JP2000051164A - Pulse wave detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse wave detector which causes small detection error by body movement and can more accurately detect a pulse wave. SOLUTION: A first piezoelectric sensor 10a is placed on an artery and a second piezoelectric sensor 10b on a place slightly off the artery. Since the piezoelectric sensor has narrow directivity, signals corresponding to a pulse waveform and a body motion wave are outputted from the first piezoelectric sensor 10a on an artery but signals corresponding only to the body movement are outputted from the second piezoelectric sensor which is not on an artery. The body motion components are canceled by taking difference of output from both piezoelectric sensors 10a, 10b to enable an accurate pulse wave to be detected. The pulse rate and the waveform information are obtained from the pulse wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse wave detecting device, and more particularly, to a pulse wave detecting device for detecting a pulse wave from an arterial pressure fluctuation caused by a blood flow.

[0002]

2. Description of the Related Art Detecting a pulse wave due to a blood flow flowing through an artery is widely used in medical practice and health care. This pulse wave detection is widely performed not only when the pulse rate is detected as a pulse rate for a predetermined time by palpation, but also when the pulse rate is automatically detected electronically using a pulse wave detection device. As a device for electronically detecting a pulse wave to obtain a pulse rate, a method using a piezoelectric element, a method for optically detecting the pulse, and the like have been put to practical use. As a method of using a piezoelectric element, a piezoelectric element of a piezo type is arranged on an artery as a sensor, and a pressure change of the epidermis accompanying a pressure change inside the artery (a displacement of the epidermis due to pressure).
From the pulse rate. FIG. 13 shows an equivalent circuit of a conventional pulse wave detection device using a piezoelectric element. As shown in FIG. 13, the conventional pulse wave detection device
One piezoelectric element 1 is used to detect a pressure change in the epidermis due to an artery as a voltage change. Then, after the waveform based on the output signal passes through the filter unit 2 and is further amplified by the amplifier unit 3, the pulse counter unit 4 detects the pulse rate from the waveform change due to the voltage change.

On the other hand, the optical detection method detects a pulse from a change in the amount of light absorbed due to a change in the amount of hemoglobin in the blood, and emits light with a light emitting diode and receives light with a phototransistor that receives the light. From the pulse.

[0004]

However, the conventional pulse wave detection device can accurately detect a pulse wave when it is detected in a hospital or home while resting. When the subject moved, body motion noise (noise based on the motion of the subject) occurred, and an accurate pulse wave could not be detected. That is, if a piezoelectric element is used,
The skin of the element moves due to the subject's body movement, and the piezoelectric element also detects body movements other than pulsation, so even if the subject is moving even within the range of daily movement, it is accurate. Pulse wave could not be detected. On the other hand, in the case of detecting blood pressure from the amount of light absorbed, similarly, since the blood flow in the artery greatly changes due to body movement, accurate pulse waves cannot be detected when the subject is moving. Was.

Accordingly, the present invention has been made to solve the problem in such a conventional pulse wave detecting device.
It is an object of the present invention to provide a pulse wave detection device that can detect a more accurate pulse wave with less detection error due to body motion.

[0006]

According to the present invention, there is provided a first piezoelectric sensor disposed on an artery for detecting pressure fluctuation on a body surface due to pulsation and body movement of the artery, and a first piezoelectric sensor disposed near the artery. A second piezoelectric sensor that is disposed and detects a pressure change on a body surface due to body movement, acquires information about a pulse wave from a detection signal from the first piezoelectric sensor and a detection signal from the second piezoelectric sensor. The pulse wave detection device is provided with a pulse wave information acquisition unit and an output unit that outputs information on the pulse wave acquired by the pulse wave information acquisition unit. As described above, by detecting body motion and pulsation on one of the two piezoelectric sensors having a narrow directivity range and detecting body motion on the other, pulse wave information can be obtained by removing a body motion component. For this reason, it is hard to be affected by body motion, and it is possible to continuously detect a pulse wave while always carrying it, even while performing a daily life. Further, in the present invention, the second piezoelectric sensor is disposed at a position near the end thereof in contact with the artery, detects a pressure change on the body surface due to pulsation of the artery and body movement, and One of the body movements is detected in a phase opposite to a detection signal from the first piezoelectric sensor. Thereby, a body motion component can be removed, and a pulsation detection signal can be obtained with a high output. Further, in the present invention, the detection signal of the first piezoelectric sensor and the detection signal of the second piezoelectric sensor with respect to the body movement are connected to the same polarity side, so that the first piezoelectric sensor and the first piezoelectric sensor are connected to each other. The second piezoelectric sensor is connected in series, and the pulse wave information obtaining means obtains information on a pulse wave from output signals of the two piezoelectric sensors connected in series. Thus, the body motion signal can be removed from both piezoelectric sensors. Further, according to the present invention, a first piezoelectric sensor for detecting pressure fluctuation, a second piezoelectric sensor disposed above the first piezoelectric sensor for detecting pressure fluctuation, and a pressure fluctuation on a body surface due to arterial pulsation. Pulsation transmitting means for transmitting pulsation to the first piezoelectric sensor, and body movement transmission for contacting the body surface at a position avoiding the artery and transmitting pressure fluctuation on the body surface due to body movement to the first piezoelectric sensor A plate, a body movement transmitting member for transmitting the pressure fluctuation of the transmission plate to a surface of the second piezoelectric sensor that detects the pressure fluctuation, a detection signal of the first piezoelectric sensor, and a second piezoelectric sensor. A pulse wave detection device includes pulse wave information acquisition means for acquiring information about a pulse wave from a signal detected by a sensor, and output means for outputting information about a pulse wave acquired by the pulse wave information acquisition means. Thus, the same body movement as that detected by the first piezoelectric sensor can be detected by the second piezoelectric sensor. Further, according to the present invention, there is provided a transmission mechanism for transmitting a force received on the surface of the second piezoelectric sensor on which the pressure fluctuation is not detected to the surface of the first piezoelectric piezoelectric sensor on which the pressure fluctuation is not detected. Thereby, the same force as the force applied from the outside to the second piezoelectric sensor can be transmitted to the first piezoelectric sensor. Further, in the present invention, a slit portion is formed along the artery in the body movement transmission plate, and the slit portion or a flexible member provided in the slit portion is defined as the pulse wave transmitting means. In the present invention, the pulse wave information acquiring unit acquires a pulse rate as information on a pulse wave, and the output unit outputs the pulse rate acquired by the pulse wave information acquiring unit. Further, in the present invention, the pulse wave information obtaining means includes a storage means for storing the pulse wave signal, obtains the pulse wave signal for a predetermined time as information on the pulse wave, stores the information in the storage means, The output means outputs the pulse wave signal stored in the storage means. In the present invention, the apparatus further comprises a display unit, wherein the pulse wave information acquiring unit acquires a pulse rate or a pulse wave waveform as information relating to the pulse wave, and the output unit comprises a pulse rate acquired by the pulse wave information acquiring unit. Alternatively, a pulse waveform is output to the display means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to FIGS. (1) Overview of First Embodiment In the first embodiment, a first piezoelectric sensor using a piezoelectric element and a second piezoelectric sensor are used, and the first piezoelectric sensor is placed on an artery and the second piezoelectric sensor is placed on an artery. Is located slightly away from the artery. Since the sensor using the piezoelectric element has a narrow directivity, a signal corresponding to the pulse wave waveform and the body motion waveform is output from the first piezoelectric sensor on the artery, but is output from the second piezoelectric sensor not on the artery. Outputs only a signal corresponding to the body motion waveform. By taking the difference between the outputs of the first and second piezoelectric sensors, the body motion component is canceled, and an accurate pulse wave can be detected, and the pulse rate and waveform information are obtained from the pulse wave.

[0008] Two conventional pulse sensors for detecting a pulse from the amount of light absorbed are used, one is disposed on the artery and the other is disposed at a position away from the artery. May be detected, but an accurate pulse wave cannot always be detected. That is, a sensor on the artery detects a body motion waveform and a pulse wave waveform, and a sensor far from the artery detects only a body motion waveform, and detects a pulse wave of a sufficient signal level from the difference between the two detection signals. It is possible. However, since a sensor that detects a pulse from the amount of light absorbed has a wide directivity range of irradiated light, even if the sensor is arranged at a position distant from the artery, a pulse wave lower than the detection level is detected. Will be. For this reason, when the difference between the detection signals obtained by the two sensors is obtained, the body motion waveform can be removed, but the signal level of the pulse wave waveform is also reduced due to the difference, so that an accurate pulse wave can be detected. Will be gone. Light from the emitting diode is also absorbed by a number of capillaries near the body surface. For this reason, sensors arranged at different positions have detected changes in the amount of light absorbed by different capillaries. further,
If the blood flow in the artery changes mainly due to body movement,
When the blood flow in the capillaries mainly changes, both the blood flow in the arteries and the blood flow in the capillaries may change, and it is impossible for both sensors to detect the change in body motion as the same waveform.

Therefore, in the present embodiment, by using a piezoelectric element having a high directivity (a narrow directivity range), a change in the epidermis due to pulsation is captured by the first piezoelectric sensor, and is not captured by the second piezoelectric sensor. Like that. The body motion transmitted to the epidermis is detected by both sensors in the same manner. Thus, by taking the difference between the two sensors, it is possible to remove (cancel) only the body movement component without weakening the pulse wave component captured by the first piezoelectric sensor, and to detect an accurate pulse wave. Becomes possible. In the first embodiment, a pulse rate is acquired from the pulse waveform as information relating to the pulse wave, and the acquired pulse rate is displayed on the display unit. Also,
As a process for acquiring information on a pulse wave, a pulse wave waveform is
The data is converted and stored in the memory, and the waveform is displayed on the display unit as an image or output to various external devices such as a personal computer and a medical diagnostic device.

(2) Details of First Embodiment FIG. 1 shows a configuration of a pulse wave detection device according to a first embodiment. As shown in FIG. 1A, the pulse wave detection device includes a first piezoelectric sensor 10a disposed on an artery.
And a second piezoelectric sensor 10b disposed at a position away from above the artery (a position near the first piezoelectric sensor 10a where there is no skin change due to pulsation), and the first and second piezoelectric sensors 10a and 10b Filters 22a and 22b for removing noise components from the output of the amplifier, and an amplifier 2 for amplifying the output
4a and 24b. For the first piezoelectric sensor 10a and the second piezoelectric sensor 10b, piezo-type piezoelectric elements having the same characteristics are used. In addition, the pulse wave detection device,
A differential unit 30 that receives the outputs of the two amplifying units 24a and 24b and obtains a pulse waveform from the difference between them, a pulse wave information obtaining unit 40 that obtains pulse wave information from a pulse waveform obtained by the differential unit 30, and And an output unit 50 for outputting the acquired pulse wave information. In FIG. 1, the piezoelectric sensors 10a and 10b are represented by an equivalent circuit using a capacitor C and a resistor R.

The pulse wave information acquiring section 40 includes a pulse counting section 41 for counting a pulse rate from the pulse wave waveform obtained by the differential section 30. The pulse counting unit 41 sets the time interval between each pulse wave to a predetermined number of times (for example, 3, 5, 7, 10, etc.).
The pulse rate V for one minute is measured from the average time T of each measurement time according to the following equation (1). V = 60 / T (1) Note that the present invention is not limited to the case where the pulse rate is obtained from the average time T between pulse waves. For example, the pulse wave number w existing within a predetermined time t (for example, 10 seconds) is detected. The pulse rate V for one minute may be obtained by the equation (2). V = w × (60 / t) (2) The pulse counting section 41 generates a pulse wave signal indicating the presence of a pulse wave such as a pulse signal for each pulse wave. The output is supplied to the output unit 50 together with the pulse rate.

The output unit 50 has a display unit 51 for displaying the pulse rate supplied from the pulse counting unit 41. The display unit 51 may be configured by a liquid crystal display device to display an image of the pulse rate or to display the pulse rate electronically on a panel.

FIG. 1B shows another circuit configuration of the pulse wave detecting device. As shown in FIG. 1B, a differential amplifier 31 is used instead of the amplifiers 24a and 24b and the differential unit 30 in FIG.
Then, both outputs of the filter sections 22a and 22b are supplied to the differential amplifier section 31, and the differential amplifier section 31 takes the difference between the two outputs and performs an amplification process so as to obtain a signal of a predetermined level. As described above, according to the configuration of FIG. 1B, the number of components is small, and the pulse wave detection device can be downsized.

FIG. 2 shows a piezoelectric sensor 10 (first and second piezoelectric sensors 10) used in the embodiment of the present invention.
a, 10b). As shown in FIG. 2, the piezoelectric sensor 10 uses a piezoelectric type piezoelectric element 11, and a diaphragm 12 made of aluminum is provided on one surface of the piezoelectric element 11. On the surface on the opposite side of the piezoelectric element 11, a film-like insulating pad 13 is provided. A spacer 14 having a thickness greater than the thickness of the piezoelectric element 11 is disposed on an outer peripheral portion of the vibration plate 12, and a support plate 15 is disposed on the spacer 14 at a predetermined distance from the other surface of the piezoelectric element 11. I have. The piezoelectric element 11 has a wiring 1 for extracting the voltage change.
6 are connected. In the piezoelectric sensor 10 configured as described above, by arranging the insulating pad 13 in contact with the body surface, a change in the body surface is transmitted to the piezoelectric element 11 via the vibration plate 12 and output from the wiring 16 as a voltage change. It has become.

FIG. 3 shows a waveform state in each part of the pulse wave detecting device thus configured. In FIG. 3, the waveform A is the first waveform placed on the radial artery 2.
3 shows the waveform after being detected by the piezoelectric sensor 10a and amplified by the amplifier 24a. As shown in the waveform A, it is easy to detect the pulse wave A1 only from the first piezoelectric sensor 10a when there is no body movement. A waveform portion A2 including both components is generated, and it becomes difficult to measure when the subject moves. On the other hand, a waveform B represents a waveform detected by the second piezoelectric sensor 10b and amplified by the amplifier 24b. As shown in the waveform B, the second piezoelectric sensor is located at a position displaced from the radial artery 2 and does not detect a pulse wave due to pulsation, but detects only a waveform B1 due to body movement. The waveform C is obtained by taking the difference between the two waveforms A and B by the differential unit 30. As shown in the waveform C, the noise due to the body movement is almost removed, and the pulse wave waveform C that is periodically repeated is detected and supplied to the pulse wave information acquisition unit 40. In the pulse wave information acquisition unit 40, the time T between peaks I in the pulse wave waveform C
1 to Tn, and the average value T thereof is calculated by the pulse wave number counting unit 41.
The pulse rate V is obtained from the obtained average value T according to the above equation (1).

FIG. 4 shows a pulse wave detecting device incorporated in a timepiece. As shown in FIG. 4, a pulse wave detecting device (watch) 60 includes a watch main body 61 and a belt 62, and a sensor 19 in which the first and second piezoelectric sensors 10a and 10b are packaged in the same part. Is attached to the inside of the belt 62. The timepiece 60 is attached to the left (or right) wrist with the timepiece main body 61 facing the back of the hand, similarly to a general timepiece. At that time, the sensor 19
As shown in (b), the position of the sensor 19 can be adjusted by moving the sensor 19 in the longitudinal direction of the belt 62 so as to be located on the radial artery. In the sensor 19, as shown in (c), the first piezoelectric sensor 10a is disposed so as to be located on the radial artery 2, and the second piezoelectric sensor 10a is located so as to be shifted from the radial artery 2. The sensor 10b is arranged.

The watch main body 61 includes a filter section 22a, 22b and an amplifying section 24 in addition to a driving section such as a movement of the watch.
a, 24b, a differential section 30, a pulse wave information acquisition section 40, and a display section 51. The sensor 19 and the filter portions 22a and 22b of the watch main body 61 are connected by wiring (not shown) incorporated in the belt 62. The display surface (clock face) of the clock main body 61 includes a clock display unit 63 on which time (or day, day of the week, etc.) as a clock is displayed, and a pulse rate V
Is displayed, and a display unit 51 including a pulse rate display unit 64 and a pulse display unit 65 is provided. The pulse counting unit 41
The pulse rate V is obtained from the pulse wave waveform C supplied from the differential unit 30, and a pulse signal is supplied to the display unit 51 every time the peak I of the pulse wave waveform C is detected. In the display unit 51, the pulse rate V is digitally displayed on the pulse rate display unit 64, and the pulse display unit 65 blinks green in response to the supplied pulse signal. The user can visually recognize his or her own pulse wave by looking at the pulse rate of the pulse rate display unit 64 and the blinking of the pulse display unit 65. The blinking color of the pulse display section 65 may be changed according to the pulse rate. For example, 69 or less flashes yellow, blue flashes when the pulse rate is 70 to 90, 91 to 110
Blinks green between, blinks orange between 111-130, 13
One or more flashes red. As described above, the blinking color of the pulse display section 65 changes according to the pulse rate, so that the current pulse state can be easily distinguished.

As described above, according to the first embodiment, two piezoelectric sensors 10 having high directivity are used,
The waveform A is detected by arranging the piezoelectric sensor 10a on the artery 2 (pulsation + body movement), and the body movement by the first piezoelectric sensor is obtained by disposing the second piezoelectric sensor 10b away from the artery 2. A body movement waveform B having substantially the same level is detected, and a pulse wave waveform C (= (pulsation + body movement) waveform A−body movement waveform B) is obtained from the difference between the two detection signals. As a result, the detected pulse wave waveform C substantially cancels the body motion component,
Since the pulse wave component A1 included in the first piezoelectric sensor 10a remains as it is, it is possible to more accurately detect the pulse wave. As described above, according to the first embodiment, a pulse wave (pulse) can be detected with a simple configuration without receiving noise due to body motion. Waves can be detected.

Next, a second embodiment will be described. In the first embodiment, the detection signal from the first piezoelectric sensor 10a and the detection signal from the second piezoelectric sensor 10b are filtered and amplified, and then the pulse wave is obtained from the difference signal between the two. According to this embodiment, it is possible to obtain an accurate pulse wave by sufficiently removing body movements such as walking and body movement. However, the detection signal of a relatively intense body movement due to movement or the like has a considerably higher level than the pulse wave waveform, and thus exceeds the capability of the amplifier. In some cases, it cannot be removed sufficiently. Therefore, in the second embodiment, the body motion component is canceled in advance by the level of the electric charge generated in the first piezoelectric sensor 10a and the second piezoelectric sensor 10b.

FIG. 5 shows a connection state between piezoelectric sensors according to the second embodiment. Piezoelectric sensor 10
The piezoelectric element 11 generates an electric charge when subjected to pressure,
One surface side is a positive pole, and the other surface side is a negative pole. In the second embodiment, as shown in FIGS. 5A to 5D, both piezoelectric sensors 10a and 10b are connected in series. At this time, one identical pole (positive poles or negative poles) is connected, and the other identical pole is connected to the output terminal of the sensor 19, respectively. Thereby, the sensor 19
Outputs a detection signal from which the body motion component (noise) has been removed. Specifically, in the example shown in FIG.
A surface that becomes a positive pole by receiving the pressure of the piezoelectric sensor 10a (hereinafter, referred to as a positive pole surface) faces the body surface,
A surface that becomes a negative pole by receiving the pressure of the piezoelectric sensor 10b (hereinafter, referred to as a negative pole surface) faces the body surface.
Then, the positive pole surface of the first piezoelectric sensor 10a is connected to one output terminal of the sensor 19, and the first piezoelectric sensor 10a
The negative pole surface of a is connected to the negative pole surface of the second piezoelectric sensor 10b, and the positive pole surface of the second piezoelectric sensor 10b is connected to the other output terminal of the sensor 19.

FIG. 5B shows another connection method, in which a first piezoelectric sensor 10a and a second piezoelectric sensor 10b are used.
In both cases, the negative pole faces face the body surface, and both negative pole faces are connected to each other. Then, both positive pole surfaces are connected to both output terminals of the sensor 19, respectively.

FIGS. 5C and 5D show still another connection method. In FIGS. 5A and 5B, the negative pole faces are connected to each other, and the positive pole face is connected to the output terminal of the sensor 19. Conversely, in (c) and (d), the positive pole surfaces are connected to each other, and the negative pole surface is connected to the output terminal of the sensor 19. Specifically, as shown in FIG. 5C, the negative pole surface of the first piezoelectric sensor 10a faces the body surface, and the positive pole surface of the second piezoelectric sensor 10b faces the body surface. Then, the first piezoelectric sensor 1
0a is connected to one output terminal of the sensor 19, the positive pole surface of the first piezoelectric sensor 10a is connected to the positive pole surface of the second piezoelectric sensor 10b, and the negative pole surface of the second piezoelectric sensor 10b is connected. The negative pole surface is connected to the other output terminal of the sensor 19. In addition, as shown in FIG. 5D, both the first piezoelectric sensor 10a and the second piezoelectric sensor 10b have the positive pole surface facing the body surface, and the two positive pole surfaces are connected to each other. Then, both negative pole surfaces are connected to both output terminals of the sensor 19, respectively.

FIG. 6 shows a sensor 19 according to the second embodiment.
1 shows a configuration of a pulse wave detection device using the same. Note that the sensor 19 is shown by an equivalent circuit. As shown in FIG. 6, in the pulse wave detection device of the present embodiment, a sensor 19 having two piezoelectric sensors 10 a and 10 b having the same polar surfaces connected, a filter unit 22, and an amplifying unit 24
And a pulse wave information acquisition unit 40 and an output unit 50. Also in this pulse wave detection device, as shown in FIG.
It can be incorporated in a clock, and the pulse wave acquisition unit 40 and the output unit 50 function similarly to the first embodiment.

According to this embodiment, the first piezoelectric sensor 1
By connecting Oa and the second piezoelectric sensor 10b in series, a waveform (before filtering and amplification) corresponding to the pulse wave C in FIG. 3 can be obtained from the sensor 19. That is, since the body motion component (noise) is removed in the sensor 19, the differential unit 30 is unnecessary, and the filter unit 22 and the amplifier unit 24 for processing the output signal may be provided by one system. The configuration can be simplified. Also, since the body motion signals (noise) detected by the two piezoelectric sensors 10a and 10b are removed at the sensor level, the sensor 19 can output a signal having the same level as the pulse wave signal. Therefore, the circuit (the filter unit 22,
The dynamic range of the amplifying unit 24) can be used effectively according to the pulse wave signal.

Next, a third embodiment will be described. In the third embodiment, the body movement and the pulsation are also detected by the second piezoelectric sensor 10b, but one of the body movement and the pulsation is detected as a waveform in phase with the detection waveform of the first piezoelectric sensor 10a, The other is detected as a waveform having a phase opposite to that of the first piezoelectric sensor 10a. Thus, when pulsation is detected in the opposite phase, the difference between the two signals is taken, and when the body motion is detected in the opposite phase, the sum of the two signals is taken to remove the body movement component, The signal level can be increased. That is, it is possible to increase the S / N ratio of the pulse wave signal to be detected.

FIG. 7 shows the arrangement relationship (a) of the two piezoelectric sensors 10a and 10b and the principle (b) of detecting a pulse wave of opposite phase in the third embodiment. This FIG.
As shown in (a), the mounting position of the sensor 19 is such that the first piezoelectric sensor 10a is arranged on the radial artery 2 and the end of the second piezoelectric sensor 10b is arranged on the radial artery 2. To adjust. That is, the belt 6 is set so that the angle of inclination with respect to the radial artery 2 is smaller than that of the sensor 19 in the first embodiment shown in FIG.
Attach to 2.

As shown in FIG. 7 (b), when the radial artery 2 pulsates, it rises as shown by an arrow P on the upper body surface, and is shown by arrows Q on both sides of the radial artery 2 due to the reaction. Will be depressed. In contrast to the pulse wave waveform detected by the first piezoelectric sensor 10a disposed in the raised portion by receiving pressure, the second piezoelectric sensor 10b disposed in the depressed portion receives a tension to produce a waveform having an opposite phase. To detect. On the other hand, the movement of the epidermis due to body movement is the first and second
There is no distinction between the two positions of the piezoelectric sensors 10a and 10b, and the piezoelectric sensors 10a and 10b make almost the same movement. Therefore, both the piezoelectric sensors 10a and 10b detect in-phase waveforms with respect to body movement.

FIG. 8 shows an output waveform with respect to the pulsation of both the piezoelectric sensors 10a and 10b. As shown in FIG. 8, the waveform detected by the first piezoelectric sensor 10a is a waveform A, and the waveform detected by the second piezoelectric sensor 10b is a waveform B. As shown in the figure, the pulse waveform A2 in the waveform A is detected by the second piezoelectric sensor 10b in an opposite phase. The waveform C is obtained by subtracting the waveform A from the waveform B. As shown in the waveform C, a higher-level pulse wave signal I can be obtained by subtracting the pulse wave waveforms A2 and B2 detected in mutually opposite phases, thereby increasing the S / N ratio. Becomes possible.

The sensor 19 in the third embodiment
The configuration of the other parts can be any of the circuit configurations shown in FIGS. 1A and 1B or FIG. In this case, by connecting the two piezoelectric sensors 10a and 10b to one of the connections shown in FIGS. 5A to 5D, the body movement component can be removed. On the other hand, as for the pulsation detected by the two piezoelectric sensors 10a and 10b, since the body motion component and the pulse wave component are detected in opposite phases by the piezoelectric sensor 10b, the connection shown in FIGS. , Both pulse wave components are added and can be extracted at a high output level.

Next, a fourth embodiment will be described. According to the first to third embodiments, it is possible to obtain a very similar body motion waveform by using two piezoelectric sensors having high directivity, thereby removing a body motion component. However, since both piezoelectric sensors are in contact with different skin surfaces, they actually detect different body movements. For this reason, it is possible to sufficiently remove the body movement component from the body movement caused by swinging the entire arm or swinging the wrist 5 back and forth. When a complicated movement is made, a body motion waveform having the same shape may not always be detected. Therefore, in the present embodiment, the two piezoelectric sensors 10a and 10b having the same characteristics are superimposed in two stages, and the same motion as the body motion transmitted to the first piezoelectric sensor 10a in contact with the body surface on the radial artery is placed on the upper side. 2nd stacked
To the piezoelectric sensor 10b, while the pulsation is
The structure is such that it is transmitted only to the piezoelectric sensor 10a.

FIG. 9 shows a sensor 19 according to the fourth embodiment.
It is a representation of the structure. As shown in FIG. 9 (a), the sensor 19 is disposed opposite to the radial artery of the first piezoelectric sensor 10a, and the second piezoelectric sensor 1 is placed thereon.
0b are superposed. Both piezoelectric sensors 10a, 10b
Is the same as that of FIG. Then, both piezoelectric sensors 10
As for a and 10b, the support plate 15a and the support plate 15b are connected by the fixing member 70, and the vibration plate 12a and the vibration plate 12b are connected by the transmission member 80 via the insulating pads 13a and 13b. This fixing member 70 functions as a transmission mechanism.

The fixed member 70 includes a fixed plate 71 fixed to the support plate 15b and a fixed plate 72 fixed to the support plate 15a.
And a plurality of fixed columns 73 connecting the fixed plates 71 and 72 in series. The transmission member 80 includes the insulating pad 13b
And a transmission plate 82 attached to the insulating pad 13a and abutting against the body surface above the artery
And a plurality of transmission columns 83. The transmission plate 81 and the transmission column 83 function as a body movement transmission member, and the transmission plate 82 functions as a body movement transmission plate.

As shown in FIG. 9A, the transmitting member 80 is formed so as to be larger than the fixing member 70 so as to protrude outward. A plurality of notches (or holes, hereinafter simply referred to as “notches” including both holes) are formed in the periphery of the transmission plate 81 at positions corresponding to the respective fixing columns 73. The fixed column 73 is inserted in a non-contact state. At the center of the transmission plate 82,
A slit 84 having a predetermined width is formed in the transmission plate 8 in the direction along the artery.
2 is divided into two. The slit portion 84 is provided with a plate-shaped flexible member 85 (pulsation transmitting means) for transmitting only pulsation to the first piezoelectric sensor 10a. Silicon is used as the flexible member 85 because it comes into contact with the skin, but rubber such as raw rubber and synthetic rubber and other various flexible materials are used. The flexible member 85 has a plate-like side surface having slit portions 84.
Is fixed by being adhered to the end face of the transmission plate 82 that forms

The sensor 19 in the fourth embodiment
The configuration of the other parts may be any of the circuit configurations shown in FIGS. 1A and 1B or FIG. In the case of adopting the circuit configuration of FIG. 6, FIG.
Any connection of (d) may be used.

Next, the operation of the sensor 19 according to the fourth embodiment will be described with reference to FIG. As shown in FIG. 9B, the pulsation p by the radial artery 2 is transmitted to the flexible member 85 disposed along the radial artery 2 and transmitted only to the first piezoelectric sensor 10a. On the other hand, the body movement q is
The power is transmitted from the transmission plate 82 to the first piezoelectric sensor 10a, and also transmitted to the second piezoelectric sensor 10b through the transmission plate 82, the transmission column 83, and the transmission plate 81. Similarly, the body movement transmitted from the belt 62 and the external force r (also included in the category of body movement) such as the pressing force when pressed from the outside of the belt 62 are similarly transmitted from the fixed plate 71 to the second. While being transmitted to the piezoelectric sensor 10b, the fixed plate 71, the fixed column 7
The light is transmitted to the first piezoelectric sensor 10a via the third and fixed plates 72.

As described above, according to the fourth embodiment, the first and second piezoelectric sensors 10a, 10b are vertically stacked in two stages, and the fixed member 70 and the transmitting member 80 determine the body movement q and the external force r. Is transmitted to both the piezoelectric sensors 10a and 10b, and the pulsation p is transmitted only to the first piezoelectric sensor 10a by the flexible member 84. For this reason, according to the present embodiment, the same body movement can be detected by the first and second piezoelectric sensors 10a and 10b, so that the removal accuracy of the body movement can be improved, and as a result, more accurate Pulse wave can be detected.

FIG. 10 shows another structure of the sensor 19 according to the fourth embodiment. The same parts as those of the sensor 19 shown in FIG. 9 are denoted by the same reference numerals, and the description thereof will be appropriately omitted, and different parts will be mainly described. In the sensor 19 shown in FIG. 10, the fixing member 70 is formed so as to be larger than the transmission member 80 so as to protrude outward. A plurality of notches (not shown) are formed at positions corresponding to the respective transmission columns 83 on the peripheral edge of the fixed plate 72, and each of the transmission columns 83 is inserted into the notch in a non-contact state. It has become. With such a structure,
The area of the transmission plate 82 in contact with the body surface can be reduced, and the range in which body movement is detected can be reduced.

The fixing member 70 and the transmitting member 80 may be formed to have the same size. In this case, the positions of the fixed columns 73 and the positions of the transmission columns 83 are shifted from each other so that they do not overlap. Then, a plurality of cutouts are formed at positions corresponding to the fixed columns 73 on the peripheral edge of the transmission plate 81, and the fixed columns 73 are inserted in a non-contact state. A plurality of notches are formed at corresponding positions, and each transmission column 83 is inserted in a non-contact state. By making the fixing member 70 and the transmitting member 80 the same size in this way, the size of the sensor 19 can be reduced.

In the sensor 19 shown in FIG. 10, a space is formed without disposing the flexible member 85 in the slit portion 84 (pulsation transmitting means). This allows
The body surface on the artery enters the slit portion 84 and comes into direct contact with the insulating pad 13. Therefore, the width of the slit part 84 is formed wider than the slit part shown in FIG.

FIG. 11 shows still another structure of the sensor 19 in the fourth embodiment. As shown in FIG. 11, the first and second piezoelectric sensors 10a, 10a,
The supporting plates 15a and 15b of the first supporting plate 15a and 15b are slightly enlarged so as to serve as the fixing plates 71 and 72.
a and 15 b are connected by a plurality of fixed columns 73. Then, the first and second piezoelectric sensors 10a, 10b
The transmission plates 82 and 81 are directly attached to the vibration plates 12a and 12b, and the insulating pads 13a and 13b are not used. For this reason, an insulating material such as an acrylic plate is used for at least the transmission plate 82 that is in contact with the skin. Further, a flexible member 85 having an insulating property is disposed in the slit portion 84 of the transmission plate 82. According to the sensor 19 shown in FIG. 11, since the number of members can be reduced, the manufacturing time can be shortened and the manufacturing cost can be reduced. Further, the entire sensor 19 can be made thin.

As another structure of the sensor 19 shown in FIG. 11, the vibration plates 12a and 12b may be made slightly larger so as to serve as the transmission plates 82 and 81. In this case, a slit portion along the artery is provided in the center of the diaphragm 12a in contact with the skin so as to divide the diaphragm 12a into two parts in the same manner as the transmission plate 82 in FIG. 9, and a flexible member 85 is provided. Arrange. Then, a film-shaped insulating pad 13a is attached to the diaphragm 12a. Insulation pad 13a
May be attached only to the diaphragm 12a, but by attaching it to the entire surface in contact with the skin including the flexible member 85, the number of attachment steps can be reduced.

(3) Modifications The invention described in each claim is not limited to each embodiment described above, and various modifications may be made within the scope described in each claim as described below. Can be adopted. In each modified example described below, the description of the same components as those described in each embodiment will be omitted, and the description will be focused on the modified portions.

(A) First Modification In each of the embodiments described above, the pulse wave information acquisition section 40 is provided with a pulse counting section 41, and a pulse rate and a pulse wave signal (pulse signal) are generated as information relating to the pulse wave. In the first modification, the pulse rate and the pulse by blinking green are displayed on the display unit 51 (the pulse rate display unit 64 and the pulse display unit 65) of the output unit 50. In the example, the pulse wave information acquiring unit 40 performs a storing process of the pulse wave waveform, and the output unit 50 outputs the pulse wave waveform to the external device.

FIG. 12 shows a configuration of the pulse wave information acquiring section 40 and the output section 50 in the first modification.
As shown in FIG. 12, the pulse wave information acquisition unit 40
A / D converter 4 for converting a pulse wave waveform into a digital signal
5 and a storage unit 46 for storing the converted pulse wave information (pulse wave waveform). The A / D converter 45 has the configuration shown in FIG.
The differential unit 30 shown in (a) and the differential amplifier unit 3 shown in (b)
1 or a pulse wave waveform output from the amplifier 24 shown in FIG. As the storage unit 46,
Various storage media for magnetically, electrically, and optically storing data, such as a DRAM, an SRAM, an EEPROM, and a hard disk, can be used. The capacity is arbitrary, but at least for one hour to one day. Preferably, a capacity capable of storing pulse wave information for one week, more preferably one month is employed. The output unit 50 includes an I / F unit 55 for connecting the pulse wave detection device to various external devices such as a personal computer and a medical diagnostic device.

According to the first modification of such a configuration, it is possible to continuously detect a pulse wave in daily life and accumulate the information. Then, an external device can be connected to the I / F unit 55 at a later date, and the accumulated pulse wave information can be output to the external device collectively. Thus, for example, in a medical diagnostic device (external device), pulse wave information for a long time can be obtained, and the state of the user can be more accurately diagnosed from a medical viewpoint. For example, by examining the pulse fluctuation, it is possible to examine whether the user is in a state of psychological tension or in a relaxed state. It is also possible to check the rhythm of the pulse wave, the magnitude of the pulse, the rising speed of the pulse (fast or slow), and the like.

The pulse wave information acquisition section 40 and output section 50
May be combined with the first modified example and each embodiment. That is, the pulse wave information acquisition unit 40
Is provided with a pulse counting unit 41, an A / D conversion unit 45, and a storage unit 46. The storage unit 46 stores the A / D converted pulse wave information (pulse wave waveform) and the pulse rate for each predetermined time. . Storage unit 4
The predetermined time when the pulse rate is stored in 6 is set by a time interval setting unit (not shown), for example, from 5 minutes to 24 hours.
Any time can be set at minute intervals. For the pulse rate, the pulse rate for each set time interval is stored together with data indicating the calculation time. Then, the display unit 5 is output to the output unit 50.
1 and an I / F unit 55, and a pulse rate 64
, A pulse wave display (green blinking) 65 is displayed. I / F 5
5 is connected to an external device, the pulse wave information stored in the storage unit 46, the pulse rate and time data at regular time intervals as needed, and the pulse signal supplied from the pulse counting unit 41. Output. The display unit 51 displays a pulse waveform (C in FIG. 3 or FIG. 8) in addition to the pulse rate and the pulse wave display (green blinking) (or in another screen by inputting a screen switching signal). You may do so. In this case, the pulse waveform may be the differential section 30, the differential amplifier section 31, or the amplifier section 2.
4 may be displayed in real time, and the past pulse wave waveform may be displayed by reading the corresponding pulse wave waveform from the storage unit 46 by designating a date and time.

(B) Second Modification In each of the embodiments described above, the sensor 19 is attached to the belt 62, but the sensor 19 is attached to the opposite side of the timepiece body 61 (the side in contact with the body surface). You may. In this case, when measuring the pulse, the watch main body 61 is placed on the opposite side of the back of the hand, and the sensor 19 is positioned on the radial artery 2. Then, when the subject presses a button for supporting the start of the pulse wave detection (or selects the start key), the detection of the pulse wave is started. By arranging the sensor 19 on the watch main body 61 in this manner, it is not necessary to incorporate the wiring into the belt 62.

(C) Third Modification As a third modification, the pulse wave detection device may be configured as a single device without being incorporated in a watch. Also in this case, similarly to the case of the timepiece, the sensor 19 and the other parts are configured separately, and the sensor 19 is arranged on the radial artery 2 by a belt, and each part other than the sensor 19 (the filter part 2)
2. The amplification unit 24, the differential unit 30, the pulse wave information acquisition unit 40, and the output unit 50) may be arranged on the back of the hand. Further, a portion other than the sensor 19 may be formed separately from the belt to which the sensor 19 is attached, and both may be connected by wiring. In this case, for example, the sensor 19 may be arranged on the brachial artery from above thin clothing such as a Y-shirt, and a portion other than the sensor 19 may be stored in a breast pocket or an inner pocket of a suit. Note that the second modification and the third modification can be combined with the first modification. Further, in addition to the radial artery and the brachial artery, the first piezoelectric sensor 10a is provided on the femoral artery, the common carotid artery, the ulnar artery, the anterior carotid artery, the posterior carotid artery, the dorsal artery, and the shitsugai artery.
May be arranged. Then, depending on the position of the artery receiving the pulse wave detection device, the sensor 19 may be fixed on the artery using a medical tape instead of a belt or a band.

In the sensor 19 shown in FIGS. 4C and 7A, the second piezoelectric sensor 10b is arranged outside the wrist of the second piezoelectric sensor 10a arranged on the radial artery 2. Alternatively, the second piezoelectric sensor 10b may be arranged on the opposite side (the inner side of the wrist above the radial artery).

In the fourth embodiment shown in FIGS. 9, 10 and 11, the transmission plate 82 is divided into two parts by the slits 84 formed along the artery. May be connected to each other with a connecting member. In this case, if the connecting member contacts the body surface on the artery, the pulsation is transmitted to the second piezoelectric sensor 10b. Therefore, the connecting member is formed in an arch shape so as not to contact the pulsating body surface. By connecting the transmission plates 82 arranged on both sides of the artery with the connecting members in this way, the strength of the transmission plates 82 can be increased. The transmission plate 82
The connection member is connected to the end by the first piezoelectric sensor 10a.
This is not necessarily an end portion as long as the position avoids the first piezoelectric sensor.

[0051]

According to the pulse wave detecting device of the present invention, the detection signal from the first piezoelectric sensor disposed on the artery and the detection signal from the second piezoelectric sensor disposed near the artery are avoided. Since the information about the pulse wave is obtained from the above, the body motion component can be removed without weakening the pulse wave component. Therefore, a detection error due to body movement is small, and a more accurate pulse wave can be detected. Further, according to the pulse wave detection device of the present invention, the same movement as the body movement transmitted to the first piezoelectric sensor in contact with the body surface on the artery is transmitted to the second piezoelectric sensor, while the pulsation is transmitted to the first piezoelectric sensor. Since the structure is transmitted only to the piezoelectric sensor, the accuracy of removing the body movement can be improved, and as a result, a more accurate pulse wave can be detected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a pulse wave detection device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a structure of a piezoelectric sensor used in the pulse wave detecting device.

FIG. 3 is a waveform chart showing a waveform state in each part of the pulse wave detection device.

FIG. 4 is an explanatory view showing a state where the pulse wave detection device is incorporated in a timepiece and a pulse wave detection state.

FIG. 5 is an explanatory diagram showing a connection state between piezoelectric sensors according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a pulse wave detection device according to a second embodiment.

FIG. 7 is an explanatory diagram showing an arrangement relationship (a) and a detection principle (b) of both piezoelectric sensors in a third embodiment.

FIG. 8 is an output waveform diagram with respect to pulsation of both piezoelectric sensors according to the third embodiment.

FIG. 9 is an explanatory diagram illustrating a structure of a sensor according to a fourth embodiment.

FIG. 10 is an explanatory diagram showing another structure of the sensor according to the fourth embodiment.

FIG. 11 is an explanatory diagram showing still another structure of the sensor according to the fourth embodiment.

FIG. 12 is a configuration diagram of a pulse wave information acquisition unit and an output unit in a first modified example.

FIG. 13 is a configuration diagram of a conventional pulse wave detection device using a piezoelectric element.

[Explanation of symbols]

 2 radial artery 5 wrist 10 piezoelectric sensor 10a first piezoelectric sensor 10b second piezoelectric sensor 11 piezoelectric element 12 diaphragm 13 insulating pad 14 spacer 15 support plate 16 wiring 19 sensor 22a, 22b filter unit 24a, 24b amplifying unit 30 difference Moving unit 31 Differential amplification unit 40 Pulse wave information acquisition unit 41 Pulse counting unit 45 A / D conversion unit 46 Storage unit 50 Output unit 51 Display unit 55 I / F unit 60 Clock 61 Clock body 62 Belt 63 Clock display unit 64 Pulse Numeral display unit 65 Pulse display unit 70 Fixing members 71, 72 Fixing plate 73 Fixing column 80 Transmission members 81, 82 Transmission plate 83 Transmission column

Continuation of the front page F term (reference) 4C017 AA09 AA10 AB02 AC03 BB12 BC07 BC11 BD01 CC04 FF15

Claims (9)

[Claims] A first piezoelectric sensor disposed on an artery for detecting pressure fluctuations on a body surface caused by pulsation and body movement of the artery; and a body surface sensor disposed near the artery and avoiding the artery. A second piezoelectric sensor that detects pressure fluctuations of the above, a pulse wave information obtaining unit that obtains information about a pulse wave from a detection signal of the first piezoelectric sensor, and a detection signal of the second piezoelectric sensor, A pulse wave detection device, comprising: output means for outputting information on the pulse wave acquired by the pulse wave information acquisition means. 2. The second piezoelectric sensor is disposed at a position where the vicinity of an end of the second piezoelectric sensor is in contact with the artery. The second piezoelectric sensor detects pressure fluctuations on the body surface due to pulsation of the artery and body movement. The pulse wave detection device according to claim 1, wherein one of the body movements is detected in a phase opposite to a detection signal from the first piezoelectric sensor. 3. The detection signal of the first piezoelectric sensor and the detection signal of the second piezoelectric sensor with respect to the body movement are connected on the same polarity side, so that the first piezoelectric sensor and the first piezoelectric sensor are connected to each other. The said 2nd piezoelectric sensor is connected in series, The said pulse wave information acquisition means acquires the information regarding a pulse wave from the output signal of both the piezoelectric sensors connected in series, The Claims 1 or 2 characterized by the above-mentioned. Item 3. A pulse wave detection device according to item 2. 4. A first piezoelectric sensor for detecting a pressure fluctuation, a second piezoelectric sensor disposed above the first piezoelectric sensor and detecting a pressure fluctuation, and a pressure fluctuation on a body surface due to arterial pulsation. Pulsation transmission means for transmitting the pressure change to the first piezoelectric sensor; and body movement transmission for contacting the body surface at a position avoiding the artery and transmitting pressure fluctuation of the body surface due to the body movement to the first piezoelectric sensor. A body movement transmitting member that transmits the pressure fluctuation of the transmission plate to a surface of the second piezoelectric sensor that detects the pressure fluctuation; a detection signal of the first piezoelectric sensor; A pulse comprising: a pulse wave information acquiring unit that acquires information about a pulse wave from a detection signal from a sensor; and an output unit that outputs information about a pulse wave acquired by the pulse wave information acquiring unit. Wave detector. 5. A transmission mechanism for transmitting a force received by a surface of the second piezoelectric sensor on which pressure fluctuation is not detected to a surface of the first piezoelectric sensor on which pressure fluctuation is not detected. The pulse wave detection device according to claim 4, wherein 6. The body movement transmitting plate is provided with a slit along the artery, and the slit or a flexible member disposed in the slit is used as the pulse wave transmitting means. The pulse wave detecting device according to claim 4 or 5, wherein 7. The pulse wave information obtaining means obtains a pulse rate as information related to a pulse wave, and the output means outputs the pulse rate obtained by the pulse wave information obtaining means. The pulse wave detection device according to any one of claims 1 to 6. 8. The pulse wave information acquisition unit includes a storage unit that stores the pulse wave signal, acquires the pulse wave signal for a predetermined time as information related to a pulse wave, and stores the information in the storage unit. The output means outputs the pulse wave signal stored in the storage means.
The pulse wave detection device according to claim 1. 9. A pulse wave information acquiring unit acquires a pulse rate or a pulse wave waveform as information related to a pulse wave, and the output unit acquires a pulse rate acquired by the pulse wave information acquiring unit. Or outputting a pulse waveform to the display means.
The pulse wave detection device according to claim 1.