JPH082351B2 - Pulse wave detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pulse wave detection device, and more particularly to a device for detecting a pulse wave generated from an artery with high accuracy.

BACKGROUND ART A pressure wave or vibration of an arterial tube wall that is generated with the pulsation of the heart and propagates in an artery is generally called a pulse wave.
It is known that various medical information such as the motion state of the heart can be obtained from this pulse wave. Then, as a device for detecting such a pulse wave, a pressure sensor such as a piezoelectric element or a strain gauge that is pressed directly above the artery on the body surface of the human body is provided, and the pulse generated from the artery by the pressure sensor. There is one that detects the pressure vibration of the wave. The device described in Japanese Utility Model Publication No. 61-60901 is an example.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, since such a conventional pulse wave detecting device only detects the pressure oscillation of the pulse wave just above the artery, the pulse wave invented from the artery is not always high. It could not be detected with accuracy. That is, conventionally, the pulse wave was generally detected by using a pressure sensor having a contact surface having a size equal to or larger than the diameter of the artery, but the contact surface of a contact surface sufficiently smaller than the diameter of the artery was detected. When a plurality of pressure sensors are arranged in the direction intersecting with the artery to detect the pulse wave, even if the pressure sensor is located just above the artery due to the difference in the tension of the arterial wall, it will be detected by its end or center. The absolute pressure value of the pulse wave is different.

Means for Solving Problems The present invention has been made to solve the above problems, and an object of the present invention is to detect a pulse wave using a pressure sensor having a contact surface smaller than the diameter of an artery. It is to be able to detect with high accuracy.

Then, in order to achieve such an object, the present invention is a device for detecting a pulse wave generated from an artery of a human body,
(A) A plurality of pulses are provided on the body surface of the human body in a direction intersecting with the artery so that at least three of them are located immediately above the artery, and the pulse generated from the artery is pressed against the body surface. A plurality of pressure sensors that respectively detect the pressure vibrations of the waves and output pulse wave signals corresponding to the pressure vibrations; and (b) the pulse wave signals output from the plurality of pressure sensors, respectively. And a selecting means for selecting the central pulse wave signal output from the pressure sensor located substantially in the center of the upper part, so as to detect the pulse wave based on the central pulse wave signal selected by the selecting means. It is characterized by having done.

Action and Effect of the Invention That is, according to the present invention, the absolute pressure value of the pulse wave detected near the center of the upper part of the artery is extremely close to the actual pressure value of the pulse wave in the artery. Focusing attention, a plurality of pressure sensors are arranged in a direction intersecting with the arteries so that at least three are located immediately above the arteries whose pulse waves are to be detected, and the pulses output from the plurality of pressure sensors respectively. From the wave signals, the central pulse wave signal output from the pressure sensor located approximately in the center immediately above is selected, and the pulse wave is detected based on the central pulse wave signal.

Therefore, according to the pulse wave detection device of the present invention,
Not only the waveform of the pulse wave, but also the absolute pressure value of the pulse wave, a pulse wave extremely close in absolute value to the actual pulse wave (pressure wave) in the artery can be obtained. It is also possible to measure values and the like.

Here, the selecting means for selecting the central pulse wave signal outputs, for example, from at least three pressure sensors located immediately above the artery from among the pulse wave signals output from the plurality of pressure sensors, respectively. And a second selecting means for selecting the central pulse wave signal from the directly above pulse wave signals selected by the first selecting means. .

Further, the first selecting means is configured to select a pulse wave signal whose amplitude is equal to or more than a predetermined reference value from the pulse wave signal as the directly above pulse wave signal, or to select among the pulse wave signals. The pulse wave signal having the maximum amplitude is selected from the pulse wave signal output from the predetermined number of pressure sensors adjacent to both sides of the pressure sensor that has output the pulse wave signal having the maximum amplitude. It can be configured to be selected as a pulse wave signal. This is because the amplitude of the pulse wave detected immediately above the artery is sufficiently larger than the amplitude of the pulse wave detected outside the region just above the artery.

In addition, the second selecting means may, for example, select a pulse wave signal whose peak value is smaller than the peak values of the pulse wave signals output from the pressure sensors adjacent to both sides from the above-mentioned pulse wave signal directly above the central pulse. It is configured to select as a wave signal. This is because even if the pulse wave is detected just above the artery, the pulse wave detected at the end of the artery has a pressure value due to the tension of the arterial canal wall, etc. The maximum value or the minimum value of the pulse wave signal is preferably used as the peak value, but both of them may be compared.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a hollow main body having an opening 12 at the lower end, and the opening 12 is detachably attached to a wrist 18 by a band 16 in a state of facing the body surface 14 of a human body. The main body 10 includes an annular side wall member 20 and a lid member 24 fixed to the upper end of the side wall member 20 with the outer peripheral edge portion of the diaphragm 22 sandwiched therebetween, and the inner peripheral edge portion of the diaphragm 22 is fixed to the pressing member 26. ing. The diaphragm 22 is made of an elastically deformable material such as rubber, and the pressing member 26 is held movably in the main body 10 via the diaphragm 22. Further, an airtight pressure chamber 28 is formed by the diaphragm 22 between the main body 10 and the pressing member 26, so that pressure air is supplied from the pressure air supply source 30 via the pressure regulating valve 32. Has become.

The pressing member 26 includes an annular side wall member 36, a lid member 38 fixed to the upper end of the side wall member 36 with the inner peripheral edge of the diaphragm 22 sandwiched therebetween, and a pressing plate disposed at the lower end of the side wall member 36. It consists of 40 and. As shown in FIG. 2, the pressing plate 40 is formed by forming a number of pressure sensitive diodes 44 on the upper surface of a semiconductor chip 42 made of single crystal silicon or the like. The signal is adapted to be taken out between a common terminal 46 and an individual terminal 48. Many pressure sensitive diodes 44 are
In the state of being attached to the, it is formed with a constant interval in a direction intersecting the radial artery 50 at which the pulse wave should be detected at a substantially right angle, and the width dimension and the interval in a direction substantially perpendicular to the artery 50 are , At least three pressure sensitive diodes 44
Is located just above the radial artery 50, that is, directly above the radial artery 50 and within a range of a length substantially the same as the diameter of the artery 50. The shape of the pressure sensitive diode 44 and the length dimension parallel to the artery 50 are appropriately set.

In addition, the pressure sensitive diode which is the lower surface 52 of the pressing plate 40
In the portion corresponding to 44, a recess is formed in each and a rubber filler 54 is embedded therein. The rubber filler 54 is filled in the recess so that the lower surface 52 is flat without giving an additional force to the pressure sensitive diode 44, and the body surface 14 immediately above the artery 50 and in the vicinity thereof is located on the pressing plate 40. While being pressed flat by the lower surface 52, the pressure vibration of the pulse wave generated from the radial artery 50 is transmitted to the pressure sensitive diode 44 via the rubber filler 54. The thickness of the semiconductor chip 42 at the portion where the recess is formed is extremely thin, for example, about 15 μm, and pressure vibration is generated at the joint portion of the pressure-sensitive diode 44 by transmitting the pressure vibration to the rubber filler 54. As a result, an electric signal corresponding to the pressure fluctuation is output from the pressure sensitive diode 44 as a pulse wave signal SM. In this embodiment, the pressure sensitive diode 44 corresponds to a pressure sensor.

The pressing plate 40 is fixed to the lower end opening of the container-shaped holding member 56 made of an insulating material disposed inside the side wall member 36 so that electrical leakage from the semiconductor chip 42 is prevented. It has become. Further, the empty space 58 surrounded by the holding member 56 and the pressing plate 40 is open to the atmosphere via the rubber tube 60, and the pressure inside the empty space 58 fluctuates due to body temperature and the like, The pulse wave signal SM output from the piezoelectric diode 44 is prevented from changing.

The pulse wave signal SM output from the pressure sensitive diode 44 is supplied to the control device 62. The control device 62 is composed of a microcomputer or the like, detects the pulse wave of the artery 50 based on the supplied pulse wave signal SM, and outputs the display signal SS to the display / recording device 64 to output the pulse wave. Is displayed and recorded, and a drive signal SD is output to the pressure regulating valve 32 to control the pressure value of the pressure air supplied into the pressure chamber 28.
FIG. 3 is a flow chart showing an example of the signal processing logic by the control device 62, and the operation of the present embodiment will be described below with reference to this flow chart.

First, in a state in which the main body 10 is attached to the wrist 18 by the band 16 so that the pressing plate 40 of the pressing member 26 covers the radial artery 50, the step S1 is executed when an activation switch (not shown) is operated, By outputting the drive signal SD, pressure air having a predetermined constant pressure is supplied into the pressure chamber 28. As a result, the pressing member 26 is moved relative to the main body 10 in the direction toward the body surface 14, and the lower surface 52 of the pressing plate 40 is pressed against the body surface 14. And
Thus, when the lower surface 52 is pressed against the body surface 14, the pressure vibration of the pulse wave generated from the artery 50 is transmitted to the pressure sensitive diode 44, and the pulse wave signal SM corresponding to the pressure vibration is output. Become. The constant pressure is set to a level at which the pressure oscillation of the pulse wave can be detected by the pressure sensitive diode 44.

Then, step S2 is executed, and the pressure sensitive diode 44
By controlling the pressure regulating valve 32 based on the pulse wave signal SM output from the pulse wave signal SM, the pressure value of the pressure air supplied into the pressure chamber 28 is changed, and the pulse wave signal SM supplied from the pressure sensitive diode 44 is changed. The pressure value of the pressure air is adjusted so that the pressing member 26 is pressed against the body surface 14 with the pressing force that maximizes the amplitude A of the. This is because if the pressing force of the pressing member 26 is too high, the artery 50 is completely blocked and a pulse wave cannot be obtained, while if it is too low, the vibration of the pulse wave transmitted to the pressure sensitive diode 44 becomes weak. , As shown in FIG. 1, the amplitude A when the artery 50 is pressed with a pressing force such that the cross-sectional shape of the artery 50 becomes flat.
Is the maximum. At this time, the upper wall of the artery 50 and the body surface 1
4. Further, it is substantially parallel to the pressing plate 40. At the time of this pressure adjustment, the amplitude A of all pulse wave signals SM is used.
Various modes can be adopted, such as maximizing the average value of the above, or maximizing the amplitude A by using one pulse wave signal SM having the maximum signal strength.

Then, by executing steps S3 to S7 in this state, the pulse wave signal SM _(P ) that represents a pulse wave approximate to the actual pulse wave (pressure wave) in the artery 50 from among a large number of pulse wave signals SM. ₎ Is selected. That is, first, in step S3, the artery
The amplitude A of the pulse wave signal SM output from a large number of pressure-sensitive diodes 44 arranged in a direction intersecting with 50 at a substantially right angle is obtained, and the maximum amplitude _max A having the largest value is determined.
Then, in step S4, and calculates the reference value A _s by multiplying the maximum amplitude _max coefficients predetermined for A k (1>k> 0 ), the amplitude A in step S5 is higher than the reference value A _s Also select a large group of pulse wave signals SM _(A) . This is because the amplitude A of each pulse wave signal SM in the direction perpendicular to the artery 50 is larger in the region directly above the artery 50 as compared with other portions as shown in FIG. As a result, the pulse wave signal SM output from at least three or more pressure sensitive diodes 44 pressed directly above the artery 50 is selected as the pulse wave signal SM _(A) . Reference value A _s is the maximum amplitude _max
Since it is based on A, the individual difference of the subject does not affect the selection of the pulse wave signal SM _(A) . This pulse wave signal SM _(A) corresponds to the pulse wave signal directly above.

When the pulse wave signal SM _(A) is selected in this way, step S6 is then executed, and the maximum peak value P _max of each of these pulse wave signals SM _(A) is detected. Maximum peak value P _max
Corresponds to the blood pressure value in the artery 50 during systole, and in the next step S7, this maximum peak value
Select P _max is the maximum peak value P _max is smaller than the minimum of the pulse wave signal SM of output from pressure sensitive diode 44 adjacent to both sides pulse wave signals SM _{(A) (A)} as a pulse wave signal SM _(P) To be done. This means that the maximum peak value P _max of each pulse wave signal SM in the direction orthogonal to the artery 50 tends to be locally small in the substantial center just above the artery 50 as shown in FIG. Above is what is called a valley) and also the arteries
Since at least three pressure sensitive diodes 44 are pressed directly above 50, the pulse wave signal SM output from the pressure sensitive diode 44 pressed almost at the center directly above the pulse wave signal SM _(P). To be selected. This pulse wave signal SM _(P) corresponds to the central pulse wave signal.

Here, the maximum peak value P _max has a minimum value in the vicinity of the center of the immediately upper portion because the vessel wall of the artery 50 in the vicinity of the center is substantially parallel to the pressing plate 40, and thus the pulse wave in a direction perpendicular to the pressure wave. Although the tension of the tube wall hardly affects the pressure vibration of the, the pressure applied to the pressure-sensitive diode 44 due to the tension of the tube wall at both ends where the tube wall of the artery 50 is curved. Is higher overall. Also,
Since there is no influence of the tension on the wall of the artery 50 near the center, the pressure value of the pulse wave represented by the pulse wave signal SM _(P) is extremely close to the actual pressure value and absolute value of the pulse wave in the artery 50. ing.
In the present embodiment, of the series of signal processing logic by the control device 62, the part that executes steps S3 to S7 corresponds to the selecting means for selecting the central pulse wave signal, and the step
The part that executes S3 to S5 constitutes the first selecting means for selecting the directly above pulse wave signal, and the part that executes steps S6 and S7 constitutes the second selecting means that selects the central pulse wave signal from the immediately above pulse wave signal. are doing.

Then, when the pulse wave signal SM _(P) is selected in this way, thereafter, this pulse wave signal SM _(P) is continuously read,
By outputting the display signal SS in step S8, the pulse wave represented by the pulse wave signal SM _(P) is displayed / recorded by the display / recording device 64.
Is displayed and recorded on. In this case, if the positional relationship between the pressing member 26 and the artery 50 changes due to the body movement of the subject,
Since the correct pulse wave cannot be obtained by the selected pulse wave signal SM _(P), by executing the steps S3 to S7 every time a fixed time or a fixed number of pulse waves are detected, the pulse wave signal or so as to monitor whether there is a change in SM _(P), it is desirable to change the pulse wave signal SM _(P) for detecting a pulse wave. It should be noted that, based on the detected pulse wave, the cardiac activity state or the like is automatically diagnosed, or the maximum peak value P _max of the pulse wave and the minimum peak value P _min to the maximum blood pressure value,
It is also possible to determine the minimum blood pressure value.

As described above, the pulse wave detection device according to the present embodiment detects the pulse wave based on the pulse wave signal SM _(P) output from the pressure sensitive diode 44 that is pressed to the approximate center of the artery 50. As a result, not only the waveform of the pulse wave but also its pressure value can be obtained as a pulse wave extremely similar to the actual pulse wave in the artery 50. In particular, in this embodiment, first, the pulse wave signal
Based on the amplitude A of the SM, a group of pulse wave signals SM _(A) output from the pressure sensitive diode 44 located immediately above the artery 50 is selected, and the maximum peak value is selected from the pulse wave signals SM _(A). since adapted to select the pulse wave signal SM _(P) on the basis of the P _max, is the pulse wave signal SM _(P) is selected with high accuracy.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, instead of steps S3 to S5 of the above embodiment, a fifth
The steps R1 and R2 shown in the figure can also be used as the first selection means. That is, first, in step R1, the pulse wave signal SM ( _max A) having the maximum amplitude _max A is determined, and then in step R2, the pulse wave signal SM (
_That is, a group of pulse wave signals SM output from a fixed number of pressure sensitive diodes 44 adjacent to both sides of the pressure sensitive diode 44 that outputs ( _max A) is selected as the pulse wave signal SM _(A) . This fixed number is set based on the width dimension, interval, etc. of the pressure sensitive diodes 44 so that the pulse wave signal SM output from the plurality of pressure sensitive diodes 44 pressed directly above the artery 50 is selected. It It should be noted that, without selecting the pulse wave signal SM _(A) by using the first selecting means as described above, the direct pulse wave signal SM ₍ based on the difference of the maximum peak value P _max shown in FIG. _P)
Can also be configured to single out.

Further, the second selecting means of the above-mentioned embodiment has the maximum peak value P _max.
The pulse wave signal SM _(P) that minimizes is selected.However, the pulse wave signal that minimizes the minimum peak value P _min during diastole is selected, and the peak values P _max and P There is no problem even if it is arranged to select the pulse wave signal with both the minimum _min , and if the minimum does not appear clearly, the pulse wave signal SM _(A) selected in step S5 It is also possible to select the pulse wave signal output from the central pressure-sensitive diode 44 among the plurality of pressure-sensitive diodes 44 that output the above as the central pulse wave signal.

Further, although the pressure-sensitive diode 44 is used as the pressure sensor in the above-mentioned embodiment, various well-known means such as a semiconductor strain gauge and a pressure-sensitive transistor can be adopted. Further, one pressure sensor may be composed of two or four pressure sensitive diodes, and a pulse wave signal may be output by a bridge circuit or the like.

In addition, although a large number of pressure-sensitive diodes 44 are arranged in the above-mentioned embodiment, for example, when the pressing member 26 can be forcibly moved in the direction intersecting with the artery 50 by an actuator, a relatively small number of pressure-sensitive diodes are detected. The provision of the piezo-electric diode 44 is sufficient. In addition, the three pressure-sensitive diodes 44 are used, and the pressing member 26 is placed so that the pressure-sensitive diode 44 at the center of the pressure-sensitive diode 44 is located substantially above the artery 50 based on the amplitude A and the maximum peak value P _max. If it is moved, the selecting means in the present invention becomes unnecessary.

Further, although the pressure sensitive diodes 44 are arranged in a line on the semiconductor chip 42, the width dimension and the interval of the pressure sensitive diodes 44 can be increased if the pressure sensitive diodes 44 are arranged in two lines by shifting by 1/2 pitch. On the other hand, if the intervals are the same, the resolution is doubled, and it becomes possible to detect a more detailed pulse wave. Also, according to the same idea,
It is also possible to provide the pressure sensitive diodes 44 in three or more rows.

Further, although the pressure sensitive diodes 44 are arranged in a direction intersecting the artery 50 at a substantially right angle in the above-described embodiment, they may be arranged so as to intersect the artery 50 at an angle. Even in that case, the space between the pressure-sensitive diodes 44 in the direction perpendicular to the artery 50 is narrowed, so that the pressure-sensitive diodes 44 are separated by 2 as described above.
The same effect as when providing more than one row is obtained.

Further, the although the embodiment is adapted to the pulse wave signal SM _(P) is selected by software by the microcomputer, to select the pulse wave signal SM _(P) by hard logic circuit performing the same function It is also possible to configure.

Further, although the pulse wave detecting device for detecting the pulse wave from the radial artery 50 has been described in the above embodiment, the present invention can be similarly applied to the case where the pulse wave is detected from another artery such as the carotid artery.

Although not illustrated one by one, the present invention can be carried out in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a pulse wave detecting device according to one embodiment of the present invention. FIG. 2 is a partially cutaway perspective view for explaining a plurality of pressure sensors provided in the apparatus of FIG. FIG. 3 is a flowchart explaining an example of the operation of the apparatus shown in FIG. FIG. 4 is a diagram for explaining the changing tendency of the amplitude and the maximum peak value of the pulse wave signal in the direction perpendicular to the artery. FIG. 5 is a diagram showing a main part of a flow chart for explaining the operation in another embodiment of the present invention. 14: body surface 44: pressure sensing diodes (pressure sensor) 50: radial artery, 62: control device SM: pulse wave signal, SM _(A): directly above pulse wave signal SM _(P): center pulse signal A _s: the reference Value, P _max : maximum peak value Steps S3, S4, S5: first selecting means Steps S6, S7: second selecting means Steps R1, R2: first selecting means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Open 51-93280 (JP, U) Open 59-111106 (JP, U) Open 58-74910 (JP, U)

Claims (6)

[Claims] 1. A device for detecting a pulse wave generated from an artery of a human body, comprising a plurality of devices in a direction intersecting with the artery so that at least three of them are located immediately above the artery on the body surface of the human body. A plurality of pressure sensors that are provided and that detect the pressure vibration of the pulse wave generated from the artery when pressed against the body surface and output a pulse wave signal corresponding to the pressure vibration; and the plurality of pressure sensors Selecting means for selecting the central pulse wave signal output from the pressure sensor located substantially in the center immediately above the pulse wave signal output from each of the pulse wave signals output from A pulse wave detecting device characterized in that the pulse wave is detected based on a central pulse wave signal. 2. The selecting means includes, from among the pulse wave signals output from each of the plurality of pressure sensors, a pulse wave signal immediately above which is output from at least three pressure sensors located immediately above the artery. 3. The first selection means for selecting the central pulse wave signal from the directly above pulse wave signal selected by the first selection means, and the second selection means for selecting the central pulse wave signal. The pulse wave detection device according to. 3. A pulse wave signal whose amplitude is equal to or greater than a reference value obtained in advance from the pulse wave signals, as the directly above pulse wave signal, wherein the first selecting means selects the pulse wave signal. The pulse wave detection device according to item. 4. The first selecting means selects a pulse wave signal having the maximum amplitude from the pulse wave signals and adjoins both sides of the pressure sensor that has output the pulse wave signal having the maximum amplitude in advance. The pulse wave detection device according to claim 2, wherein a pulse wave signal output from a predetermined number of pressure sensors is selected as the directly above pulse wave signal. 5. The second selecting means selects, from the directly above pulse wave signals, a pulse wave signal having a peak value smaller than a peak value of the pulse wave signals output from the pressure sensors adjacent to both sides of the central pulse wave signal. The pulse wave detection device according to any one of claims 2 to 4, which is selected as a pulse wave signal. 6. The method according to claim 5, wherein the peak value is at least one of a maximum value and a minimum value of the pulse wave signal.
The pulse wave detection device according to item.