BLOOD PRESSURE MEASURING DEVICE, CONTROL METHOD OF AN ELECTRONIC BLOOD PRESSURE MEASURING DEVICE AND CONTROL PROGRAM OF THE ELECTRONIC BLOOD PRESSURE MEASURING DEVICE

Abstract

Blood pressure measuring device (1) which features: a fluid bellows (13); an inflation unit for injecting fluid into the fluid bellows and for inflating the fluid bellows (13); an air outlet unit which includes a valve (22) which is provided in the fluid bellows (13) and for emptying the fluid from the fluid bellows (13) and for releasing air from the fluid bellows (13); a sensor (23) for measuring a change in the internal pressure of the fluid bellows (13); a blood pressure measuring unit for calculating a blood pressure value based on the change in the internal pressure of the fluid bellows (13) obtained by the sensor (23) in an air outlet process of emptying the fluid from the fluid bellows (13) through the air outlet unit; and a control unit for controlling the inflation unit, the air outlet unit and the blood pressure measuring unit, wherein the control unit determines an opening of the valve (22), which is a control amount for controlling a discharge rate of the fluid through the air outlet unit, such that the discharge rate is proportional to an air outlet velocity of the fluid bellows (13) in the air outlet process, and controls the discharge rate by performing a control in order to maintain the opening of the valve (22) at the determined opening in the air outlet process, and the control unit compensates for the influence of the manufacturing tolerance of the valve (22) by adjusting the specified control amount so that the air outlet velocity of the fluid bellows (13) is within a prescribed range for a prescribed period of time from the start of the air outlet process, where: the control unit further adjusts the set control amount so that the air outlet velocity of the fluid bellows (13) is faster than a prescribed velocity during the measurement, which is carried out after the prescribed time period, and the control unit further adjusts the set control amount, if a pulse pressure superimposed on the internal pressure of the fluid bellows (13) is equal to or greater than a prescribed frequency detected in the air discharge process; and / or The control unit assesses whether the air outlet velocity of the fluid bellows (13) is within the prescribed range by comparing a consumption flow of the valve (22) with a threshold value; and / or the prescribed time period is a time period from the start of the air outlet process until at least one pulse beat before a pulse wave which is initially superimposed on the internal pressure of the fluid bellows (13) in the air outlet process.

Description

Technical area

[0001] This invention relates to a blood pressure measuring device, a control method of an electronic blood pressure measuring device, and a control program of an electronic blood pressure measuring device, and more particularly, to a blood pressure measuring device for measuring blood pressure using a wristband (cuff) including a fluid bladder, a control method of an electronic blood pressure measuring device, and a control program of an electronic blood pressure measuring device. Background of the state of the art

[0002] A method for calculating blood pressure to which an electronic sphygmomanometer is applied is an oscillometric method for calculating blood pressure by deflating a wristband (cuff) containing a fluid bladder which is wrapped around a part of a living body, and wherein the change in volume of the fluid bladder caused by the change in volume of the compressed blood vessels is derived as a change in pressure (pressure pulse wave amplitude) of the fluid bladder.

[0003] A characteristic of the fluid bellows is that the pressure of the fluid bellows and the volume of the fluid bellows are related, as shown in Fig. 24. That is, with reference to Fig. 24, in the area shown in Part A, where the pressure of the fluid bladder is low, the volume of the fluid bladder increases sharply relative to the increase in the pressure of the fluid bladder. Also, as the pressure of the fluid bladder increases, the rate of increase of the volume of the fluid bladder gradually decreases relative to the increase in the pressure of the fluid bladder, as shown in Part B. Fig. 25 and Fig. 26 are diagrams each representing a change in the volume of the fluid bladder (B), a change in the fluid density in the fluid bladder (C), and a change in the pressure of the fluid bladder (D) following a change in the volume of the blood vessels (A) when the fluid density in the fluid bladder is low and when the fluid density in the fluid bladder is high. Also shown are Fig. 27 and Fig. 28 are diagrams showing a change in the volume of the fluid bladder (B) and a change in the pressure of the fluid bladder (C) following a change in the volume of the blood vessels (A) when the emptying rate of the fluid from the fluid bladder is fast, ie, when the emptying rate per unit time is high, and when the emptying rate of the fluid from the fluid bladder is slow, ie, when the emptying rate per unit time is low. The following features can be obtained from Fig. 25 to Fig. 28 can be interpreted in terms of the detection accuracy of changes in the volume of blood vessels: (1) The fluid density in the fluid bellows is higher, the higher the pressure of the fluid bellows is; (2) since the change in fluid density in the fluid bladder following a change in the volume of blood vessels is smaller the larger the volume of the fluid bladder is, the detection accuracy of the changes in the volume of blood vessels is low; (3) since the change in fluid density in the fluid bladder following a change in the volume of the fluid bladder is larger the higher the pressure in the fluid bladder is, the detection accuracy of the changes in the volume of the blood vessels increases in the case of the same change in the volume of the fluid bladder; (4) since the magnitude of the change in the volume of the fluid bladder resulting from a change in the volume of the blood vessels varies depending on the emptying rate of the fluid in the fluid bladder, the detection accuracy of the changes in the blood vessels differs even for the same pressure of the fluid bladder; and (5) Since a change in the volume of the fluid bladder resulting from a change in the volume of the blood vessels is smaller, the larger the emptying rate of the fluid in the fluid bladder is, the detection accuracy of the changes in the volume of the blood vessels decreases.

[0004] Therefore, in an electronic blood pressure monitor using the oscillometric method, the detection accuracy of changes in the volume of blood vessels depends on the fluid density in the fluid bladder and the emptying rate of the fluid from the fluid bladder.

[0005] As in Fig. 29A to Fig. 29C, in a blood pressure monitor that releases the air from the fluid bladder at a constant speed, the amount of fluid that is emptied from the fluid bladder is controlled by a valve according to variables such as the pressure of the fluid bladder and the environment of the measurement site ( Fig. 29B) to discharge the air of the fluid bellows at a constant speed ( Fig. 29A). This means that, as shown in Fig. As shown in Figure 29C, the pressure pulse wave amplitude relative to a constant change in blood vessel volume is larger in the region where the fluid bladder pressure is higher, and the pressure pulse wave amplitude relative to a constant change in blood vessel volume is smaller in the region where the fluid bladder pressure is lower. Also, since the amount of change in blood vessel volume following a change in fluid bladder pressure differs depending on the measurement site, these factors cause errors in blood pressure measurement.

[0006] Methods such as the following are disclosed as technologies for solving these problems. For example, JP H06-245911A (Patent Document 1) discloses a technology for adjusting the discharge rate of a valve according to the circumference of the measurement site, or a technology for providing a fluid storage unit in communication with the fluid bellows, and performing control while maintaining the sum volume of the fluid bellows and the fluid storage unit constant, corresponding to the wrapped circumference of the fluid bellows around the measurement site. The air discharge velocity can thereby be kept constant even when the circumference of the measurement site varies.

[0007] Also, in JP 5-329113A (Patent Document 2), a method is disclosed in which the volume change characteristics of the fluid bladder relative to the pressure of the fluid bladder are provided in advance, a signal indicating a change in pressure of the fluid bladder is converted back into a change in volume, and a blood pressure value is measured using the change in volume.

[0008] Also, in JP H04 - 250 133 A (Patent Document 3), a method of closing a valve for emptying the fluid in the fluid bladder is disclosed to prevent attenuation of the change in the volume of the blood vessels following a change in the volume of the fluid bladder in a pulse wave arrival interval. Citation listPatent document Patent document 1: JP H06 - 245 911 A Patent document 2: JP H05 - 329 113 A Patent document 3: JP H04 - 250 133 A

[0009] JP 2008 - 099 819 A describes an electronic hemomanometer in which the pressure in a pressure cuff bag is measured when the pressure is reduced. A control initial value is set, which is used to adjust the degree of opening of an outlet valve during the next measurement. Summary of the inventionTechnical problem

[0010] Although differences in the air discharge velocity due to differences in the measurement site circumference can be eliminated with the method disclosed in Patent Document 1, the pulse pressure wave amplitude changes depending on the fluid bladder pressure as a result of the valve discharge rate, which changes in conjunction with the fluid bladder pressure to maintain the air discharge velocity constant. Therefore, even if control is performed while keeping the sum volume of the fluid bladder and the fluid storage unit constant, only differences in volume due to the measurement site circumference are eliminated, and the magnitude of the change in the fluid bladder pressure relative to the change in the blood vessel volume changes depending on the fluid bladder pressure. Therefore, the problem remains that errors in blood pressure measurement occur.

[0011] Also, with the method disclosed in Patent Document 2, the pressure and volume change characteristics of the fluid bladder must be provided in advance. However, there is a problem that since these change characteristics change infinitely depending on factors such as how the fluid bladder is wound, the thickness of the arm, and the flexibility of the human body, sufficient correction cannot be performed. There is also the problem of impracticality, which is due to the need for numerous complicated corrections (flow rate detection, size detection of the measurement location, wrapping state detection, consistency detection of the human body, etc.), and thus the need for a large-sized device.

[0012] Also, although a change in the volume of blood vessels can be precisely interpreted as a change in the pressure of the fluid bladder with the method published in Patent Document 3, there is a problem in that difficulties are involved during air discharge because the valve is always closed when a pulse wave occurs.

[0013] In other words, with the methods disclosed in these patent documents, the flow rate of the fluid discharged from the fluid bladder varies depending on the measurement site size and the fluid bladder pressure in the case where blood pressure is measured while the air is being released from the fluid bladder, because the pressure and volume of the fluid bladder are not proportional. Therefore, the detection accuracy of the pressure pulse wave amplitude relative to a change in blood vessel volume varies depending on the measurement site size, the fluid bladder pressure, and the like. Accordingly, there is a problem in that the accuracy of blood pressure measurement decreases because errors in the measurement of the pressure pulse wave amplitude occur depending on factors such as the blood pressure value and the measurement site size, even for the same change in blood vessel volume.

[0014] The present invention has been made in view of such problems and has as an object to provide a blood pressure measuring device, a control method of an electronic blood pressure measuring device, and a control program of an electronic blood pressure measuring device capable of approximating the pressure pulse wave amplitude to a constant value relative to a constant change in the volume of the blood vessels and improving the accuracy of blood pressure measurement by configuring the flow rate of the fluid from the fluid bladder and the air outlet speed in a proportional relationship. Solution to the problem

[0015] To achieve the above object, a blood pressure measuring device according to claim 1 is provided.

[0016] Preferably, the control unit further sets the set control amount so that the air outlet speed of the fluid bladder is faster than a prescribed speed while the measurement is performed after the prescribed period of time.

[0017] Preferably, the control unit sets a drive voltage for driving the valve as the control amount.

[0018] Preferably, the control unit sets a consumption current of the valve as the control amount.

[0019] Preferably, the control unit decides on the opening of the valve, which is the control amount, so as to achieve an air outlet speed in which at least a prescribed number of pulse beats is included in a time required for the internal pressure of the fluid bladder to change from a systolic blood pressure to a diastolic blood pressure.

[0020] To achieve the above object, a blood pressure measuring device according to another aspect of the present invention includes: a fluid bladder, an inflation unit for injecting fluid into a fluid bladder and inflating the fluid bladder, an air discharge unit including a valve provided in the air bladder and for discharging fluid from the fluid bladder and discharging air from the fluid bladder, a sensor for measuring a change in internal pressure of the fluid bladder, a blood pressure measuring device for calculating a blood pressure value based on the change in internal pressure of the fluid bladder obtained by the sensor in an air discharge process of discharging fluid from the fluid bladder through the air discharge unit, and a control unit for controlling the inflation unit, the air discharge unit, and the blood pressure measuring unit.The control unit decides an opening of the valve, which is a control amount for controlling a discharge rate of the fluid through the air discharge unit so that the discharge rate is proportional to an air discharge speed of the fluid bladder in the air discharge process, and controls the discharge rate by performing control so as to keep the opening of the valve at the set opening in the air discharge process, and the control unit corrects an influence of an environmental condition such as temperature or humidity by adjusting the set control amount so that the air discharge speed of the fluid bladder is within a prescribed range during a prescribed period from a start of the air discharge process.

[0021] Preferably, the blood pressure measuring device further includes an input unit for entering the environmental condition.

[0022] To achieve the above object, a blood pressure measuring device according to claim 8 is provided.

[0023] In order to achieve the above object, a control method of an electronic blood pressure monitor according to another aspect of the present invention is provided, a control method of an electronic blood pressure monitor according to claim 9.

[0024] To achieve the above object, a control program of an electronic blood pressure monitor according to another aspect of the present invention is provided with a control program according to claim 10. Advantageous effects of the invention

[0025] This invention allows the detection accuracy of changes in blood vessel volume to be approximated to a constant value in a blood pressure measuring device regardless of the fluid bladder pressure. Blood pressure measurement errors can thereby be reduced. The rate of change in the detection accuracy of changes in blood vessel volume can also be approximated to a constant value, even if the fluid bladder volume varies depending on the circumference of the measurement site. Blood pressure measurement errors can thereby be reduced. The need to correct the fluid bladder volume, which varies depending on the circumference of the measurement site, is also eliminated. Short description of the drawings Fig. 1 is a block diagram showing a specific example of a hardware configuration of a blood pressure monitor serving as a blood pressure measuring device according to a first embodiment of the present invention. Fig. 2 is a flowchart showing a first specific example of the processing flow executed at the timing at which a measurement switch is operated in the blood pressure meter according to the first embodiment of the present invention. Fig. 3 is a flowchart showing a second specific example of the processing flow executed at the timing at which the measurement switch is operated in the blood pressure meter according to the first embodiment of the present invention. Fig. Figure 4A is a graph showing the relationship between the circumference of the measurement site and the inflation velocity. Fig. Figure 4B is a graph showing the relationship between the circumference of the measurement site and the inflation time. Fig. Figure 5 is a graph showing the degree of change in the air outlet velocity relative to the fluid bellows pressure in the case where the drive voltage of a valve is kept constant for different circumferences of the measuring location. Fig. 6 is a diagram showing the relationship between the driving voltage of a valve and the circumference of the measurement site set in the blood pressure monitor according to the first embodiment of the present invention. Fig. Figure 7 is a graph showing the degree of change in the air outlet velocity relative to the fluid bellows pressure in the case where the circumference of the measuring location is the same for different valve openings. Fig. 8 is a flowchart showing a change in processing executed at the timing at which the measurement switch is operated in the blood pressure meter according to the first embodiment of the present invention. Fig. 9 is a graph showing the relationship between the driving voltage of a valve and the circumference of the measurement site set in the blood pressure monitor according to the modification of the first embodiment of the present invention. Fig. 10A is a graph showing the relationship between the pressure of the fluid bladder and the air outlet speed in the blood pressure monitor according to the first embodiment of the present invention. Fig. 10B is a graph showing the relationship between the pressure of the fluid bladder and the discharge rate of the fluid in the blood pressure monitor according to the first embodiment of the present invention. Fig. 10C is a graph showing the relationship between the fluid bladder pressure and the pressure pulse wave amplitude value relative to a constant change in volume in the sphygmomanometer according to the first embodiment of the present invention. Fig. Figure 11 is a diagram to illustrate the relationship between the fluid bladder pressure and the detected pulse wave amplitude. Fig. 12 is a block diagram showing another specific example of the hardware configuration of the blood pressure monitor serving as a blood pressure measuring device according to the first embodiment of the present invention. Fig. 13 is a block diagram showing a specific example of the hardware configuration of the blood pressure monitor serving as a blood pressure measuring device according to a second embodiment of the present invention. Fig. 14 is a flowchart showing a specific example of the processing performed at the time lapse when the measurement switch is operated in the blood pressure meter according to the second embodiment of the present invention. Fig. 15A is a diagram showing another specific example of the configuration of the blood pressure monitor according to the second embodiment of the present invention. Fig. 15B is a diagram showing another specific example of the configuration of the blood pressure monitor according to the second embodiment of the present invention. Fig. 15C is a diagram showing another specific example of the configuration of the blood pressure monitor according to the second embodiment of the present invention. Fig. Figure 16 is a graph representing the difference in air outlet velocities due to the type of outlet valves for different ambient conditions. Fig. Figure 17 is a graph representing the difference in air outlet velocities due to the installation orientation of an outlet valve. Fig. Figure 18 is a diagram showing the relationship between the fluid bladder pressure and the detected pulse wave amplitude. Fig. 19 is a diagram for illustrating a principle for adjusting the driving voltage of a discharge valve in the blood pressure monitor according to a third embodiment of the present invention. Fig. 20 is a diagram for illustrating a principle for adjusting the driving voltage of a discharge valve in the blood pressure monitor according to the third embodiment of the present invention. Fig. 21 is a block diagram showing a specific example of a hardware configuration of the blood pressure monitor according to the third embodiment of the present invention. Fig. 22 is a flowchart showing a specific example of the processing flow performed by the blood pressure monitor according to the third embodiment of the present invention. Fig. 23 is a flowchart showing another specific example of the processing flow performed by the blood pressure monitor according to the third embodiment of the present invention. Fig. Figure 24 is a diagram showing the characteristics of the fluid bellows. Fig. 25 is a graph illustrating a change in the volume of the fluid bladder, a change in the fluid density in the fluid bladder, and a change in the pressure of the fluid bladder following a change in the volume of the blood vessels when the fluid density in the fluid bladder is low. Fig. 26 is a diagram illustrating a change in the volume of the fluid bladder, a change in the fluid density in the fluid bladder, and a change in the pressure of the fluid bladder following a change in the volume of the blood vessels when the fluid density in the fluid bladder is high. Fig. 27 is a graph illustrating a change in the volume of the fluid bladder and a change in the pressure of the fluid bladder following a change in the volume of the blood vessels when the emptying rate of the fluid from the fluid bladder is fast, that is, when the emptying rate per unit time is high. Fig. 28 is a graph illustrating a change in the volume of the fluid bladder and a change in the pressure of the fluid bladder following a change in the volume of the blood vessels when the emptying rate of the fluid from the fluid bladder is slow, ie, when the emptying rate per unit time is low. Fig. Figure 29A is a graph showing the relationship between the fluid bladder pressure and the air outlet velocity in a sphygmomanometer that lets air out of the fluid bladder at a constant velocity. Fig. Figure 29B is a graph showing the relationship between the fluid bladder pressure and the fluid deflation rate in a sphygmomanometer that deflates the fluid bladder at a constant rate. Fig. Figure 29C is a graph showing the relationship between the fluid bladder pressure and the pressure pulse wave amplitude value relative to a constant change in volume in the sphygmomanometer which is letting air out of the fluid bladder at a constant rate. Description of the embodiments

[0026] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals are given to the same components and constituent elements. The names and functions thereof are also the same. First embodiment

[0027] With reference to Fig. 1, a blood pressure monitor 1 serving as a blood pressure measuring device according to a first embodiment of the present invention is provided with a main unit 2 and a cuff 5 wrapped around a measurement site, and these components are connected via a tube 10. An operation unit 3 constructed by switches and the like, and a display unit 4 displaying measurement results and the like are arranged on the front of the main unit 2. The operation unit 3 includes a power switch 31 for instructing on / off of the power supply, a measurement switch 32 for instructing that measurement is started, a stop switch 33 for instructing that measurement is stopped, and a record call switch 34 for calling and displaying the measured values ​​that are recorded. A fluid bladder 13 is arranged in the cuff 5.Air, for example, can be used as the fluid that is injected into and discharged from the fluid bellows 13. The fluid bellows 13 is pressed against the measurement site by wrapping the cuff 5 around the measurement site. The measurement sites include, for example, the upper arm or the wrist.

[0028] The fluid bladder 13 is connected to a pressure sensor 23 for measuring the change in the internal pressure of the fluid bladder 13, a pump 21 for injecting / discharging the fluid with respect to the fluid bladder 13, and a valve 22. The pressure sensor 23, the pump 21, and the valve 22 are respectively connected to an oscillation circuit 28, a pump driving circuit 26, and a valve driving circuit 27, and further, the oscillation circuit 28, the pump driving circuit 26, and the valve driving circuit 27 are all connected to a central processing unit (CPU) 40, which controls the entire blood pressure monitor 1.

[0029] The CPU 40 is also connected to the display unit 4, the operation unit 3, a memory 6 which serves as a work area when the programs executed by the CPU 40 are stored and the programs are executed, a memory 7 which stores the measurement results and the like, and a power supply 53.

[0030] The CPU 40 is driven when power is supplied from the power supply 53. The CPU 40 includes a circumference information acquisition unit 41 and a valve drive voltage setting unit 43. These components are formed in the CPU 40 as a result of the CPU 40 executing a prescribed program stored in the memory 6 based on an operation signal input from the operation unit 3. The circumference information acquisition unit 41 acquires circumference information, which is the dimension of the measurement location, and inputs the acquired circumference information to the valve drive voltage setting unit 43. The valve drive voltage setting unit 43 sets the voltage (hereinafter, the drive voltage E) to drive the valve 22 based on the circumference information.The CPU 40 outputs a control signal corresponding to the drive voltage E set by the valve drive voltage setting unit 43 to the valve drive circuit 27. Also, the CPU 40 executes a prescribed program stored in the memory 6 based on the operation signal input from the operation unit 3 and outputs a control signal to the pump drive circuit 26.

[0031] The pump drive circuit 26 and the valve drive circuit 27 drive the pump 21 and the valve 22 according to the control signals. The pump 21 injects fluid into the fluid bellows 13 when its drive is controlled by the pump drive circuit 26, which operates according to the control signal from the CPU 40. The valve 22 discharges the fluid into the fluid bellows 13 when its opening / closing and opening width (hereinafter referred to as an opening) are controlled by the valve drive circuit 27, which operates according to the control signal from the CPU 40.

[0032] The pressure sensor 23 is a capacitance pressure sensor, and the capacitance value changes due to changes in the internal pressure of the fluid bladder 13. The oscillation circuit 28 converts the change in the capacitance value of the pressure sensor 23 into an oscillation frequency signal and inputs the oscillation frequency signal to the CPU 40. The CPU 40 performs prescribed processing based on the changes in the internal pressure of the fluid bladder obtained from the pressure sensor 23 and outputs the above control signals to the pump drive circuit 26 and the valve drive circuit 27 according to the processing result. The CPU 40 also calculates the blood pressure value based on the change in the internal pressure of the fluid bladder 13 obtained from the pressure sensor 23, performs processing for displaying the measurement result on the display unit 4, and outputs the data and a control signal to cause the display of the display unit 4.Also, the CPU 40 executes the processing to store the blood pressure value in the memory 7.

[0033] Fig. Fig. 2 is a flowchart showing a first specific example of the processing carried out at a time when the measurement switch 32 in the blood pressure monitor 1 is operated. The process shown in the flowchart of Fig. 2 is realized as a result of the CPU 40 executing a prescribed program stored in the memory 6.

[0034] With reference to Fig. 2, the CPU 40 monitors the input of the operation signals from the operation unit 3, and upon detecting that the measurement switch 32 has been operated, the circumference information acquisition unit 41 of the CPU 40 acquires the circumference information representing the circumference of the measurement location, which is the dimension of the measurement location, in step S101. Here, it is assumed that the circumference information, such as "thick" or "thin," is input during measurement using a switch or a similar structure of the operation unit 3, and that the circumference information acquisition unit acquires the circumference information from the operation signal of the operation unit 3.

[0035] Note that the method of acquiring the circumference information by the circumference information acquiring unit 41 is not limited to the above-mentioned method. For example, as a second specific example of the processing flow executed at the timing when the measurement switch 32 in the blood pressure monitor 1 is operated, the circumference information may be acquired in the processing of steps S201 to S205, instead of the above step S101, as shown in Fig. 3. Specifically, in step S201, the CPU 40 outputs a control signal for driving the pump 21 at a prescribed voltage previously defined in the pump driver circuit 26, whereby the pump 21 is driven at the prescribed voltage and the fluid bladder 13 is filled until the fluid bladder 13 reaches a prescribed pressure previously defined. When the prescribed pressure is reached (YES in step S203), the CPU 40 stores the inflation time required for the fluid bladder 13 to reach the prescribed pressure in step S205. As shown in Fig. 4A, the inflation speed decreases as the circumference of the measuring location increases, in the case of the same drive voltage for driving the pump 21. Accordingly, the inflation time increases as the circumference of the measuring location increases, as shown in Fig. 4B. In other words, the inflation time required for the fluid bladder 13 to reach the prescribed pressure can be taken as an index representing the circumference of the measurement location. In view of this, the circumference information acquisition unit 41 acquires the inflation time stored in step S205 as circumference information. Note that the circumference information can also be similarly obtained by the circumference information acquisition unit 41 from the number of rotations of the pump 21 and the pressure of the fluid bladder 13, instead of the inflation time.Also, as another example, the sliding resistance is included in the fabric (not shown) serving as a mechanism for wrapping the fluid bladder 13 around the measurement site, and the circumferential information acquiring unit 41 can acquire the circumferential information from the resistance value obtained from the above sliding resistance when the fluid bladder 13 is wrapped around the measurement site.

[0036] In steps S103 and S105, the CPU 40 outputs a control signal to the pump drive circuit 26 and inflates the fluid bladder 13 until the fluid bladder 13 reaches a prescribed pressure, which is defined in advance. Once the prescribed pressure is reached (YES in step S105), the CPU 40 outputs a control signal to the pump drive circuit 26 in step S207 and stops the inflation of the fluid bladder 13. Thereafter, in step S109, the valve drive circuit setting unit 43 of the CPU 40 sets the drive voltage E of the valve 22 based on the circumference information acquired in step S101 or in steps S201 to S205. In step S111, the CPU 40 outputs a control signal to the valve drive circuit 27 so as to drive the valve 22 while holding the drive voltage E set in step S109, and starts the deflation of the fluid bladder 13.In step S113, the CPU 40 extracts the oscillation component accompanying the change in the volume of the artery superimposed on the internal pressure of the fluid bladder 13 obtained during air discharge, and calculates a blood pressure value using a prescribed arithmetic operation. Note that if a blood pressure value is not calculated in the above step S113 because the air discharge speed in the above step S111 is too fast, or conversely, if the deflation does not proceed because the air discharge speed in the above step S111 is too slow (NO in step S114), the CPU 40, in step S117, having determined that an error has occurred, outputs a control signal to the valve drive circuit 27 so as to release the valve 22 and quickly discharges the fluid into the fluid bladder 13. If this is not the case, i.e.When a blood pressure value is calculated at the above step S113 (YES at step S114), the valve 22 is released according to a control signal from the CPU 40 at step S115, and the fluid in the fluid bladder 13 is discharged.

[0037] The process flow to set the drive voltage E by the valve drive voltage setting unit 43 in the above step S109 will be described.

[0038] Here, the degree of change in the air outlet velocity relative to the pressure of the fluid bellows in the case where the driving voltage E is kept constant differs depending on the circumference of the measuring location, as shown in Fig. 5. Specifically, with reference to Fig. 5, the smaller the circumference of the measurement location, the greater the degree of change in the air outlet velocity, and the larger the circumference of the measurement location, the smaller the degree of change in the air outlet velocity. In other words, the circumference of the measurement location can be regarded as a parameter to determine the driving voltage E from the relationship shown in Fig. 5 is shown.

[0039] In the above step S109, the valve driving voltage setting unit 43 sets the driving voltage E using the relationship shown in the above-mentioned Fig. 5. As a specific example, the valve drive voltage setting unit 43 sets the drive voltage E by substituting the amount information acquired in the above step S101 or the above steps S201 to S205 into the following equation (1): Driver voltage E=α×circumference information+β

[0040] By using the above-mentioned equation (1) in step S109, the driving voltage E is set at a dimension proportional to the circumference of the measuring location, as shown in Fig. 6 is shown.

[0041] Here, the degree of change in the air outlet velocity relative to the pressure of the fluid bellows in the case where the circumference of the measuring location is the same differs depending on the dimension of the opening of the valve 22, ie the magnitude of the driving voltage, as shown in Fig. 7. Especially with reference to Fig. 7, the degree of change in the air outlet speed increases, the larger the opening of the valve 22 is, and the degree of change in the air outlet speed decreases, the smaller the opening is. Accordingly, from the relationship shown in Fig. 7, the size of the opening is preferably such that the air discharge velocity of the fluid bladder 13 is within a prescribed range of velocities from the calculation of the systolic blood pressure to the calculation of the diastolic blood pressure. More specifically, the size of the opening is preferably such that the number of pulse beats detectable between the systolic blood pressure and the diastolic blood pressure during air discharge is equal to or greater than a prescribed number. More specifically, the "prescribed number" is 5.This is because it is considered appropriate that the orifice size be adjusted taking into account the performance of the algorithm used to measure air release, so as to control the air release rate so that approximately five pulses are measured between the systolic blood pressure and the diastolic blood pressure during air release, as also described in Japanese Patent No. 3179873, previously filed and published by the applicant. Note that it is assumed that the orifice size allowing five or more pulses to be measured between the systolic blood pressure and the diastolic blood pressure during air release is obtained through experimentation or the like and is previously stored in the memory 6. Specifically, the value is preferably approximately 5 mmHg / sec to 20 mmHg / sec.Accordingly, the coefficients α and β in the above equation (1) can be set to values ​​resulting from the blood pressure air outlet velocity at which the fluid bladder pressure is in a range comparable to the blood pressure values ​​set within the target air outlet velocity range of approximately 5 mmHg / sec to 20 mmHg / sec. It is assumed that such coefficients α and β are previously derived through experimentation or the like and stored in the memory 6 of the blood pressure monitor 1.Note that in the above example, it is assumed that the driving voltage E is set by inputting the detected circumference information into the above equation (1) in step S109, although instead of the equation (1), the memory 6 may store a table defining the relationship between the circumference information and the driving voltages E, and the valve driving voltage setting unit 43 may read out the driving voltage E corresponding to the detected circumference information from the table. variation

[0042] Fig. Fig. 8 is a flowchart showing a variation of the process flow executed at the time when the measurement switch 32 is operated in the blood pressure monitor 1. In the process flow shown in Fig. 8, the circumference of the measurement location is estimated based on the inflation time required for the pressure of the fluid bladder 13 to reach the prescribed pressure at steps S201 to S205, similarly to the second specific example shown in Fig. 3, and in the subsequent inflation process, the CPU 40 estimates the systolic blood pressure value in step S301 based on the change in the internal pressure of the fluid bladder obtained from the pressure sensor 23, and calculates the inflation end pressure of the fluid bladder 13 in step S303. The sphygmomanometer 1 is configured to calculate a blood pressure value based on the change in the internal pressure of the fluid bladder obtained in the air discharge process performed after the fluid bladder 13 is inflated to the prescribed pressure. Therefore, preferably, the CPU 40 calculates a blood pressure value higher than the systolic blood pressure value estimated in step S301 by a prescribed pressure value as the inflation end pressure in step S303.Subsequently, once the pressure of the fluid bladder 13 reaches the final inflation pressure calculated in step S303 (YES in step S105'), the drive voltage E is set similarly to the process flow shown in FIG. Fig. 2 or Fig. 3, and a blood pressure value is calculated in the air discharge process in which the control is performed so as to drive the valve while holding the drive voltage E.

[0043] Note that in the variation, the valve driving voltage setting unit 43 in step S109, taking into account the systolic blood pressure value estimated in step S301, sets the driving voltage E instead of or in addition to the above-mentioned relationship shown in Fig. 5. As a specific example, the valve drive voltage setting unit 43 sets the drive voltage E by substituting the amount information acquired through the above step S101 or the above steps S201 to S205 into the following equation (2): Driver voltage E=α×circumference information+β+offset amount S,Offset amount S=estimated systolic blood pressure value ×γ

[0044] By using the above-mentioned equation (2) in step S109 in the variation, the driving voltage E is set at a value proportional to the circumference of the measurement site and at a value corresponding to the estimated systolic blood pressure, as shown in Fig. 9 is shown.

[0045] From the relationship, which is made using Fig. 7, the size of the opening is preferably such that the blood pressure air discharge rate at which the pressure of the fluid bladder 13 is in a range comparable to the blood pressure values ​​is set within the target air discharge rate range. Accordingly, the coefficient γ in the above equation (2) can be set to a value resulting from the air discharge rate from the calculation of the systolic blood pressure to the calculation of the diastolic blood pressure of the fluid bladder 13, which is set within the target deflation rate range of approximately 5 mmHg / sec to 20 mmHg / sec.

[0046] In the above step S111, control is performed by the CPU 40 to drive the valve 22 while maintaining the drive voltage E, which is set in the above step S109. That is, control is performed so that the opening of the valve 22 is constant during air discharge. The air discharge speed of the fluid bellows 13 changes as shown in Fig. 10A, during the air discharge, which follows the change in the pressure of the fluid bellows 13. That is, it is Fig. 10A, it is clear that in the case where the pressure of the fluid bladder 13 drops below a given pressure, the air outlet velocity of the fluid bladder 13 remains substantially unchanged by the subsequent change (decrease) in pressure at approximately the same value, regardless of the size of the circumference of the measurement location. Likewise, the emptying rate of the valve 22 changes relative to the pressure of the fluid bladder 13, as shown in Fig. 10B, during the air release following the change in the pressure of the fluid bellows 13. That is, it is Fig. 10B that in the case where the pressure of the fluid bellows 13 falls below a given pressure, the discharge rate from the valve 22 remains substantially unchanged by the subsequent change (decrease) in pressure, at a value corresponding to the circumference of the measuring location. In other words, it is clear from the relationships shown in Fig. 10A and Fig. 10B, it is clear that performing the control so that the drive voltage E is constant, that is, performing the control to keep the opening of the valve 22 constant, can be regarded as controlling the drive voltage E so that the discharge rate of the valve 22 and the air discharge speed of the fluid bladder 13 are in a proportional relationship.

[0047] The CPU 40, which performs the control in this way, allows the air outlet velocity of the fluid from the fluid bladder 13 to approach a proportional relationship in the blood pressure monitor 1. The detection accuracy of the changes in the volume of the blood vessels can thereby be approximated to a constant value, and the measurement accuracy can be improved. In other words, as in Fig. 10C, the pressure pulse wave amplitude can be kept constant relative to a constant change in volume, at a value corresponding to the circumference of the measurement location, regardless of the change in pressure of the fluid bladder 13.

[0048] (A) in Fig. Figure 11 shows the change in pressure of the fluid bladder 13 as a function of time and the change in intra-arterial pressure. The dashed line A in (A) of the Fig. Fig. 11 shows a conventional pressure change of the fluid bladder 13 in the case where the control is performed so as to reduce the pressure of the fluid bladder at a uniform speed. In contrast, in the blood pressure monitor 1, the change in the pressure of the fluid bladder 13 in the case of deflating the fluid bladder by performing the control such that the drive voltage E is constant, that is, such that the opening of the regulator 22 is constant, is shown by the solid line B. As a result of the fluid bladder being deflated by performing the control such that the drive voltage E is constant, that is, such that the opening of the valve 22 is constant, conventionally, the intra-arterial pressure corresponding to the change in the pressure (deflating) of the fluid bladder 13, as shown in (B) of the Fig. 11 is measured, as shown in (C) of the Fig. 11. Especially in (C) the Fig. 11 is the line segment obtained by connecting each measured value of the intra-arterial pressure shown in (B) of the Fig. 11, shown by the dashed line. In a conventional blood pressure monitor which is controlled so as to reduce the pressure of the fluid bladder at a uniform speed, the detection accuracy of the changes in the volume of the blood vessels decreases in the areas where the pressure of the fluid bladder is low compared to the areas where the pressure is high, even at the same intra-arterial pressure, as shown in Fig. 25 and Fig. 26. In contrast, in the blood pressure monitor 1, as can be seen by comparing (B) and (C) of the Fig. As shown in Figure 11, it can be clearly seen that the detection accuracy of changes in blood vessel volume in regions where the pressure of the fluid bladder 13 is low is greater than the detection accuracy of a conventional blood pressure monitor controlled to reduce the pressure of the fluid bladder at a uniform speed. Similarly, it is shown that the detection accuracy of changes in blood vessel volume in regions where the pressure is high is also improved.

[0049] Note that in the above example, the CPU 40 performs control to maintain the drive voltage E at the drive voltage E set by the valve drive voltage setting unit 43 in the above step S109, that is, to maintain the drive voltage E constant in the air discharge process of the above step S111. However, in addition to the configuration shown above, the blood pressure monitor 1 may further include a flow meter 55 that measures the discharge rate of the valve 22, as shown, for example, in Fig. 12, and the drive voltage E can be updated by the valve drive voltage setting unit 43 in the air discharge process so that the discharge rate of the valve 22 and the air discharge speed are in a proportional relationship. In this case, the CPU 40 performs feedback control, wherein the control is performed so as to change the drive voltage E to the set drive voltage E at a specific timing, such as a prescribed time interval, and maintain the resulting drive voltage E. Performing such feedback control allows the flow rate of the fluid from the fluid bladder 13 and the air discharge speed to be more closely approximated to a proportional relationship.This allows the pressure pulse wave amplitude to be approximated to a constant value relative to a constant change in blood vessel volume and improves measurement accuracy. Second embodiment

[0050] With reference to Fig. 13, a blood pressure monitor 1' serving as a blood pressure measuring device according to a second embodiment of the present invention is further provided with a tank 54 for storing a non-compressible fluid, which is connected to the fluid bladder 13 via the tube 10, in addition to the hardware configuration of the blood pressure monitor to the first embodiment shown in Fig. 1. The tank 54 is connected to a pump 51 and a valve 52. The pump 51 and the valve 52 are respectively connected to a pump driving circuit 56 and a valve driving circuit 57, and further, the pump driving circuit 56 and the valve driving circuit 57 are respectively connected to the CPU 40. The CPU 40, by executing a prescribed program stored in the memory 6, sets a voltage for driving the pump 51 and the valve 52 based on an operation signal input from the operation unit 3, and outputs a control signal corresponding to the set voltage to the pump driving circuit 56 and the valve driving circuit 57. The incompressible fluid stored in the tank 54 flows into the fluid bellows 13 via the hose 10 by driving the pump 51. The incompressible fluid in the fluid bellows 13 is discharged by driving the valve 52.

[0051] A filter 9 is provided in the portion of the fluid bellows 13 and the valve 22. To prevent the incompressible fluid from escaping from the valve 22 for injecting the fluid into the fluid bellows 13 and discharging the fluid from the fluid bellows 13 when the incompressible fluid moves into the tank 54 toward the fluid bellows 13, the material of the filter 9 is preferably a material that allows the fluid to pass through but does not allow the incompressible fluid to pass through.

[0052] Fig. Fig. 14 is a flowchart showing a specific example of the processing flow executed at the time when the measurement switch 32 in the blood pressure monitor 1' is operated. The processing flow executed in the time of Fig. 14 is realized by the CPU 40, which executes a prescribed program stored in the memory 6.

[0053] With reference to Fig. 14, in the blood pressure monitor 1', the CPU 40 outputs a control signal to the valve drive circuit 27 in step S401 to close the valve 22, blocking the fluid inflow port and the fluid discharge port of the fluid bladder 13. Subsequently, a control signal is output to the pump drive circuit 56 in step S403 to drive the pump 51, and the incompressible fluid in the tank 54 can flow out of the fluid bladder 13 until the fluid bladder 13 reaches a previously defined prescribed inflation pressure or reaches a prescribed inflation speed. In other words, the incompressible fluid is moved from the tank 54 to the fluid bladder 13.Once the internal pressure of the fluid bladder 13 reaches a prescribed pressure or once the inflation rate of the fluid bladder reaches a prescribed inflation rate (YES in step S405), the CPU 40 outputs a control signal to the valve drive circuit 57 in step 407 to close the valve 52, blocking the inflow port of the incompressible fluid to the fluid bladder 13. After blocking the inflow port, the CPU 40 then outputs a control signal to the valve drive circuit 27 in step S309 to open the valve 22, releasing the pressure in the fluid bladder 13. A prescribed amount of incompressible fluid is thereby injected into the fluid bladder 13, and also the internal pressure equalizes to atmospheric pressure.

[0054] Thereafter, the process flow of steps S103 to S107, which is similar to the process flow according to the first embodiment, is executed. The fluid bladder 13 is inflated until the fluid bladder 13 reaches a prescribed pressure that is defined in advance, and the inflation of the fluid bladder 13 is stopped in this state. Subsequently, a blood pressure value is calculated in step S113, while the air is released from the fluid bladder 13 in step S111.

[0055] In the blood pressure monitor 1', once the calculation of a blood pressure value is completed (YES in step S411), the CPU 40 outputs a control signal to the valve drive circuit 57 in step S413 to open the valve 52, discharging the incompressible fluid into the fluid bladder 13. Thereafter, the valve 22 is opened according to a control signal from the CPU 40, and the fluid in the fluid bladder 13 is discharged.

[0056] The blood pressure monitor 1' is characterized by injecting a prescribed amount of incompressible fluid into the fluid bladder 13 before inflating the fluid bladder 13 in the above step S103 to increase the volume of the fluid bladder 13 and reduce the volume of the fluid that was injected. As previously described using Fig. 24, a change in the volume of the fluid bellows 13 in the area in which the internal pressure of the fluid bellows 13 is low, which in the partial area A in Fig. 24, is thereby suppressed, compared to the method in which the fluid bladder 13 is filled with only the fluid from an initial state. Accordingly, the detection accuracy of changes in the volume of blood vessels in the blood pressure monitor 1' can be improved.

[0057] Note that, although an incompressible fluid is injected into the fluid bladder 13 as a mechanism for suppressing a change in the volume of the fluid bladder 13 in the above example in a low pressure range, a filling member may be previously applied to the fluid bladder 13 as another specific example of the above mechanism. For example, a method may also be used in which a gel material, such as microspheres, is previously filled into the fluid bladder 13 as a filling member, as shown in Fig. 15A. Also, for example, an elastic material such as sponges or springs may be applied in advance as a filling member in the fluid bellows 13, as shown in Fig. 15B and Fig. 15C. The volume of the fluid bladder 13 can be increased before filling by applying these filling members to the fluid bladder 13 in advance. Note that the filling member is not limited to the above-mentioned gel material or elastic material, and other materials may be used. The filling material may also be a combination of a variety of these materials.

[0058] Furthermore, the control at the time of air discharge according to the first embodiment and the configuration according to the second embodiment may be combined with each other. In other words, in the processing of the blood pressure monitor 1', the processing of the above step S109 may be performed after stopping the filling of the fluid bladder 13 at the above step S107, and the fluid bladder 13 may be deflated while controlling such that the opening of the valve is constant. This allows the flow rate and the air discharge speed of the fluid from the fluid bladder 13 to be more closely approximated to a proportional relationship. This allows the detection accuracy of the changes in the volume of the blood vessels to be thereby approximated to a constant value, and the measurement accuracy to be improved. Third embodiment

[0059] In the above first embodiment and the second embodiment, the discharge rate of the valve 22 and the air discharge speed of the fluid bladder 13 are established in a proportional relationship by keeping the opening of the valve 22 constant by performing control so as to keep the drive voltage E constant. However, an exhaust valve is ultimately affected by factors such as the manufacturing tolerance of the valve and the environmental conditions.

[0060] Specifically, general discharge valves include a type (A-type) that opens and closes the valve by a pressure force resulting from a magnetic force generated when an electric current is passed through a solenoid, for example, and a type (B-type) whose discharge port consists only of a rubber with a slit (opening / closing aperture) and gradually discharges the fluid. The A-type further includes a type (A-1 type) that is provided with a mechanism for controlling the closed opening of the valve by using gravity to reciprocally move a solenoid (raising or lowering) in the pressure direction or the gravity direction, and a type (A-2 type) in which control is only possible to fully open or fully close the valve.Discharge valves other than the above A-1 type are not capable of fine opening / closing control, and furthermore, the A-2 type discharge valve is only capable of fully opening or fully closing the valve. Also, in the above B type discharge valve, the slit narrows as the pressure increases and widens as the pressure decreases, and the valve opening depends on the elasticity of the rubber rather than being arbitrarily controlled. Accordingly, the A-1 type, which can preferably control the discharge rate, is suitably used as the valve 22.

[0061] An elastic base member, such as a rubber boot, is generally used in every type of discharge valve, not only in the above A-1 type discharge valve. Therefore, since the discharge characteristics change due to the variability in the hardness of the elastic base member due to manufacturing tolerance, and environmental conditions such as temperature change, the valve 22 is affected. In view of this, the inventors measured the air discharge velocity using three of the above A-1 type discharge valves, each manufactured in different production batches, under the same environmental conditions (temperature, humidity). Furthermore, the air discharge velocity was measured with the environmental conditions (temperature, humidity) changed.As a result of this measurement, it was confirmed that the ejection speed differs due to the manufacturing tolerance and environmental conditions even in the case where the same voltage was applied as shown in . Fig. 16 is shown.

[0062] Furthermore, since the opening of the valve is controlled by mutually utilizing gravity to move the solenoid, the above Type A-1 discharge valve is also affected by the relationship between the power in the pressure direction and the power in the gravity direction acting on the solenoid. That is, specifically in the case where the above Type A-1 discharge valve is used as the valve 22, the valve is affected by its orientation relative to the gravity direction, that is, by the inclination of the sphygmomanometer itself (how the sphygmomanometer is placed). The inventors measured the air discharge velocity for the Type A-1 discharge valve while varying the inclination. As a result of this measurement, it was confirmed that the discharge velocity differs due to the inclination, even for the same internal pressure of the fluid bladder 13, as shown in Fig. 17 is shown.

[0063] Even if the valve 22 is driven while maintaining the drive voltage E set in the sphygmomanometer 1 or the sphygmomanometer 1' in the above step S109, the air discharge velocity of the fluid bladder 13 may not reach the intended air discharge velocity due to a change in the environmental conditions, the production tolerance, or the placement of the sphygmomanometer as mentioned above. That is, compared with an ideal change in the internal pressure of the fluid bladder 13, which does not consider the influence of a change in the environmental conditions or the like, as shown by the curve (3) in (A) of the Fig. 18, a change in internal pressure which differs from an ideal change in internal pressure may lead to a case in which these influences are felt, as shown by curve (1) and curve (2).

[0064] In the case where the air discharge speed is lower than the ideal change in pressure, especially on the low pressure side, that is, in the case where the change in the internal pressure of the fluid bladder 13 is the curve (1), the intra-arterial pressure is measured according to the change in pressure (air discharge) of the fluid bladder 13, as shown in (B) of the Fig. 18. In this case, the diastolic blood pressure is not calculated. On the other hand, it takes a long time before the diastolic blood pressure can be calculated, which increases the burden on the person taking the measurement.

[0065] In the case where the air discharge speed is higher than the ideal change in pressure, especially on the high pressure side, ie, in the case where the change in the internal pressure of the fluid bladder 13 is the curve (2), the intra-arterial pressure is measured according to the change in pressure (air discharge) of the fluid bladder 13, as shown in (C) of the Fig. 18. In this case, the systolic blood pressure is not calculated. On the other hand, the accuracy of calculating the blood pressure value decreases.

[0066] In view of this, in a blood pressure monitor 1" according to the third embodiment, the drive voltage E of the valve 22 is adjusted so that the change in pressure of the fluid bellows 13 approaches the curve (3) using the following principle. That is, with reference to Fig. 19 and Fig. 20, in the air discharge process, after inflating the fluid bladder 13 to a pressure Pmax obtained by adding a pressure α, which is defined in advance, to the systolic blood pressure value P1 predicted from the change in the internal pressure of the fluid bladder 13 in the inflation process, the air discharge speed of the fluid bladder 13 at the time point at which the internal pressure P2 of the fluid bladder 13 has deflated or decreased by a prescribed pressure of Pmax is set as a target air discharge speed, which is defined in advance, so that the internal pressure drops within a range which is between a dashed line A and a dashed line B.Note that in the following description, the point at which the internal pressure of the fluid bladder 13 reaches the predicted systolic blood pressure value P1 in the inflation process is called the “SBP predicted point”, the point at which the internal pressure of the fluid bladder 13 is filled to Pmax is called the “maximum inflation point”, the point at which the internal pressure of the fluid bladder 13 is deflated from Pmax to P2 is called the “adjustment point”, and the point at which the internal pressure of the fluid bladder 13 reaches the actual systolic blood pressure value P1' in the deflation process is called the “SBP actual measurement point”, as shown in FIG. Fig. 20 is shown.

[0067] The dashed line A and the dashed line B, which are in Fig. 20 are the upper and lower limits of the pressure change range, which are approximately 5 mmHg / sec to 20 mmHg / sec between the systolic blood pressure and the diastolic blood pressure during subsequent deflation. In other words, with the pressure change range represented by these dashed lines, at least five pulse beats are measured between the systolic blood pressure and the diastolic blood pressure during subsequent deflation. This is because at least five pulse beats are required between the systolic blood pressure and the diastolic blood pressure during deflation to ensure measurement accuracy.

[0068] Also, with reference to Fig. 20, an example is given in which a time range t1 from the adjustment point to the SBP current measurement point is, for example, equal to at least one pulse beat in the time range or to approximately 2 seconds. That is, the adjustment point is a point of at least one pulse beat in time before the SBP current measurement point. This is because, in order to calculate the systolic blood pressure value from a measured value, not only the measured value at the SBP current measurement point but also a measured value at least one pulse beat before or after is required. Furthermore, for a similar reason, the maximum inflation point is also a point at least one pulse beat before the SBP current measurement point, and the amount of inflation α added to the pressure P1 is adjusted based on the time of at least one pulse beat.

[0069] Based on this principle, in the blood pressure monitor 1", the drive voltage E of the valve 22 is adjusted so that the air outlet speed of the fluid bladder 13 falls between the maximum inflation point and the set point within the range of the target air outlet speeds, and thereafter, the set drive voltage E is maintained at least until the calculation of a blood pressure value is completed. From this, the time period from the maximum inflation point to the set point, which is determined by a time period I in Fig. 19 and Fig. 20 can be regarded as a “(drive voltage E) setting period”, and the period of time from then until the calculation of a blood pressure value is completed, which is represented by a period of time II, can be regarded as a “(drive voltage E) set period”.

[0070] It is possible to preset the set point (or setting period) and the target air outlet speeds, for example, based on statistical results from a large amount of measurement data. In the blood pressure monitor 1" using the above principle, the set point is preset and stored. Regarding the set point, a point that is deflated or lowered by 20 mmHg from the maximum inflation point, i.e., Pmax, which is obtained by adding the pressure α to the predicted systolic blood pressure value point P1, can be set, for example. Regarding the target air outlet speed, for example, 15 mmHg / sec can be set. The following specific example is described assuming that these values ​​are set.

[0071] With reference to Fig. 21, in the blood pressure measuring device 1" for measuring the blood pressure using the above principle, the CPU 40 includes a threshold storage unit 45 and a setting judgment unit 47, instead of the circumference information acquisition unit 41 and the valve drive voltage decision unit 43, besides the hardware configuration of the blood pressure measuring device 1 of the first embodiment shown in Fig. 1. These are formed in the CPU 40 as a result of the CPU 40 executing a prescribed program stored in the memory 6 based on an operation signal input from the operation unit 3. The threshold storage unit 45 stores a target air outlet speed. The stored target air outlet speed may be a constant range. The adjustment decision unit 47 sets the drive voltage E of the valve 22 based on a change in the internal pressure of the fluid bladder 13 and adjusts the drive voltage E by comparing the air outlet speed of the fluid bladder 13 with the stored target air outlet speed.

[0072] Fig. Fig. 22 is a flowchart showing a first specific example of the process flow executed during the time lapse in which the measurement switch 32 in the blood pressure monitor 1" is operated. The process flow shown in the flowchart of Fig. 22 is realized as a result of the CPU 40 executing a prescribed program stored in the memory 6. In Fig. 22 is the process flow which is given the same step number as in the flowchart of the Fig. 2, similar to the process flow in the blood pressure monitor 1.

[0073] With reference to Fig. 22, the CPU 40 monitors the input of the operation signals from the operation unit 3. When the operation of the measurement switch 32 is detected, it outputs a control signal to the pump drive circuit 26 in steps S103 and S105 without executing the circumference information acquisition of step S101 in the sphygmomanometer 1, and inflates the fluid bladder 13 until the fluid bladder 13 reaches a prescribed pressure that has been previously defined. When the prescribed pressure is reached (YES in step S105), the CPU 40 outputs a control signal to the pump drive circuit 26 in step S107 and stops the inflation of the fluid bladder 13. This point is equal to the maximum inflation point.

[0074] Thereafter, steps S501 to S509 are processed instead of the process flow for setting the drive voltage E of step S109. That is, after stopping the filling of the fluid bladder 13 in step S107, a control signal is output to the pump drive circuit 26 in step S501, and the air discharge is started. In the air discharge process, in the case where it is within the adjustment period, that is,In the case where the difference between the internal pressure of the fluid bladder 13 and the internal pressure Pmax of the maximum inflation point is less than 20 mmHg (YES in S503), the CPU 40 compares the air outlet speed of the internal pressure of the fluid bladder 13 with 15 mmHg / sec, which is the target air outlet speed stored in the threshold storage unit 45, in the adjustment judgment unit 47. If it does not match or if it is not within a prescribed range of 15 mmHg / sec (NO in S503), it corrects the current drive voltage of the current valve 22 in step S507 by adding a correction amount ΔV, which is defined beforehand. Alternatively, the following arithmetic operation, for example, can be performed to calculate the correction amount ΔV, and the drive voltage E can be corrected: ΔV=A(Vt−V)+B, where A is a correction coefficient (a gain), B is a correction coefficient (an offset), Vt is the target emptying speed, and V is the air outlet speed of the fluid bladder 13.

[0075] The correction of the drive voltage E at these steps S505 and S507 is repeated within the adjustment period until the air outlet speed of the internal pressure of the fluid bladder 13 fits or falls within a prescribed range of the target air outlet speed of 15 mmHg / sec. In the case where the air outlet speed of the internal pressure of the fluid bladder 13 fits or falls within a prescribed range of the target air outlet speed of 15 mmHg / sec (YES in S505), or in the case where the adjustment period ends, that is, the internal pressure of the fluid bladder 13 deflates or falls more than 20 mmHg from the internal pressure Pmax of the highest inflation point.is decreased (NO at S503), the CPU 40 sets the drive voltage E-adjustment at that time as the subsequent drive voltage E of the valve 22 in the adjustment judging unit 47, holds the drive voltage E, outputs a control signal to the valve drive circuit 27 so as to drive the valve 22, and proceeds to the air discharge of the fluid bellows 13.

[0076] Subsequently, a blood pressure value is calculated from the measured value with the drive voltage E fixed in step S505, in a manner similar to steps S113 to S117 of the Fig. 2, and the series of processes is completed.

[0077] As a result of the above processing performed by the blood pressure monitor 1", the driving voltage E of the valve 22 is adjusted during the period from the maximum inflation point to the adjustment point, the influence of the manufacturing tolerance, the change in the environmental conditions and the placement (condition of inclination) on the valve 22 can be eliminated, and the change in the pressure of the fluid bladder 13 can be satisfied by the curve (3) of (A) of the Fig. 18. Even in the case where the valve 22 is affected by the manufacturing tolerance, the change in the environmental conditions, or the placement (condition of inclination), the detection accuracy of the changes in the volume of the blood vessels can thereby be approximated to a constant value, and the measurement accuracy can be improved.

[0078] Also, as a result of performing such control, the process for acquiring circumference information, and the process for setting the drive voltage E according to the circumference, which were required in the blood pressure monitor 1, and the like, are no longer necessary. The total measurement time can be shortened, and the burden on the person can be reduced.

[0079] Note that the drive voltage E of the valve 22 is assumed to be fixed in voltage after setting for a fixed period of time after the set point in the above example, although in the case where the difference (blood pressure range) between the systolic blood pressure and the diastolic blood pressure of the measured person is large, the internal pressure of the fluid bladder 13 may remain within the blood pressure range for a long time even after the required measurement for calculating the blood pressure value is completed. An example of the required measurement for calculating the blood pressure value includes a measurement for which approximately 5 pulse beats are measured between the systolic blood pressure and the diastolic blood pressure during air release, as mentioned previously.Accordingly, since the measurement site remains compressed by the fluid bellows 13, if the measurement is continued for a longer period, the burden on the person being measured increases. In view of this, the CPU 40 of the blood pressure monitor 1" preferably executes the processing sequence shown in . Fig. 23 is shown.

[0080] That is, with reference to Fig. 23, after performing a similar process flow as mentioned above up to step S509, the CPU 40 monitors the number of pulses measured by the change in the internal pressure of the fluid bladder 13 in the subsequent measurement flow in the adjustment judgment unit 47. For example, "5" or the like is previously stored in the adjustment judgment unit 47 as the number of pulses required to calculate a blood pressure value. If it is detected that the number of measured pulses is equal to or greater than the stored number of required pulses (YES in S511), the adjustment judgment unit 47 compares the air discharge rate of the internal pressure of the fluid bladder 13 with an air discharge rate serving as a threshold for judging an appropriate air discharge rate, which is previously stored in the threshold storage unit 45.In the case where the air discharge speed of the internal pressure of the fluid bellows 13 is lower than the air discharge speed serving as a threshold, that is, in the case where the air discharge speed is slow (NO in S513), the adjustment judging unit 47 adds a correction amount ΔV' defined in advance and corrects the current drive voltage of the valve 22 in step S515. Alternatively, the correction amount ΔV' may be calculated similarly to the correction amount ΔV.

[0081] In this way, the burden on a measuring person having a wide blood pressure range can be reduced by additionally adjusting the driving voltage of the valve 22 in the state where the internal pressure of the fluid bellows 13 becomes low.

[0082] Note that with the blood pressure monitor 1", it is assumed that the adjustment judgment unit 47 compares the air outlet speed of the fluid bladder 13 with a target air outlet speed previously stored in the threshold storage unit 45, using the principle described in Fig. 19 and Fig. 20. However, this is an example, and another method may be used as long as the drive voltage E of the valve 22 is adjusted so that the internal pressure of the fluid bellows 13 is approximately close to a planned curve shown by the curve (3) in (A) of the Fig.18. For example, in the case where a measuring mechanism is provided that measures the consumption current of the valve 22, a target current value may be previously stored in the threshold storage unit 45, and the drive voltage E may be adjusted by comparing the consumption current value in the valve 22 with the stored target current value. Alternatively, the adjustment judgment unit 47 may adjust the consumption current instead of the drive voltage E of the valve 22.Alternatively, a configuration may be adopted in which the threshold storage unit 45 stores the correspondence between the environmental conditions, placement (tilt condition), and the like, and the drive voltages E suitable for these conditions in advance, and the adjustment judgment unit 47 reads and sets the drive voltage E corresponding to the detected environmental condition, placement (tilt condition), or the like. Further, in this case, the adjustment judgment unit 47 may receive an input signal of an environmental condition from the operation unit 3 and use this input environmental condition in the adjustment.

[0083] The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The technical scope of the invention is defined by the claims, and all changes that come within the meaning and range of equivalents of the claims are intended to be embraced therein. List of reference symbols 1, 1', 1" blood pressure monitor 2 main unit 3 Control unit 4 Display unit 5 cuff 6, 7 memory 9 filters 10 hose 13 Fluid bellows 31 circuit breakers 21 Pump 22 Valve 23 Pressure sensor 26 Pump driver circuit 27 Valve driver circuit 18 Oscillation circuit 32 measuring switches 33 Stop switch 34 Recording call switch 40 CPU 41 Scope information acquisition unit 43 Valve drive voltage setting unit 45 Threshold storage unit 47 Adjustment Assessment Unit 51 Pump 52 Valve 53 Power supply 54 Tank or container 55 Flowmeter 56 Pump driver circuit 57 Valve driver circuit

Claims

[1] Blood pressure measuring device (1), which comprises: a fluid bellows (13); an inflation unit for injecting fluid into the fluid bladder and for inflating the fluid bladder (13); an air outlet unit including a valve (22) provided in the fluid bellows (13) and for emptying the fluid from the fluid bellows (13) and discharging air from the fluid bellows (13); a sensor (23) for measuring a change in the internal pressure of the fluid bladder (13); a blood pressure measuring unit for calculating a blood pressure value based on the change in the internal pressure of the fluid bladder (13) obtained by the sensor (23) in an air discharge process of discharging the fluid from the fluid bladder (13) through the air discharge unit; and a control unit for controlling the inflation unit, the air outlet unit and the blood pressure measuring unit, wherein the control unit sets an opening of the valve (22), which is a control amount for controlling an emptying rate of the fluid through the air outlet unit so that the emptying rate is proportional to an air outlet speed of the fluid bladder (13) in the air outlet process, and controls the emptying rate by performing a control so as to keep the opening of the valve (22) at the set opening in the air outlet process, and the control unit adjusts an influence of the manufacturing tolerance of the valve (22) by setting the predetermined control amount so that the air outlet speed of the fluid bellows (13) is within a prescribed range during a prescribed period of time from a start of the air outlet process, where: the control unit further sets the set control amount so that the air outlet speed of the fluid bellows (13) is faster than a prescribed speed during the measurement which is carried out after the prescribed period of time, and the control unit further sets the set control amount, when a pulse pressure superimposed on the internal pressure of the fluid bladder (13) is equal to or greater than a prescribed frequency detected in the air discharge process; and / or the control unit judges whether the air discharge speed of the fluid bellows (13) is within the prescribed range by comparing a consumption current of the valve (22) with a threshold value; and / or the prescribed time period is a time period from the start of the air discharge process to at least one pulse beat before a pulse wave initially superimposed on the internal pressure of the fluid bellows (13) in the air discharge process. [2] The blood pressure measuring device (1) according to claim 1, wherein the control unit sets a drive voltage for driving the valve (22) as the control value. [3] The blood pressure measuring device (1) according to claim 1, wherein the control unit sets a consumption current of the valve (22) as the control value. [4] Blood pressure measuring device (1) according to claim 1, wherein the control unit sets the opening of the valve (22) which is the control value so as to achieve an air outlet speed at which at least a prescribed number of pulse beats are included in a time required for the internal pressure of the fluid bladder (13) to change from a systolic blood pressure to a diastolic blood pressure. [5] Blood pressure measuring device (1), which comprises: a fluid bellows (13); an inflation unit for injecting the fluid into a fluid bladder (13) and inflating the fluid bladder (13); an air outlet unit including a valve (22) provided in the fluid bellows (13) and for emptying the fluid from the fluid bellows (13) and discharging air from the fluid bellows (13); a sensor (23) for measuring a change in the internal pressure of the fluid bellows (13); a blood pressure measuring unit for calculating a blood pressure value based on the change in the internal pressure of the fluid bladder (13) obtained by the sensor (23) in an air discharge process of discharging the fluid from the fluid bladder (13) through the air discharge unit; and a control unit for controlling the inflation unit, the air outlet unit and the blood pressure measuring unit, wherein the control unit sets an opening of the valve (22) which is a control value for controlling an emptying rate of the fluid through the air outlet unit, such that the discharge rate is proportional to an air discharge speed of the fluid bellows (13) in the air discharge process, and controls the discharge rate by performing a control so as to keep the opening of the valve (22) at the specified opening in the air discharge process, and the control unit corrects an influence of an environmental condition, such as temperature or humidity, by adjusting the predetermined control value so that the air outlet speed of the fluid bellows (13) is within a prescribed range during a prescribed period of time from a start of the air outlet process. [6] Blood pressure measuring device (1) according to claim 6, which further comprises an input unit for inputting the environmental condition. [7] Blood pressure measuring device (1), which comprises: a fluid bellows (13); an inflation unit for injecting fluid into a fluid bladder (13) and inflating the fluid bladder (13); an air outlet unit including a valve (22) provided in the fluid bellows (13) and for emptying the fluid from the fluid bellows (13) and discharging air from the fluid bellows (13); a sensor (23) for measuring a change in the internal pressure of the fluid bellows (13); a blood pressure measuring unit for calculating a blood pressure value based on the change (23) in the internal pressure of the fluid bladder (13) obtained by the sensor (23) in an air discharge process of discharging the fluid from the fluid bladder (13) through the air discharge unit; an adjustment decision unit (47) configured to determine a drive voltage (E) of the valve (22) based on a change in the internal pressure of the fluid bellows (13) and to adjust the drive voltage (E) by comparing the air outlet speed of the fluid bellows (13) with the stored target air outlet speed, a control unit for controlling the inflation unit, the air outlet unit and the blood pressure measuring unit, wherein the control unit sets an opening of the valve (22) which is the drive voltage (E) for controlling a discharge rate for the fluid through the air discharge unit, so that the discharge rate is proportional to an air discharge speed of the fluid bellows (13) in the air discharge process, and controls the discharge rate by performing a control so as to keep the opening of the valve (22) at the set opening in the air discharge process, and the control unit corrects an influence of an installation inclination of the valve (22) relative to the direction of gravity by adjusting the predetermined drive voltage (E) so that the air discharge speed of the fluid bellows (13) is within a prescribed range during a prescribed period of time from a start of the air discharge process. [8] A control method of an electronic blood pressure measuring device (1) including a fluid bladder (13) and an arithmetic operation unit for calculating a blood pressure value based on a change in the internal pressure of the fluid bladder (13), wherein the fluid bellows (13) is provided with a valve (22), and the control method comprising the following steps: Inflating the fluid bellows (13) to a prescribed pressure; Setting a voltage for driving the valve (22) after inflation; Maintaining an opening of the valve (22) at a predetermined opening and releasing air from the fluid bellows (13) by operating the valve (22) at the predetermined voltage; Calculating a blood pressure value from the change in the internal pressure of the fluid bellows (13) in the air discharge process; and outputting the blood pressure value, wherein the step of setting the voltage for driving the valve (22) comprises setting the opening of the valve (22) as a control value for controlling a discharge rate of the fluid, such that the discharge rate is proportional to an air discharge speed of the fluid bellows (13) in the air discharge process, further providing: Correcting the voltage for driving the valve (22) based on an environmental condition such as temperature or humidity by setting a predetermined control amount so that the air discharge speed of the fluid bellows (13) is within a prescribed range during a prescribed period from a start of the air discharge process, and / or an inclination of the electronic sphygmomanometer relative to the direction of gravity. [9] A control program for causing an electronic blood pressure measuring device (1) including a fluid bellows (13) and an arithmetic operation unit for calculating a blood pressure value based on a change in the internal pressure of the fluid bellows (13) to perform a blood pressure measuring operation, wherein the fluid bellows (13) is provided with a valve (22), and The program causes the electronic blood pressure monitor to perform the following steps: Inflating the fluid bellows (139) to a prescribed pressure; Setting a voltage for driving a valve (22) after inflation; Maintaining an opening of the valve (22) at a specified opening and releasing air from the fluid bellows by operating the valve (22) at the specified voltage; Calculating a blood pressure value from the change in the internal pressure of the fluid bellows in the air discharge process; and outputting the blood pressure value, wherein the step of setting the voltage for driving the valve (22) comprises setting the opening of the valve (22) which serves as a control value for controlling an emptying rate of the fluid so that the emptying rate is proportional to an air discharge speed of the fluid bellows (13) in the air discharge process, further providing: Correcting the voltage for driving the valve (22) based on an environmental condition such as temperature or humidity by setting a predetermined control amount so that the air discharge speed of the fluid bellows (13) is within a prescribed range during a prescribed period from a start of the air discharge process, and / or an inclination of the electronic sphygmomanometer relative to the direction of gravity.

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