JP2009100934A - Pulse wave measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse wave measuring apparatus capable of highly accurately measuring the pulse wave information of a living body in the configuration of not enlarging a pulse wave sensor. <P>SOLUTION: A first storage means 3 stores and outputs detection signals from a pulse wave sensor 2. A first filter 5 extracts the pulse wave signals of the frequency band of the pulse waves of the living body from the detection signals outputted from the first storage means 3, and a second filter 6 extracts noise signals from the detection signals outputted from the first storage means. A first operation means 7 calculates the signal strength of the pulse wave signals, and a second operation means 8 calculates the signal strength of the noise signals. A processing means 9 obtains the relative signals of pulse wave strength signals and noise strength signals. A prescribed threshold is stored in a second storage means 11, the prescribed threshold and the relative signals are compared in a first comparison means 10, and measurement sensitivity display linked with a compared result is displayed at a measurement state display part 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pulsation measuring device that measures a pulsation of a living body with a pulsation sensor attached to a living body, and more particularly to a pulsation measuring device that can measure a pulsation of a living body with high accuracy.

    Various biological information such as pulse rate, stress, blood vessel age, apnea state, etc. can be obtained from the biological pulse information. In order to measure the pulse information of this living body, various proposals have been made in which a pulse wave sensor equipped with a photoelectric light emitting element and a light receiving element is mounted on a living body, and the pulse wave sensor is used to acquire the pulse information of the living body. (Patent Document 1, Patent Document 2, Patent Document 3, etc.). When acquiring the pulsation state of the living body by the pulsation sensor, if the pulsation sensor is not correctly attached to the measurement target part of the living body to which the pulsation sensor is attached, the measurement sensitivity of the pulsation sensor is reduced, It becomes difficult to measure the pulse information of a living body with high accuracy.

  Therefore, as a conventional technique, for example, a pulsation sensor provided with a large number of light emitting elements and light receiving elements is used, and this pulsation sensor is attached to the wrist of a living body as a measurement target, and the large number of light emitting elements and light receiving elements. Among them, there is one that acquires pulse information by a signal from an element with high measurement sensitivity (Patent Document 4).

(For example, refer to Patent Document 1).
JP 2003-339678 A JP 2004-016279 A JP 2004-202190 A Japanese Patent Laid-Open No. 11-131474

  However, in the above-described conventional technology, since a large number of light emitting elements and light receiving elements are used for the pulse group sensor, it is difficult to reduce the size of the pulse group sensor. There is also a problem of high costs.

  Therefore, the present invention provides a pulse group measurement device that can measure the pulse group information of a living body with high accuracy with the configuration of a small pulse group sensor.

  In order to solve the above-described problem, in a pulsation measuring device that includes a pulsation sensor that is attached to a part of a living body and detects a pulsation of a living body, and that measures a pulsation from a pulsation signal from the pulsation sensor A first storage means for storing and outputting a detection signal from the pulse sensor, and a pulse having a first frequency band substantially corresponding to the frequency band of the biological pulse from the detection signal output from the first storage means A first filter for extracting a signal; a second filter for attenuating the detection signal in the first frequency band from the detection signal output from the first storage means; and extracting a noise signal from the detection signal; and the pulse signal First calculation means for calculating the signal strength of the second signal, second calculation means for calculating the signal strength of the noise signal, pulse strength signal calculated by the first calculation means, and noise intensity calculated by the first calculation means Find the signal relative to the signal Processing means; second storage means in which a predetermined threshold value is stored; first comparison means for comparing the predetermined threshold value in the second storage means with a relative signal from the processing means; and the first comparison means. And a measurement state display unit for displaying measurement sensitivity linked to the comparison result.

    It is possible to measure the pulse information of the living body with high accuracy by adjusting the mounting position of the pulse group sensor mounted on the subject's fingertip etc. to the correct position while the subject visually checks the display information on the measurement state display unit. It becomes possible. Since the pulse wave sensor does not require a plurality of light receiving elements and light emitting elements, it is possible to measure the pulse wave information of a living body with high accuracy with a small pulse wave sensor configuration.

  Next, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a system block diagram of the pulse group measurement device of the present invention. The pulse measuring device 1 includes a first storage unit 3, a timer 4, a first filter 5, a second filter 6, a first calculation unit 7, a second calculation unit 8, a processing unit 9, a first comparison unit 10, and a second comparison unit. A storage unit 11, a third storage unit 12, a second comparison unit 13, a fourth storage unit 14, and a measurement state display unit 20 are provided. The measurement state display unit 20 includes a measurement preparation display unit 21, a measurement sensitivity display unit 22, and a measurement error display unit 23.

  The pulse group sensor 2 includes a light emitting element and a light receiving element, is attached to a fingertip that is a part of a living body, and outputs a pulse group signal. The light emitting element emits light, and the light reflected by the blood vessel of the fingertip is received by the light receiving element. The light receiving element outputs a detection signal having a higher frequency as the amount of received light increases. At this time, if the pulse sensor 2 is not correctly attached to the fingertip, the measurement sensitivity of the pulse sensor 2 is reduced, and it is difficult to measure biological pulse information with high accuracy.

  The first storage means 3 stores a detection signal from the pulse sensor 2 and outputs a detection signal having a fixed number of data every time a predetermined time counted by the timer 4 elapses. As shown in FIG. 2, the first storage means 3 samples the detection signal from the pulse group sensor 2 every sampling period Ts [s], stores and outputs N detection signals (in FIG. 2). (1)). Thereafter, the first storage means 3 samples a new τ / Ts detection signals in the timer 4 until the time τ [s] is counted, and outputs the latest N detection signals (FIG. 2). (2)). After that, the first storage means 3 newly samples τ / Ts detection signals at the timer 4 until the time τ [s] is counted, and outputs the latest N detection signals (FIG. 2). (3)). In this way, the first storage means 3 sequentially outputs the latest N detection signals obtained by adding the latest τ / Ts detection signals to the already stored detection signals. The N detection signals include a noise signal in addition to a pulse signal indicating the strength of blood flow in a living body. If the pulsation sensor 2 is not correctly worn on the fingertip of the living body, the detection signal contains a lot of noise signals, and it becomes difficult for the pulsation measuring apparatus 1 to measure the pulsation information of the living body with high accuracy.

  The N detection signals are separated into a pulse signal and a noise signal using the first filter 5 and the second filter 6. FIG. 3 shows the filtering characteristics of the first filter and the second filter. The first filter 5 is a so-called bandpass filter (hereinafter referred to as “BPF”) that extracts a signal of a predetermined frequency band, and extracts a pulse signal from the detection signal. The biological pulse group fluctuates in the frequency band of the biological pulse rate. When not exercising vigorously, the pulse rate of the living body is about 20 to 120 per minute. Therefore, the set frequency band (first frequency band) of the first filter is 0.5 Hz to 2.5 Hz, and the pulse signal is extracted by the first filter.

  The second filter is a so-called band elimination filter (hereinafter referred to as “BEF”) that attenuates a signal in a predetermined frequency band and extracts a signal outside the predetermined frequency band, and extracts a noise signal from the detection signal. . In order to extract a noise signal other than the pulse signal from the detection signal, the second filter attenuates the signal in the same frequency band as the set frequency band (first frequency band) of the first filter from the detection signal, and other than the pulse signal A noise signal that is a signal of (2) is extracted from the detection signal. Note that the denominator of the transfer function of the first filter and the numerator of the transfer function of the first filter, and the numerator of the transfer function of the first filter and the denominator of the transfer function of the first filter both have the same order, as shown in FIG. As described above, the filtering characteristics are symmetrical.

  The pulse signal strength that is the signal strength of the pulse signal is calculated by the first calculation means, and the noise strength signal that is the signal strength of the noise signal is calculated by the second calculation means. In the embodiment of the present invention, N pulse signals and noise signals are integrated, the integrated value is divided by time N × Ts [s], the square root of the divided value is obtained, and the value is used as the pulse signal. Strength and noise signal strength.

  Next, a relative signal between the pulse signal strength and the noise signal strength is obtained by the processing means. In the embodiment of the present invention, the signal-to-noise ratio between the pulse signal intensity and the noise signal intensity is a relative signal. The S / N ratio is shown below when the pulse signal strength is Ms and the noise signal strength is Mn.

  As the pulse sensor 2 is correctly attached to the fingertip, the noise signal is reduced with respect to the pulse signal, and the pulse information of the living body can be measured with high accuracy. Therefore, it can be said that the pulse signal information of the living body can be measured with higher accuracy as the noise signal is smaller than the pulse signal, that is, as the SN ratio is larger. Therefore, the S / N ratio that makes it difficult to measure biological pulse information is the first threshold (25%), and the S / N ratio that makes it possible to measure biological pulse information with a certain degree of accuracy is the second threshold ( 50%), the SN ratio that can measure the biological pulse information with high accuracy is set as the third threshold (75%).

  The second storage means 11 stores a first threshold value, a second threshold value, and a third threshold value. The first comparison unit 10 compares the SN ratio output from the processing unit 9 with the first threshold value, the second threshold value, and the third threshold value stored in the second storage unit 11. As a result of the first comparison means 10 comparing the SN ratio with each threshold, if the SN ratio does not exceed the first threshold, a first comparison result signal is output, and if the SN ratio is not less than the first threshold and not more than the second threshold, A second comparison result signal is output. If the SN ratio is not less than the second threshold and not more than the third threshold, a third comparison result signal is output. If the SN ratio exceeds the third threshold, a fourth comparison result signal is output. .

  The first comparison result signal indicates that it is impossible to measure biological pulse information. The second comparison result signal can measure biological pulse information, but it is difficult to measure biological pulse information with high accuracy. The third comparison result signal indicates that it is possible to measure biological pulse information with a certain degree of accuracy. The fourth comparison result signal indicates that the pulse information of the living body can be measured with high accuracy.

  A case where each comparison result signal is notified from the first comparison unit to the measurement state display unit 20 will be described with reference to FIG. FIG. 4 shows the display unit 30 of the pulse group measurement device 1. The display unit 30 includes a pulse group display unit 31 that displays the pulse series time-series data 32 and a measurement state display unit 20 that indicates the measurement state of the pulse group sensor 2.

  When the measurement of the pulse group is started, the measurement preparation display unit 21 of the measurement state display unit 20 is turned on to display that it is in the measurement preparation state. The measurement preparation display unit 21 is a blue LED. When the measurement preparation display unit 21 is in a measurement preparation state, the blue LED is lit. When the second comparison result signal indicating that measurement of the pulse information of the living body is possible is output from the first comparison unit 10, the measurement preparation display unit 21 is turned off.

  Further, when the second comparison result signal indicating that the pulse information of the living body can be measured is output from the first comparison unit 10, the measurement sensitivity display unit 22 starts blinking. The measurement sensitivity display unit 22 is a green LED, changes the blinking state according to the comparison result signal from the first comparison unit, and displays the detection state of the pulse group sensor 2. The measurement sensitivity display unit 22 repeats blinking at a cycle of 1 second, and changes the time from turning on to turning off, that is, the lighting duty according to the comparison result signal.

  For example, when the first comparison result signal is output from the first comparison means 10, the lighting duty becomes 25%, and the measurement sensitivity display unit 22 repeats turning on for 0.25 seconds and turning off for 0.75 seconds. When the second comparison result signal is output from the first comparison means 10, the lighting duty becomes 50%, and the measurement sensitivity display unit 22 repeats lighting for 0.5 seconds and turning off for 0.5 seconds. When the third comparison result signal is output from the first comparison means 10, the lighting duty becomes 75%, and the measurement sensitivity display unit 22 repeats turning on for 0.75 seconds and turning off for 0.25 seconds. When the fourth comparison result signal is output from the first comparison means 10, the lighting duty is 100%, and the measurement sensitivity display unit 22 remains lit.

  The subject with pulse information can adjust the pulse group sensor 2 attached to the fingertip of the subject to the correct position while viewing the measurement sensitivity display unit 22. For example, when the lighting time of the measurement sensitivity display unit 22 is short, the pulsation sensor 2 attached to the fingertip is shifted little by little so that the lighting time becomes long, and the lighting state remains at a position where the lighting remains on. A pulse group sensor 2 can be arranged. As a result, the noise signal is reduced, and the pulse information can be measured with high accuracy.

  If a predetermined measurement sensitivity cannot be obtained even after a certain time has elapsed, the measurement error display unit 23 is turned on. When a first comparison result signal indicating that it is impossible to measure biological pulse information is output from the first comparison means 10, the number of times of notification of the first comparison result signal is stored in the third storage means 12. The On the other hand, the fourth storage means 14 stores a predetermined number of setting errors. The second comparison unit 13 compares the number of notifications of the first comparison result signal stored in the third storage unit 12 with the set number of times stored in the fourth storage unit 14, and the number of notifications of the first comparison signal is set. When the number of errors is exceeded, an error signal is output.

  The measurement error display unit 23 starts lighting when an error signal is notified from the second comparison unit. The measurement error display unit 23 is a red LED, and when a measurement error occurs, error information is transmitted to the subject with red light.

  Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment only in the measurement state display unit 20, and the other parts are the same. Therefore, only the measurement display unit 20 will be described, and description of the other parts will be omitted. As shown in FIG. 5, the measurement sensitivity display unit 22 and the measurement error display unit 23 of the measurement state display unit 20 of the second embodiment are so-called LED indicators in which a plurality of LEDs are arranged on a straight line. This LED indicator can be lit in green and red.

  When the first comparison result signal is output from the first comparison means 10, the lighting duty of the LED indicator becomes 25%, the LED indicator functions as the measurement sensitivity display unit 22, and the LED indicator turns green until “25% display”. Light. When the second comparison result signal is output from the first comparison means 10, the lighting duty of the LED indicator becomes 50%, the LED indicator functions as the measurement sensitivity display unit 22, and the LED indicator turns green until “50% display”. Light. When the third comparison result signal is output from the first comparison means 10, the lighting duty of the LED indicator becomes 75%, the LED indicator functions as the measurement sensitivity display unit 22, and the LED indicator turns green until "75% display". Light. When the fourth comparison result signal is output from the first comparison means 10, the lighting duty of the LED indicator is 100%, the LED indicator functions as the measurement sensitivity display unit 22, and the LED indicator reaches “100% display”. That is, all the LEDs are lit in green.

  The subject with pulse information can adjust the pulse group sensor 2 attached to the fingertip of the subject to the correct position while viewing the measurement sensitivity display unit 22. For example, when all the LED indicators functioning as the measurement sensitivity display unit 22 are not lit in green, the pulse sensor 2 attached to the fingertip is gradually shifted so that the number of LEDs lit in green increases. Thus, the pulse group sensor 2 can be arranged at a position where more LEDs light up in green. As a result, the noise signal is reduced, and the pulse information can be measured with high accuracy.

  When an error signal is notified from the second comparing means, the LED indicator functions as the measurement error display unit 23, all the LEDs of the LED indicator are lit red, and the error information is transmitted to the subject by red light.

  In this way, by using the pulse wave measuring device 1 configured to display the measurement state of the pulse wave sensor 2 attached to the fingertip of the subject on the measurement state display unit 22, the pulse wave can be measured at a correct position. The mounting position of the group sensor 2 can be adjusted, and the pulse group information can be measured with high accuracy. Since a large number of light emitting elements and light receiving elements are not required as in the prior art, a small pulse sensor 2 is obtained and the cost is not increased.

It is a block diagram of a pulse group measuring device in an embodiment of the present invention. It is a figure explaining the detection signal memorize | stored and output by the 1st memory | storage means in embodiment of this invention. It is a figure explaining the filtering characteristic of the 1st filter and 2nd filter in the embodiment of the present invention. It is a figure which shows the structure of the display part in the 1st Embodiment of this invention. It is a figure which shows the structure of the display part in the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulse group measuring apparatus 2 Pulse group sensor 3 1st memory | storage means 5 1st filter 6 2nd filter 7 1st calculating means 8 2nd calculating means 9 Processing means 10 1st comparison means 11 2nd storage means 12 3rd storage means 20 Measurement state display unit 21 Measurement preparation display unit 22 Measurement sensitivity display 23 Measurement error display unit

Claims (6)

In a pulsation measuring device that is attached to a part of a living body and includes a pulsation sensor that detects a pulsation of a living body,
First storage means for storing and outputting a detection signal from the pulse sensor;
A first filter that extracts a pulse signal of a first frequency band substantially corresponding to the frequency band of a biological pulse wave from the detection signal output from the first storage means;
A second filter for attenuating the detection signal in the first frequency band from the detection signal output from the first storage means and extracting a noise signal from the detection signal;
First calculating means for calculating the signal strength of the pulse signal;
Second computing means for calculating the signal strength of the noise signal;
Processing means for obtaining a relative signal between the pulse intensity signal calculated by the first calculation means and the noise intensity signal calculated by the first calculation means;
Second storage means in which a predetermined threshold value is stored;
First comparison means for comparing the predetermined threshold value of the second storage means with a relative signal from the processing means;
A pulse group measurement measure, comprising: a measurement state display unit for displaying a measurement sensitivity linked to a comparison result of the first comparison unit.   2. The pulse group measurement device according to claim 1, wherein the relative signal obtained by the processing means is an SN ratio of the first signal intensity signal to the second signal intensity signal. In the pulse wave measuring device according to claim 2,
The second storage means stores a first threshold value and a second threshold value larger than the first threshold value,
The first comparison unit compares the SN ratio with the first threshold value and the second threshold value, and outputs a first comparison result signal when the SN ratio does not exceed the first threshold value. When the ratio is greater than or equal to the first threshold and less than or equal to the second threshold, a second comparison result signal is output.
The measurement state display unit is configured to display a measurement preparation display until the second comparison result signal is notified from the first comparison unit, and after the second comparison result signal is notified from the comparison unit. Comprises a measurement sensitivity display unit for displaying a measurement sensitivity linked to at least one of the first comparison result signal, the second comparison result signal, and the third comparison result signal. measuring device. In the pulse wave measuring device according to claim 2,
The second storage means stores a first threshold, a second threshold greater than the first threshold, and a third threshold greater than the second threshold;
The first comparison means compares the SN ratio with the first threshold value, the second threshold value, and the third threshold value. When the SN ratio does not exceed the first threshold value, the first comparison result signal is output. And outputs a second comparison result signal when the SN ratio is not less than the first threshold value and not more than the second threshold value, and outputs a third comparison result signal when the SN ratio is not less than the second threshold value and not more than the third threshold value. When the SN ratio exceeds the third threshold value, a fourth comparison result signal is output,
The measurement state display unit is configured to display a measurement preparation display until the second comparison result signal is notified from the comparison unit, and after the second comparison result signal is notified from the comparison unit, A measurement sensitivity display unit that displays a measurement sensitivity linked to at least one of the first comparison result signal, the second comparison result signal, the third comparison result signal, and the fourth comparison result signal. Characteristic pulse measuring device. The pulse group measurement device according to claim 3, further comprising third storage means for storing the number of notifications of the first comparison result signal output from the first comparison means,
The measurement state display unit includes a measurement error display unit that displays a measurement error when the first comparison result signal is stored a predetermined number of times or more in the third storage unit. apparatus. The pulse wave measuring device according to claim 5 is:
A fourth storage means for storing the number of setting errors;
A second comparison means for comparing the number of notifications of the first comparison result signal stored in the third storage means with the number of setting errors stored in the fourth storage means;
The second comparison means outputs an error signal when the number of notifications of the first comparison result signal exceeds the set error number,
The pulse error measurement device, wherein the measurement error display unit displays an error when an error signal is notified from the second comparison means.

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