JP2010154903A - Electronic hemomanometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic hemomanometer measuring blood pressure by a Korotkoff method and enhancing the measuring precision of blood pressure. <P>SOLUTION: The cuff of the electronic hemomanometer is provided with a microphone 51 for measuring Korotkoff sounds at the position coming into contact with the measuring region on the peripheral side of the cuff. Further, a microphone 54 for measuring the noise of the outside is provided on the outside of the cuff at the position near to the microphone 51. The sound inputted from the microphone 54 is compounded with the sound inputted from the microphone 51 after being reversed so as to become an inverse phase. By this constitution, the noise component inputted from the microphone 51 along with the Korotkoff sounds is reduced and the Korotkoff sounds are accurately extracted from the inputted sound from the microphone 51. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic sphygmomanometer, and more particularly to an electronic sphygmomanometer that measures blood pressure by the Korotkoff method.

  The blood pressure can be measured with an electronic sphygmomanometer by sending air into an air bag for compressing the arteries of the human body and calculating the blood pressure from the pressure pulse wave information of the human body generated from the air bag. Two methods are generally used: a Korotkoff method for measuring using a Korotkoff sound (hereinafter referred to as K sound) measured by a stethoscope and a microphone provided in the vicinity of the side artery.

  In the electronic sphygmomanometer adopting the Korotkoff method among the above two methods, a microphone (hereinafter referred to as a K sound microphone) for measuring K sound is provided on the downstream side of the arm band portion wound around the human body including the air bag. At the time of measurement, K sound corresponding to the sound of blood flow hitting the artery wall is measured in the process of gradually reducing pressure after sending air into the air bag to compress the measurement site and closing the artery. The blood pressure is calculated based on the air bag internal pressure when the K sound is detected for the first time since the start of decompression and when the K sound that has been detected continuously disappears thereafter.

  For this reason, an electronic sphygmomanometer that employs the Korotkoff method needs to accurately measure the K sound. As a technique for measuring an accurate K sound, for example, Japanese Patent Laid-Open No. 57-51836 (hereinafter referred to as Patent Document 1) discloses a plurality of K sounds in the arm circumferential direction at a position downstream of the arm band. A method is disclosed that enables measurement even when the winding position deviates from the arterial position by installing a microphone and selecting the output of the K-sound microphone that produces the largest output. Japanese Patent Application Laid-Open No. Sho 62-148641 (hereinafter referred to as Patent Document 2) installs a thin metal plate wider than the K-sound microphone in the arm circumferential direction at a position on the downstream side of the arm band. A method is disclosed in which the measurement range of the K sound is expanded by contacting with a metal, and the measurement can be performed even when the winding position deviates from the artery position.

  However, in the electronic sphygmomanometer disclosed in these documents, environmental sound that is ambient sound other than K sound (for example, rubbing sound when an air bag is inflated, external noise, etc.) is input to the K sound microphone. Will be. Therefore, if the ambient noise or body movement is large, the generated environmental sound is also input as a signal to the K sound microphone, and the measured K sound is easily affected by the environmental sound. As a result, the K sound is not accurately measured.

In order to deal with this problem, for example, Japanese Patent Application Laid-Open No. 61-247430 (hereinafter referred to as Patent Document 3) discloses a K sound microphone and a microphone (hereinafter referred to as C sound) for detecting sound from the cuff (hereinafter referred to as C sound). , C sound microphone), and a technique for discriminating cuff noise measured by the C sound microphone in the sound measured by the K sound microphone.
JP-A-57-51836 Japanese Patent Laid-Open No. 62-148641 JP-A 61-247430

  However, with the technique disclosed in Patent Document 3, it is possible to separate the downstream K sound and the noise sound (C sound) generated in the cuff, but noise such as ambient noise is a C sound microphone, Since both sound microphones are input, it is impossible to separate K sound from ambient noise using sound measured by the C sound microphone. Therefore, when the sound measured by the K sound microphone is affected by the surrounding environmental sound, noise is added to the measured K sound. In addition, since the K sound that the blood flow generated in the cuff hits the artery wall also affects the C sound, the pure K sound can be obtained even if the sound measured by the C sound microphone is excluded from the sound measured by the K sound microphone. It may not be only. Therefore, even with such a technique, there is a problem that it is difficult to measure an accurate K sound and the accuracy of the measurement result may be reduced.

  The present invention has been made in view of such a problem, and reduces noise components that are noise signals caused by measurement ambient sound, environmental sound, sound generated in a measurement cuff, and the like input to a K sound microphone. Thus, an object is to provide an electronic sphygmomanometer that accurately extracts K sound and improves the accuracy of blood pressure measurement.

  In order to achieve the above object, according to one aspect of the present invention, an electronic sphygmomanometer is provided with a fluid bag, mounting means for mounting the fluid bag in contact with the measurement site, and Korotkoff sounds from the measurement site. The first voice input means, the second voice input means for inputting a noise sound outside the mounting means in a state where the fluid bag is mounted on the measurement site by the mounting means, and the first voice input means Voice processing means for subtracting a component corresponding to the second voice inputted by the second voice input means from the first voice, and extraction for extracting Korotkoff sounds from the voice processed by the voice processing means And a calculating means for calculating a blood pressure value based on the extraction timing of the Korotkoff sound and the change in the internal pressure of the fluid bag obtained when the fluid bag is attached to the measurement site by the attaching means.

  Preferably, the sound processing means includes reversing means for reversing the second sound in reverse phase, and synthesizing means for synthesizing the second sound reversed in reverse phase by the reversing means with the first sound.

  More preferably, the sound processing means is configured so that the output level of the predetermined frequency range of the second sound is equal to the output level of the predetermined frequency range of the first sound. Adjustment means for adjusting the output level is further included, and the inversion means inverts the second sound adjusted by the adjustment means to an opposite phase.

  Preferably, the electronic sphygmomanometer further includes a third voice input unit for inputting a noise sound between the mounting unit and the measurement site in a state where the fluid bag is mounted on the measurement site by the mounting unit, and the voice processing unit Performs sound processing for subtracting the component corresponding to the second sound and the third sound input by the third sound input means from the first sound.

  Preferably, the voice processing means synthesizes the second voice and the third voice and generates a synthesized voice, an inverting means for inverting the synthesized voice to an opposite phase, and an inverting means for causing the opposite phase. And a second synthesis means for synthesizing the synthesized voice inverted to the first voice.

  More preferably, the speech processing means adjusts the output level of the synthesized speech over the entire frequency range so that the output level of the synthesized speech within the predetermined frequency range is equal to the output level of the first speech within the predetermined frequency range. And an inverting means for inverting the synthesized speech adjusted by the adjusting means to an opposite phase.

  Preferably, the second voice input means is provided on the side opposite to the fluid bag of the mounting means. Preferably, the third voice input means is provided between the mounting means and the fluid bag.

  Preferably, the electronic sphygmomanometer is provided with a member that prevents the voice input to the first voice input means at a position that is not in contact with the measurement site in a state of being attached to the measurement site by the mounting means of the first voice input unit. It is done.

  According to the present invention, K sound can be accurately extracted even in a noisy surrounding environment, and the accuracy of blood pressure measurement can be improved. Furthermore, artifacts due to body movement can be reduced and K sound can be extracted accurately, and the accuracy of blood pressure measurement can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

[First Embodiment]
An electronic sphygmomanometer (hereinafter referred to as a sphygmomanometer) 1A according to the first embodiment includes a cuff that encloses an air bag 13 (see FIG. 2). Wrap. The internal pressure of the air bladder 13 is controlled by a control mechanism that will be described later, and the blood pressure at the measurement site is calculated by measuring the pressure change in the air bladder 13.

  FIG. 1 is a diagram illustrating a specific example of the configuration of the cuff provided in the sphygmomanometer 1A. Referring to FIG. 1, the cuff provided in sphygmomanometer 1A includes air bag 13 used for blood pressure measurement inside an outer cloth. In the cuff, a central side corresponding to the upstream side of the artery and a peripheral side corresponding to the downstream side are predetermined. A Korotkoff sound (hereinafter referred to as “K sound”) measurement microphone (hereinafter referred to as “K sound microphone”) 51 is provided on the distal side of the cuff, that is, downstream of the artery and closest to the measurement site. It is done. That is, the K-sound microphone 51 is provided at a position on the downstream side of the artery and in contact with the measurement site when the cuff is attached to the measurement site. A microphone 54 for measuring external sound (hereinafter referred to as “noise microphone”) is provided on the distal side of the cuff, that is, downstream of the artery and outside the outer cloth. That is, the noise microphone 54 is provided at a position on the outer side of the outer cloth and opposite to the measurement site when the cuff is attached to the measurement site. As a result, K sound is mainly input to the K sound microphone 51, and sound outside the cuff is input to the noise microphone 54. In the following description, the sound outside the cuff is referred to as “noise”.

  Preferably, a sound absorbing material is provided between the K sound microphone 51 and the noise microphone 54 in a state of wrapping the distal side of the air bag 13. The material of the sound absorbing material is not limited to a specific material, and may be, for example, foamed neoprene rubber. In FIG. 1, an example in which the sound absorbing material is provided between the K sound microphone 51 and the noise microphone 54 is shown, but the sound absorbing material is used to block the input of sound other than Korotkoff sound in the K sound microphone 51. Since it is provided, it may be provided so as to cover at least a part of the part other than the part in contact with the measurement part of the K sound microphone 51, preferably all. However, even if a sound absorbing material is provided, it is difficult to completely block noise input to the K sound microphone 51, and it is considered that a certain amount of noise is input together with the K sound. Noise outside the cuff affects the extraction accuracy of the K sound. Therefore, the sphygmomanometer 1A has a function of reducing the noise component from the voice input to the K sound microphone 51 and extracting the K sound to calculate the blood pressure.

  FIG. 2 is a diagram showing functional blocks for realizing the above functions in the sphygmomanometer 1A. Referring to FIG. 2, sphygmomanometer 1 </ b> A includes an air system 20 connected to air bag 13 via an air tube, and a CPU (Central Processing Unit) 40 that controls the operation of air system 20.

  The air system 20 includes an air pump 21, an air valve 22, and a pressure sensor 23. The air pump 21 is connected to the drive circuit 26. The air valve 22 is connected to the drive circuit 27. The drive circuit 26 and the drive circuit 27 are both connected to the CPU 40 and drive the air pump 21 or the air valve 22 according to a control signal from the CPU 40, respectively. The air pump 21 is driven by a drive circuit 26 controlled by the CPU 40 and sends a predetermined amount of compressed gas into the air bag 13. Thereby, the air bag 13 is pressurized. The air valve 22 is driven by a drive circuit 27 controlled by the CPU 40 to open and close, and the air bag 13 is opened or closed. Thereby, the internal pressure of the air bag 13 is maintained or reduced.

  The pressure sensor 23 detects the pressure of the air bladder 13 and outputs a sensor signal corresponding to the detected value to the amplifier 28. The amplifier 28 amplifies the sensor signal output from the pressure sensor 23 and outputs it to the A / D converter 29. The A / D converter 29 digitizes the sensor signal, which is an analog signal output from the amplifier 28, and outputs it to the CPU 40.

  The K sound microphone 51 provided in the cuff is connected to the CPU 40 via the amplifier 52 and the A / D converter 53. The noise microphone 54 is connected to the CPU 40 via the amplifier 55 and the A / D converter 56. The K sound microphone 51 includes a sound pressure sensor (not shown), mainly detects the sound pressure in the K sound frequency band, and outputs a sound signal, which is a sensor signal corresponding to the detected value, to the amplifier 52. . The amplifier 52 amplifies the sensor signal output from the sound pressure sensor included in the K sound microphone 51 and outputs the amplified signal to the A / D converter 53. The A / D converter 53 digitizes the audio signal that is an analog signal output from the amplifier 52 and outputs the digitized audio signal to the CPU 40. The noise microphone 54 includes a sound pressure sensor (not shown), detects a sound pressure in a frequency band that is somewhat wider than the detection range of the sound pressure sensor included in the K sound microphone 51, and a sensor signal corresponding to the detected value. Is output to the amplifier 55. The amplifier 55 amplifies the sensor signal output from the sound pressure sensor included in the noise microphone 54 and outputs the amplified signal to the A / D converter 56. The A / D converter 56 digitizes the audio signal that is an analog signal output from the amplifier 55 and outputs it to the CPU 40.

  An operation unit 3 including a key for starting measurement, a key for calling up and displaying a memory, and the like is provided at a position where the blood pressure monitor 1A body is easy to operate, such as the front. Moreover, the display part 4 comprised with a liquid crystal display etc. is provided in the position where it is easy to see. The operation unit 3 is connected to the CPU 40 and inputs an operation signal according to a key operation to the CPU 40. The display unit 4 is connected to the CPU 40 and displays a designated screen in accordance with a control signal from the CPU 40. The blood pressure monitor 1A further includes a memory 41. The memory 41 stores measurement results and programs executed by the CPU 40.

  The CPU 40 includes a blood pressure calculation unit 42 and an audio signal processing unit 43. These are functions mainly formed in the CPU 40 when the CPU 40 reads out and executes the program stored in the memory 41 in accordance with an operation signal from the operation unit 3, but at least some of these functions are included. The hardware configuration shown in FIG. 2 may be used. The audio signal processing unit 43 receives the audio signal input from the K sound microphone 51 via the amplifier 52 and the A / D converter 53 and the sound input from the noise microphone 54 via the amplifier 55 and the A / D converter 56. A K sound is extracted by processing the signal, and a signal indicating the K sound is input to the blood pressure calculation unit 42. The blood pressure calculation 42 calculates a blood pressure value based on the signal input from the audio signal processing unit 43 and the sensor signal input from the pressure sensor 23 via the amplifier 28 and the A / D converter 29. Specifically, the blood pressure value calculated here corresponds to systolic blood pressure that means the highest blood pressure value and diastolic blood pressure that means the lowest blood pressure value.

  FIG. 3 is a diagram illustrating a specific example of the configuration of the audio signal processing unit 43. With reference to FIG. 3, the audio signal processing unit 43 includes an input unit 431, an adjustment unit 432, an inversion unit 433, a first synthesis unit 434, and an extraction unit 435.

  The input unit 431 inputs the audio signal from the K sound microphone 51 via the amplifier 52 and the A / D converter 53 and the audio signal from the noise microphone 54 via the amplifier 55 and the A / D converter 56. Accept the input. Among the input audio signals, the audio signal from the K sound microphone 51 is input to the first synthesis unit 434 and the adjustment unit 432. The audio signal from the noise microphone 54 is input to the adjustment unit 432. The adjustment unit 432 determines the level of the sensor value in a predetermined frequency range among the audio waves indicated by the audio signal from the noise microphone 54, and the sensor in the predetermined frequency range of the audio wave indicated by the audio signal from the K sound microphone 51. The value is adjusted so as to be the same as the value level, and is input to the inverting unit 433. The inversion unit 433 performs inversion processing so that the audio wave indicated by the audio signal from the noise microphone 54 adjusted by the adjustment unit 432 has an opposite phase, and inputs the audio wave to the first synthesis unit 434. The first synthesizing unit 434 indicates an audio wave indicated by the audio signal from the K sound microphone 51 input from the input unit 431 and an audio signal from the noise microphone 43 that has been input from the inversion unit 433 and that has been subjected to the adjustment and inversion processing. The sound wave is synthesized and input to the extraction unit 435. The extraction unit 435 extracts the K sound from the voice wave synthesized by the first synthesis unit 434 and inputs a signal indicating the K sound to the voice calculation unit 42.

  FIG. 4 is a diagram for specifically explaining the relationship between an audio wave indicated by an audio signal input from the K sound microphone 51, an audio wave indicating noise, and an audio wave indicating K sound. In FIG. 4, waveform 1 represents an audio wave representing noise, waveform 2 represents an audio wave of K sound, and waveform 3 represents an audio wave indicated by an audio signal input from K sound microphone 51. Since the K sound microphone 51 receives a certain amount of noise in addition to the K sound as described above, the sound wave indicated by the sound signal input from the K sound microphone having the waveform 3 is the K sound and the outside of the cuff. It represents a composite wave with noise.

  The frequency range of a person's K sound is defined statistically. That is, as shown in FIG. 4, the K sound wave represented by the waveform 2 exists in the range of the frequencies F1 to F2, and does not exist in the other ranges. That is, it can be said that the sound wave in the range of the frequencies F1 to F2 is a sound wave caused by noise.

  5 and 6 are diagrams for explaining the principle of audio processing in the audio signal processing unit 43. In FIG. 5, a waveform 1 ′ represents an audio wave indicated by an audio signal input from the noise microphone 54. The adjustment unit 432 adjusts the sound pressure level of the sound signal input from the noise microphone 54 using the fact that the sound wave of the K sound exists in the range of the frequencies F1 to F2 and does not exist in the other ranges. The sound level is adjusted to be equal to the level of the audio signal input from the K sound microphone 51. That is, the adjustment unit 432 stores in advance the range of the frequencies F1 to F2 as the frequency range of the human K sound, and sets the sound pressure level outside the range of the frequencies F1 to F2 of the waveform 1 ′ to the waveform 3 Adjustment is made to be equal to the sound pressure level outside the range of the frequencies F1 to F2. In the example of FIG. 5, the adjustment unit 432 generally adjusts the sound pressure of the waveform 1 ′ because the sound pressure level outside the range of the frequencies F1 to F2 of the waveform 1 ′ is higher than that of the waveform 3. A process of decreasing the predetermined amount is performed. As shown in FIG. 1, since the noise microphone 54 is installed outside the cuff, more noise is input than the K sound microphone 51 installed inside the cuff. For this reason, it is generally considered that the sound pressure level outside the range of the frequencies F1 to F2 of the waveform 1 ′ is generally higher than that of the waveform 3, so that the adjustment unit 432 performs the sound processing of the waveform 1 ′ as the adjustment process. A process of reducing the pressure by a predetermined amount as a whole is performed. However, depending on the performance of the K sound microphone 51 and the noise microphone 54 and the sensor level, the sound pressure level may be detected in reverse. Therefore, the adjustment unit 432 may perform the reverse process, that is, a process of increasing the sound pressure of the waveform 1 ′ by a predetermined amount as a whole. As a result, the waveform 1 ′ becomes the sound pressure level indicated as waveform 1 in FIG. 5, and the sound pressure level outside the range of the frequencies F1 to F2 becomes equal to that of the waveform 3. That is, it can be said that the waveform 1 after the adjustment processing corresponds to the noise component in the waveform 3.

  The inversion unit 433 and the first synthesis unit 434 include a so-called noise removal circuit. FIG. 6 is a diagram illustrating noise processing using a noise removal circuit in the inversion unit 433 and the first synthesis unit 434.

  Referring to FIG. 6, the inversion unit 433 performs inversion processing so that the phase of the sound wave due to noise adjusted to have waveform 1 in FIG. 5 is reversed, and the first synthesis unit 434 performs waveform processing in FIG. 5. 3, the noise component in the waveform 3 is canceled by the anti-phase noise component to be synthesized. Thereby, the noise component in the waveform 3 can be reduced.

  FIG. 7 is a flowchart showing a specific example of the flow of blood pressure measurement operation in the sphygmomanometer 1A. The operation shown in the flowchart of FIG. 7 is started when a key instructing the start of measurement included in the operation unit 3 is pressed, and the CPU 40 reads the program stored in the memory unit 41 to read the program shown in FIGS. This is realized by controlling each unit shown in FIG.

  Referring to FIG. 7, when the operation is started, each part is initialized in CPU 40 in step S1, and then in step S2, a control signal is output to drive circuits 26 and 27 to add air bag 13. Pressure is started. When the pressure signal from the pressure sensor 23 detects that the internal pressure of the air bag 13 has reached a predetermined pressure (YES in step S5), the CP 40 outputs a control signal to the drive circuit 26 in step S7 to The pressurization is ended, a control signal is output to the drive circuits 26 and 27, the air valve 22 is opened, and the pressure reduction of the air bag 13 is started. The predetermined pressure is higher than a general systolic blood pressure and is, for example, about 200 mmHg. After step S7, the air bag 13 is depressurized at a predetermined depressurization speed of, for example, about 4 mmHg / sec.

  When the decompression of the air bladder 13 starts in step S7, the CPU 40 starts sound measurement using the K sound microphone 51 and the noise microphone 5 in step S9. When voice measurement is started in step S9, voice signals are input to the input unit 431 from the K-sound microphone 51 and the noise microphone 54 at predetermined intervals. In step S11, the voice signal processing unit 43 performs the above-described voice signal. Processing is executed.

  The extraction unit 435 determines that the K sound has started when the K sound is first detected from the input audio signal (YES in Step S13), and inputs a signal indicating that to the blood pressure calculation unit 42. In step S <b> 15, the blood pressure calculation unit 42 calculates systolic blood pressure that is a maximum blood pressure value based on the pressure signal at that time from the pressure sensor 23.

  The extraction unit 435 continues to extract the K sound from the input audio signal after the K sound is started in step S13. Thereafter, when it is no longer detected, it is determined that the K sound has disappeared from the audio signal input at that time (YES in step S17), and a signal indicating that is input to the blood pressure calculation unit. In step S <b> 19, the blood pressure calculation unit 42 calculates diastolic blood pressure that is a minimum blood pressure value based on the pressure signal at that time from the pressure sensor 23.

  When the calculation of the blood pressure value is completed, the CPU 40 outputs a control signal to the drive circuits 26 and 27 in step S21 to release the pressure in the air bladder 13 to atmospheric pressure. In step S23, the CPU 40 displays the systolic blood pressure, which is the highest blood pressure value calculated in step S15, and the diastolic blood pressure, which is the lowest blood pressure value calculated in step S19, on the display unit 4 as measurement results. Processing is performed, the measurement result is displayed, and the series of operations is terminated.

  The sound pressure, the internal pressure of the air bladder 13 and the calculated blood pressure value in the above operation will be specifically described with reference to FIG. FIG. 8A shows the pressure change of the air bladder 13 during the above series of operations. FIG. 8B is a sound pressure input from a sound pressure sensor (not shown) included in the K sound microphone 51 and the noise microphone 54, and represents a change in the sound pressure after the above processing.

  By performing the above-described audio signal processing in the audio signal processing unit 43 in step S11, the audio input from the K sound microphone 51 is input from the noise microphone 54 indicated by the dotted line in FIG. 8B. The noise component corresponding to the voice is reduced. As a result, as represented by a thick line in FIG. 8B, the sound pressure representing the K sound is more accurately extracted. When the K sound is extracted by the extraction unit 435 as shown in FIG. 8B, it is determined in step S13 that the K sound has started at time t1 in FIG. 8B. In step S17, it is determined that the K sound has disappeared at time t2 in FIG. Therefore, in step S15, the blood pressure calculation unit 42 calculates the systolic blood pressure based on the internal pressure of the air bladder 13 at time t1, and in step S19, calculates the diastolic blood pressure based on the internal pressure of the air bladder 13 at time t2. Is done.

  Thus, since the blood pressure monitor 1A can reduce the noise component from the voice measured as described above, the start point and the vanishing point of the Korokotov sound can be accurately extracted, and the maximum blood pressure value and the minimum Measurement accuracy of the blood pressure value can be improved.

[Second Embodiment]
By the way, the K sound microphone 51 receives not only the K sound and the noise outside the cuff but also the sound in the cuff such as a rubbing sound between the air bag 13 and the measurement site and a sound accompanying body movement. Hereinafter, the sound in the cuff that is input to the K sound microphone 51 together with the K sound and the noise outside the cuff is referred to as “C sound”. Similar to the noise outside the cuff, the C sound component also affects the extraction accuracy of the K sound. Therefore, the sphygmomanometer 1B according to the second embodiment reduces the noise component outside the cuff and the C sound component from the sound input from the K sound microphone 51.

  FIG. 9 is a diagram illustrating a specific example of the configuration of the cuff provided in the sphygmomanometer 1B. Referring to FIG. 9, the cuff provided in sphygmomanometer 1B includes an outer cloth and air bag 13 in the cuff in addition to K sound microphone 51 and noise microphone 54 included in the cuff provided in sphygmomanometer 1A. A microphone for measuring C sound (hereinafter referred to as “C sound microphone”) 57 is provided at a position as close as possible to the K sound microphone 51. That is, the C sound microphone 57 is located in the vicinity of the K sound microphone 51 located on the downstream side of the artery when the cuff is attached to the measurement site, in contact with the air bag 13 and not directly in contact with the measurement site. Provided. As a result, C sound such as a rubbing sound of the air bag 13 generated in the cuff and a sound accompanying body movement is input to the C sound microphone 57.

  FIG. 10 is a diagram showing functional blocks for realizing the above functions in the sphygmomanometer 1B. Referring to FIG. 10, sphygmomanometer 1B further includes an amplifier 58 and an A / D converter 59 in addition to the configuration of sphygmomanometer 1A shown in FIG. 2, and C sound microphone 57 included in the cuff includes an amplifier. 58 and an A / D converter 59 to be connected to the CPU 40. The C sound microphone 57 includes a sound pressure sensor (not shown), detects the sound pressure, and outputs a sound signal, which is a sensor signal corresponding to the detected value, to the amplifier 58. The amplifier 58 amplifies the sensor signal output from the sound pressure sensor included in the C sound microphone 57 and outputs the amplified signal to the A / D converter 59. The A / D converter 59 digitizes the audio signal that is an analog signal output from the amplifier 58 and outputs the digitized signal to the CPU 40.

  FIG. 11 is a diagram illustrating a specific example of the configuration of the audio signal processing unit 43 included in the CPU 40 of the sphygmomanometer 1B. Referring to FIG. 11, audio signal processing unit 43 further includes a second synthesis unit 436 in addition to the configuration of audio signal processing unit 43 included in CPU 40 of sphygmomanometer 1A shown in FIG.

  The input unit 431 inputs an audio signal from the K sound microphone 51 via the amplifier 52 and the A / D converter 53, and receives an audio signal from the noise microphone 54 via the amplifier 55 and the A / D converter 56. An input and an audio signal input from the C sound microphone 57 via the amplifier 58 and the A / D converter 59 are received. Among the input audio signals, the audio signal from the K sound microphone 51 is input to the first synthesis unit 434 and the second synthesis unit 436. The audio signal from the noise microphone 54 and the audio signal from the C sound microphone 57 are input to the second synthesis unit 436. The second synthesis unit 436 synthesizes the voice wave indicated by the input voice signal from the noise microphone 54 and the voice wave indicated by the voice signal from the C sound microphone 57, and then inputs the synthesized voice wave to the adjustment unit 432. Similar to the sphygmomanometer 1 </ b> A, the adjustment unit 432 is a sensor value outside the range of the above-described frequencies F <b> 1 to F <b> 2 among the synthesized wave obtained from the audio signal from the noise microphone 54 and the audio signal from the C sound microphone 57. Is adjusted to be the same as the level of the sensor value in the above range of the sound wave indicated by the sound signal from the K sound microphone 51, and is input to the inverting unit 433. The 1st synthetic | combination part 434 and the extraction part 435 are the functions similar to sphygmomanometer 1A.

  The sphygmomanometer 1B performs the same operation as the sphygmomanometer 1A shown in FIG. However, in the sphygmomanometer 1B, voice measurement using the K sound microphone 51, the noise microphone 54, and the C sound microphone 57 is started in step S9. In step S11, the audio signal processing unit 43 performs audio signal processing based on the same principle as that shown in FIGS. However, in the sphygmomanometer 1 </ b> B, as the waveform 1, a synthesized wave of the audio signal from the noise microphone 54 and the audio signal from the C sound microphone 57 is used. That is, in the audio signal processing unit 43 of the sphygmomanometer 1B, the phase of the synthesized wave of the audio signal from the noise microphone 54 and the audio signal from the C sound microphone 57 is reversed in phase at the inversion unit 433 in step S11. The inversion process is performed, and the first synthesis unit 434 synthesizes the voice wave indicated by the voice signal input from the K sound microphone 51.

  The blood pressure value obtained by performing the above operation with the sphygmomanometer 1B will be specifically described with reference to FIG. FIG. 12A shows the pressure change of the air bladder 13 during the above series of operations. FIG. 12B represents a change in sound pressure indicating the K sound extracted by the sound signal processing. FIG. 12C shows a change in sound pressure that is input from the K sound microphone 51 and includes changes in sound pressure including Korotkoff sounds and other noises (noise input from the external environment, cuff noise sounds). Yes. FIG. 12D shows sound pressure indicating a synthesized voice of the voice input from the noise microphone 54 and the voice input from the C sound microphone 57.

  In step S11, the audio signal processing unit 43 performs the above-described audio signal processing, so that the audio input from the K sound microphone 51 shown in FIG. 12C is represented by a dotted line in FIG. The synthesized voice of the inverted voice input to the noise microphone 54 and the voice input from the C sound microphone 57 is synthesized, and the noise component and the C sound component are generated from the voice input from the K sound microphone 51. It is reduced. As a result, the sound pressure representing the K sound is more accurately extracted as represented by the thick line in FIG. When the extraction unit 435 extracts the K sound as shown in FIG. 12B, it is determined in step S13 that the K sound has started at time t1 in FIG. 12B. In step S17, it is determined that the K sound has disappeared at time t2 in FIG. Therefore, in step S15, the blood pressure calculation unit 42 calculates the systolic blood pressure based on the internal pressure of the air bladder 13 at time t1, and in step S19, calculates the diastolic blood pressure based on the internal pressure of the air bladder 13 at time t2. Is done.

  Thus, since the blood pressure monitor 1B can reduce the noise component and the C sound component from the voice measured as described above, the start point and the vanishing point of the Korokotov sound can be extracted more accurately, The measurement accuracy of the maximum blood pressure value and the minimum blood pressure value can be further improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the specific example of a structure of the cuff with which the blood pressure meter concerning 1st Embodiment is equipped. It is a figure which shows the functional block of the blood pressure meter concerning 1st Embodiment. It is a figure which shows the specific example of a structure of the audio | voice signal processing part contained in CPU of the blood pressure meter concerning 1st Embodiment. It is a figure explaining concretely the relation of the voice wave which shows the voice signal inputted from the microphone for K sound measurement, the voice wave which expresses noise, and the voice wave which expresses K sound. It is a figure explaining the principle of the audio | voice processing in an audio | voice signal processing part. It is a figure explaining the principle of the audio | voice processing in an audio | voice signal processing part. It is a flowchart which shows the specific example of the flow of the blood-pressure measurement operation | movement with the blood pressure meter concerning 1st Embodiment. It is a figure which shows the relationship between the sound pressure in the blood pressure meter concerning 1st Embodiment, the internal pressure of an air bag, and the calculated blood pressure value. It is a figure which shows the specific example of a structure of the cuff with which the blood pressure meter concerning 2nd Embodiment is equipped. It is a figure which shows the functional block of the blood pressure meter concerning 2nd Embodiment. It is a figure which shows the specific example of a structure of the audio | voice signal processing part contained in CPU of the blood pressure meter concerning 2nd Embodiment. It is a figure which shows the relationship between the sound pressure in the blood pressure meter concerning 2nd Embodiment, the internal pressure of an air bag, and the calculated blood pressure value.

Explanation of symbols

  1A, 1B Blood pressure monitor, 13 air bag, 20 air system, 21 air pump, 22 air valve, 23 pressure sensor, 26, 27 drive circuit, 28, 52, 55, 58 amplifier, 29, 53, 56, 59 A / D conversion , 40 CPU, 42 Blood pressure calculation unit, 43 Audio signal processing unit, 51 K sound microphone, 54 Noise microphone, 57 C sound microphone, 431 input unit, 432 adjustment unit, 433 inversion unit, 434 first synthesis unit, 435 extraction Part, 436 2nd synthetic | combination part.

Claims (9)

A fluid bag;
A mounting means for mounting the fluid bag in contact with the measurement site;
First voice input means for inputting a Korotkoff sound from the measurement site;
A second voice input means for inputting a noise sound outside the mounting means in a state where the fluid bag is mounted on the measurement site by the mounting means;
Voice processing means for performing voice processing for subtracting a component corresponding to the second voice input by the second voice input means from the first voice input by the first voice input means;
Extraction means for extracting the Korotkoff sound from the voice processed by the voice processing means;
Electronic blood pressure, comprising: a calculating means for calculating a blood pressure value based on the extraction timing of the Korotkoff sound and a change in the internal pressure of the fluid bag obtained in a state where the fluid bag is attached to the measurement site by the attaching means. Total. The voice processing means is
Reversing means for reversing the second sound to an opposite phase;
The electronic sphygmomanometer according to claim 1, further comprising a synthesizing unit that synthesizes the second sound inverted by the inverting unit in an opposite phase with the first sound. The voice processing means is configured to make the output level of the second voice in the predetermined frequency range equal to the output level of the first voice in the predetermined frequency range. And adjusting means for adjusting the output level of
The electronic sphygmomanometer according to claim 2, wherein the reversing unit reverses the second sound adjusted by the adjusting unit to an opposite phase. A third voice input means for inputting a noise sound between the mounting means and the measurement site in a state where the fluid bag is mounted on the measurement site by the mounting means;
2. The voice processing unit according to claim 1, wherein the voice processing unit performs voice processing for subtracting a component corresponding to the second voice and the third voice input by the third voice input unit from the first voice. Electronic blood pressure monitor. The voice processing means is
First synthesis means for synthesizing the second voice and the third voice to generate a synthesized voice;
Inverting means for inverting the synthesized speech to an opposite phase;
The electronic sphygmomanometer according to claim 4, further comprising: a second synthesizing unit that synthesizes the synthesized voice inverted by the inverting unit in an opposite phase with the first voice. The voice processing means sets the output level of the entire frequency range of the synthesized voice so that the output level of the synthesized voice in the predetermined frequency range is equal to the output level of the first voice in the predetermined frequency range. And further includes adjusting means for adjusting,
The electronic sphygmomanometer according to claim 5, wherein the reversing unit reverses the synthesized speech adjusted by the adjusting unit to an opposite phase.   The electronic sphygmomanometer according to claim 1, wherein the second voice input unit is provided on the opposite side of the mounting unit from the fluid bag.   The electronic sphygmomanometer according to claim 4, wherein the third voice input unit is provided between the mounting unit and the fluid bag.   A member for blocking voice input to the first voice input means is provided at a position that is not in contact with the measurement site in a state of being mounted on the measurement site by the mounting unit of the first voice input unit. Item 9. The electronic blood pressure monitor according to any one of Items 1 to 8.

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