JPH0320247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cuff pressure change rate adjusting device in a blood pressure measuring device, and particularly to a cuff pressure change rate adjusting device that has a function of adjusting the amount of cuff pressure change per beat to a constant level in order to improve blood pressure measurement accuracy. The present invention relates to a cuff pressure change rate adjusting device suitable for use in an oscillometric blood pressure measuring device.

As a type of blood pressure measurement device, there is a cuff that is attached to a part of the subject's body to change the compression state of that part as appropriate, and a pulse wave that appears as pressure vibrations within the cuff due to the pulsation of the artery. A so-called oscillometric blood pressure measuring device is known, which is equipped with a pulse wave sensor that detects the pulse wave and outputs a pulse wave signal representing the pulse wave, and measures blood pressure based on the pulse wave. There is.

In this type of blood pressure measuring device, like other blood pressure measuring devices, such as microphone-type blood pressure measuring devices that measure blood pressure values based on Korotkoff sounds, the cuff pressure change rate regulating device is important for the accuracy of blood pressure measurement. For the purpose of blood pressure measurement, it is desirable that the cuff pressure change rate be maintained at a predetermined constant rate appropriate for blood pressure measurement, and in this sense, various blood pressure measurement devices have been proposed in the past. A pressure change rate regulator (strictly speaking, a pressure drop rate regulator) can be applied, but when these conventionally proposed pressure change rate regulators are applied to an oscillometric blood pressure measuring device, In the past, it could not necessarily be said that high measurement accuracy could be obtained for a wide range of subjects.

For example, conventionally proposed pressure change rate regulating devices adjust the amount of gas discharged from an exhaust valve according to the magnitude of the pressure within the cuff, or adjust the rate of pressure drop within the cuff to a predetermined reference pressure. There are devices that adjust the amount of gas discharged from the exhaust valve to follow the rate of descent, but with these devices, a nearly constant rate of pressure decrease is achieved regardless of the pressure inside the cuff or the volume of the cuff. On the other hand, the disadvantage is that the amount of pressure drop in the cuff per beat according to the pulse rate of the person to be measured changes depending on the individual difference of the person being measured, and the accuracy of blood pressure measurement varies depending on the person being measured. It was hot.

On the other hand, the present applicant has developed a device that eliminates the shortcomings of the conventional pressure change rate adjusting device as described above and can always obtain highly accurate blood pressure values for a wider range of subjects regardless of their pulse rate. Special request 1987-
There is a device proposed in No. 9717, in which, as an example of the device, the applicant of the present invention changes the pressure of the cuff so that the amount of change in the pressure of the cuff per beat matches a predetermined target amount of pressure change. In controlling the speed, we have proposed a device that controls the amount of gas discharged from the cuff by controlling the drive of a pulse motor. However, even with such a device that controls the drive of a pulse motor to control the amount of gas discharged from the cuff, thereby controlling the rate of pressure change in the cuff, it is difficult to use oscillometric measurement. When this method is applied to a blood pressure measuring device based on this method, there is a risk that good blood pressure measurement accuracy may not be obtained when measuring some subjects.

In other words, devices that use a pulse motor to control the amount of gas discharged from the cuff may cause pressure fluctuations (vibrations) within the cuff during the evacuation operation, and may cause In the case of a person with extremely weak arterial pulsations, there was a risk that fluctuations in the pressure inside the cuff caused by such evacuation operations could be mistakenly interpreted as pulse waves based on arterial pulsations. When blood pressure measurement is performed on such a subject, highly accurate blood pressure values are not always required.

The present invention has been made against this background, and its purpose is to enable even people with weak arterial pulsations to be subjected to blood pressure measurement. To provide a cuff pressure change rate adjusting device suitable for use in an oscillometric blood pressure measuring device, which allows highly accurate blood pressure measurements to be obtained for a very wide range of subjects. be.

In order to achieve this object, the present invention provides an oscillometric blood pressure measuring device equipped with the cuff and a pulse wave sensor as described above, in which the amount of air exhausted from the cuff or the amount of air supplied to the cuff is adjusted. and a device that adjusts the rate of pressure change within the cuff,
(1) A control valve means that is connected to the cuff and that controls the amount of ventilation that can be controlled to control exhaust air from the cuff or air supply to the cuff; A DC motor that can be changed to
(3) Drive the DC motor so that the actual pressure change in the cuff between pulse wave signals output from the pulse wave sensor becomes equal to the predetermined target pressure change. It is characterized in that it includes a pressure change rate control means for adjusting the pressure change rate in the cuff by controlling the amount of airflow of the regulating valve means.

That is, in the present invention, as shown in FIG. 1, a control valve means for variable ventilation is connected to the cuff,
While the air flow rate of the control valve means can be changed continuously by a DC (direct current) motor, a pressure change speed control means is provided, and with this pressure change speed control means,
Based on the pulse wave signal from the pulse wave sensor, the drive of the DC motor is controlled so that the actual pressure change in the cuff between each pulse wave signal is equal to the predetermined target pressure change. This allows the rate of change in pressure within the cuff to be adjusted by controlling the amount of air flow through the regulating valve means.

In this way, the amount of change in pressure per pulse can be maintained at a constant value suitable for blood pressure measurement regardless of the pulse rate of the subject, making it easier to measure blood pressure than with conventional devices of this type. Not only can the range of subjects that can be measured be greatly expanded, but the pressure within the cuff can be changed continuously and smoothly using a DC motor, so blood pressure can be measured using a device driven by a pulse motor. Even when the subject is a person with weak arterial pulsation, which could reduce measurement accuracy, it is possible to stably obtain highly accurate blood pressure values, and the subject of blood pressure measurement This makes it possible to further expand the range of people who can be measured.

EMBODIMENT OF THE INVENTION Hereinafter, in order to clarify the present invention more specifically, one embodiment of the present invention will be described in detail together with a blood pressure measuring device based on the drawings.

In Fig. 2, reference numeral 2 denotes a bag-shaped cuff that is attached to a part of the body of the person to be measured to compress that part. A pressure sensor 4 is connected which outputs a pressure signal SP representing pressure. A pulsation detector 6 and an A/D converter 8 are connected to the pressure sensor 4, and a pressure signal SP is supplied to them.

The pulsation detector 6 is composed of a bandpass filter and an A/D converter, and detects the pulse wave (vibration component) included in the pressure signal SP, and detects the magnitude of the pulse wave in synchronization with the pulse wave. pulse wave signal
Output SM and supply it to I/O port 10. Therefore, in this embodiment, the pulsation detector 6 and the pressure sensor 4 constitute a pulse wave sensor.

On the other hand, the A/D converter 8 is equipped with a low-pass filter, extracts a signal representing a static pressure value without vibration components from the pressure signal SP, and converts this into a digital coded pressure value signal PV to the I/O. Supplied to port 10. Further, a start push button 12 is connected to the I/O port 10,
By pressing the start push button 12, a start signal SS is supplied to the I/O port 10.

I/O port 10 is connected via the data bus line.
CPU (processing unit) 14, RAM 16 and ROM
18, and supplies the pressure value signal PV, pulse wave signal SM, and start signal SS to the data bus line according to commands from the CPU 14. CPU
14 executes signal processing using the temporary storage function of the RAM 16 according to a program stored in the ROM 18 in advance, and sends the pump drive signal SA, the discharge amount adjustment signal SE, and the sudden output via the I/O port 10. The discharge stop signal QE is sent to the pump drive circuit 20,
While supplying the signal to the DC motor drive circuit 22 and the rapid exhaust valve 24, the display signal DD representing a predetermined blood pressure value, which is a signal processing result, is supplied to the display 26, and the blood pressure measurement value is displayed numerically.

The pump drive circuit 20 operates the electric pump 2 connected to the cuff 2 while receiving the pump drive signal SA.
Driving power is supplied to cuff 8, during which air is pumped into cuff 2.

The DC motor drive circuit 22 is connected to the I/O port 10
A D/A converter 30 for converting the emission adjustment signal SE from
It is equipped with an integrating amplifier 32 that integrates the emission amount adjustment signal SE' converted into an analog signal by the converter 30, amplifies the integrated emission amount adjustment signal SE', and outputs it as a DC motor drive signal SD,
Emission adjustment signal supplied from I/O port 10
A DC motor drive signal SD whose voltage varies smoothly according to variations in the contents of SE is supplied to the DC motor 34. Then, this DC motor 34
Displacement control valve 3 as control valve means connected to
6, the amount of air emitted from the cuff 2 is continuously adjusted.

That is, as shown in FIG. 3, the displacement control valve 36 includes a block-shaped main body 38 to which the DC motor 34 is integrally assembled, and a block-shaped main body 38 connected between the main body 38 and the cuff 2. The amount of gas exhausted from the cuff 2 through the exhaust hose 40 is continuously adjusted in accordance with the rotation of the output shaft of the DC motor 34. As is clear from the figure, the main body 38 includes a cylinder bore 44 in the form of a circular hole with a bottom, into which a cylindrical plunger 42 is slidably fitted.
A valve chamber 46 in the form of a circular hole with a small diameter and a bottom is formed following the valve chamber 46, and an exhaust port 48 is connected to the valve chamber 46.
and a connection port 50 to which the exhaust hose 40 is connected, and a valve seat 52 is formed at a portion where a passage communicating with the exhaust port 48 opens into the valve chamber 46 . On the other hand, a small diameter portion 54 that fits into the valve chamber 46 is formed on the valve chamber 46 side of the plunger 42, and a tapered needle valve portion 56 is formed following this small diameter portion 52. By moving the needle valve 42 in the axial direction, the cross-sectional area through which gas can flow between the valve seat 52 and the needle valve portion 56 can be changed. The plunger 42 is provided perpendicularly to the axial direction of the plunger 42.
As the output shaft of the DC motor 34 rotates, a cam 58 fixed to the output shaft moves the plunger 42 in the axial direction against the urging force of a compression spring 60 inserted in the cylinder bore 44. This allows the cross-sectional area through which the gas can flow to be adjusted, thereby adjusting the amount of gas, such as air, discharged from the cuff 2.

Note that the quick exhaust valve 24 is connected to the I/O port 1.
When the sudden ejection stop signal QE is not supplied from 0,
The valve opens and the air inside the cuff 2 is rapidly exhausted.

Hereinafter, the operation of this embodiment will be explained together with the operation of the blood pressure measuring device.

When a power switch (not shown) is turned on, power is supplied to each part of the device, and the CPU 14 is set to ROM in advance.
The control operation is performed according to the main program flowchart shown in FIG. 4 stored in 18.

First, step S1 is executed, and the operating state of the start push button 12 is determined. Start push button 12
The execution of step S1 is repeated while the button is not operated, but the start button 12 is pressed to start blood pressure measurement.
When is pressed and the start signal SS is supplied to the I/O port 10, the next step S2 and S3
is executed. In step S2, a sudden exhaust stop signal QE is sent to the rapid exhaust valve 24, and
An exhaust amount adjustment signal SE having a predetermined content is supplied to the DC motor drive circuit 22 for a predetermined period of time to close the rapid exhaust valve 24 and set the exhaust amount adjustment valve 36 to the closed state. Also, in step S3,
The pump drive signal SA is supplied to the pump drive circuit 20, and the electric pump 28 begins pumping air into the cuff 2. Then, after step S3,
Step S4 is immediately executed.

In step S4, it is determined whether the actual pressure P within the cuff 2 represented by the pressure value signal PV is greater than a preset target upper limit pressure PM.
While the actual pressure P is still smaller than the target upper limit pressure PM, step S4 is repeated, but if, on the other hand, it exceeds the target upper limit pressure PM, steps S5 and S6 are immediately executed. That is, in step S5, the supply of the pump drive signal SA to the pump drive circuit 20 is stopped, and the pressure feeding of air into the cuff 2 is stopped, and in step S6, the pulse wave interval of the average subject is stopped. A displacement adjustment signal SE having a content that follows a predetermined initial displacement curve corresponding to the interval is supplied to the DC motor drive circuit 22, and the DC motor 34 is actuated in accordance with the content on the valve chamber 46 side of the plunger 42. The valve seat 52 is started to rotate in a direction that allows movement in the side direction.
and the needle valve portion 56 such that the amount of air discharged from the opening, that is, the amount of air discharged from the displacement adjustment valve 36, follows the initial displacement curve.
adjusted. After step S6 is completed, the pulse wave detection routine of step S7 is subsequently executed.

In this step S7, the magnitude (peak value) of the pulse wave signal SM corresponding to each pulse wave included in the pulse wave signal SM is determined according to a program not shown, and when the peak value is detected, The actual pressure P in the cuff 2 is stored in the RAM 16 together with the peak value.

After step S7 is completed, step S8 is executed,
A desired blood pressure value is calculated according to a program (not shown) based on the peak value of each pulse wave signal SM obtained in step S7, and when all desired blood pressure values are calculated, the display signal DD is Display 26
and the blood pressure value is displayed, and step S9 is subsequently executed, and conversely, the pulse wave signal SM
If all desired blood pressure values have not yet been calculated due to insufficient data, step S10 is immediately executed. The above blood pressure value calculation is performed by detecting a pulse wave signal SM having a peak value of a predetermined ratio with respect to the maximum peak value of the pulse wave signal SM in the process in which the peak value of the pulse wave signal SM gradually increases. The actual pressure P in the cuff 2 at the time when the pulse wave signal SM is the systolic blood pressure value, and in the process where the peak value of the pulse wave signal SM gradually decreases, the pulse wave signal has a peak value of a predetermined ratio to the maximum peak value. Cuff 2 when signal SM is detected
The internal pressure P is taken as the diastolic blood pressure value.

In step S9, which is executed after all desired blood pressure values have been calculated and displayed, the sudden evacuation stop signal QE is
The rapid exhaust valve 24 whose supply of air to the rapid exhaust valve 24 has been stopped is opened, and thereby the air within the cuff 2 is rapidly exhausted. Then, the main program is immediately terminated.

On the other hand, if the calculation of the blood pressure value has not been completed yet, in step S10, the already detected pulse wave signal is
It is determined whether the number n of SM peak values has reached 2 or not. Steps S6 to S8 are repeated until the peak value number n has not yet reached 2, but when the number n reaches 2 or more, the discharge amount adjustment routine of step S11 is executed.

The displacement adjustment routine is executed according to the flowchart shown in FIG. First, in step SR1, the interval between the peak values of the pulse wave signals SM, that is, the interval between the pulse wave signals SM is determined. Therefore, in this embodiment, step SR1 serves as pulse wave signal interval detection means.

After step SR1 as a pulse wave signal interval detection means is executed, step SR2 as a target pressure value determination means is executed. That is, in step SR2, the pulse wave signal SM interval obtained in step SR1 is calculated based on the target pressure drop amount FP of the cuff 2 per beat, which is preset to an appropriate value for blood pressure measurement. Thus, the target pressure value OV at each moment between successive pulse wave signals SM is calculated. Although the program for calculating the target pressure value OV is not shown, an example of the program is as follows.
First, considering the case where the pressure P inside the cuff 2 fluctuates uniformly within the interval between the pulse wave signals SM, calculate the amount of pressure drop inside the cuff 2 at each moment based on the target pressure drop amount FP, Next, the latest pulse wave signal SM
It is determined by subtracting the amount of pressure drop at each moment from the actual pressure P in the cuff 2 at the time when the peak value of P is detected. In this case, since the intervals between adjacent pulse wave signals SM are almost equal, the previous interval between pulse wave signals SM is regarded as the interval between consecutive pulse wave signals SM, and thereby each moment in the interval between consecutive pulse wave signals SM There is no practical problem in finding the target pressure value OV.

Following step SR2, step SR3 is executed as pressure value comparison means. This step
In SR3, the target pressure value OV at each instant obtained in step SR2 is compared with the actual pressure P at each instant in the cuff 2, and the content is determined according to the comparison difference, that is, which one is larger. A comparative difference signal with the following content is obtained. Then, in step SR4, which is executed immediately after executing step SR3, the comparison difference signal is added to the current emission amount adjustment signal SE, and the emission amount adjustment signal SE to which the comparison difference signal has been added is Configures motor drive control means
It is supplied to the DC motor drive circuit 22.

That is, if the actual pressure P exceeds the target pressure value OV in step SR3, the discharge amount adjustment signal SE is increased in step SR4 according to the excess, and conversely, the target pressure value OV is increased. If the actual pressure P is exceeded, the discharge amount adjustment signal SE is made smaller than the current value in accordance with the difference.

The emission control signal SE thus adjusted is converted into an analog signal by the D/A converter 30 of the DC motor drive circuit 22. Analog signal that fluctuates stepwise (emission adjustment signal)
SE′) is a smoothly fluctuating DC
By supplying the DC motor drive signal SD to the DC motor 34, the rotational speed of the DC motor 34 becomes the discharge amount adjustment signal.
faster or slower depending on the variation of SE.
This results in extremely smooth and continuous control. By transmitting smooth fluctuations in the rotational speed of the DC motor 34 to the plunger 42 via the cam 58, the opening amount of the gap between the valve seat 52 and the needle valve portion 56 is smoothly adjusted. In addition, it is continuously adjusted, and as a result, the amount of air discharged from the cuff 2, and thus the rate of decrease of the pressure P within the cuff 2, is adjusted smoothly and continuously in accordance with the amount of discharge adjustment signal SE. The Rukoto. Here, by adjusting the rotational speed of the DC motor 34, the rate at which the pressure P within the cuff 2 decreases can be adjusted because as the pressure P within the cuff 2 decreases, the amount of discharge decreases even with the same opening amount. It is from.

After step SR4 is executed, the emission adjustment routine (step S11) is finished and step SR4 is executed.
Steps S7 and subsequent steps are repeated again, and finally, as described above, the main program is terminated through step S9. However, as is clear from the above description, in this embodiment, the discharge amount adjustment routine at step S11 is completed. Since the intervals between adjacent pulse wave signals SM are almost equal, the immediately preceding interval between pulse wave signals SM is regarded as the interval between consecutive pulse wave signals SM, and each interval within cuff 2 in the interval between consecutive pulse wave signals SM is instantaneous pressure P
is constantly compared with the target pressure value OV at each moment determined based on the interval between the pulse wave signals SM and the predetermined target pressure drop amount FP per beat, and based on the comparison results. DC motor drive circuit 2
2 to control the rotational speed of the DC motor 34,
Furthermore, based on the control of the rotational speed of the DC motor 34, the opening amount of the displacement control valve 36 is adjusted to adjust the pressure change rate so that the actual pressure P in the cuff 2 follows the target pressure value OV. By adjusting
The rate of pressure change in the cuff 2 is adjusted so that the actual pressure drop in the cuff 2 during the interval between pulse wave signals SM becomes equal to the target pressure drop FP. In this embodiment, the discharge amount adjustment routine in step S11 and the DC motor drive circuit 22 constitute a pressure change rate control means.

As is clear from the above description, according to this embodiment, since the amount of air discharged from the cuff 2 can be adjusted continuously and smoothly, the pressure P inside the cuff 2 can also be adjusted extremely smoothly. This eliminates the risk of causing unnecessary vibrations within the cuff 2 due to the exhaust operation from the cuff 2, which makes it difficult to obtain highly accurate blood pressure values when driven by a pulse motor. Even when measuring infants, etc., whose arterial pulsation is extremely weak, it is now possible to always measure their blood pressure with high precision.

In the above embodiment, the actual pressure P in the cuff 2 is constantly compared with the target pressure value OV, and the pressure change rate is adjusted based on the comparison difference signal that is the result of the comparison. However, the present invention is not necessarily limited to such a configuration; for example, the emission amount adjustment routine S11 according to the flowchart shown in FIG.
It is possible to obtain some effect.

That is, in the emission amount adjustment routine according to the flowchart of FIG.
, cuff 2 between the immediately preceding pulse wave signals SM
The actual pressure drop amount ΔP within is determined. In other words,
This step SR'1 is used as means for calculating the amount of pressure change between pulse wave signals.

Then, in step SR'2, which is a pressure change comparison means that is executed following step SR'1, the actual pressure drop amount ΔP and the target pressure drop amount FP are compared, and a comparison is made according to the comparison difference. A difference signal is determined. Then, the comparison difference signal is sent to a step that constitutes a DC motor drive control means together with the DC motor drive circuit 22, similar to the embodiment described above.
In SR4, a pulse wave signal is added to the current emission adjustment signal SE and is followed by the emission adjustment signal SE.
The pulse wave signal SM continues to be supplied to the DC motor drive circuit 22 during the period of SM.
The rotational speed of the DC motor 34, and thus the speed of pressure drop within the cuff 2, is adjusted so that the actual pressure drop amount ΔP during this period is equal to the target pressure drop amount FP. The exhaust amount adjustment routine ends after step SR4 is executed, as in the previous embodiment.

Note that, as is clear from the above description, in this example as well, the steps are similar to the above example.
The discharge amount adjustment routine of S11 and the DC motor drive circuit 22 constitute a pressure change rate control means, and the fluctuation of the discharge amount adjustment signal SE at the boundary between adjacent pulse wave signals SM is controlled by the DC motor drive circuit 22. It is smoothed by the integrating amplifier 32 of the motor drive circuit 22. That is, in this embodiment as well, a pressure change rate adjusting device is achieved in which the amount of pressure drop per beat is maintained at an appropriate value for blood pressure measurement, and the pressure P within the cuff 2 fluctuates smoothly. It is.

In each of the above embodiments, the magnitude of the emission amount adjustment signal SE is adjusted depending on which of the comparison difference signals is larger.
As a result, the pressure drop rate was adjusted so that the actual pressure drop ΔP between the successive pulse wave signals SM was equal to the target pressure drop FP, but it is difficult to determine which of the comparison difference signals is larger. Depending on the content, the discharge amount adjustment signal SE may be increased or decreased by a predetermined value, thereby adjusting the pressure drop rate so that the drop amount ΔP and FP almost match. , there is no difference whatsoever.

Further, in the embodiment described above, an integrating amplifier 32 is provided in the DC motor drive circuit 22, and the step-like portion appearing in the emission amount adjustment signal SE from the D/A converter 30 is converted into a smooth curve by the integrating amplifier 32. As a result, the DC motor 34
Although the pressure P in the cuff 2 is smoothly adjusted by the integrator amplifier 32, it goes without saying that any circuit that performs the same function may be used.

Furthermore, the DC motor 34 is not limited to one whose rotational speed is controlled by voltage, but it is also possible to use a type whose rotational speed is controlled by current. However, the DC motor 36 is not limited to the configuration of the above embodiment.
The opening amount of the valve can be adjusted continuously according to the rotation of the valve.
Any device that can continuously adjust the amount of air discharged from the cuff 2 can be used.

In addition, the pressure change rate adjusting device according to the present invention is applicable not only to a blood pressure measuring device that measures blood pressure values during the process of decreasing the pressure P in the cuff 2, but also to devices that measure blood pressure values during the process of increasing the pressure P. In addition, the program, etc. can be changed as necessary.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram. FIG. 2 is a block diagram showing an example of an oscillometric blood pressure measuring device equipped with a pressure change rate adjusting device according to the present invention, and FIG. 3 is a block diagram showing an example of a regulating valve means used in the device. FIG. 4 is a flowchart of a main program for explaining the operation of the pressure change rate adjusting device shown in FIG. 2 together with the operation of the blood pressure measuring device, and FIG.
6 is a flowchart of a program of the discharge amount adjustment routine shown in FIG. 6, and FIG. 6 is a diagram corresponding to FIG. 5 for explaining another embodiment of the present invention. 2: Cuff, {4: Pressure sensor, 6: Pulse detector}
(pulse wave sensor), 14: CPU (processing unit), 1
6: RAM, 18: ROM, 22: DC motor drive circuit, 30: D/A converter, 32: Integral amplifier, 36: displacement control valve (control valve means).

Claims (1)

[Claims] 1. A cuff that is attached to a part of the body of a person to be measured and changes the compression state of that part as appropriate, and a pulse wave that appears as pressure vibrations within the cuff due to the pulsation of an artery. In an oscillometric blood pressure measurement device that includes a pulse wave sensor that detects a pulse wave and outputs a pulse wave signal representing the pulse wave, and measures blood pressure based on the pulse wave, A device that adjusts the rate of pressure change in the cuff by adjusting the amount of air exhausted or the amount of air supplied to the cuff, and a vent that is connected to the cuff and controls the amount of air exhausted from the cuff or the amount of air supplied to the cuff. a DC motor capable of activating the regulating valve means to continuously change the amount of ventilation; By controlling the drive of the DC motor and changing the ventilation amount of the control valve means so that the actual pressure change amount in the cuff becomes equal to a predetermined target pressure change amount,
A pressure change speed adjusting device for a cuff in a blood pressure measuring device, comprising: a pressure change speed control means configured to adjust the pressure change speed within the cuff. 2. The pressure change rate control means includes: a pulse wave signal interval detection means for detecting an interval between each pulse wave signal in the pulse wave signals output from the pulse wave sensor; Based on the interval between the pulse wave signals and the target pressure change amount,
Target pressure value determining means for determining a target pressure value at each moment between successive pulse wave signals; and a target pressure value determined by the target pressure value determining means and the actual pressure value in the cuff at each moment. a pressure value comparison means for comparing and outputting a comparison difference signal according to the difference; and a pressure value comparison means for making the actual pressure value equal to the target pressure value based on the comparison difference signal output from the pressure value comparison means. 2. The pressure change rate adjusting device according to claim 1, further comprising: DC motor drive control means for controlling drive of said DC motor. 3. The pressure change rate control means includes: a pulse wave signal-to-pulse signal pressure change amount calculation means for calculating an actual pressure change amount between each pulse wave signal among the pulse wave signals output from the pulse wave sensor; pressure change amount comparison means for comparing the actual pressure change amount calculated by the signal-to-signal pressure change amount calculation means with the target pressure change amount and outputting a comparison difference signal according to the difference; DC motor drive control means for controlling the drive of the DC motor so that the actual pressure change amount between successive pulse wave signals becomes equal to the target pressure change amount based on the comparison difference signal output from the comparison means; A pressure change rate adjusting device according to claim 1, comprising: