JPH02211121A - Constant speed exhaust device and control device therefor and control method for constant speed exhaust device - Google Patents

Abstract

PURPOSE:To enable constant speed and quick exhaust processes and the free adjustment of an exhaust quantity via a single operation body by setting the polarization direction of a pair of piezoelectric ceramics used for the open and close mechanism of a valve mechanism in a way reversed from the case of the conventional bimetal. CONSTITUTION:A metal plate 3 is placed between piezoelectric ceramics 1 and 2, integrated with the ceramics 1 and 2, and so arranged as to reverse a polarization direction from the conventional constitution, thereby enabling the elongation of the plate 3 upon voltage application. One end of a piezoelectric operation element 4 is fixed and the other end is provided with a valve 5 comprising rubber and the like. One end of an exhaust port 6 is continuous to the side of an arm body 53. In a constant speed exhaust condition, voltage is applied to the piezoelectric ceramic 1 and the piezoelectric operation element 4 is displaced lower. Also, the valve 5 is placed near the opening of the exhaust port 6 and air A from the arm body 53 is thereby discharged at the predetermined speed. For discharging quickly air stagnating in the arm body 53, voltage is applied to the piezoelectric ceramic 2 and the whole of the piezoelectric operation element 4 is deflected up, thereby setting a large gap between the valve 5 and the exhaust port 6.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a device for discharging gas pumped into a specific space at a constant rate and a method related to the device, and in particular to a device that can be suitably used in an automatic blood pressure monitor. The present invention relates to a quick exhaust device, a control device for the device, and a control method thereof.

[Prior Art and Problems to be Solved by the Invention] In an automatic blood pressure monitor, air is automatically pumped into the arm cuff and constant-speed exhaust for blood pressure measurement is performed automatically.

First, as a constant-speed exhaust mechanism, a slit is formed in the rubber cylinder, and constant-speed exhaust is performed by balancing the pressure on the pressurized cuff side and the elasticity of the rubber cylinder, and blood pressure measurement is completed. After that, there is a mechanism that uses a solenoid valve to rapidly release the air inside the cuff.

FIG. 12 shows the structural concept of this mechanism.

When the arm cuff 53 is attached to the arm of the person being measured for blood pressure, the pump drive circuit 51 activates the pump 52 according to a command from the central processing unit 50.
is driven to pump air to the cuff 53. Pressure sensor 54 monitors the pressure within cuff 53 and sends a pressure signal to central processing unit 50 . When the pressure inside the arm cuff reaches a preset value, the central processing unit 50 activates the constant speed exhaust valve 5.
5, the air in the cuff is exhausted at a constant speed, and blood pressure is measured during this time. Next, when the blood pressure measurement is completed, the electromagnetic valve 57 for quick exhaust is activated via the electromagnetic valve drive circuit 56, and the air remaining in the cuff 53 is rapidly exhausted. However, this constant speed exhaust mechanism has the following problems.

In other words, due to differences in the thickness of the subject's arms, or more specifically, due to differences in arm cuff capacity based on differences in arm size, the pumping speed during constant-speed pumping will differ, which may affect the accuracy of blood pressure measurement. The problem is that it can have a negative impact.

Figure 13 shows the difference in pumping speed.As is clear from the figure, when the pump is turned off and pumping is performed at a constant speed, if the arm is thin, the pumping speed will be high, and if the arm is thick, the speed will be lower. descend. Figure 14 shows the armband capacity in a small capacity (300cc).
) and large capacity (600 cc), and it was confirmed that the pumping speed differed significantly depending on the size of the capacity. In addition to these problems, due to the structure of the mechanism, a solenoid valve for rapid exhaust is provided separately from the mechanism for constant-speed exhaust, making the entire device complicated and expensive.

On the other hand, in order to improve the problems of the above-mentioned mechanism, the exhaust system is equipped with only a solenoid valve.
Mechanisms have been proposed that provide rapid exhaustion of both sides.

FIG. 15 shows the mechanism of this constant speed/rapid exhaust system.

In this figure, when the pump 52 is activated in response to a command from the central processing unit 50, a solenoid valve 61 for constant discharge/sudden discharge is activated.
is closed, and the air pumped from the pump 52 is supplied to the cuff 53 via the capacity tank 58. When the pressure inside the cuff reaches a predetermined value, the pump 52 is turned off, and the mode is then set to constant speed exhaust mode. In this case, due to the characteristics of the solenoid valve operation, the exhaust 59 is stepped by ON/OFF operation of the solenoid valve 61.
By doing so, constant speed exhaust must be performed. In the step of performing this stepwise exhaust 59 (see FIG. 16),
An unstable state of air pressure (air pressure ripple) occurs when the solenoid valve is opened to remove air and then the valve is closed, and whether this phenomenon is caused by Korotkoff sound or the oscillometric method, blood pressure values This had a negative impact on judgment accuracy.

For this reason, it is necessary to form a small diameter portion R to reduce the amount of air pressure ripple transmitted to the pressure sensor 54 side, and furthermore, it is necessary to arrange a capacity tank to absorb as much of the air pressure ripple as possible. However, due to the provision of these mechanical filters, even with this configuration, the mechanism cannot actually be simplified. Furthermore, there is a problem in that the burden on the software section including the mechanism control increases because of the control of various mechanical sections and the software-based removal process of air pressure ripples.

[Means to solve the problem]

The present invention has been constructed in view of the problems of the conventional configurations described above.

That is, the present invention uses one type of valve mechanism for exhaust as in the conventional configuration described later, and is configured so that both constant-speed exhaust and rapid exhaust can be performed by this valve mechanism. The configuration is such that it can be performed smoothly in a non-step manner, and furthermore, by freely adjusting the pumping speed, it is possible to accurately measure the blood pressure value regardless of the cuff capacity.

In order to achieve the above technical objectives, a pair of piezoelectric elements such as a piezoelectric element is used as the opening/closing mechanism of the valve mechanism, and the polarization direction of the pair of piezoelectric ceramics is set opposite to that of the conventional bimorph. The structure is expanded so that constant speed exhaust and adjustment of the exhaust amount, rapid exhaust and adjustment of the exhaust amount, etc. can be performed freely with one operating body.

[Effect]

By applying a voltage to either one of the pair of piezoelectric elements constituting the bimorph, which is a valve driving section, the bimorph is deformed in a predetermined direction, thereby freely adjusting the valve opening degree.

Air from the arm cuff side is discharged according to the valve opening, so
Regardless of whether the pump is at constant speed or during rapid pumping, the pumping speed is determined according to the instructions from the central processing unit, thereby achieving accurate blood pressure value determination.

〔Example〕

The present invention will be explained in detail below.

First, a bimorph (hereinafter referred to as a "piezoelectric actuating member" or simply "actuating member") constituting a valve opening/closing device, which is the central mechanism of the present invention, will be explained with reference to FIGS. 1 and 2.

FIG. 1 shows the operating state of a general type bimorph, and FIG. 2 shows the operating state of a piezoelectric element actuating member which is a valve driving device of the invention.

First, FIG. 1 shows a conventional structure and its operating state.

1' and 2' are piezoelectric elements such as piezoelectric ceramics (hereinafter referred to as "
3' is a metal plate placed between these piezoelectric ceramics 1' and 2'. When a voltage is applied to one piezoelectric ceramic 1' of this member, this piezoelectric ceramic 1' expands, and the member as a whole is displaced in the F1 direction. Further, the piezoelectric ceramic 2' is laminated to the piezoelectric ceramic 1' with the polarization direction aligned. Therefore, when a voltage is applied to the piezoelectric ceramic 1', the entire member becomes F1.
When the piezoelectric ceramic 2' is displaced in the direction and a voltage is also applied to the piezoelectric ceramic 2', the piezoelectric ceramic 2' contracts, so that the deformation of the entire member becomes even larger.

The piezoelectric element operating member shown in FIG. 2 is integrally formed with a metal plate 3 interposed between piezoelectric ceramics 1 and 2, and its structure itself is the same as that of FIG. 1. However, both piezoelectric ceramics 1 and 2 are arranged so that their polarization directions are opposite to those of the conventional configuration so that they expand when a voltage is applied. Therefore, when a voltage is applied to the piezoelectric ceramic 1, the piezoelectric ceramic 1 expands, and the piezoelectric element operating member as a whole is displaced in the F1 direction. Conversely, when a voltage is applied to the piezoelectric ceramic 2, the piezoelectric ceramic 2
expands, and the piezoelectric element actuating member as a whole is displaced in the F2 direction. Further, the amount of displacement can be adjusted by adjusting the applied voltage for displacement in any direction.

3 and 4 show the structure and operating state of an exhaust system using the piezoelectric element actuating member shown in FIG. 2 as a valve actuating member.

Reference numeral 4 denotes a piezoelectric element actuating member, and as shown in FIG. 2, it consists of piezoelectric ceramics 1 and 2 whose polarization directions are set so as to expand each time a voltage is applied, and a metal plate 3 disposed between them. It is integrally constituted by. One end of this piezoelectric element actuating member 4 is fixed to the main body of the device (not shown), so that its position does not change even if a voltage is applied. On the other hand, a valve 5 made of a material with good sealing properties such as rubber is attached to the other end. Reference numeral 6 denotes an exhaust port whose opening is located opposite to the valve 5, and the other end communicates with the arm cuff 53 via a rubber tube or the like.

The piezoelectric element actuating member shown in FIG. 3 shows the state during constant speed evacuation, and FIG. 4 shows the state during rapid evacuation.

First, in the constant speed exhaust state, by applying a voltage to the piezoelectric ceramic 1 side, the piezoelectric element actuating member 4 is displaced downward,
The valve 5 located at the tip thereof is located close to the opening of the exhaust port 6, and the air A flowing out from the cuff 53 is discharged at a preset speed.

In this case, the voltage applied to the piezoelectric ceramic 1 is adjusted to adjust the amount of displacement of the piezoelectric element actuating member 4, thereby adjusting the gap between the opening of the exhaust port 6 and the valve 5, and thereby adjusting the exhaust speed. do. The symbol W1 in the figure indicates the adjustment range of the valve during constant speed exhaust, and the range is generally several tens of μm.

FIG. 4 shows the displacement state of the piezoelectric element actuating member during rapid evacuation.

When the blood pressure measurement is completed and the air remaining in the cuff 53 is to be rapidly exhausted, a voltage is applied to the piezoelectric ceramic 2 of the piezoelectric element actuating member 4 to warp the entire piezoelectric element actuating member 4 upward. In return, the gap between the valve 5 and the exhaust port opening is set large. As a result, air flowing out from the cuff 53 side is rapidly exhausted. In this case as well, it is possible to adjust the gap by adjusting the voltage applied to the piezoelectric ceramic 2, if necessary.

FIG. 5 shows a mechanism for controlling the operation of the exhaust device comprising the piezoelectric element actuating member shown above.

First, when the person to be measured for blood pressure wears a wrist cuff and becomes ready for blood pressure measurement, and turns on the blood pressure needle switch (not shown), the central processing unit 7 issues a command to the constant speed exhaust control circuit 8. A signal is generated, a voltage is applied to the piezoelectric ceramic 1 of the piezoelectric element actuating member 4, and the piezoelectric element actuating member 4 is displaced.

This brings the valve 5 into pressure contact with the opening of the exhaust port 6, sealing the exhaust port 6. Subsequently, the pump 10 is operated via the pump drive circuit 9 to pump air into the cuff 53. The pressure of the cuff 53 is constantly monitored by the pressure sensor 11, and its measured value is output to the central processing unit 7. The central processing unit 7 activates the pump 10 when the pressure inside the cuff 53 reaches a set value.
stops operating and enters blood pressure measurement mode.

When the blood pressure measurement mode is entered, the central processing unit 7 displaces the piezoelectric element actuating member 4 via the constant speed exhaust control circuit 8 to form a gap between the valve 5 and the exhaust port 6.
The air on the arm cuff 53 side is exhausted at a preset speed. In this case as well, the pressure sensor 11 monitors the pressure within the cuff 53 and outputs the measured value to the central processing unit 7. The central processing unit 7 determines the actual exhaust speed in real time based on the fed-back measurement value, and adjusts the opening degree of the valve 5 so that the exhaust speed becomes the set value.

In this way, constant speed exhaustion is performed accurately as preset, and during this time the blood pressure value is determined. Subsequently, when the blood pressure value has been determined, the central processing unit 7 applies a voltage to the piezoelectric ceramic 2 of the piezoelectric element actuating member 4 via the rapid exhaust control circuit 12 to widen the valve 5 and release the arm. 2. Remove the air remaining in the band 53. Release quickly.

FIG. 6 shows the exhaust state when the above device is used. As is clear from this figure, when constant-speed exhaust is performed after the pump is turned off, constant-speed exhaust can be performed smoothly as in the conventional device using a rubber cylinder shown in FIG.

Next, FIG. 8 shows the test results of actually measuring the constant speed exhaust state using this device.

Similar to the case of the conventional device shown in Figure 14, this test measured the difference in pumping speed when the armband capacity was divided into small capacity (300cc) and large capacity (600cc). While the pumping speed differed greatly depending on the size of the pump, it was confirmed that with this device, there was almost no difference in the speed. Note that the pumping speed was 4 mmHg/sec.

Moreover, FIG. 9 shows the results of measuring the intake amount and exhaust amount using the sphygmomanometer. In the figure, G1 indicates the state during machining of the arm cuff, G2 indicates the constant speed exhaust state, and G3 indicates the rapid exhaust state. As is clear from this figure, the constant speed exhaust state G2
It was confirmed that very stable constant-speed evacuation was achieved and that rapid evacuation after blood pressure measurement was also performed very quickly.

FIG. 7 shows an example of a configuration in which the piezoelectric element actuating member described above is incorporated into a blood pressure monitor.

Reference numeral 14 denotes a mounting base, and this base itself is fixed within the body of the blood pressure monitor. Rear end of piezoelectric element actuating member 4 (right side in the figure)
A metal plate 3 is disposed between the upper and lower piezoelectric ceramics 1 and 2 and protrudes therefrom, and the protrusion 3a of this metal plate 3 is disposed on the step 14a of the mounting base 14. In this state, the retaining member 12 is fixed to the mounting metalwork 4 with a fixing means such as a screw, thereby sandwiching the protrusion 3a, thereby supporting the entire piezoelectric element actuating member 4 in a cantilevered manner. A valve 5 is attached to the lower part of the piezoelectric element actuating member 4, and by arranging the piezoelectric element actuating member 4 at a predetermined position, the valve 5 is inserted through the mounting base 14 and opens the exhaust port 6. The piezoelectric element operating member 4 opens and closes the valve by operating the piezoelectric element operating member 4.

Note that the configuration of the constant-speed exhaust device, such as the arrangement of the piezoelectric element actuating member 4, is not limited to that shown in the drawings, and the configuration may be modified, such as arranging the exhaust port above the piezoelectric element actuating member, depending on the configuration of the blood pressure monitor. It can be changed as appropriate.

FIGS. 10 and 11 show an example of constant speed exhaust control of a blood pressure monitor using the piezoelectric actuating member.

This control device basically consists of a piezoelectric element actuating member 4, which is an actuating part that directly adjusts the amount of air, as shown in FIG.
Combination of valve 5 and exhaust port 6 and pressure sensor 11
, a central processing unit 7 , and a DA converter 13 that converts a digital signal into an analog signal according to a command from the central processing unit 7 and applies a DC voltage to the piezoelectric element actuating member 4 .

First, the arm cuff is attached to the arm of the person to be measured, and the pump 10 pumps air to bring the pressure inside the cuff 53 to a predetermined value, and then the blood pressure value measurement operation is performed.

10 and 11, in measuring the blood pressure value, the central processing unit 7 first monitors the pressure within the cuff 53 for a certain period of time (for example, 1 second or 1 heartbeat) via the pressure sensor 11. The gap between the valve 5 of the piezoelectric element actuating member 4 and the exhaust port 6 is set so that a preset exhaust speed is achieved. This set gap is arithmetic processed in the central processing unit 7, the amount of deformation of the piezoelectric element actuating member corresponding to the set gap is set, and a piezoelectric element deformation signal is digitally output. This digital signal is output as an analog direct current (DC) voltage in the D/A converter 13. This DC voltage deforms the piezoelectric element actuating member 4 to set the opening degree of the valve 5 and perform constant-speed exhaust. This constant speed exhaust is monitored by a pressure sensor 11, and the measurement results are fed back to the central processing unit 7, and if the constant speed exhaust is performed at the set value, the blood pressure value is measured. When the measurement of the blood pressure value is completed, the piezoelectric element actuating member 4 is displaced in the opposite direction to rapidly discharge the remaining air in the cuff.

〔effect〕

As explained above, the present invention uses a piezoelectric element such as a piezoelectric ceramic as a valve opening/closing mechanism, and configures the polarization direction of the pair of piezoelectric ceramics to be set opposite to that of the conventional bimorph, so that the valve actuating member is configured. Because of the structure, the deformation range of the operating member is wide (constant speed exhaust and rapid exhaust can be reliably performed with one operating body, and the exhaust amount can be freely adjusted during constant speed exhaust, Sakae, and rapid exhaust. In particular, when this device is used in an automatic blood pressure monitor, blood pressure values can be measured quickly and accurately.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the operating principle of a bimorph shown for comparison with the piezoelectric actuating member of the present invention, Fig. 2 is a diagram of the operating principle of the piezoelectric actuating member of the present invention, and Fig. 3 is a diagram showing the principle of operation of the piezoelectric actuating member of the present invention. Fig. 4 is a vertical cross-sectional view of the main parts of the constant-speed exhaust system shown in Fig. 3 in a rapid exhaust state, and Fig. 5 is a longitudinal cross-sectional view of the main parts of the constant-speed exhaust system shown in Fig. 3 in a rapid exhaust state. 6 is a diagram showing the exhaust state of the device shown in FIG. 5, FIG. 7 is an exploded perspective view showing an example of the configuration of the valve opening/closing part of the constant speed exhaust device, and FIG. 8 is a block diagram showing an example of the configuration of the device shown in FIG. is a diagram showing the constant speed exhaust state of the device shown in FIG. 5 at different arm cuff capacities, FIG. 9 is a diagram showing the pressurization / constant speed exhaust / rapid exhaust state of the same device,
Fig. 10 is a block diagram showing an example of the control state of the constant speed exhaust device, Fig. 11 is a flow diagram showing the control method of the device shown in Fig. 1O, and Fig. 12 shows the constant speed exhaust valve and the rapid exhaust valve. 13 is a diagram showing the constant speed exhaust state at different arm cuff capacities when using the device shown in FIG. 12, and FIG. A diagram showing actual measured values of exhaust conditions. Figure 15 is a block diagram of another conventional device that performs constant-speed exhaust and rapid exhaust with one solenoid valve. Figure 16 shows the constant-speed exhaust condition of the device shown in Figure 15. FIG. 1.2...Piezoelectric ceramic 3...Metal plate 4...Piezoelectric element operating member 5...
・Valve 6...Exhaust port 7...Central processing unit 8...Constant speed exhaust control circuit 10・ 11...Pressure sensor troll circuit 13・ 14...Mounting base pump...Rapid exhaust controller D /A converter... Engraving of armband drawing (no change in content) Fig. 3 Fig. 4 Fig. 5 Fig. 6 Call volume (shini) ginr11 (see) Time (sec) Fig. 11 Time ( sec) Fig. 12 Time (Spe) Fig. 15 Fig. 16 Time (sec) Proceeding person nt Authorized letter (spontaneous) March 15, 1999 6 Contents of amendments As per the attached sheet However, (1) Attached drawings is an engraving drawing (no change in content) (2) Power of attorney is supplemented by this amendment 3゜4゜ Constant speed exhaust system, control device for the same device, and control method of constant speed exhaust system Relationship with the case of the person amending the control method of the constant speed exhaust system Patent Applicant address: 2-23-22 Oizumi Gakuencho, Nerima-ku, Tokyo Name: Knee & Day Co., Ltd. Representative: Yo Furukawa Agent: 102 Ta (264) 6862 Address:
Raft, 3-1-8 Kojimachi, Chiyoda-ku, Tokyo

Claims (6)

[Claims] (1) A device that discharges gas at a predetermined speed from a space filled with pressurized gas, such as an arm cuff, which directly connects a pair of piezoelectric elements with polarization directions such that they each expand when a voltage is applied. or a piezoelectric element actuating member is constructed by laminating them indirectly through a member such as a metal plate, and a valve attached to the piezoelectric element actuating member is positioned close to an exhaust part for discharging gas from the pressurized space, and the piezoelectric element is A constant speed exhaust device characterized in that a valve mechanism is configured to perform both constant speed exhaust and rapid exhaust by changing the voltage applied to each piezoelectric element of the actuating member. (2) By applying a voltage to one of the piezoelectric elements of the piezoelectric element actuating member, the valve is moved closer to the exhaust section, and by further changing this voltage, the gap between the exhaust section and the valve is adjusted and fixed. A control unit that adjusts the exhaust speed during rapid exhaust, and a control unit that applies a voltage to the other piezoelectric element to separate the valve from the exhaust unit to increase the gap between the two, thereby performing rapid exhaust. A constant speed exhaust device according to claim (1), characterized in that: (3) Consisting of a mounting base that supports one end of the piezoelectric element actuation member in a cantilevered manner, an exhaust port opening in the mounting base, and a valve attached to the piezoelectric element operation member so as to be positioned opposite to the opening of the exhaust port. A constant speed exhaust device characterized by: (4) A pressure sensor that measures the pressure in a pressurized space such as an arm cuff, a central processing unit that inputs the measurement signal of this pressure sensor, and a DA converter that outputs a DC voltage corresponding to the digital signal of the central processing unit. 1. A control device for a constant speed exhaust system, characterized in that the controller is configured to displace a piezoelectric element operating member for opening and closing a valve using a direct current voltage output from the DA converter. (5) Set the exhaust speed of the gas exhausted from the pressurized space such as an arm cuff, then set the gap between the valve and the exhaust part that corresponds to the set exhaust speed, and calculate the amount of movement corresponding to the set gap. 1. A method for controlling a constant speed exhaust device, the method comprising: applying a voltage to a piezoelectric element actuating member to achieve the desired effect. (6) The amount of movement of the piezoelectric element actuating member corresponding to the set gap is digitally output as a piezoelectric element deformation signal, this digital output is outputted as an analog DC voltage value, and the piezoelectric element actuating member is deformed by this DC voltage. The method for controlling a constant speed exhaust system according to claim 5, further comprising feeding back the actual exhaust speed to the control section.