Blood pressure measuring device and control procedure for the blood pressure measuring device

Abstract

Blood pressure measuring device (1) which features: a cuff (40) which, when worn on a blood pressure measuring surface, pressurizes an artery in the measuring surface at the pressure of a fluid in the cuff; a piezoelectric pump (31) which increases the pressure inside the cuff (40); an air outlet unit (32) which reduces the pressure inside the cuff (40); a pressure detection unit (33) which detects the cuff pressure, which is the pressure inside the cuff (40); and a control unit (20), wherein the control unit (20) includes: a determining device which determines an amplitude and a frequency of a voltage which is applied to the piezoelectric pump (31) (step S112, step S113); a control device for the applied voltage, which performs the control so that a voltage at the amplitude and frequency determined by the determining device is applied to the piezoelectric pump (31) (step S114); and a blood pressure measuring device (1) which calculates a blood pressure value based on the cuff pressure detected by the pressure detection unit (33) during inflation when the cuff pressure is increased by the piezoelectric pump (31) (step S115), and wherein the determining device determines a first control frequency (fo1) as the first driving control frequency at which a pump efficiency of the piezoelectric pump is maximal in the case in which the fluid is supplied to the cuff (40) at a required flow velocity during inflation, using a previously determined first voltage (Vo1) as the voltage (step S112); wherein the determining device determines a second control voltage (Vo2) at which the pump efficiency is at its maximum, in the case in which the fluid is supplied to the cuff (40) at a required flow velocity during inflation, wherein a previously determined second frequency (fo2) is used as the second driving frequency (fo2) (step 113); The control device of the applied voltage performs a first control, which applies a voltage at the amplitude of the previously determined first voltage (Vo1) and at the first control frequency (fo1), which is determined by the determining device from the beginning of the inflation until a previously determined time, halfway through the inflation process, and The control device of the applied voltage performs a second control, which applies the previously determined second frequency (fo2) and the second control voltage (Vo2), which is determined by the control device, from the previously determined time until the end of the inflation (step S114).

Description

Technical area

[0001] This invention relates to blood pressure measuring devices and control methods for blood pressure measuring devices, and more specifically, it relates to blood pressure measuring devices suitable for measuring blood pressure during the inflation of a cuff, and to control methods for such blood pressure measuring devices. Background of the state of the art

[0002] An electronic blood pressure monitor that uses oscillometric technology is known as a typical electronic blood pressure monitor. In an electronic blood pressure monitor using oscillometric technology, a cuff containing an air bladder is wrapped around a part of the body. Changes in the volume of an arterial vessel, which is pressurized by inflating or deflating the air bladder, are measured as changes in the pressure amplitude within the air bladder (the cuff pressure), which are then used to calculate blood pressure. To accurately measure blood pressure during cuff inflation, it is necessary to appropriately control the rate at which the pressure within the cuff is increased.

[0003] In JP 2009-74418A (hereinafter referred to as "Patent Reference 1"), a piezoelectric micropump driven by a piezoelectric element is proposed, and the application of such a pump in an electronic blood pressure monitor is discussed. Meanwhile, in JP 2010-255447A (hereinafter referred to as "Patent Reference 2"), JP 2010-162487A (hereinafter referred to as "Patent Reference 3"), and so on, the setting of a drive frequency according to the material of a piezoelectric element and a diaphragm, and the execution of the control near the drive frequency, are proposed.

[0004] However, if the pump is driven in this way at high pressure, the piezoelectric pump will consume more power, and consequently, fewer blood pressure measurements can be taken before replacing the battery. Therefore, it is necessary to improve the pump's mechanical efficiency.

[0005] In JP 2006-129920 A (hereinafter referred to as “Patent Literature 4”) a method for pump flow velocity discharge control is proposed, using a current, a voltage, a duty cycle or the like. List of citations from patent literature Patent Literature 1: JP 2009-74418A Patent Literature 2: JP 2010-255447A Patent Literature 3: JP 2010-162487A Patent Literature 4: JP 2006-129920A

[0006] US 6,171,254 B1 describes an automatic, non-invasive blood pressure monitor consisting of a cuff, a pump, a valve, and a pressure sensor, all connected to a microprocessor. During an initial inflation phase, the cuff size is automatically determined based on the pressure-time characteristic curve. The microprocessor then sets inflation- and deflation-related parameters such as target inflation pressure, inflation rate, deflation rate, and pressure drop increment.

[0007] US 2005 / 0225202A1 describes a pump with a piezoelectric actuator and a control circuit that generates a control pulse as a sequence of digital pulses. The circuit includes a pulse generator, a converter, and utilizes the capacitance of the piezoelectric actuator to integrate the charge packets and shape the control voltage. The circuit can process various input signals, utilize feedback, control multiple actuators, and dynamically adjust operating parameters. Summary of the invention: Technical problem

[0008] However, according to the technology described in patent literature 4, even if the pump flow rate output is the same, there are cases in which the energy efficiency of the pump will change depending on a voltage and a frequency, and the maximum energy efficiency of the pump cannot be achieved.

[0009] Having gained knowledge of the aforementioned problem, it is an object of this invention to provide a blood pressure measuring device and a control method for a blood pressure measuring device which are able to reduce the amount of power consumed in the case in which a piezoelectric pump is used when a cuff pressure is increased for the purpose of blood pressure measurement. Solution to the problem

[0010] To fulfill the aforementioned task, a blood pressure measuring device includes the features according to claim 1.

[0011] Preferably, the predetermined time is a time at which the cuff pressure reaches a predetermined pressure, the predetermined pressure is predetermined for each of a plurality of required flow velocities, and the required flow velocities are predetermined based on a dimension of the cuff, a dimension of the measuring surface, and a state of the cuff when it is borne on the measuring surface.

[0012] A control method for a blood pressure measuring device according to yet another aspect of the invention is a control method with the features of claim 3. Advantageous effects of the invention

[0013] According to this invention, the blood pressure measuring device determines the amplitude and frequency of a voltage applied to the piezoelectric pump, controls the device so that a voltage at the predetermined amplitude and frequency is applied to the piezoelectric pump, and calculates a blood pressure value based on the cuff pressure detected by the pressure detection unit during inflation when the cuff pressure is increased by the piezoelectric pump. A control frequency is determined at which the pump efficiency of the piezoelectric pump is maximized when the fluid is delivered to the cuff at the required flow rate during inflation, using a predetermined voltage.The first control, in which a voltage is applied at the amplitude of the previously determined voltage and at the previously determined control frequency, is then executed.

[0014] Accordingly, the piezoelectric pump is driven at the control frequency and predetermined voltage at which its pump efficiency is maximized. This predetermined voltage is used when the fluid is delivered to the cuff at the required flow rate during inflation. Consequently, the amount of power consumed can be reduced compared to driving the piezoelectric pump at a different control frequency and predetermined voltage. As a result, it is possible to provide a blood pressure measuring device and a control method for such a device that are capable of reducing the amount of power consumed when the cuff pressure is increased for blood pressure measurement using the piezoelectric pump. Brief description of the drawings Fig. Figure 1 is a perspective view of the exterior of a blood pressure measuring device according to an embodiment of the invention. Fig. Figure 2 is a block diagram that describes the overall configuration of the blood pressure monitor according to the embodiment. Fig. Figure 3 is a graph that represents the pump efficiency when a voltage applied to a piezoelectric pump is varied. Fig. Figure 4 is a graph that represents a frequency at which the piezoelectric pump can achieve a maximum flow velocity relative to a voltage value. Fig. Figure 5 is a graph that represents the pump efficiency when a voltage of 35 V is applied to the piezoelectric pump. Fig. Figure 6 is a diagram showing variations in the pump efficiency of the piezoelectric pump when a voltage applied during inflation control at constant speed is controlled. Fig. Figure 7 is a diagram showing changes in the pump efficiency of the piezoelectric pump when a driving frequency of an applied voltage is controlled during inflation control at constant speed. Fig. Figure 8 is a diagram that shows a comparison between the pump efficiencies during frequency control and voltage control, as well as between an applied voltage and a driving frequency. Fig. Figure 9 is a flowchart illustrating the sequence of a blood pressure measurement process performed by a blood pressure measuring device according to the embodiment. Description of the embodiments

[0015] An embodiment of the invention is described in detail below with reference to the drawings. Note that identical or corresponding elements in the drawings are given the same reference numerals, and descriptions thereof are not repeated.

[0016] The following describes a piezoelectric pump drive control when it performs an inflation-based measurement using an oscillometric blood pressure monitor that takes measurements during inflation, as one embodiment of the invention. However, the invention is not limited to this and can, for example, be applied to another type of blood pressure monitor, as long as the blood pressure monitor performs an inflation process using a piezoelectric pump, such as a blood pressure monitor that performs an air-release-based measurement.

[0017] First, a configuration of a blood pressure measuring device 1 according to this embodiment is described. Fig. Figure 1 is a perspective view of the exterior of the blood pressure monitor 1 according to this embodiment of the invention. As in Fig. As shown in Figure 1, the blood pressure monitor 1 according to this embodiment comprises: a main part 10, a cuff 40, and an air hose 50. The main part 10 includes a box-shaped housing, and a display unit 21 and an operating unit 23 are provided on its upper surface. During measurement, the main part 10 is used by placing it on a surface, such as a table or similar.

[0018] The cuff 40 primarily comprises a band-shaped, air-bellow-shaped outer cover 41 and a pressurizing air bellows 42, which is contained within the outer cover 41 and serves as a pressurizing fluid bellows; the cuff 40 has an overall ring-shaped form. During measurement, the cuff 40 is used by wrapping it around the upper arm of a person being measured and wearing it on that arm. The air hose 50 connects the main part 10 and the cuff 40, which are configured as separate units.

[0019] Fig. Figure 2 is a block diagram illustrating the overall configuration of the blood pressure monitor 1 according to this embodiment. As shown in Fig. As shown in Figure 2, in addition to the previously mentioned display unit 21 and operating unit 23, the main part 10 includes a control unit 20, a storage unit 22, a power supply unit 24, a piezoelectric pump 31, an outlet valve 32, a pressure sensor 33, a DC-DC amplifier circuit 61, a voltage control circuit 62, a driving control circuit 63, an amplifier 71, and an A / D converter 72. The piezoelectric pump 31 and the outlet valve 32 correspond to an inflation / air discharge mechanism to increase / decrease the internal pressure of the pressurizing air bellows 42.

[0020] The pressurizing air bellows 42, when worn on the upper arm, supplies it with pressure and has an internal chamber. The pressurizing air bellows 42 is connected to the aforementioned piezoelectric pump 31, the outlet valve 32, and the pressure sensor 33, each via the aforementioned air hose 50. As a result, the pressurizing air bellows 42 is inflated and expands under the drive of the piezoelectric pump 31; the internal pressure is maintained, the pressurizing air bellows 42 is deflated, i.e., air is released from it and it contracts, and so on, by controlling the operation of the outlet valve 32.

[0021] The control unit 20, for example, is configured with a CPU (central processing unit) and is a unit for controlling the blood pressure monitor 1 as a whole.

[0022] The display unit 21, for example, is configured with an LCD (liquid crystal display) and is a unit for displaying measurement results and the like.

[0023] The memory unit 22, for example, is configured from a ROM (read-only memory), a RAM (access memory), or similar, and stores programs to instruct the control unit 20 and similar to perform the processes for measuring a blood pressure value, storing the measurement results, and so on.

[0024] The operating unit 23 is a unit for receiving operations or controls performed by a measuring person or similar, and for entering such external commands into the control unit 20, the power supply unit 24 and similar.

[0025] The power supply unit 24 is a unit for supplying power to the various units of the blood pressure monitor 1, such as the control unit 20 and the piezoelectric pump 31, and is a battery in this embodiment. However, the power supply unit 24 is not limited to this and can receive power supplied by an external power source, such as an AC wall socket.

[0026] The control unit 20 sends control signals to the voltage control circuit 62 and the driving control circuit 63, respectively, for driving the piezoelectric pump 31 and the outlet valve 32, and inputs the blood pressure values, which serve as measurement results, into the display unit 21 and the storage unit 22. The control unit 20 also includes a blood pressure information maintenance unit (not shown), which receives a blood pressure value from a test subject based on a pressure value detected by the pressure sensor 33 via the amplifier 71 and the A / D converter 72. The blood pressure value obtained by the blood pressure information maintenance unit is entered into the aforementioned display unit 21 and the storage unit 22 as a measurement result.

[0027] Note that the blood pressure monitor 1 may also include a separate output unit that transmits a blood pressure reading to an external device, such as a PC (personal computer), a printer, or similar. For example, a serial communication line, a device that records to various types of media, or similar devices could be used as the output unit.

[0028] The DC-DC amplification circuit 61 is a circuit which amplifies the voltage of the battery, which serves as the voltage supply unit 24, to a voltage suitable for driving the piezoelectric pump 31.

[0029] The voltage control circuit 62 controls the voltage supplied to the piezoelectric pump 31 based on a voltage value indicated by a control signal input from the control unit 20.

[0030] The driving control circuit 63 controls the piezoelectric pump 31 and the outlet valve 32 based on a control signal input from the control unit 20. Specifically, the driving control circuit 63 controls the frequency of the current supplied to the piezoelectric pump 31, based on a control frequency specified by the control signal input from the control unit 20. Additionally, the driving control circuit 63 controls the outlet valve 32, opening and closing it based on the control signal input from the control unit 20.

[0031] The piezoelectric pump 31 is a unit for increasing the internal pressure of the pressurizing air bellows 42 (hereinafter also referred to as "cuff pressure") by supplying air to the interior of the pressurizing air bellows 42, and its operations are controlled by the aforementioned driving control circuit 63. The piezoelectric pump 31 discharges air at a predetermined flow rate by applying an AC current of a predetermined amplitude V0 at a predetermined driving frequency f0. Note that a sinusoidal AC current can be applied, a square wave AC current can be applied, and so on. In the following, the value of a peak-to-peak potential difference Vp-p can be used when discussing the value of a voltage applied to the piezoelectric pump 31. The amplitude is half the value of Vpp.Relative to Vp-p, the value of the voltage changes into a range of values ​​from, for example, -Vp-p / 2 to Vp-p / 2.

[0032] The outlet valve 32 is a unit to maintain the internal pressure in the pressurizing air bellows 42, to open the interior of the pressurizing air bellows 42 to the outside and to reduce the cuff pressure, and so on, and its operations are controlled by the previously mentioned driving control circuit 63.

[0033] The pressure sensor 33 detects the internal pressure of the pressurizing air bellows 42 and inputs an output signal to the amplifier 71 based on the detected pressure. The amplifier 71 amplifies the level of the signal input from the pressure sensor 33. The A / D converter 72 converts the signal, amplified by the amplifier 71, into a digital signal and inputs the generated digital signal to the control unit 20.

[0034] Fig. Figure 3 is a graph that represents a pump efficiency when a voltage applied to the piezoelectric pump 31 is varied. Fig. Figure 4 is a graph representing the frequency at which the piezoelectric pump 31 can achieve its maximum flow velocity relative to a given voltage value. The pump efficiency is represented by the ratio of pump output to pump inlet and is calculated using the formula: Pump efficiency (%) = Pressure (measuring instrument pressure) × Flow velocity / Power consumed.

[0035] As in Fig. Figure 3 shows the changes in pump efficiency, together with an increase in cuff pressure when the cuff 40 is inflated, for cases where the voltage applied to the piezoelectric pump 31 is 10 V, 25 V, 30 V, 35 V and 38 V respectively.

[0036] Meanwhile, it shows Fig. 4, that the frequencies at which the maximum flow velocity can be achieved when the voltages are 10 V, 25 V, 30 V, 35 V and 38 V are approximately 23.30 kHz, 22.95 kHz, 22.85 kHz, 22.8 kHz and 22.65 kHz respectively. Therefore, the piezoelectric pump 31 is driven at the frequencies which are in Fig. 4 are shown when the corresponding voltage, which is in Fig. 3 is shown, it is set up.

[0037] In this way, the pump efficiency reaches a maximum while the sleeve pressure rises and then falls, regardless of the applied voltage. The higher the voltage, the higher the sleeve pressure will be when the pressure is at its maximum. Furthermore, the higher the voltage, the higher the pump efficiency will be when the pump efficiency is at its maximum.

[0038] Fig. Figure 5 is a graph representing the pump efficiency when a voltage of 35 V is applied to the piezoelectric pump 31. As in Fig. As shown in Figure 5, when the voltage applied to the piezoelectric pump 31 is set to 35 V, the pump efficiency achieved when the cuff pressure increases as the cuff 40 is inflated is improved by 20% or more if the optimal frequency for reaching the maximum flow velocity is 23.8 kHz as opposed to 22.8 kHz. The frequency f0 of 23.8 kHz is the frequency that optimizes the pump efficiency until the cuff pressure reaches 150 mmHg.

[0039] In this way, the voltage and driving frequency at which the pump efficiency is optimal differ depending on the range of the cuff pressure. Accordingly, it is conceivable to control the voltage applied to the pump and the driving frequency based on the range of the cuff pressure.

[0040] Fig. Figure 6 is a diagram showing variations in the pump efficiency of the piezoelectric pump 31 when a voltage is applied during inflation control at constant speed. As in Fig. As shown in Figure 6, it is necessary to inflate the cuff at a constant rate so that the blood pressure monitor 1 can measure blood pressure. Accordingly, changes in pump efficiency are described in the case where a cuff pressure P (mmHg) is increased to 200 mmHg at a constant rate, as shown in Figure (A). Fig. 6 is displayed.

[0041] As in (B) the Fig. 6 indicates a flow rate Qt (mL / min) or (ml / min) required to increase the cuff pressure P at a constant rate, as shown in (A) of the Fig. The value shown in 6 can be determined when a cuff wrapping state and an arm circumference are set. In this way, the cuff pressure P can be increased at a constant velocity by causing the flow velocity Qt to decrease slowly.

[0042] Next, as in (C) the Fig. 6 is shown in the case where the voltage is controlled to cause the piezoelectric pump 31 to pump air at the flow velocity At which is shown in (B) of the Fig. 6 is shown, to discharge, a voltage Vo2 can be increased according to the voltage-flow velocity characteristics of the pump. Note that a driving frequency fo2 is a frequency at which the piezoelectric pump 31 can discharge at the maximum flow velocity, corresponding to the value of the voltage Vo2, and this can be determined based on the graph shown in Fig. 4 is shown.

[0043] As in (D) the Fig. 6 is indicated, a pump efficiency η2 (%) increases, which results from driving the piezoelectric pump 31 at the voltage Vo2 and the driving frequency fo2, which is shown in (C) of the Fig. The number 6 is displayed, resulting in inflation, and then it drops.

[0044] Fig. Figure 7 is a diagram showing changes in the pump efficiency of the piezoelectric pump 31 when the driving frequency of the voltage applied during inflation control at constant speed is controlled. (A) and (B) in Fig. 7 are the same as (A) and (B) respectively in Fig. 6.

[0045] As in (C) the Fig. 7 is shown to draw air from the piezoelectric pump 31 at the flow velocity Qt, which is shown in (B) of the Fig. As indicated in Figure 7, the driving frequency can be controlled such that, in the case where a constant voltage Vo1 is applied, the driving frequency fo1 is reduced based on the original voltage-flow velocity characteristics of the pump. Note that, although the applied voltage Vo1 has a constant value in this embodiment, the invention is not limited to this, and the voltage can be varied in an adjustable manner.

[0046] As in (D) the Fig. 7 is displayed, a pump efficiency η1 (%) increases, which results from driving the piezoelectric pump 31 at the voltage Vo1 and the driving frequency fo1, which is shown in (C) of the Fig. 7 are shown, resulting, during inflation and then falling, in the same way as in the case where the applied voltage is controlled, as in (D) of the Fig. 6 is displayed.

[0047] Fig. Figure 8 is a diagram that compares the pump efficiencies during frequency control and voltage control, as well as for an applied voltage and a driving frequency. As shown in (A) of the Fig. Figure 8 shows the intersection of the respective pump efficiencies η1 and η2, which are achieved when frequency control and voltage control are implemented when the cuff pressure P is P1 (150 mmHg). In other words, frequency control results in a higher pump efficiency value when the cuff pressure is lower than P1. Conversely, voltage control results in a higher pump efficiency value when the cuff pressure is higher than P1.

[0048] Accordingly, as in (B) the Fig. As indicated in 8, if the cuff pressure is lower than P1, the constant voltage Vo1 is applied and the driving frequency fo1 is controlled, whereas if the cuff pressure is higher than P1, the applied voltage Vo2 is controlled, and the driving frequency fo2, at which the maximum flow velocity can be achieved, is obtained accordingly with the voltage Vo2.

[0049] This allows the piezoelectric pump 31 to be driven by the frequency control, which achieves the pump efficiency η1, which is higher than the pump efficiency η2, which is achieved by the voltage control when the sleeve pressure is lower than P1, whereas the piezoelectric pump 31 can be driven by the voltage control, which achieves the pump efficiency η2, which is higher than the pump efficiency η1, which is obtained by the frequency control when the sleeve pressure is higher than P1.

[0050] Fig. Figure 9 is a flowchart illustrating the sequence of a blood pressure measurement process performed by the blood pressure monitor 1 according to this embodiment. As shown in Fig. As shown in Figure 9, in step S101 the control unit 20 of the blood pressure monitor 1 first measures the wrapping state of the cuff 40 and the arm circumference. Specifically, an initial inflation is performed by controlling the piezoelectric pump 31, so that a predetermined amount of air is discharged into the cuff from a state in which there is no pressure in the cuff 40; at this time, the inflation rate is measured, and the wrapping state and the arm circumference are estimated based on the measured inflation rate. The method disclosed in International Publication WO 2010 / 089917 can be given as an example of this method.

[0051] Next, in step S102, the control unit 20 calculates the flow rate Qt required to inflate the cuff 40 at a constant rate, based on the wrapping state of the cuff 40 and the arm circumference measured in step S101. Specifically, the data displayed in the graphs shown in (B) of the Fig. 6 and Fig. 7 are shown, previously stored in the memory unit 22 of the blood pressure measuring device 1 for each of a multitude of settings of the winding states of the cuff 40 and arm circumferences, and the data which show the graph of the required flow velocity Qt, according to the setting of the measured winding state and arm circumference are read from the memory unit 22.

[0052] Next, in step S111, the control unit 20 determines whether the cuff pressure, indicated by the pressure sensor 33 and by a signal input to the control unit 20 via the amplifiers 71 and the A / D converter 72, is less than P1, which with reference to Fig. 8 is described.

[0053] In the case where it is determined that the cuff pressure is less than P1 (that is, in the case where a determination of JA is carried out in step S111), in step S112 the control unit 20 calculates the driving frequency fo1 for the frequency control at the constant voltage value Vo1, based on the required flow velocity Qt and the current cuff pressure, as is done with reference to Fig. 7 is described.

[0054] On the other hand, in the case where it is determined that the cuff pressure is not less than P1 (that is, in the case where a determination of NO is carried out in step S111), in step S113 the control unit 20 calculates the voltage Vo2 for voltage control at the previously determined driving frequency fo2, based on the required flow velocity Qt and the current cuff pressure, as is done with reference to Fig. 6 is described.

[0055] Then, in step S114, the control unit 20 sends a signal indicating the voltage value to the voltage control circuit 62, and a signal indicating the driving frequency to the driving control circuit 63, in order to drive the piezoelectric pump 31 at the voltage and driving frequency found in step S112 or step S113.

[0056] Next, in step S115, the control unit 20 calculates a blood pressure value according to a conventional method, based on changes in the cuff pressure, which is detected by the pressure sensor 33 and indicated by a signal that is input into the control unit 20 via the amplifier 71 and the A / D converter 72.

[0057] Then, in step S116, the control unit 20 determines whether the blood pressure measurement is complete or not. If it is determined that the blood pressure measurement is not complete (that is, if a determination of NO is made in step S116), the control unit 20 returns the processing that has been carried out to the process in step 111.

[0058] On the other hand, in the case where it is determined that the blood pressure measurement is complete (that is, in the case where a determination of YES has been carried out in step S116), in step S117 the control unit 20 controls the voltage control circuit 62 and the driving control circuit 63 to stop the driving of the piezoelectric pump 31.

[0059] Next, in step S118, the control unit 20 controls the display unit 21 to show the blood pressure measurement result. After step S118, the control unit 20 ends the blood pressure measurement process.

[0060] By performing the blood pressure measurement process in this way, the piezoelectric pump 31 can be controlled so that the cuff 40 can be inflated at a constant speed, and the piezoelectric pump 31 can be controlled so that the pump efficiency improves throughout the entire inflation process at a constant speed, as described in relation to Fig. 8 is described.

[0061] The blood pressure measuring device 1, according to the embodiments described above, achieves effects such as those described below. (1) The blood pressure measuring device 1 includes the cuff 40, which, when worn on a blood pressure measuring surface, pressurizes an artery in the measuring surface at the pressure of the air in the cuff, the piezoelectric pump 31, which increases the pressure inside the cuff 40, the outlet valve 32, which reduces the pressure inside the cuff 40, the pressure sensor 33, which detects the cuff pressure, which is the pressure inside the cuff 40, and the control unit 20.

[0062] The control unit 20 determines an amplitude and a frequency of the voltage applied to the piezoelectric pump, as described in step S112 and step S113 of the Fig. 9 is displayed, the controller executes such that a voltage at the previously specified amplitude and frequency is applied to the piezoelectric pump 31, as shown in step S114, and calculates a blood pressure value based on the cuff pressure detected by the pressure sensor 33 during inflation, when the cuff pressure is increased by the piezoelectric pump 31, as shown in step S115.The control unit 20 also determines the control frequency fo1 at which the pump efficiency of the piezoelectric pump 31 is at its maximum, in the case in which the fluid is supplied to the cuff 40 at a required flow velocity Qt during inflation, using the previously defined voltage Vo1 as the voltage, and performs a first control which applies a voltage at the amplitude Vo1 of the previously defined voltage and at the previously defined control frequency Vo1, as shown in step S112 and step S114.

[0063] Accordingly, the piezoelectric pump 31 is operated at the control frequency fo1 and the predetermined voltage Vo1, at which the pump efficiency of the piezoelectric pump 31 is maximized. The predetermined voltage Vo1 is used as the voltage in the case where the fluid is delivered to the cuff 40 at a required flow velocity At during inflation. This reduces the amount of power consumed compared to the case where the piezoelectric pump is driven at a different control frequency and the predetermined voltage. As a result, the amount of power consumed can be reduced when the cuff pressure for blood pressure measurement increases while using the piezoelectric pump 31.

[0064] (2) Meanwhile, the control unit 20 determines the control voltage Vo2 at which the pump efficiency is at its maximum when the fluid is supplied to the cuff 40 at the required flow velocity Qt during inflation, using the predetermined frequency fo2 as the frequency, and performs the first control from the start of inflation until a predetermined time, halfway through the inflation process, and then performs the second control, which applies the predetermined frequency fo2 and the predetermined control voltage Vo2 from the predetermined time until the end of inflation, as described in steps S113 and S114 of the Fig. 9 is displayed.

[0065] Accordingly, the piezoelectric pump 31 is driven at the control voltage Vo2 and the predetermined frequency fo2, at which the pump efficiency of the piezoelectric pump 31 is maximized. The predetermined frequency fo2 is used as the frequency in the case where the fluid is delivered to the cuff 40 at a required flow velocity Qt during inflation. This reduces the amount of power consumed compared to the case where the piezoelectric pump is driven at a different control frequency and predetermined voltage. As a result, the amount of power consumed can be reduced when the cuff pressure is increased for blood pressure measurement using the piezoelectric pump 31.

[0066] (3) The second control mentioned above can be executed better than the first control mentioned above. Even in such a case, the same effects can be achieved as those described in (2) above.

[0067] (4) Furthermore, the predetermined time is a time at which the cuff pressure reaches the predetermined pressure P1, which is in Fig. As shown in 8, the previously determined pressure P1 is determined beforehand for each of the required flow velocities Qt, and the required flow velocities Qt are determined beforehand based on the dimension of the cuff 40, the dimension of the arm circumference which serves as the measuring surface, and a state of the cuff 40 when it is worn on the measuring surface.

[0068] Next, variations of the previously mentioned embodiments will be described. (1) The embodiments mentioned above list air as the fluid supplied to the cuff 40 by the piezoelectric pump 31. However, the fluid supplied to the cuff 40 by the piezoelectric pump 31 is not limited to air, and another fluid, such as a liquid or a gel, can also be used. The invention is also not limited to a fluid, and uniform particles, such as microspheres or the like, can be used instead. (2) Although the embodiments mentioned above describe the dimension of the measuring surface as corresponding to the wrist circumference, the invention is not limited to this, and different dimensions can be applied for different measuring surfaces. For example, in the case where the measuring surface is the arm, the dimension is the circumference of the arm. (3) In the aforementioned embodiment, the execution of the frequency control is described by varying the driving frequency fo1 at the constant voltage value Vo1 in the case where the cuff pressure is less than P1, as is the case in step S111, step S112 and step S114 of the Fig. 9 and with reference to Fig. 8 is described.

[0069] However, the invention is not limited thereto, and the frequency control can be carried out by varying the driving frequency fo1 at a voltage value Vo1 which is subject to the previously defined changes (which, for example, increases or decreases), in the case where the cuff pressure is less than P1.

[0070] (4) In the aforementioned embodiment, the voltage control is carried out by varying the voltage value Vo2 at the driving frequency fo2, which is subject to predetermined changes (for example, decreases) in the case where the cuff pressure is greater than or equal to P1, as is the case in step S111, step S113 and step S114 of the Fig. 9 and with reference to Fig. 8 is described.

[0071] However, the invention is not limited thereto, and the voltage control can be carried out by varying the voltage value Vo1 at a constant driving frequency fo1 or at a driving frequency fo1 which is subject to the previously defined changes (for example, increases) in the case where the cuff pressure is greater than or equal to P1.

[0072] (5) The embodiments mentioned above describe the blood pressure monitor 1 as a device invention. However, the invention is not limited to this and can also be used as a control method for the blood pressure monitor 1. The invention can also be used as a control program for the blood pressure monitor 1.

[0073] It should be noted that the embodiments described above are to be understood as being in any way exemplary and in no way limiting. The scope of the present invention is not defined by the aforementioned descriptions, but by the scope of the appended claims, and all modifications which are in the same essential spirit as the scope of the claims are likewise included therein. Reference symbol list 1 blood pressure monitor 10 Main unit 20 Control unit 21 Display unit 22 storage units 23 Control unit 24 Power supply unit 31 piezoelectric pump 32 Exhaust valve 33 Pressure sensor 40 cuff 41 outer cover 42 Applying pressure to the air bellows 50 air hose 61 DC-DC amplifier circuit 62 Voltage control circuit 63 driving control circuit 71 amplifiers 72 converters

Claims

[1] Blood pressure measuring device (1) which includes: a cuff (40) which, when worn on a blood pressure measuring surface, pressurizes an artery in the measuring surface at the pressure of a fluid in the cuff; a piezoelectric pump (31) which increases the pressure inside the cuff (40); an air outlet unit (32) which reduces the pressure inside the cuff (40); a pressure detection unit (33) which detects the cuff pressure, which is the pressure inside the cuff (40); and a control unit (20), wherein the control unit (20) includes: a determining device which determines an amplitude and a frequency of a voltage which is applied to the piezoelectric pump (31) (step S112, step S113); a control device for the applied voltage, which performs the control so that a voltage at the amplitude and frequency determined by the determining device is applied to the piezoelectric pump (31) (step S114); and a blood pressure measuring device (1) which calculates a blood pressure value based on the cuff pressure detected by the pressure detection unit (33) during inflation when the cuff pressure is increased by the piezoelectric pump (31) (step S115), and wherein the determining device determines a first control frequency (fo1) as the first driving control frequency at which a pump efficiency of the piezoelectric pump is maximal in the case in which the fluid is supplied to the cuff (40) at a required flow velocity during inflation, using a previously determined first voltage (Vo1) as the voltage (step S112); wherein the determining device determines a second control voltage (Vo2) at which the pump efficiency is at its maximum, in the case in which the fluid is supplied to the cuff (40) at a required flow velocity during inflation, wherein a previously determined second frequency (fo2) is used as the second driving frequency (fo2) (step 113); The control device of the applied voltage performs a first control, which applies a voltage at the amplitude of the previously determined first voltage (Vo1) and at the first control frequency (fo1), which is determined by the determining device from the beginning of the inflation until a previously determined time, halfway through the inflation process, and The control device of the applied voltage performs a second control, which applies the previously determined second frequency (fo2) and the second control voltage (Vo2), which is determined by the control device, from the previously determined time until the end of the inflation (step S114). [2] Blood pressure measuring device (1) according to claim 1, where the predetermined time is a time at which the cuff pressure reaches a predetermined pressure; The predetermined pressure is determined beforehand for each of a variety of required flow rates; and The required flow velocities are determined beforehand, based on a dimension of the cuff (40), a dimension of the measuring surface and a state of the cuff (40) when it is worn on the measuring surface. [3] Control procedure for a blood pressure measuring device (1), wherein the blood pressure measuring device (1) comprises: a cuff (40) which, when worn on a blood pressure measuring surface, pressurizes an artery in the measuring surface at the pressure of a fluid in the cuff (40); a piezoelectric pump (31) which increases the pressure inside the cuff (40); an air outlet unit (32) which reduces the pressure inside the cuff (40); a pressure detection unit (33) which detects the cuff pressure, which is the pressure inside the cuff (40); and a control unit (20), and wherein the control procedure includes the steps of the control unit (20) exhibits: Determining an amplitude and a frequency of a voltage applied to the piezoelectric pump (31) (step S112, step S113); Execute the control such that a voltage at the previously defined amplitude and frequency is applied to the piezoelectric pump (31) (step S114); and Calculating a blood pressure value based on the cuff pressure detected by the pressure detection unit (33) during inflation when the cuff pressure is increased by the piezoelectric pump (step S115), wherein the determining step includes determining a first control frequency (fo1) as the first driving frequency (fo1) at which a pump efficiency of the piezoelectric pump is maximal, in the case in which the fluid of the cuff (40) is supplied at a required flow velocity during inflation, using a previously determined first voltage (Vo1) as the voltage (step S112) wherein the determining step includes determining a second control voltage (Vo2) at which the pump efficiency is maximal, in the case where the fluid is supplied to the cuff (40) at a required flow velocity during inflation, using a previously determined second frequency (fo2) as the second driving frequency (fo2) (step S113); and The step of executing the control involves executing a first control, which applies a voltage at the amplitude of the previously defined first voltage (Vo1) and at the previously determined control frequency (fo1), from the start of inflation at a previously determined time, halfway through the inflation process, and The step of executing the control includes executing a second control, which specifies the previously determined second frequency (fo2) and the second control voltage (Vo2). which is determined by the control unit, from the previously specified time until the end of the inflation (step S114).

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