JP2001008911A - Pulse wave detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse wave detector which can detect pulse wave with low consumption electricity and can extend a using time. SOLUTION: 10 MHz frequency of an ultrasonic wave f0 which is generated from a transmitter is sent from a surface of a body to an artery and a reflected wave f1 whose frequency is modulated by Doppler effect of blood which flows in the artery is received by a receiver. The received wave is detected with FM then pulse wave information is extracted and the pulse is calculated and shown. A pulsation detecting part outputs a pulse wave P at a peak of the pulse wave. The driving control part stops a transmission of the ultrasonic wave from the pulse P after a fixed time t1. A time t4 from the pulse P to a next (peak of) pulse is expected from a driving control part and the ultrasonic wave is sent from the transmitter once more prior to a time t3 from the time t4 including a changing time, i.e., a point of time which passes a fixed time t2 from a stop of transmission of ultrasonic wave (the time t1+t2 from the pulse wave P).

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 by transmitting and receiving an ultrasonic wave to and from an artery.

[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 and obtaining a pulse rate, a piezo-type piezoelectric element is arranged on an artery as a sensor, and a pulse is detected from a pressure change of the epidermis (a displacement of the epidermis due to pressure) due to a pressure change inside the artery. There are those that detect the pulse rate and those that detect the pulse rate using ultrasonic waves. As a pulse wave detecting device using an ultrasonic wave, there is a device using a Doppler effect due to a blood flow, and it is proposed in, for example, JP-A-1-214335 and US Pat. No. 4,086,916.

FIG. 17 shows how the frequency of an ultrasonic wave changes due to such a Doppler effect. Now
When an ultrasonic wave having a frequency f0 as shown in FIG. 17A is transmitted from the body surface toward an artery, the transmitted ultrasonic wave is reflected by blood flowing through the artery. When this reflected wave is received by the receiving element, a change in the frequency of the reflected wave can be detected. That is, assuming that the frequency of the received wave is f1, FIG.
As shown in FIG. 7 (b), during the systole of the heart, the speed of the blood flow flowing through the artery is high, so that the frequency of the reflected wave becomes higher due to the Doppler effect (portion A). Since the blood flow velocity is low, the frequency is lower than that of the part A (part B). In this way, the ultrasonic wave is applied to the blood flow in the artery whose flow velocity changes according to the heartbeat, and the pulse wave is detected by detecting the change in the frequency, and further, the pulse rate is detected,
For example, the blood flow velocity can be detected.

[0004]

As described above, in a pulse wave detecting apparatus for detecting a pulse wave using the ultrasonic Doppler effect,
Since ultrasonic waves are used, there is a problem that power consumption is very large. Therefore, the conventional pulse wave detection device must be used in an environment such as a hospital or home where power can be sufficiently supplied, or when used in an environment other than such an environment, the pulse wave is detected only for a short period of time. There was a problem that can not be measured. Particularly, in the case of a pulse wave detection device having a portable size and weight, such as a pulse wave detection device incorporated in a wristwatch, the use time is further shortened because the capacity of the battery is limited. There is.

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 detecting device that can detect a pulse wave with low power consumption and can extend a use time.

[0006]

According to the pulse wave detecting device of the present invention, a transmitting means for transmitting an ultrasonic wave toward an artery and an ultrasonic wave transmitted from the transmitting means and reflected by blood flowing through the artery are received. Receiving means, a pulse wave information acquiring means for acquiring pulse wave information on a pulse wave from an ultrasonic wave received by the receiving means, and an output means for outputting pulse wave information acquired by the pulse wave information acquiring means. From the pulse wave information acquired by the pulse wave information acquiring means, a pulse estimating means for estimating the next pulse, and the ultrasonic wave is transmitted for a predetermined time including the pulse expected by the pulse estimating means. Intermittent drive control means for intermittently driving the transmission means. The pulse wave information acquisition unit has a frequency detection unit that detects a change in the frequency of the ultrasonic wave received by the reception unit or an amplitude detection unit that detects a change in the amplitude of the ultrasonic wave. The frequency detection unit or the amplitude detection unit Obtain pulse wave information from the detection signal.

As described above, the pulse wave information is acquired, the next pulse is predicted from the pulse wave information, and the ultrasonic wave is transmitted for a predetermined time including the predicted pulse, so that the power consumption is suppressed to the drive duty ratio. be able to. Then, since the pulse wave detection device can be a low power consumption device, it can be used for a long time on a daily basis by incorporating the pulse wave detection device into a watch, for example. In this case, a part or all of the oscillating means used in the timepiece can be shared as the drive control means of the present invention, whereby the configuration can be further simplified. In the pulse wave detection device according to the present invention, the pulse wave information acquisition unit includes a storage unit that stores the pulse wave information, and the output unit outputs the pulse wave information stored in the storage unit. It may be. That is, pulse information and detection information for a predetermined period of time are stored in the storage means and output to, for example, an external device such as a medical diagnosis device, so that it can be used for comprehensive medical diagnosis. Further, in the pulse wave detection device of the present invention, the pulse wave information obtaining means obtains a pulse rate from the detected signal as pulse wave information, and the output means calculates the pulse rate obtained by the pulse wave information obtaining means. It may be output. Thereby, the most common pulse can be confirmed on a daily basis. Further, the pulse wave detection device of the present invention further includes a display unit, wherein the pulse wave information obtaining unit obtains a pulse rate or a pulse wave waveform as information on a pulse wave from the detection signal, and the output unit outputs the pulse wave. The pulse rate or the pulse waveform acquired by the wave information acquiring means may be output to the display means. Accordingly, by displaying the pulse rate or the pulse wave waveform, the pulse rate and the pulse wave waveform can be easily confirmed even in daily life.

Further, in the present invention, the drive control means intermittently drives the transmitting means for a predetermined time including the pulse. By thus intermittently driving the transmitting means, power consumption can be further reduced. Further, the intermittent driving of the transmitting means and the receiving means may be intermittently driven. In this case, by adjusting the intermittent driving timing of both, it is possible to adjust the rise time of transmission and reception to an optimal state. Can be. For example, by starting the driving of the receiving unit with a delay of a predetermined time from the driving timing of the transmitting unit, the receiving unit may not receive the signal until the output of the ultrasonic wave is stabilized after starting the transmission. Can be. Further, in the pulse wave detection device of the present invention, the drive control means drives both the transmitting means and the receiving means intermittently and changes the driving time of the transmitting means and the driving time of the receiving means. By making the driving times of the transmitting means and the receiving means independently adjustable, for example, the driving time of the receiving means can be shortened, and stable ultrasonic waves can be reliably received. Further, by extending the driving time of the receiving means, all of the transmitted ultrasonic waves can be reliably received. Further, in the pulse wave detection device of the present invention, the drive control means changes a drive time for intermittent drive and a drive stop time. By making the drive time and the drive stop time adjustable, it is possible to achieve optimal drive while reducing power consumption. Further, in the pulse wave detection device of the present invention, the drive control means intermittently drives at a frequency that is at least twice the assumed maximum pulse rate. For example, at an assumed maximum pulse rate of 240 beats / min, at least one of the transmitting means and the receiving means is intermittently driven at a frequency of 8 Hz or more. As described above, the pulse wave is always intermittently driven at twice or more the frequency of the test wave, so that the pulse wave can always be stably detected. In this case, even if the assumed pulse rate is low (up to 100 beats / minute only at rest)
Intermittent driving is performed at the same frequency of 8 Hz. Further, in the pulse wave detection device of the present invention, the drive control means intermittently drives at a frequency that is at least twice the frequency of commercial power. That is, a commercial frequency of 50 Hz, a frequency of 120 H, which is twice or more of 60 Hz.
By performing intermittent driving at z, it is possible to reduce the influence of noise due to the commercial frequency. In this case, by setting the frequency of the intermittent driving to 128 Hz, the oscillation frequency of 32 KHz of the oscillator used in the timepiece can be divided and used, and a simple configuration can be obtained when the pulse wave detection device is arranged in the timepiece. It can be. Further, in the pulse wave detection device of the present invention, the drive control means intermittently drives at a frequency that is twice or more the frequency of the commercial power and at a frequency at which the duty ratio is the lowest.

In the pulse wave detecting apparatus according to the present invention, the pulse estimating means acquires a pulse rate or a pulse interval from the pulse wave information acquired by the pulse wave information acquiring means. The next pulse is predicted based on the pulse rate or the pulse interval. In this case, the pulse estimating means acquires a plurality of pulse rates or intervals of a plurality of beats from the pulse wave information acquired by the pulse wave information acquiring means, and calculates the pulse rate or the interval of the beats. The next pulse may be expected based on the change. A pulse candidate detecting unit that detects a pulse candidate having a possibility of a pulse and a detection timing thereof from the pulse wave information acquired by the pulse wave information acquiring unit; and a pulse candidate detected by the pulse candidate detecting unit. Pulse determining means for determining a pulse from the pulse based on a difference between the detection timing of the pulse and the pulse timing predicted by the pulse predicting means, wherein the pulse predicting means is determined by the pulse determining means. The pulse rate or the interval between the beats may be obtained based on the pulse.

The present invention further provides a pulse candidate for detecting a pulse candidate having a possibility of a pulse and a detection timing of the pulse from the pulse wave information acquired by the pulse wave information acquiring means. Detecting means, and a pulse determining means for determining a pulse from the pulse sign based on a difference between the detection timing of the pulse candidate detected by the pulse candidate detecting means and the pulse timing predicted by the pulse predicting means. The drive control unit provides a pulse wave detection device that stops driving the transmission unit when the pulse is determined by the pulse determination unit regardless of before the predetermined time has elapsed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the pulse wave detecting device according to the present invention will be described below in detail with reference to FIGS. (1) Overview of the present embodiment In the pulse wave detecting device of the present embodiment, an ultrasonic wave f0 having a frequency of 10 MHz is transmitted from the transmitter 11 toward the artery 2 from the body surface (transmitting means), and a reflection target (measurement target) The receiver 21 receives the reflected wave f1 frequency-modulated by the Doppler effect of the blood flow as an object (receiving means). A pulse wave is extracted by FM detection of the received wave, and the pulse is further counted (pulse wave information obtaining means) and displayed (output means). From this pulse wave information, the pulse detector 35 outputs a pulse wave P at the peak of the pulse wave. The drive control unit 52 determines a predetermined time t1 from the pulse wave P.
Later, transmission of the ultrasonic wave is stopped. Then, the drive control unit 52
Is the time t from the pulse P to the next pulse (peak point)
4 is predicted from the pulse rate, and a time t3 before the time t4 including the fluctuation time from the time t4, that is, a predetermined time t2 from the stop of the transmission of the ultrasonic wave (the time t1 + t from the pulse wave P)
2) When the time has elapsed, the ultrasonic wave is transmitted again from the transmitter 11. By controlling the drive so that the ultrasonic wave from the transmitter 11 is transmitted for a predetermined time (t1 + t3) before and after the expected pulse, power consumption can be reduced, and a small battery such as a clock can be used. It is possible to attach even a portable device having a small size and use it for a long time.

(2) Details of the present embodiment FIG. 1 shows a configuration of a pulse wave detecting device according to the first embodiment. As shown in FIG. 1, the pulse wave detection device includes a transmitter 11, a drive circuit 12, and a high-frequency oscillation circuit 13 for transmitting an ultrasonic wave toward the artery 2. In addition, the pulse wave detecting device is provided with a receiver 21 for receiving an ultrasonic wave reflected by blood flowing through an artery to obtain a pulse.
, A high-frequency amplifier circuit 31, an F / V conversion circuit 32, a detection circuit 33, a sample and hold circuit 34, a pulsation detection unit 35, a pulse rate calculation unit 36, and a display device 41.

Further, the pulse wave detecting device includes a drive control section 52 functioning as a pulse estimating means and a drive control means. The drive control unit 52 includes a timing unit (not shown), and includes a pulse signal P supplied from the beat detection unit 35,
From the pulse rate supplied from the pulse rate calculator 36, the next pulse is predicted, and the drive signal F0 that is turned on for a predetermined time before and after the next pulse is converted into a high-frequency oscillation circuit 13, a high-frequency amplifier circuit 31, and an F / V converter. The circuit 32 and the detection circuit 33 are supplied.

The high frequency oscillation circuit 13 has a frequency of 10 MHz.
And the drive signal F0 supplied from the drive control unit 52 is turned on (high-level signal).
The high frequency signal of 10 MHz generated during the period is output. The drive circuit 12 amplifies the high-frequency signal supplied from the high-frequency oscillation circuit 13 to output power, and supplies the amplified power to the transmitter 11 to transmit the ultrasonic wave f0 to the transmitter 1.
This is a circuit for transmitting from 1.

The ultrasonic wave f0 transmitted from the transmitter 11 is
Reflected by the blood flow of the artery 2 while undergoing frequency modulation,
The reflected wave f1 is received by the receiver 21 and supplied to the high-frequency amplifier circuit 31. The high-frequency amplifier circuit 31 is a circuit that amplifies the reflected wave f1 and supplies it to the F / V conversion circuit 32. The F / V conversion circuit 32 is a circuit that outputs a voltage according to a frequency value by using a change in a voltage gain according to a frequency value. The detection circuit 33 is a circuit that outputs a voltage (a voltage waveform that changes according to a pulse waveform) corresponding to the envelope by amplitude detection. The pulsation detector 35 supplies the voltage waveform supplied from the detection circuit to the pulse rate calculator 36 as it is, and detects a peak of the voltage waveform to output the pulse signal P. The pulse rate calculation unit 36 calculates the pulse rate N per minute from the voltage waveform detected by the detection circuit 33 and supplied via the pulse detection unit 35. Pulse rate calculator 36
The pulse rate N calculated in is supplied to the display device 41,
It is supplied to the drive control unit 52. The pulse rate calculator 36 also supplies a pulse waveform (voltage waveform) to the display device 41. The display device 41 includes a display unit and a drive unit, and digitally displays the supplied pulse wave waveform and pulse rate N.

Next, the operation of the present embodiment configured as described above will be described. First, the principle of detecting a pulse wave from the fact that the ultrasonic wave transmitted to the artery 2 is frequency-modulated by the Doppler effect of the blood flow velocity will be described.
The blood flowing through the artery 2 changes its blood flow speed depending on the systole (pulse) and the diastole of the heart. Therefore, the frequency of the transmitted ultrasonic wave changes due to the Doppler effect when reflected by the blood flow. The frequency f1 of the reflected wave in this case is f0 of the ultrasonic wave, v is the blood flow velocity, c is the sound velocity in the body,
When the incident angle of the ultrasonic wave with respect to the blood flow velocity is θ, it can be obtained from the following equation (1). f1 = f0 (1 + 2v × cos θ / c) (1) Then, the frequency of the ultrasonic wave is changed from f0 to f1 by reflection.
And the deviation df is given by the following equation (2). df = f1−f0 = f0 × 2v × cos θ / c (2) Therefore, for example, each value is c = 155 m / s and v = 0.3
Assuming that m / s and f0 = 9.5, the frequency deviation df is 3.
8 KHz. In the equation (2), since the blood flow velocity v varies depending on the pulse, the frequency deviation df varies in a range from about 2 kHz to 4 kHz. In the present embodiment, a pulse wave is detected by detecting the change of the frequency deviation df by a demodulation method of a frequency modulation wave.

FIG. 2 shows output waveforms at respective components of the pulse wave detecting device. In the drive control unit 52,
As shown in FIG. 2A, a driving signal F0 that is turned on for a predetermined time is determined from a pulse signal P supplied from the pulse detector 35 and a pulse rate N supplied from the pulse rate calculator 36, using a high-frequency oscillation circuit. 13, high frequency amplifier circuit 31, F / V conversion circuit 3
2, and to the detection circuit 33. High frequency oscillation circuit 13
Is a driving signal F0 supplied as shown in FIG.
While the is ON, a high-frequency signal f0 having a frequency of 10 MHz is generated and supplied to the drive circuit 12. In the drive circuit 12,
By amplifying the output power of the supplied high-frequency signal f0 and supplying the amplified power to the transmitter 11 composed of a piezoelectric element, the transmitter 1
From 1, an ultrasonic wave f0 similar to the high frequency f0 shown in FIG. 2B is transmitted toward the artery 2.

The transmitted ultrasonic wave f0 has a frequency-modulated (FM-modulated) reflected wave f1 due to the Doppler effect when reflected by blood flowing through the artery 2, as shown in FIG. 2 (c). It is received by the receiver 21. This reflected wave f
1 is supplied to the F / V conversion circuit 32 after being amplified by the high frequency amplifier 31. The F / V conversion circuit 32 converts the frequency change of the amplified reflected wave f1 into a voltage change, that is, an amplitude change, as shown in FIG. By detecting the change in the amplitude in the detection circuit 33, a pulse waveform whose voltage changes corresponding to the envelope is obtained as shown in FIG. This pulse wave waveform is supplied to the pulse detection unit 35. Further, the pulse wave waveform is further converted to a pulse rate calculation unit 36.
Is also supplied to the display device 41 via the. The pulsation detection unit 35 detects a peak corresponding to a pulsation from the supplied pulse waveform of FIG. 2E, as shown in FIG. 2F, and sends the pulse signal P to the drive control unit 52. Supply.

The pulse rate calculating section 36 generates a pulse wave when the comparison value exceeds a comparison value, for example, and sets the time interval of the pulse wave to a predetermined number of times (for example, three times, five times,
7 times, 10 times, etc.), and the average time T of each measurement time
, The pulse rate N for one minute is calculated according to the following equation (3). N = 60 / T (3) Note that the present invention is not limited to the case where the pulse rate is obtained from the average time T between pulses. For example, the number of pulses w generated within a predetermined time t (for example, 10 seconds) is detected, and The pulse rate N for one minute may be obtained by the following equation (4). N = w × (60 / t) (2) The pulse rate calculator 35 displays the obtained pulse rate N on the display device 4.
1 to the drive control unit 52.

In the display device 41, the supplied pulse rate N
Is digitally displayed on the liquid crystal display screen together with the pulse waveform. Further, the presence of a pulse is indicated by performing a green blinking display according to the supplied pulse signal. The user can visually recognize his or her pulse wave by seeing this green blinking. Note that a pulse sound may be output according to the supplied pulse signal so that the presence of a pulse can be recognized by hearing.

As shown in FIGS. 2A and 2F, when the pulse signal P corresponding to the pulsation is supplied from the pulsation detection unit 35, the drive control unit 52 sets the time t1 after the pulse signal P. The drive signal F0 is turned off (low level). Thus, the transmission of the ultrasonic wave f0 from the transmitter 11 is stopped.
Then, the drive control unit 52 predicts the time t4 from the pulse rate from the pulse rate N supplied from the pulse rate calculation unit 36.
From this time t4, the time immediately before the time t3 including the fluctuation time, that is, a predetermined time t2 (time t1 + t from the pulse wave P) after the drive signal F0 is turned off (the transmission of the ultrasonic wave is stopped)
2) The drive signal F0 is turned on again after the lapse of time. As a result, the ultrasonic wave f0 is transmitted again from the transmitter 11 a predetermined time t3 before the next pulse is generated. As described above, in the present embodiment, the ultrasonic wave from the transmitter 11 is transmitted for a predetermined time (t3 + α) + after t1 before and after the expected pulse, and the ultrasonic wave is transmitted during the time t2 between the pulses. By controlling the drive to stop, power consumption can be reduced, and even a small portable device such as a timepiece having a small battery capacity can be attached and used for a long time. Here, α is the error time between the predicted next pulse and the pulse signal P output based on the actual pulse.

FIG. 3 shows a state in which a pulse wave is detected by a pulse wave detecting device incorporated in a timepiece. This figure 3
As shown in (1), the pulse wave detection device (watch) 60 includes a watch main body 61 and a belt 62, and the sensor 19 is mounted inside the belt 62. The timepiece 60 is attached to the left (or right) wrist 2a with the timepiece main body 61 facing the back of the hand, like a general timepiece. At this time, as shown in FIG. 3B, 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. The sensor 19 includes a transmitter 11 and a receiver 21,
As shown in FIG. 3 (c), the belt 62 is arranged in a direction orthogonal to the length direction of the belt 62 along the radial artery 2, and the transmitter 11 is arranged on the hand side and the receiver 21 is arranged on the shoulder side. The positions of the transmitter 11 and the receiver 21 may be reversed.

The watch body 61 includes a drive circuit 12, a high-frequency oscillation circuit 13, a high-frequency amplifier circuit 31, an F / V conversion circuit 32, and a detection circuit 3 in addition to a drive unit such as a watch movement.
3, beat detection unit 35, pulse rate calculation unit 36, display device 4
1 and a drive control unit 52. Sensor 19
And the drive circuit 12 of the watch main body 61 and the high-frequency amplifier circuit 31
And are connected by wiring (not shown) incorporated in the belt 62. Display surface of clock main body 61 (dial)
Includes a clock display unit 63 on which time, date, day of the week, and the like are displayed as a clock, and a display device 41. The display device 41 has a pulse rate display section 64 on which the pulse rate N is displayed, and a pulse display section 65 which blinks green in accordance with each pulse. The blinking color of the pulse display section 65 may be changed according to the pulse rate. For example, yellow blinking below 69,
The pulse rate is between 70 and 90, blue blinking, between 91 and 110 green blinking, between 111 and 130 orange blinking, and 131 and above red blinking. 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, the ultrasonic wave f0 transmitted from the transmitter 11 is transmitted only before and after a pulse, and the transmission is stopped between pulses.
Power consumption can be suppressed to the drive duty ratio. Therefore, even a small portable device having a limited battery capacity, such as the timepiece shown in FIG. 3, can be used for a long time by reducing power consumption.

Next, a second embodiment will be described. The configuration of the pulse wave detection device according to the second embodiment is the same as the configuration of the first embodiment shown in FIG. 1 except that the functions, operations, and output signals of each unit are partially different. Will be described, and descriptions of the same portions will be omitted as appropriate. In the first embodiment, the ultrasonic wave of 10 MHz is continuously transmitted only for the time of t3 (+ α; error time from the expected time) + t1 after the pulse. However, in the second embodiment, the pulse During the time (t3 + α + t2) before and after, the ultrasonic waves are output intermittently at 64 Hz.

FIG. 4 shows waveforms at various points in the second embodiment. As shown in FIG. 4A, the drive control unit 52 uses the pulse signal P and the pulse rate N supplied from the pulse detection unit 35 and the pulse rate calculation unit 36 as in the first embodiment, as shown in FIG. The drive signal F0 is generated internally. 32K oscillated from a low frequency oscillation circuit (not shown)
Hz oscillation signal is divided by 1/500 to obtain an intermittent drive signal F1 having a frequency of 64 Hz as shown in FIG.
It is supplied to the high frequency oscillation circuit 13, the high frequency amplification circuit 31, and the like. Note that the drive control unit 52 may include a low-frequency oscillation circuit that outputs an oscillation signal of 32 KHz, and is used in a timepiece when the pulse wave detection device is incorporated in the timepiece as shown in FIG. A transmitter having a transmission frequency of 32 KHz may also be used.

When the intermittent drive signal F1 is supplied, the high-frequency oscillation circuit 13 intermittently supplies the high-frequency signal f0 of 10 MHz to the drive circuit 12, as shown in FIG. The drive circuit 12 amplifies the output power of the supplied high-frequency signal f0 and supplies the amplified power to the transmitter 11, so that the transmitter 11 outputs an ultrasonic wave similar to the high-frequency f0 shown in FIG. f0 is transmitted intermittently to the artery 2.

The transmitted ultrasonic wave f0 is frequency-modulated when reflected by the blood flowing through the artery 2, and is reflected by the reflected wave f1.
Is received by the receiver 21 as shown in FIG. After the reflected wave f1 is amplified by the high frequency amplifier 31, the frequency change is converted by the F / V conversion circuit 32 into an amplitude change due to a voltage as shown in FIG. By detecting the change in the amplitude in the detection circuit 33, a pulse waveform whose voltage changes corresponding to the envelope is obtained as shown in FIG. Since this pulse wave waveform is intermittent in correspondence with the intermittent drive signal F1, the detection circuit 33 performs a sample and hold process, as shown in FIG.
The continuous signal is supplied to the beat detection unit 35.

The pulsation detecting unit 35 and the pulse rate calculating unit 36
As in the first embodiment, the pulse signal P and the pulse rate N corresponding to the pulse are obtained from the pulse waveform supplied from the detection circuit 33.
Is supplied to the drive control unit 52. As in the first embodiment, the drive control unit 52 turns off the drive signal F0 after the time t1 from the pulse signal P and stops the output of the intermittent drive signal F1. Further, the drive control unit 52 calculates the times t4 and t2 from the pulse rate N, and calculates the time t1 +
After t2, the intermittent drive signal F1 is supplied to the high frequency oscillation circuit 13.

As described above, according to the second embodiment, not only the ultrasonic waves are transmitted only before and after the expected pulse, but also the ultrasonic waves are intermittently transmitted during this period, so that the power consumption can be further reduced. it can.

Next, a third embodiment will be described. In the first and second embodiments, by setting the frequency of the ultrasonic wave transmitted from the transmitter 11 to 10 MHz, the pulse wave is changed from the frequency change by paying attention to the change in the frequency of the reflected wave changing in the blood flow. This is to detect. On the other hand, in the third embodiment, a pulse wave is obtained by utilizing the attenuation of the ultrasonic wave due to the blood flow amount flowing through the artery.

First, the principle and outline of pulse wave detection according to the present embodiment will be described with reference to FIG. In the artery, when the blood flow changes due to the pulse wave, the transfer coefficient when the ultrasonic wave propagates changes. It is considered that this is because the blood flow and blood density of the artery change due to the pulse wave, and the attenuation rate of the ultrasonic wave changes. In the present embodiment, based on the above principle, the transmitter 11 transmits the ultrasonic waves shown in FIG. 5A toward the artery. The frequency f3 of the ultrasonic wave in this case
Is f3 = 32 KH, which is smaller than the frequency f0 = 10 MHz of the ultrasonic wave for frequency modulation by blood flow.
By setting z, the signal is transmitted to the receiver 21 while propagating in the artery 2. This ultrasonic wave is propagated while being attenuated by the pulse flow in the artery 2, and as shown in FIG. 5B, the ultrasonic wave (propagating wave) attenuated (arrow G portion) corresponding to the pulse is received by the receiver 2.
The pulse wave waveform (pulse wave information) H shown in FIG. 5C is obtained by performing amplitude detection of the ultrasonic wave received and received at 1.

In the present embodiment, a pulse wave is detected by detecting a change in the attenuation of the ultrasonic wave transmitted from the transmitter 11 based on such a principle. Then, similarly to the first embodiment and the second embodiment, according to the drive signal F0 or the intermittent drive signal F1 supplied from the drive control unit 52, the ultrasonic wave f0 is transmitted only before and after the pulse. According to the present embodiment, while the frequency change due to the Doppler effect is a small value of 2 to 4 KHz (range of several%) with respect to the transmission frequency of 10 MHz, the change amount of the attenuation rate is 10% of the output power.
As described above, in the present embodiment, it is possible to more accurately detect a change in the attenuation rate due to the pulse wave. Also,
Since there is no change in the blood flow rate (blood flow rate) itself even if there is body movement, it is difficult for the body movement to become noise with respect to the change in the amplitude of the ultrasonic wave. it can.

Next, a fourth embodiment of the present invention will be described. The configuration of the pulse wave detection device according to the fourth embodiment is the same as the configuration of the first embodiment shown in FIG. 1 except that the functions, operations, and output signals of each unit are partially different. And the like, and description of the same portions will be omitted as appropriate.

In the first embodiment, t3 (+
(α: error time from the prediction), an ultrasonic wave is generated, and among the peaks of the obtained pulse wave waveform, those exceeding a predetermined threshold are specified as the peaks corresponding to the pulsation. Then, after the beat is detected (pulse signal is generated), an ultrasonic wave is transmitted for a time t1. In the present embodiment, an ultrasonic wave is transmitted for a predetermined length before and after an expected pulse, and is stopped after a predetermined time irrespective of detection of an actual pulse. Then, among the peaks of the pulse wave waveform during the transmission of the ultrasonic wave, the peak that has exceeded the predetermined threshold value and that has occurred closest to the expected timing is specified as the one corresponding to the pulsation.

FIG. 6 is a flowchart showing the flow of the pulse wave detection processing according to the present embodiment. When the pulse wave detection process is started in the present embodiment, first,
As shown in FIG. 6, the drive control unit 52 controls the drive signal F
0 is turned on. When the drive signal F0 is on,
The high frequency signal f0 is supplied from the drive circuit 12, and the transmitter 1
1 transmits an ultrasonic wave f0 (step 1). Then, the reflected wave reflected on the blood of the artery is received by the receiver 21. A signal based on the reflected wave from the receiver 21 passes through a high-frequency amplifier circuit 31, an F / V conversion circuit 32, and a detection circuit 33, and is converted into a pulse wave waveform. And its timing are detected. The pulse waveform from the detection circuit 33 is output to a pulse rate calculator 36 via a pulse detector 35, and the pulse rate calculator 35 calculates the pulse rate N based on the peak detected from the pulse waveform. The calculated value is output to the drive control unit 52 (step 3).

In the above-described detection of the pulsation immediately after the start of driving, it is possible to detect a peak of a pulse waveform (voltage waveform) exceeding a predetermined threshold as a peak corresponding to the pulsation. it can. Alternatively, the pulsation may be detected by differentiating the voltage waveform output from the detection circuit 33 and determining the peak of the differentiated waveform that exceeds a predetermined threshold value as the pulsation. FIG. 7 illustrates a waveform output from the detection circuit 33 and a waveform obtained by differentiating the waveform.
(A) is a waveform output from the detection circuit 33, and (b) is a waveform obtained by differentiating the waveform of (a). As shown in FIG. 7, the pulse wave waveform is differentiated, so that the difference between the peak height due to the noise and the peak height due to the pulsation increases, so that the peak corresponding to the pulsation is obtained from the differentiated waveform. , It is possible to prevent noise from being erroneously detected.

After turning on the drive signal F0 for a predetermined time, the drive control section 52 turns off the drive signal F0 and stops the transmission of ultrasonic waves from the transmitter 11 (step 7). And
After the drive signal F0 is turned off (after step 7), the timing of the next pulse is predicted from the pulse rate N obtained from the pulse rate calculation unit 35 and the timing of the pulse obtained from the pulse detection unit 35 ( Step 11). FIG. 8 is an explanatory diagram illustrating the prediction of the timing of the next beat and the setting of the zone in the drive control unit 52. As shown in FIG. 8, in the present embodiment, the time interval between the two most recent (last) peaks P00 and P0 specified as a pulsation based on the pulse rate N in the pulse rate calculation unit 36. RR0,
The timing of the next pulse P1 is predicted on the assumption that the time interval t4 from the timing of the latest pulse P0 to the next pulse P1 of the pulse P0 is the same as the timing of the pulse P0. I do. That is, the timing of t4 after the timing of the beat P0 is predicted as the timing of the next beat. As described above, in the present embodiment, the next beat is predicted using the pulse interval RR of the two beats acquired before the previous beat, and the amount of calculation for predicting the next beat is small. And the required storage capacity can be reduced.

When the next pulsation is predicted, the drive control unit 52
A zone setting process is performed (step 13). In this example, in the zone setting process, a zone (drive zone Z) in which the drive signal F0 is on is determined. As shown in FIG. 8, the drive zone Z has a pulsation interval RR0 (= t) before and after the expected timing of the next pulse.
4) is set to be Y%.

FIG. 9 shows a state in which the pulse signal P is detected at the time of rest and relaxation, and the interval R between the pulse signal P and the preceding pulse signal P is detected.
9 is a table showing the results of calculating the rate of change of R, pulse rate N, and pulsation interval RR. FIG. 10 is a graph of the table of FIG. 9, wherein (a) represents a temporal change of the pulsation interval RR, (b) represents a temporal change of the pulse rate N, c) represents the rate of change of the pulsation interval RR. As shown in FIGS. 9 and 10,
At rest or relaxation, the interval between beats and pulse rate is approximately ± 10% of the interval between beats and pulse rate before.
% Range. That is, with respect to the timing after the same interval as the previous beat interval (expected timing of the next beat), the actual next beat is changed from 10% before to 10% after the beat interval. Motion has been detected. Accordingly, in the pulse wave detection at the time of rest and relaxation, the driving zone Z
Can be almost detected by setting each to 20% of the predetermined time t4. In addition, if it exceeds 20% or more, the detection accuracy can be further improved. However, if the ratio with respect to t4 is increased, power consumption is increased. Therefore, the ratio is preferably about 20% to 50%. Also,
Although not shown in these figures, the fluctuation of the pulse wave during exercise or tension is smaller than at rest / relaxation, so that the drive zone Z is set to 20% or less of t4, for example, 10%.
Even if it is set to about 15%, the pulsation can be detected almost accurately.

The length of the drive zone Z (the value of Y) is determined based on the pulse rate and the pulse interval at the start of the pulse wave detection processing, such as between steps 1 to 7, when the subject rests and relaxes. It may be determined by judging whether the user is nervous or exercising, or by input from the operator side. For example, the length of the drive zone Z may be set to 20% of t4 during rest and relaxation, and may be set to 10% of t4 during tension and exercise. As described above, by increasing or decreasing the drive zone Z according to the state of the subject, it is possible to reliably detect the pulse while further reducing the power consumption. Further, the length of the driving zone Z (the value of Y) may be increased during the period near the start of driving, and may be reduced according to the pulse rate and the pulse interval thereafter. As a result, it is possible to reduce erroneous detection shortly after the start of the measurement, and to set the driving zone Z in accordance with the actual pulse wave state of the subject, thereby suppressing power consumption.

After the zone setting process (step 1)
3), the drive control unit 52 sets (RR0) × (Y%) before the expected beat timing (at the start of the drive zone Z).
Then, the drive signal F0 is turned on and the ultrasonic wave f0
(Step 15), and (P)
RO) × (Y%) (at the end of driving zone Z)
The drive signal F0 is stopped (step 17). While the drive signal is on, the pulsation detection unit 35 detects a peak corresponding to the pulsation from the voltage waveform (pulse wave waveform) output from the detection circuit 33 (pulsation identification processing). In the pulsation identification process, when there is only one peak in the pulse wave waveform, this peak is determined to be a pulsation. If there are a plurality of peaks, the peak detected at the timing closest to the predicted pulsation timing among the peaks is determined to be the pulsation. Then, when the peak due to the pulse is determined from the pulse waveform, the generation timing of the peak corresponding to the pulse is read from the timing recorded corresponding to the pulse waveform, and is output to the drive control unit 52. Further, the pulse rate calculating section 36 calculates the pulse rate N from the peak of the pulse wave waveform. The pulse rate N is displayed on the display device 41 and output to the drive control unit 52.

After the drive signal F0 is turned off (step 17)
After that, the drive control unit 52 outputs the pulse rate N from the pulse detection unit 35.
The presence or absence of the timing input is monitored (step 21).
If the pulsation is not specified and there is no input from the pulsation detection unit 35 (Step 21; N), the process proceeds to Step 31 and a timeout process is performed (Step 31). As the time-out process, the peak corresponding to the pulsation is switched, for example, by switching to the continuous operation in which the drive signal F0 is continuously turned on, or by setting the value of the fluctuation rate Y to be longer and setting the output time of the drive signal F0 longer. A process of changing the setting so as to be easily detected, a process of displaying on the display device 41 that there is a possibility that the position of the sensor may be shifted or a process of generating a beep to alert the wearer, and In addition, a process is performed in which the pulse rate and the pulse interval are set to the same values as the previous time, assuming that a pulse is detected at the predicted beat timing.

When the pulsation timing is input from the pulsation detecting section 35 in step 21 (step 21;
Y), and after the timeout process (after step 31)
The drive control unit 52 checks whether or not there is an end command (step 23). If there is no end command (step 23; N), the process returns to step 11 to calculate the new beat timing and pulse rate N. The timing of the next beat is predicted, and the same processing is repeated thereafter. When the end command is detected (step 23; Y), the pulse wave detection process ends. Thus, in the present embodiment, the predetermined time range (drive zone Z)
, The peaks of all the pulse waveforms are detected, and the peak at the timing closest to the expected pulsation is specified as the one corresponding to the pulsation, and the pulsation is detected.

Next, a fifth embodiment of the pulse wave detecting device according to the present invention will be described. The configuration of the pulse wave detection device according to the fifth embodiment is the same as the configuration of the fourth embodiment except that the functions, operations, and output signals of each unit are partially different. Will be described, and the description of the same portions will be omitted as appropriate.

In this embodiment, the driving zone Z is divided into a plurality of zones. That is, in the present embodiment, the drive zone Z includes the I-th zone (first zone) before the predicted beat timing, and includes the expected beat timing in the first zone. The following I
An I zone (second zone) is included. In the present embodiment, the drive zones are only these two zones. For the detected peak, it is determined which of the zones includes the timing, and for the peak detected in the I-th zone, the pulse is determined. Is determined, and the peak detected in the I-th zone is immediately identified as corresponding to the pulsation. In this way, different processing is performed depending on which of the zones includes the timing of the detected peak, and when the probability that the peak corresponds to the pulsation is high, the peak signal is immediately pulsated. , And the drive signal F0 is turned off in the drive zone Z.

FIG. 11 is a flowchart showing the flow of the pulse wave detection process according to the present embodiment, and is a diagram corresponding to FIG. 6 in the fourth embodiment. As shown in FIG. 11, in the pulse wave detection process according to the present embodiment,
As in the above-described fourth embodiment, first, continuous driving is performed to acquire the peak timing and the pulse rate N, and the timing of the next pulse is predicted from these (steps 1 to 11). Each of these operations is the same as in the fourth embodiment.

After predicting the timing of the next beat, a zone setting process is performed (step 13). FIG.
FIG. 4 is an explanatory diagram showing prediction of the timing of the next beat and setting of a zone in the present embodiment. In the present embodiment, in the zone setting process (step 13),
As shown in FIG. 12, the zone (drive zone Z) in which the drive signal F0 is on as in the fourth embodiment described above.
And the zone I and the zone II are determined. The I-th zone is set in the driving zone Z in a range where the time is before the predicted timing of the beat P1. The zone II is set so as to cover a range other than the zone I in the driving zone Z, includes the timing of the predicted pulsation P1, and is set to a time after the zone I. The range of the driving zone Z, the I-th zone and the I-th zone
The range of the I zone includes a pulse interval RR0 calculated based on the pulse rate N obtained from the pulse rate calculation unit 36, a drive zone Z start from the obtained pulse stored in the memory in advance,
A ratio (A, A) to the pulsation interval RR0 until the boundary between the zone I and the zone II and the end of the driving zone Z.
B, C).

When the driving zone Z determined by the zone setting processing is reached, the driving control section 52 sets the driving signal F0.
Is turned on (step 15). While the drive signal is on, the pulsation detection unit 35 detects a peak corresponding to the pulsation from the voltage waveform (pulse wave waveform) output from the detection circuit 33 (pulsation identification processing).

FIG. 13 is a flowchart showing the flow of the pulsation determination process by the pulsation detection unit 35 of the present embodiment. As shown in FIG. 13, in the pulsation determination process, the pulsation detection unit 35 detects a peak from a pulse wave waveform (step 151). Then, when a peak is detected (Step 151; Y), it is checked whether or not the timing of the acquired peak is in the I-th zone (Step 153). Since there is a possibility that a peak closer to the predicted timing may be detected later, the determination that the peak is a beat is suspended, and the data of the detection timing is stored in a memory (step 155). At this time, if the peak data has already been stored in the memory, the stored data is discarded because the peak detected later in the I-th zone is closer to the expected timing. Then, the new peak signal data is overwritten and stored. Then, the process returns to step 151, and the presence or absence of a peak is monitored again.

A peak is detected (step 151;
Y) If the peak timing is in the zone II (step 153; N), it is checked whether or not there is peak timing data (reserved data) which is reserved and stored in the memory (step 153). 157) If there is no pending data, this peak is more likely to be closer to the predicted timing than the peak detected later, so that the pulsation is determined based on this peak and the pulsation is determined. The movement timing is output to the control driving device 52 (step 159). When the reserved data is stored in the memory, the reserved data is detected in the I-th zone. Then, for each of the detected data and the hold data, the difference between the predicted beat timing and the predicted beat timing is compared, and a peak close to the predicted beat timing is determined as a beat and output to the drive control unit 52. (Step 161).

If no peak is detected in step 151 (step 151; N), it is checked whether or not the current time is within the driving zone (step 163).
63; Y), it is checked whether or not the pending data is stored in the memory (step 165). If data is stored in the memory, the pending data
It is the data of the peak detected most recently in the zone. Then, the peak of the reserved data is determined to correspond to the beat, and the timing of this peak is output to the drive control unit 52. If the peak has not been detected and the timeout has not occurred, the process returns to step 151 to continue monitoring whether or not a peak has been detected. After the peak corresponding to the beat is determined, and the timing of the determined peak is output to the drive control unit 52 (after step 159, step 161)
After that, and when the timeout occurs without detecting the peak (step 165; N), the pulsation determination processing is ended.

While the drive signal F0 is on, the drive control unit 52 monitors the presence or absence of the input of the peak timing corresponding to the pulsation from the pulsation detection unit 35 (step 1).
8). If the pulsation is not specified and there is no input from the pulsation detection unit 35 (Step 21; N), the driving zone Z
It is determined whether or not a time-out has occurred (step 30). If a time-out has occurred (step 30; Y), a time-out process is performed (step 31). If the time-out has not occurred (Step 30; N), the process returns to Step 18, and the input of the peak timing corresponding to the pulsation is monitored again.

When the timing of the peak corresponding to the pulsation is input, the drive control unit 52 stops outputting the control signal F0 (step 22), and if there is no end command by the input of the operator (step 23; N), the process returns to step 11, and the processing after the determination of the drive zone Z is repeated. If there is an end command (step 23; Y), the pulse wave detection processing is ended as it is.

As described above, in the present embodiment, the drive zone Z in the predetermined range before and after the predicted beat is set to the first zone whose time is before the predicted beat timing and the predicted beat. If the peak signal is not detected in the I-th zone but is detected for the first time in the II-th zone, the peak signal is determined as a pulse signal. Then, as soon as the pulse signal is determined, the driving circuit 52 is stopped and the output of the ultrasonic wave is stopped. Therefore, in the present embodiment, the pulse signal may be determined before the entire range of the driving zone Z has elapsed, and the output of the ultrasonic wave is stopped immediately after the determination of the pulse signal. In addition, power consumption for ultrasonic output can be effectively suppressed.

Next, a sixth embodiment of the present invention will be described. The configuration of the pulse wave detection device according to the sixth embodiment is the same as that of the above-described fifth embodiment except that the functions, operations, and output signals of each unit are partially different.
Only different parts such as functions will be described, and description of the same parts will be omitted.

FIG. 14 is an explanatory diagram showing the prediction of the timing of the next beat and the setting of the zone in the beat detector 35.

In the present embodiment, in the zone setting process (step 13), as shown in FIG. 14, the zone (drive zone Z) of the ON time of the drive signal F0 and the I-th zone , Zone II, and I
The II zone is determined. Zone I is drive zone Z
Is set in a range where the time is closer to the timing of the predicted beat P1. The zone II is a zone after the zone I in the driving zone Z and includes the predicted timing of the pulsation P1, and the zone III extends over a range excluding the zones I and II. Is set to In the present embodiment, the elapsed time in zone I and the elapsed time in zone III are set to be equal.

The range of the driving zone Z, and the ranges of the I-th zone and the II-th zone are stored in a memory in advance and a pulsation interval RR0 calculated based on the pulse rate N obtained from the pulse rate calculating section 36. The ratio can be determined from the ratio (Y%) of the driving zone Z to the acquired beat interval RR0 and the ratio (D%) of the zone II.

FIG. 15 is a flowchart showing the flow of the pulsation determination process of this embodiment. As shown in FIG. 15, in the pulsation determination process, the pulsation detection unit 35 detects a peak from the pulse waveform (step 251). Then, when a peak is detected (Step 251: Y), it is checked whether or not the timing of the acquired peak is the I-th zone (Step 253). When the vehicle is in zone I (step 253; Y), the determination of whether or not the peak corresponds to the pulsation is suspended because a peak closer to the predicted timing may be detected later. Then, the data of the detection timing is stored in a memory (step 255). If there is already reserved data at this time, the existing data is of the peak detected earlier in zone I. Among the peak signals detected in the I-th zone, since the later detected signal is close to the predicted timing, the stored data is discarded, and the data of the new peak signal is overwritten and stored. Then, the process returns to step 251.

After passing the zone I (step 251; Y
And step 253; N) When a peak signal is detected in zone II (261; Y), zone II is closer to the expected beat timing than the other zone I or III. Irrespective of the presence or absence of the data held in the memory, the peak detected in the zone II is determined to correspond to the pulsation, and is output to the data drive control unit 52 (step 263). The determination processing ends.

When a peak signal is detected in zone III (step 251; Y, 253; N, 2
61; N), it is checked whether or not the pending data is stored in the memory (step 265). If there is no pending data (step 265; N), the peak signal is detected for the first time in zone III and is closer to the predicted timing than the later detected peak signal.
This peak is determined as corresponding to the pulsation, output to the data drive control unit 52 (step 269), and the pulsation determination processing ends. If a peak signal is detected in the zone III and there is data already stored in the memory (step 265; Y), the data stored in the memory is the peak of the zone I. Then, for each of the timing of the peak of the zone I and the timing of the newly detected peak signal of the zone III, the deviation from the predicted timing is compared,
The peak close to the predicted timing is detected as corresponding to the beat, and this data is output to the drive control unit 52 (step 267), and the beat determination processing ends.

In step 251, if the drive zone Z has passed without a peak being detected (step 251; N) and a timeout has occurred (step 257; Y), it is checked whether or not there is any pending data. The data reserved at this time is the data of the peak detected in zone I. If there is pending data (step 259), this peak is determined to correspond to the pulsation, and this data is output to the drive control unit 52 (step 267), and the pulsation determination processing ends. When no peak is detected (Step 251; N), timeout occurs (Step 257; Y), and there is no pending data (Step 2).
58) N) is a case where the timeout has occurred without the peak being detected since the start of the beat determination process. At this time, the pulsation determination processing ends without outputting data to the drive control unit 52.

As described above, in the present embodiment, the drive zone Z within a predetermined range before and after the next predicted beat is divided into the I-th zone whose time is earlier than the predicted beat timing.
A zone II including a predicted beat and following the zone I, and a zone III following the zone II, and a peak is not detected in the zone I but is detected for the first time in the zone II Determines that the peak corresponds to a beat. Then, as soon as the pulsation is determined, the driving circuit 52 is stopped and the output of the ultrasonic wave is stopped. Therefore,
In the present embodiment, the pulsation may be determined before the entire range of the driving zone Z has elapsed, and the output of the ultrasonic wave is stopped immediately after the pulsation is determined. In addition, power consumption for ultrasonic output can be effectively suppressed.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the configuration of this embodiment, and other embodiments may be adopted and modified within the scope of the present invention. Is possible. For example, in the embodiment described above, both the transmission of the ultrasonic wave and the reception of the reflected wave (including the propagation wave) are intermittently driven by the intermittent drive signal F1, but in the present invention, only one of them is intermittently driven. Even when driven, power consumption can be reduced as compared with the conventional case.

The output timing of the high frequency f0 output by the intermittent drive by the high frequency oscillation circuit 13 and the processing timing of the reflected wave f1 in the high frequency amplification circuit 31 to the detection circuit 33 may be adjustable. By making the intermittent drive timing of the transmission side or the reception side adjustable in this way, the rise time of transmission and reception can be adjusted to an optimal state. For example, by starting the driving of the receiving side with a predetermined time delay from the driving timing of the transmitting side, the receiving side should not receive the signal until the output of the ultrasonic wave is stabilized after starting the transmission. Can be.

In the pulse wave detecting device, the driving time on the transmitting side and the driving time on the receiving side may be independently adjustable. For example, by shortening the driving time on the receiving side, stable ultrasonic waves can be reliably received. Conversely, by extending the driving time on the receiving side, all of the transmitted ultrasonic waves can be reliably received. Further, in the pulse wave detection device, the ratio between the drive time for intermittent drive and the drive stop time may be adjustable. By making the drive time and the drive stop time adjustable, it is possible to achieve optimal drive while reducing power consumption. The ratio of drive time and stop time is
It may be adjustable for both sender and receiver,
Only one of them may be adjustable.

In the second embodiment described above, the frequency F1 of the intermittent drive signal is set to F1 = 64 Hz. However, the intermittent drive signal may be driven at a frequency that is at least twice the assumed maximum pulse rate.
For example, the assumed maximum pulse rate may be 240 beats / minute, and the frequency of the intermittent drive signal may be F1 = 8 Hz or higher. When F1 = 8 Hz, the drive control unit 5
2 divides the frequency of the 32 KHz oscillation signal by 1/4000. Further, the intermittent drive signal may have a frequency F1 = 128 Hz. As described above, by setting the intermittent drive signal to a frequency that is twice or more the frequency of the commercial power, it is possible to reduce the influence of noise due to the commercial frequency. In this case, the drive control unit 52 outputs the oscillation signal 1/25 of 32 KHz.
Divide to zero. In the pulse wave detection device, the intermittent drive signal may be a frequency that is twice or more the frequency of the commercial power and that has the lowest duty ratio.

In the first embodiment described above, the intermittent drive signal F1 output from the drive control section 52 is supplied to the high-frequency oscillation circuit 13 as shown in FIG.
2 may be supplied. In this case, the high-frequency oscillation circuit 13 continuously supplies a high frequency of f0 = 10 MHz to the drive circuit 12, and the drive circuit 12 outputs the intermittent drive signal F
The signal is intermittently amplified according to 1 and supplied to the transmitter 11.

In each of the embodiments described above, the drive control unit 52 obtains the time t4 between the pulse and the next expected pulse using the pulse rate N supplied from the pulse rate calculation unit 36.
The time from the previous pulse signal supplied from the pulse detection unit 35 may be measured by the drive control unit 52, and this may be used as the expected time t4 between the next pulses.

In each of the above embodiments, the peak of the voltage waveform is detected by the pulsation detecting section 25 as pulse wave information obtaining means, and the pulse rate N is obtained by the pulse rate calculating section 36 based on the voltage waveform. Based on the pulse rate N, the drive control unit 52 determines a predetermined time t4 during which ultrasonic waves are transmitted from the transmitter 11. However, the predetermined time t4 for transmitting the ultrasonic wave from the transmitter 11 does not have to be determined based on the pulse wave information acquired by the pulse wave information acquiring means. For example, the time may be a time previously stored in the storage unit of the pulse wave detection device. In this case, the storage unit assumes 1000 msec (60 beats / sec) or
Even if only one predetermined time such as msec (70 beats / second) is stored, a plurality of values such as the above-mentioned values at rest and values at the time of tension and exercise are stored and operated. May be selectable. Further, what the operator inputs with a button or the like may be stored, and this value may be set as the predetermined time t4.

In the above embodiments, the predetermined time t4 is determined based on the pulse rate. However, the pulse interval is obtained from the pulse wave information, and the predetermined time t4 is determined based on the pulse interval. May be performed.

In each of the above-described embodiments, immediately after the driving of the pulse wave detecting device is started, the driving signal F
0 is continuously output to obtain the pulse rate, and thereafter, the mode is switched to the intermittent drive. However, the pulse rate is 60 beats / min (t4 = 1000).
msec) or 70 beats / min (t4 = 857 msec)
Assuming c), intermittent driving can be performed from the beginning. Alternatively, a change in the interval between a plurality of consecutive beats obtained at a predetermined time interval or a change in the pulse rate of the continuous pulse may be obtained, and the predetermined time t4 may be determined from any of these changes. For example, as shown in FIG. 16, when the pulse rate of the continuous pulse interval is reduced by approximately 7%, the next pulse interval is also expected to be in the range D before and after the previous value reduced by 7%. ,
The next pulse and the predetermined time t4 are predicted based on the beat interval. In this way, by predicting the next pulse taking into account changes in the pulse interval and pulse rate, even when the pulse changes due to the start and end of exercise, tension, etc., the next pulse can be obtained with high accuracy. Pulse can be predicted.

[0074]

According to the pulse wave detecting device of the present invention, the next pulse is predicted and the ultrasonic wave is transmitted for a predetermined time including the predicted next pulse. Can be detected, and the use time can be extended. Further, according to the pulse detection device of the present invention, since the ultrasonic waves are transmitted intermittently for a predetermined time including the expected next pulse, the power consumption can be further reduced.

[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 an output waveform in each component of the pulse wave detection device.

FIG. 3 is an explanatory diagram showing a state in which a pulse wave is detected by a pulse wave detecting device incorporated in a watch.

FIG. 4 is an explanatory diagram showing output waveforms of respective components according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating the principle and outline of pulse wave detection according to a third embodiment of the present invention.

FIG. 6 is a flowchart illustrating a flow of a process performed by a drive control unit in a pulse wave detection process according to each of the first to third embodiments of the present invention.

FIGS. 7A and 7B show a waveform output from the detection circuit and a waveform obtained by differentiating the waveform in the pulse wave detection process. FIG. 7A shows a waveform output from the detection circuit, and FIG. This is a waveform obtained by differentiating the waveform of a).

FIG. 8 is an explanatory diagram showing prediction of timing of a next beat and setting of a zone in the drive control unit.

FIG. 9 detects a pulse signal P at the time of rest / relaxation, an interval RR from the previous pulse signal P, a pulse rate N,
9 is a table showing the results of calculating the rate of change of the pulsation interval RR.

10 is a graph of the table of FIG. 9,
(A) represents the change over time of the pulsation interval RR, (b)
Represents the temporal change of the pulse rate N, and (c) represents the rate of change of the pulsation interval RR.

FIG. 11 is a flowchart illustrating a flow of a pulse wave detection process performed in a fourth embodiment of the present invention, and is a diagram corresponding to FIG. 6 in the first to third embodiments.

FIG. 12 is an explanatory diagram showing prediction of the timing of the next beat and setting of a zone in the drive control unit.

FIG. 13 is a flowchart illustrating a flow of a pulse signal determination process according to the embodiment.

FIG. 14 is an explanatory diagram showing prediction of a timing of a next beat and setting of a zone performed by a drive control unit in a fifth embodiment of the present invention.

FIG. 15 is a flowchart illustrating a flow of a pulse signal determination process according to the embodiment.

FIG. 16 shows a predetermined time t4 in another embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a method of determining the position of a target.

FIG. 17 is an explanatory diagram showing a state of a frequency change of an ultrasonic wave due to the Doppler effect.

[Explanation of symbols]

 2 Artery 11 Transmitter 12 Drive circuit 13 High-frequency oscillation circuit 19 Sensor 21 Receiver 31 High-frequency amplifier circuit 32 F / V conversion circuit 33 Detection circuit 35 Pulse detector 36 Pulse rate calculator 41 Display device 52 Drive controller 60 Clock 61 Clock body 62 Belt 63 Clock display 64 Pulse rate display 65 Pulse display

Continued on the front page (72) Inventor Chiaki Nakamura 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Inside Seiko Instruments Inc. (72) Inventor Kazumi Sakumoto 1-8-8 Nakase, Nakase-Mihama-ku, Chiba-shi (72) Inventor Masataka Shinogi 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. (72) Inventor Takashi Kamoto 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments F term (reference) 4C017 AA09 AA10 AB02 AC20 AC23 BB12 BC21 CC01 FF15 4C301 DD10 EE18

Claims (7)

[Claims] A transmitting means for transmitting an ultrasonic wave toward an artery; a receiving means for receiving an ultrasonic wave transmitted from the transmitting means and reflected by blood flowing through the artery; and an ultrasonic wave received by the receiving means. Pulse wave information acquisition means for acquiring pulse wave information relating to a pulse wave from a sound wave, output means for outputting pulse wave information acquired by the pulse wave information acquisition means, and pulse wave acquired by the pulse wave information acquisition means From the information,
Pulse predicting means for predicting the next pulse; and drive control means for driving the transmitting means so as to transmit the ultrasonic wave for a predetermined time including the pulse predicted by the pulse predicting means. Pulse wave detection device. 2. The apparatus according to claim 1, wherein said pulse wave information acquiring means has a frequency detecting means for detecting a frequency change of the ultrasonic wave received by said receiving means or an amplitude detecting means for detecting an amplitude change. The pulse wave detection device according to claim 1, wherein pulse wave information is obtained from a detection signal by the detection unit. 3. The pulse wave detection device according to claim 1, wherein the drive control means drives the transmission means intermittently for a predetermined time including the pulse. 4. The pulse estimating means acquires a pulse rate or a pulse interval from the pulse wave information acquired by the pulse wave information acquiring means, and obtains a next pulse rate or a pulse interval based on the pulse rate or the pulse interval. The pulse wave detection device according to any one of claims 1 to 3, wherein the pulse is predicted. 5. The pulse estimating means obtains a plurality of pulse rates or intervals of a plurality of beats from the pulse wave information acquired by the pulse wave information acquiring means, and obtains the pulse rate or the beats. The pulse wave detection device according to claim 4, wherein the next pulse is predicted based on a change in the interval. 6. A pulse candidate detecting means for detecting a pulse candidate having a possibility of a pulse and its detection timing from the pulse wave information acquired by the pulse wave information acquiring means, and a pulse candidate detected by the pulse candidate detecting means. Pulse determining means for determining a pulse from the pulse based on a difference between the detected pulse candidate timing and the pulse timing predicted by the pulse predicting means, wherein the pulse predicting means includes the pulse determining means. The pulse wave detection device according to claim 4 or 5, wherein the pulse rate or the interval between the beats is acquired based on the pulse determined in (5). 7. A pulse candidate detecting means for detecting a pulse candidate having a possibility of a pulse and a detection timing thereof from the pulse wave information acquired by the pulse wave information acquiring means, and a pulse candidate detected by the pulse candidate detecting means. Pulse determining means for determining a pulse from the pulse based on the difference between the detected pulse candidate timing and the pulse timing predicted by the pulse predicting means, wherein the drive control means comprises: 7. The pulse wave detecting apparatus according to claim 1, wherein when the pulse is determined by the following, the driving of the transmitting unit is stopped regardless of before the lapse of the predetermined time.