Patent Application
20170209054
Technical Field
The present invention relates to the field of medical measurement, and in particular, to a feedback photoplethysmography measuring device and a measuring method thereof.
Related Art
With rapid development of industry and commerce, people's working pressure is bigger and bigger, plus an imbalanced diet, the population of cardiovascular disease is increasingly more. According to the statistics of ten leading causes of death made by the ministry of treatments of the executive yuan from 2008 to 2012, nearly half of the project is cardiovascular-related diseases, such as heart diseases, cerebrovascular diseases and hypertensive diseases. The cardiovascular-related diseases deaths accounted for 30.3% of all deaths in Taiwan in 2012, and heart diseases and cerebrovascular diseases are two leading causes of death from the cardiovascular-related diseases.
For the cardiovascular-related measurement, traditionally, a photoplethysmography measuring device is used to measure oxyhemoglobin saturation and photoplethysmography signals, which may be divided into a transmissive or reflective photoplethysmography measuring device; however, the photoplethysmography measuring device in the prior art mostly uses a light emitter that fixes brightness of light to irradiate background tissues of human bodies, and thus measured signals are often poor due to different background tissues (e.g., fingers, arms, head, stomach, legs and so on).
In view of the foregoing problems, an objective of the present invention is to provide a feedback photoplethysmography measuring device and a measuring method thereof, which can adjust brightness of light emitted by a light emitter of the photoplethysmography measuring device to be optimal with respect to different background tissues of a human body to be measured, to make the background tissues of the human body measured by the photoplethysmography measuring device have optimal measurement signals.
A first aspect of the present invention provides a feedback photoplethysmography measuring device, including:
a measuring device, including:
a light emitter that emits light with a particular wavelength to a human body; and
a light receiver that receives the light with a particular wavelength transmitted through the human body or reflected by the human body, and converts the light to a photoplethysmography signal which is an electrical signal;
an analog/digital conversion unit that converts the photoplethysmography signal converted by the light receiver which is an analog signal to a photoplethysmography value which is a digital value;
a variation-degree calculation unit that calculates a photoplethysmography variation value according to the photoplethysmography value converted by the analog/digital conversion unit; and a feedback emitted light amplitude adjustment unit that controls brightness of the light emitted by the light emitter according to a plurality of preset control values or the adjusted photoplethysmography variation value calculated by the variation-degree calculation unit, and adjusts the photoplethysmography variation value to a minimum variation value, to control the brightness of the light emitted by the light emitter to be optimal.
A second aspect of the present invention provides a feedback photoplethysmography measuring device, including:
a measuring device, including:
a plurality of light emitters that emit light with a particular wavelength but in different sequences to a human body respectively; and
a light receiver that receives the light with a particular wavelength but in different sequences transmitted through the human body or reflected by the human body, and converts the light to a plurality of photoplethysmography signals which are electrical signals;
a light emission sequence control unit that sends each of a plurality of emitted light sequence signals to each of the light emitters through phase, pulse or sine-wave control, to control time and frequency of the light emitted by each of the light emitters;
an analog/digital conversion unit that converts the photoplethysmography signals converted by the light receiver which are analog signals to a photoplethysmography value which is a digital value respectively;
a variation-degree calculation unit that calculates a plurality of photoplethysmography variation values according to the photoplethysmography values converted by the analog/digital conversion unit; and
a feedback emitted light amplitude adjustment unit that controls brightness of the light emitted by each of the light emitters according to a plurality of preset control values or the adjusted photoplethysmography variation values calculated by the variation-degree calculation unit, and adjusts at least one of the photoplethysmography variation values to a minimum variation value, to control the brightness of the light emitted by the light emitter corresponding to the minimum variation value to be optimal.
A third aspect of the present invention provides a measuring method of a feedback photoplethysmography measuring device, including:
emitting, by a light emitter, light with a particular wavelength to a human body;
receiving, by a light receiver, the light with a particular wavelength transmitted through the human body or reflected by the human body, and converting the light to a photoplethysmography signal which is an electrical signal;
converting, by an analog/digital conversion unit, the photoplethysmography signal converted by the light receiver which is an analog signal to a photoplethysmography value which is a digital value;
calculating, by a variation-degree calculation unit, a photoplethysmography variation value according to the photoplethysmography value converted by the analog/digital conversion unit; and
adjusting, by a feedback emitted light amplitude adjustment unit, the photoplethysmography variation value, and controlling brightness of the light emitted by the light emitter according to a plurality of preset control values or the adjusted photoplethysmography variation value calculated by the variation-degree calculation unit;
wherein the feedback emitted light amplitude adjustment unit judges whether the adjusted photoplethysmography variation value is the minimum variation value.
A fourth aspect of the present invention provides a measuring method of a feedback photoplethysmography measuring device, including:
emitting, by a plurality of light emitters, light with a particular wavelength but in different sequences to a human body;
receiving, by a light receiver, the light with a particular wavelength but in different sequences transmitted through the human body or reflected by the human body, and converting the light to a plurality of photoplethysmography signals which are electrical signals;
sending, by a light emission sequence control unit, each of a plurality of emitted light sequence signals to each of the light emitters through phase, pulse or sine-wave control, to control time and frequency of the light emitted by each of the light emitters;
converting, by an analog/digital conversion unit, the photoplethysmography signals converted by the light receiver which are analog signals to a plurality of a photoplethysmography value which is a digital value;
calculating, by a variation-degree calculation unit, a plurality of photoplethysmography variation values according to the photoplethysmography values converted by the analog/digital conversion unit; and
adjusting, by a feedback emitted light amplitude adjustment unit, the photoplethysmography variation values, and controlling brightness of the light emitted by each of the light emitters according to a plurality of preset control values or the adjusted photoplethysmography variation values calculated by the variation-degree calculation unit respectively;
wherein the feedback emitted light amplitude adjustment unit judges whether at least one of the adjusted photoplethysmography variation values is the minimum variation value.
For the purposes of promoting an understanding of the principles of the invention, the feedback photoplethysmography measuring device and method of the present invention are described below, and in applicants' Taiwanese priority application No. 105102054, filed Jan. 22, 2016, the entire contents of which are hereby incorporated herein by reference. The written description and drawings are intended to illustrate the invention in a manner that allows persons of ordinary skill in the art to be able to understand and appreciate the broad scope of the invention and its preferred embodiments, and to enable any person skilled in the art to which the invention pertains, or with which it is most nearly connected, to make and use the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, with such alterations and modifications to the illustrated device being contemplated as would normally occur to one skilled in the art to which the invention relates.
The light emission sequence control unit 160 sends an emitted light sequence signal to the light emitter 102 through phase, pulse or sine-wave control, to control time and frequency of the light emitted by the light emitter 102. As shown in
The light with a particular wavelength emitted by the light emitter 102 may be green light with a wavelength of 495 nm to 570 nm, red light with a wavelength of 620 nm to 750 nm or infrared light with a wavelength of 780 nm to 1000 nm.
The light receiver 104 receives light with a particular wavelength transmitted through background tissues of a human body or reflected by the background tissues of the human body, and converts the light to a photoplethysmography signal which is an electrical signal, as shown in
The analog/digital conversion unit 120 converts the photoplethysmography signal converted by the light receiver which is an analog signal 104 to a photoplethysmography value which is a digital value. The variation-degree calculation unit 180 calculates a photoplethysmography variation value Var according to the photoplethysmography value converted by the analog/digital conversion unit 120.
As shown in
wherein N is the total data number of the photoplethysmography value through sequence analysis or Fourier transform, I[n] is the corresponding light intensity of the photoplethysmography value via sequence analysis or Fourier transform at the time n, and M is an average value of I[n].
The feedback emitted light amplitude adjustment unit 140 controls the brightness of the light emitted by the light emitter 102 according to a plurality of preset control values or the adjusted photoplethysmography variation value Var calculated by the variation-degree calculation unit 180, and until the photoplethysmography variation value Var converted and calculated according to the photoplethysmography signal converted by the light receiver 104 is a minimum variation value, the feedback emitted light amplitude adjustment unit 140 controls the brightness of the light emitted by the light emitter 102 to be optimal.
The light receiver 104 receives the light with a particular wavelength transmitted through background tissues of a human body or reflected by the background tissues of the human body, and converts the light to a photoplethysmography which is an electrical signal, the analog/digital conversion unit 120 converts the photoplethysmography signal converted by the light receiver which is an analog signal 104 to a photoplethysmography value which is a digital value, and the variation-degree calculation unit 180 calculates a photoplethysmography variation value Var according to the photoplethysmography value converted by the analog/digital conversion unit 120 (step S504).
Next, the feedback emitted light amplitude adjustment unit 140 receives the photoplethysmography variation value Var calculated by the variation-degree calculation unit 180, and judges whether all control values have been used to adjust the brightness of the light emitted by the light emitter 102 (step S506).
As the feedback emitted light amplitude adjustment unit 140 adjusts the brightness of the light emitted by the light emitter 102 with the first control value but not all the control values are used, next, step S500 is performed, to adjust the brightness of the light emitted by the light emitter 102 with a second control value, and when step S500 is performed subsequently, the brightness of the light emitted by the light emitter 102 is adjusted with a subsequent control value.
If the feedback emitted light amplitude adjustment unit 140 has used all the control values to adjust the brightness of the light emitted by the light emitter 102, the feedback emitted light amplitude adjustment unit 140 seeks for a minimum value in each photoplethysmography variation value Var corresponding to each control value, and the minimum value is the minimum variation value with which the feedback emitted light amplitude adjustment unit 140 controls the brightness of the light emitted by the light emitter 102 to be optimal (step S508).
The light receiver 104 receives the light with a particular wavelength transmitted through background tissues of the human body or reflected by the background tissues of the human body, and converts the light to a photoplethysmography signal which is an electrical signal (step S522).
The analog/digital conversion unit 120 converts the photoplethysmography signal converted by the light receiver which is an analog signal 104 to a photoplethysmography value which is a digital value, and the variation-degree calculation unit 180 calculates a photoplethysmography variation value Var according to the photoplethysmography value converted by the analog/digital conversion unit 120 (step S524).
Next, the feedback emitted light amplitude adjustment unit 140 receives the photoplethysmography variation value Var calculated by the variation-degree calculation unit 180, and judges whether the light emitter 120 is controlled to emit light for the first time (step S526).
As the feedback emitted light amplitude adjustment unit 140 controls the light emitter 120 to emit light for the first time, the feedback emitted light amplitude adjustment unit 140 adjusts the size of the received photoplethysmography variation value Var to control the brightness of the light emitted by the light emitter 102 to increase (step S528), and next, step S500 is performed, to control the brightness of the light emitted by the light emitter 102 with the adjusted photoplethysmography variation value Var (step S530).
When steps S520, S522 and S524 are performed more than twice, in step S526, this is not the first time that the feedback emitted light amplitude adjustment unit 140 controls the light emitter 102 to emit light, the feedback emitted light amplitude adjustment unit 140 judges whether the current photoplethysmography variation value Var calculated by the variation-degree calculation unit 180 is less than the previous photoplethysmography variation value Var (step S530).
If the current photoplethysmography variation value Var is less than the previous photoplethysmography variation value Var, steps S520, S522, S524, S526, S528 and so on are performed; if the current photoplethysmography variation value Var is greater than the previous photoplethysmography variation value Var, the feedback emitted light amplitude adjustment unit 140 adjusts the size of the received photoplethysmography variation value Var to control the brightness of the light emitted by the light emitter 102 to decrease (step S532), and the feedback emitted light amplitude adjustment unit 140 controls the brightness of the light emitted by the light emitter 102 with the adjusted photoplethysmography variation value Var (step S534).
The light receiver 104 receives the light with a particular wavelength transmitted through background tissues of the human body or reflected by the background tissues of the human body, and converts the light to a photoplethysmography signal which is an electrical signal (step S536).
The analog/digital conversion unit 120 converts the photoplethysmography signal converted by the light receiver which is an analog signal 104 to a photoplethysmography value which is a digital value, and the variation-degree calculation unit 180 calculates a photoplethysmography variation value Var according to the photoplethysmography value converted by the analog/digital conversion unit 120 (step S538).
The feedback emitted light amplitude adjustment unit 140 judges whether the current photoplethysmography variation value Var calculated by the variation-degree calculation unit 180 is less than the previous photoplethysmography variation value Var (step S540).
If the current photoplethysmography variation value Var is less than the previous photoplethysmography variation value Var, steps S532, S534, S536, S538 and so on are performed; if the current photoplethysmography variation value Var is greater than the previous photoplethysmography variation value Var, the previous photoplethysmography variation value Var is a minimum variation value, and the feedback emitted light amplitude adjustment unit 140 controls the brightness of the light emitted by the light emitter 102 to be optimal with the minimum variation value.
The signal processing unit 200 calculates a heart rate value with the photoplethysmography value when the photoplethysmography variation value is the minimum variation value. The heart rate value=60/time difference (heart rate/minute), and the time difference is a time length between adjacent crests in the photoplethysmography value.
A measuring method of a feedback photoplethysmography measuring device according to the first embodiment of the present invention is described with reference to the block diagram of the feedback photoplethysmography measuring device according to the first embodiment of the present invention.
The light receiver 104 receives the light with a particular wavelength transmitted through background tissues of the human body or reflected by the background tissues of the human body, and converts the light to a photoplethysmography signal which is an electrical signal as shown in
The analog/digital conversion unit 120 converts the photoplethysmography signal converted by the light receiver which is an analog signal 104 to a photoplethysmography value which is a digital value (step S44). The variation-degree calculation unit 180 calculates a photoplethysmography variation value Var according to the photoplethysmography value converted by the analog/digital conversion unit (step S46).
When the photoplethysmography variation value Var in the steps of the flow as shown in
As the steps of the flow shown in
The light emission sequence control unit 160 sends two groups of pulse signals which are emitted light sequence signals to the first light emitter 3021 and the second light emitter 3022 through phase, pulse or sine-wave control, to control time and frequency of the light emitted by the first light emitter 3021 and the second light emitter 3022. As shown in
The light emitted by the first light emitter 3021 may be red light with a wavelength of 620 nm to 750 nm and the light emitted by the second light emitter 3022 may be infrared light with a wavelength of 780 nm to 1000 nm.
The light receiver 304 receives red light and infrared light with a particular wavelength transmitted through background tissues of a human body or reflected by the background tissues of the human body, and converts the light to a first photoplethysmography signal and a second photoplethysmography signal which is an electrical signal, as shown in
The analog/digital conversion unit 120 converts the first photoplethysmography signal and the second photoplethysmography signal converted to analog signals by the light receiver 104 to a first photoplethysmography value and a second photoplethysmography value which are digital values respectively. The variation-degree calculation unit 180 calculates a first photoplethysmography variation value and a second photoplethysmography variation value as the above photoplethysmography variation value Var according to the first photoplethysmography value and the second photoplethysmography value converted by the analog/digital conversion unit 120, as shown in
The feedback emitted light amplitude adjustment unit 140 controls sizes of the brightness of the light emitted by the first light emitter 3021 and the second light emitter 3022 respectively according to a plurality of preset control values or the adjusted first photoplethysmography variation value and second photoplethysmography variation value calculated by the variation-degree calculation unit 180, as the steps of the flow shown in
The signal processing unit 200 calculates a ratio R with the first photoplethysmography value and the second photoplethysmography value when the first photoplethysmography variation value and the second photoplethysmography variation value are a minimum variation value respectively, and obtains a blood oxygen concentration value by looking up a table.
The blood oxygen concentration value is
wherein SR_max is the crest value in the photoplethysmography variation value of which the corresponding minimum variation value is red light, SR_min is the trough value in the photoplethysmography variation value of which the corresponding minimum variation value is red light, SR_mean=(SR_max+SR_min)/2, SIR_max is the crest value in the photoplethysmography variation value of which the corresponding minimum variation value is infrared light, SIR_min is the trough value in the photoplethysmography variation value of which the corresponding minimum variation value is infrared light, and SIR_mean=(SIR_max+SIR_min)/2.
A measuring method of a feedback photoplethysmography measuring device according to the second embodiment of the present invention is described with reference to the block diagram of the feedback photoplethysmography measuring device according to the second embodiment of the present invention.
The light receiver 304 receives the red light and the infrared light with a particular wavelength transmitted through background tissues of the human body or reflected by the background tissues of the human body, and converts the light to a first photoplethysmography signal and a second photoplethysmography signal which is an electrical signal as shown in
The analog/digital conversion unit 120 converts the first photoplethysmography signal and the second photoplethysmography signal converted to analog signals by the light receiver 304 to a first photoplethysmography value and a second photoplethysmography value which are digital values (step S64).
The variation-degree calculation unit 180 calculates a first photoplethysmography variation value and a second photoplethysmography variation value according to the first photoplethysmography value and the second photoplethysmography value converted by the analog/digital conversion unit 120 (step S66).
When the first photoplethysmography variation value and the second photoplethysmography variation value in the steps of the flow as shown in
As the steps of the flow shown in
The light emission sequence control unit 160 sends three groups of pulse signals which are emitted light sequence signals to the first light emitter 4021, the second light emitter 4022 and the third light emitter 4023 through phase, pulse or sine-wave control, to control time and frequency of the light emitted by the first light emitter 4021, the second light emitter 4022 and the third light emitter 4023 respectively. As shown in
The light receiver 404 receives light with particular wavelengths and having different brightness and different frequencies transmitted through background tissues of a human body or reflected by the background tissues of the human body, and converts the light to a first photoplethysmography signal, a second photoplethysmography signal and a third photoplethysmography signal which are electrical signals, as shown in
The analog/digital conversion unit 120 converts the first photoplethysmography signal, the second photoplethysmography signal and the third photoplethysmography signal converted to analog signals by the light receiver 404 to a first photoplethysmography value, a second photoplethysmography value and a third photoplethysmography value which are digital values, and the first photoplethysmography value, the second photoplethysmography value and the third photoplethysmography value respectively correspond to light with different brightness and different frequencies. The variation-degree calculation unit 180 calculates a first photoplethysmography variation value, a second photoplethysmography variation value and a third photoplethysmography variation value as the above photoplethysmography variation value Var according to the first photoplethysmography value, the second photoplethysmography value and the third photoplethysmography value converted by the analog/digital conversion unit 120, as shown in
The feedback emitted light amplitude adjustment unit 140 controls sizes of the brightness of the light emitted by the first light emitter 4021, the second light emitter 4022 and the third light emitter 4023 respectively according to a plurality of preset control values or the adjusted first photoplethysmography variation value, second photoplethysmography variation value and third photoplethysmography variation value calculated by the variation-degree calculation unit 180, as the steps of the flow shown in
The signal processing unit 200 calculates the heart rate value with the photoplethysmography value which is the minimum variation value when one of the first photoplethysmography variation value, the second photoplethysmography variation value and the third photoplethysmography variation value is the minimum variation value. Photoplethysmography measurement is carried out with a plurality of light emitters, and when one of the plurality of light emitters is at the optimal brightness, the heart rate value is calculated with the photoplethysmography value of the light emitter which is correspondingly at the optimal brightness, in this way, the heart rate value can be quickly obtained during photoplethysmography measurement.
In another embodiment, a first group of multiple light emitters emit different-brightness and different-frequency red light with particular wavelengths, a second group of multiple light emitters emit different-brightness and different-frequency infrared light with particular wavelengths, and the signal processing unit 200 calculates the ratio R with the photoplethysmography value in the first group of multiple light emitters which is a minimum variation value and the photoplethysmography value in the second group of multiple light emitters which is a minimum variation value, and obtains a blood oxygen concentration value by looking up a table.
The light receiver 404 receives a plurality of different-frequency and different-brightness light with the particular wavelengths transmitted through the background tissues of the human body or reflected by the background tissues of the human body, and converts the light to a first photoplethysmography signal, a second photoplethysmography signal and a third photoplethysmography signal which are electrical signals as shown in
The analog/digital conversion unit 120 converts the first photoplethysmography signal, the second photoplethysmography signal and the third photoplethysmography signal converted to analog signals by the light receiver 404 to a first photoplethysmography value, a second photoplethysmography value and a third photoplethysmography value which are digital values (step S84).
The variation-degree calculation unit 180 obtains a first photoplethysmography variation value, a second photoplethysmography variation value and a third photoplethysmography variation value respectively through calculation with the first photoplethysmography value, the second photoplethysmography value and the third photoplethysmography value converted by the analog/digital conversion unit 120 (step S86).
When the first photoplethysmography variation value, the second photoplethysmography variation value and the third photoplethysmography variation value in the steps of the flow as shown in
As the steps of the flow shown in
In another embodiment, a first group of multiple light emitters emit different-brightness and different-frequency red light with particular wavelengths, a second group of multiple light emitters emit different-brightness and different-frequency infrared light with particular wavelengths, and the signal processing unit 200 calculates the ratio R with the photoplethysmography value in the first group of multiple light emitters which is a minimum variation value and the photoplethysmography value in the second group of multiple light emitters which is a minimum variation value, and obtains a blood oxygen concentration value by looking up a table.
The present invention provides a feedback photoplethysmography measuring device and a measuring method thereof, which can adjust brightness of light emitted by a light emitter of the photoplethysmography measuring device to be optimal with respect to different background tissues of a human body to be measured, to make the background tissues of the human body measured by the photoplethysmography measuring device have optimal measurement signals, and measure photoplethysmography with a plurality of light emitters, which can rapidly measure the heart rate value and the blood oxygen concentration value of the human body.
Although the present invention has been stated as above with reference to preferred embodiments and exemplary drawings, they should not be regarded as limitative. Various modifications, omissions and variations made by those skilled in the art to the forms and the contents of the embodiments do not depart from the scope claimed by the claims of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 105102054 | Jan 2016 | TW | national |
