the filter is off, and black text indicates that the filter is on (see Figure 5, described below). Although not shown, when the filter is on, the area surrounding the black text may be displayed in different colors for "weak" and "strong." For example, the area surrounding the black text for "strong" is displayed in red to make it more noticeable on the screen than "weak." The numbers displayed next to each of "MF," "AC," and "DF" indicate the level of noise contamination. The noise contamination levels will be described later. Here, "5" is displayed as the maximum level of myoelectric noise. The minimum levels of AC noise and drift noise are displayed as "1."

[0052] (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 noise (myoelectric noise, AC noise, and drift noise) mixed into the electrocardiogram. The degree 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 leads I, II, and V1 to V6. The degree of AC noise is calculated for all leads together, and the degree of drift noise is also calculated for all leads together.

[0053] The method for calculating the degree of mixing of myoelectric noise, AC noise, and drift noise is as described above, so explanation will be omitted here, but the calculation unit 13 calculates the degree of mixing of myoelectric noise, AC noise, and drift noise every predetermined time period, for example, every 4 seconds.

[0054] (Step S13) The control unit 19 determines whether the mixing levels of myoelectric noise, AC noise, and drift noise are equal to or greater than a threshold value in order to determine whether to change the filter strength in the determination unit 14. If any one of the mixing levels of myoelectric noise, AC noise, and drift noise is equal to or greater than a threshold value (YES), the process proceeds to step S14, and if all of them are less than the threshold value (NO), the process returns to step S11.

[0055] To improve the reliability of the determination, the process may proceed to step S14 if the degree of inclusion of any one of myoelectric noise, AC noise, and drift noise exceeds the threshold value for a predetermined number of consecutive times. In this case, if the number of consecutive times that the degree of inclusion of any of myoelectric noise, AC noise, and drift noise exceeds the threshold value is less than the predetermined number of consecutive times, the process returns to step S11.

[0056] The above-mentioned threshold value and the predetermined number of consecutive times can be changed by the user of the electrocardiograph 10 depending on the measurement environment, etc. For example, regarding the threshold value, a plurality of threshold values ​​for classifying the degree of noise contamination into a plurality of levels (for example, 5 levels) are set in advance, and the user can select an appropriate threshold value depending on the measurement environment, etc. The levels are indicated by integers from 1 to 5, for example, and the smaller the level number, the smaller the degree of noise contamination.

[0057] The predetermined number of consecutive times can be changed to, for example, short, normal, or long, and the short number is set to three times, the normal number to four, and the long number to five.

[0058] (Step S14) The control unit 19 checks the current filter strength, and if the filter strength is "strong" (YES), returns to step S11, and if the filter strength is not "strong" (NO), proceeds to step S15. As described above, as an example, the removal unit 15 has filters with three levels of strength for each of myoelectric noise, AC noise, and drift noise: "OFF" for no filtering, "weak" for a weak filter strength, and "strong" for a strong filter strength. If the filter strength is "strong," there is no filter with a stronger strength, so the control unit 19 returns to step S11 and measures an electrocardiogram while maintaining the filter strength at "strong."

[0059] (Step S15) The control unit 19 determines whether or not to display the operation window, and if the operation window is to be displayed (YES), the process proceeds to step S17, and if the operation window is not to be displayed (NO), the process proceeds to step S16. Whether or not to display the operation window is set in advance by the user, and the control unit 19 determines whether or not to display the operation window by checking this setting.

[0060] (Step S16) If the control unit 19 determines in step S15 not to display the operation window, it displays an examination screen D2 including a message M1 shown in Fig. 4 on the operation display unit 16. Fig. 4 is a diagram showing the examination screen D2 including a message M1 that is displayed when noise is detected in an electrocardiogram.

[0061] If the user selects not to display the operation window, when the control unit 19 detects the above-mentioned noise in the electrocardiogram, it notifies the user that noise has been detected and that the filter strength will be changed by displaying a message M1 (notification unit) on the examination screen D2. In this case, the filter strength is automatically changed without the user having to perform any operation. In this example, a myoelectric noise of level "5" has occurred in lead V3, so the examination screen D2 shown in FIG. 4 displays a message M1 stating, "Noise has been detected. The filter will now be turned on. (MF)." Similar messages are also displayed in the cases of AC noise and drift noise.

[0062] (Step S17) On the other hand, when the control unit 19 determines in step S15 to display the operation window, it displays the examination screen D3 including the operation window W1 shown in Fig. 5 on the operation display unit 16. Fig. 5 is a diagram showing the examination screen D3 including the operation window W1 that is displayed when noise is detected in the electrocardiogram.

[0063] If the user selects the setting to display the operation window, the control unit 19 displays the operation window W1 (notification unit and input unit) on the examination screen D3 when the above-mentioned noise is detected in the electrocardiogram. By displaying the operation window W1, the user is notified that noise has been detected, and the user is prompted to input whether or not to allow the filter strength to be changed.

[0064] In this example, myoelectric noise of level "5" occurs in lead V3, so the operation window W1 displays the message "Noise detected. The filter will now be turned on. (MF)." The operation window W1 also displays the filter settings for myoelectric noise if they are to be changed. Note that no AC noise or drift noise is occurring, so the filter settings for AC noise and drift noise are displayed as "OFF."

[0065] The operation window W1 also displays a back button B11, a cross button B12, and an advanced settings button B13, which accept user operation inputs. When the user presses any of the back button B11, the cross button B12, and the advanced settings button B13, the control unit 19 determines whether or not to permit the filter change.

[0066] (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.

[0067] (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 mixed noise.

[0068] 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.

[0069] 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.

[0070] That is, in step S12, the calculation unit 13 also calculates the degree of noise mixed into the electrocardiogram after the noise removal process in step S19. Then, in step S13, the determination unit 14 determines whether or not to change the strength of the filter that removes noise mixed into the electrocardiogram, depending on the degree of noise mixed into the electrocardiogram after the noise removal process in step S19.

[0071] Then, the control unit 19 performs the processes of steps S14 to S18 described above. Steps S14 to S16 are basically the same as those described above, so redundant explanations will be omitted here.

[0072] Then, in steps S17 to S18, the control unit 19 displays an examination screen D5 including an operation window W2 shown in Fig. 7 on the operation display unit 16. Fig. 7 is a diagram showing an examination screen D5 including an operation window W2 that is displayed when noise is detected in an electrocardiogram after noise removal processing.

[0073] 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 examination screen D5. By displaying the operation window W2, the user is notified that noise has been detected, and the control unit 19 requests the user to input whether or not to allow the change in the filter strength.

[0074] 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 the message "Noise detected. Filter will now be turned on. (MF)." The operation window W2 also displays the filter settings for myoelectric noise if they are to be changed. Note that since no AC noise or drift noise is occurring, the filter settings for AC noise and drift noise are displayed as "OFF." The operation window W2 also displays the back button B21, the cross button B22, and the advanced settings button B23, which are the same as those in the operation window W1.

[0075] 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.

[0076] Then, in step S19, if the judgment unit 14 judges that the filter strength should be changed for the electrocardiogram after the noise removal process has been performed by the removal unit 15 last time, the removal unit 15 increases the filter strength by one step and uses the filter to remove any mixed noise.

[0077] 8 shows an examination screen D6 that displays an electrocardiogram after further noise removal processing. In this case, myoelectric noise has occurred 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.

[0078] (Step S20) In step S18, if the user presses the Advanced Settings button B13 displayed in the operation window W1, the control unit 19 stops the auto-filter function, that is, stops the function of automatically setting the filter strength described above. The same applies when the user presses the Advanced Settings button B23 displayed in the operation window W2. This is because the filter settings made by the user are given priority. Thereafter, the electrocardiograph 10 will measure an electrocardiogram using the filter set by the user (including when the filter is set to off).

[0079] As described above, the electrocardiograph 10 of this embodiment changes the filter strength depending on the degree of noise mixed into the measured electrocardiogram, and also changes the filter strength depending on the degree of noise mixed into the electrocardiogram after noise removal processing.

[0080] Therefore, the electrocardiograph 10 automatically sets a filter of appropriate strength depending on the degree of noise contamination. By setting a filter of appropriate strength, noise processing can be performed appropriately and electrocardiogram measurement and examination can be performed.

[0081] Furthermore, since a filter of appropriate strength is automatically set, the effort required for the user to perform operations can be reduced, and individual differences in filter settings by users can be eliminated, improving the quality of electrocardiogram measurements and examinations.

[0082] Furthermore, at the start of the test, the filter of the electrocardiograph 10 is turned off, so that if there is no noise, it is possible to measure and test an electrocardiogram with little distortion.

[0083] It should be noted that the above-described embodiments are merely examples of specific embodiments of the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be embodied in various forms without departing from the gist or main features thereof. [Explanation of symbols]

[0084] 10 Electrocardiograph 11 electrode group 12 A / D conversion section 13 Calculation section 14 Judgment section 15 Removal section 16 Operation display section 17 Memory section 18 Communications Department 19 Control Unit 20 Printers

Claims

1. a removal unit that changes a filter strength according to a degree of noise contamination in the biological signal and removes the noise from the biological signal using the filter; a control unit that displays the state of the filter corresponding to the type of noise on a screen of a display unit. Biosignal processing device.

2. the control unit displays the strength of the filter as the state of the filter. The biological signal processing device according to claim 1 .

3. The strength of the filter includes a state in which the filter is off. The biological signal processing device according to claim 2 .

4. The control unit displays the biological signal and the degree of contamination on the screen in association with each other. The biological signal processing device according to claim 1 .

5. the biological signal is an electrocardiogram of a living body; the control unit displays the degree of mixing of the noise into the leads of the electrocardiogram in association with the leads. The biological signal processing device according to claim 4 .

6. The control unit displays the degree of mixing using levels classified into a plurality of stages based on the mixed noise. The biological signal processing device according to claim 4 .

7. the control unit displays the degree of mixing in association with the type of noise. The biological signal processing device according to claim 4 .

8. a notification unit that notifies a user that the strength of the filter will be changed by the removal unit, The biological signal processing device according to claim 1 .

9. the notification unit displays an input unit on the screen through which the user inputs permission or denial of permission to change the strength of the filter; The removal unit When permission is input to the input unit, a process of changing the strength of the filter according to the degree of contamination is executed; If "not permitted" is input to the input unit, the process of changing the strength of the filter according to the degree of contamination is not executed. The biological signal processing device according to claim 8 .

10. A biological signal processing device that processes a biological signal, a calculation unit that calculates a degree of noise mixed into the biological signal; a determination unit that determines whether or not to change the strength of a filter that removes the noise mixed into the biological signal, depending on the calculated degree of mixing; a removal unit that, when the determination unit determines that the strength of the filter should be changed, changes the strength of the filter and removes the noise mixed in the biological signal using the filter; the calculation unit calculates a degree of noise mixing into the biological signal after the noise has been removed by changing the strength of the filter; the determination unit determines whether to change the strength of a filter that removes the noise mixed into the biological signal after the noise has been removed, according to the degree of mixing calculated from the biological signal after the noise has been removed. Biosignal processing device.

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