KR20190081527A - Earphone for monitoring blood pressure and method for monitoring blood pressure using the same - Google Patents

Abstract

The present invention relates to an earphone for monitoring blood pressure and a method for monitoring blood pressure using the same. An earphone for monitoring blood pressure according to an embodiment of the present invention includes a body part, a sensor part including a force sensor, a photodiode and a light emitting diode, a communication part for wired and wireless communication with an external device, and a control part which is coupled to the body part, the sensor part, and the communication part and estimates the blood pressure of a user by processing a photoplethysmography(PPG) signal detected through the sensor part. It is possible to measure the blood pressure accurately.

Description

TECHNICAL FIELD [0001] The present invention relates to an earphone for monitoring blood pressure and a blood pressure monitoring method using the earphone.

The present invention relates to an earphone for monitoring blood pressure and a blood pressure monitoring method using the same. More particularly, the present invention relates to a system capable of monitoring a user's blood pressure in real time through an earphone capable of measuring blood pressure using a photoelectric pulse wave (PPG) of a user.

Recently, the rapid development of science and technology has improved the quality of life of the whole human being, and many changes have occurred in the medical environment. In the past, medical images such as X-ray, CT, and fMRI were taken in the hospital, and it was possible to read the images only after several hours or several days.

However, after 10 years of medical imaging, a PACS (Picture Archive Communication System) has been introduced, which allows images to be transferred to a monitor screen of a radiologist and then read out immediately. In addition, many ubiquitous healthcare-related medical devices that can confirm their blood sugar and blood pressure at any time without going to a hospital are widely used, and blood glucose patients or hypertensive patients use them in their own homes or offices.

In particular, with respect to hypertension, which is a major cause of various diseases and has an increased prevalence, there is a need for a system that continuously measures blood pressure and informs it in real time, and various types of studies related thereto have been attempted.

As an example of the blood pressure measuring method, blood pressure measurement is performed by inserting a blood pressure measuring sensor into a pulmonary artery of a patient with chronic heart disease, and the blood pressure is measured in real time. When the blood pressure is transmitted to the primary care physician using wireless communication, Ubiquitous healthcare (u-Health, ubiquitous healthcare), which monitors changes and communicates prescriptions to patients, has been introduced and has the advantage of dramatically reducing the number of times patients require hospitalization. However, while this technique can continuously and accurately measure blood pressure, it involves an invasive blood pressure measurement method and thus has disadvantages such as difficulty in operation, risk of arterial injury, and infection.

Therefore, a system for real-time measurement of blood pressure in a non-invasive manner without inserting a sensor for blood pressure measurement into arterial blood vessels has been continuously studied. In addition, research has been conducted to monitor the blood pressure in the ubiquitous environment, and to allow the user to adjust the blood pressure by biofeedback the measured blood pressure to the user.

On the other hand, although a technique of applying a method of measuring a blood pressure by attaching a cuff to an arm has also appeared, in this method, since someone has to operate the blood pressure meter necessarily (the user himself or others) in order to obtain the blood pressure measurement value, There was a problem that measurement was difficult.

In particular, in order to inform the patient of the risk of hypertension within a short time, and to allow the patient to receive emergency treatment within a short period of time, the patient is able to prevent and manage hypertension by informing the blood pressure measurement result in real time as well as continuously measuring the blood pressure The introduction of technology to make it possible.

Photoplethysmography (PPG) is a pulse wave signal measured in peripheral blood vessels when blood ejected during ventricular systole is delivered to peripheral blood vessels. The photoelectric pulse wave (PPG) signal can be measured using the optical characteristics of a living tissue. For example, after attaching a PPG sensor module (optical sensor module) capable of measuring pulse wave signals at the locations where peripheral blood vessels are distributed, such as fingertips or toes, the change in blood flow rate, which is the volume change of peripheral blood vessels, .

The PPG signal can be measured by irradiating the human body with red light generated by the light emitting unit of the PPG sensor module and then observing a change in the amount of light reflected by the human body and received by the light receiving unit. The PPG signal is used not only as a PPG signal but also as a correlation between a PPG signal and an ECG signal so that a pulse transit time (PTT) (PWV, Pulse Wave Velocity) can be extracted and used for diagnosis of cardiovascular diseases.

Meanwhile, a technique for measuring an electrocardiogram (ECG), which is one of living body signals using earphones according to the related art, is not a method of collecting a living body signal only by wearing earphones for measuring a living body signal, (The upper arm of the earphone wearer), which is inconvenient.

In order to solve the above problems, according to an embodiment of the present invention,

An object of the present invention is to provide an earphone having a sensor unit for blood pressure monitoring without a separate device for collecting a living body signal.

It is also an object of the present invention to provide an earphone for blood pressure monitoring capable of more accurately estimating a blood pressure based on data detected from a force sensor and data detected from a photodiode.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, A sensor unit including a force sensor, a photodiode, and a light emitting diode; A communication unit for wired / wireless communication with an external device; And a controller coupled to the body, the sensor, and the communication unit for processing a PPG signal detected through the sensor unit to estimate a blood pressure of the user.

In an embodiment of the present invention, the controller detects a PPG signal in an anti-tragus region of the user's ear through the photodiode.

In addition, in the embodiment of the present invention, the light emitting diode is composed of at least two light emitting diodes which emit light of different wavelengths.

Further, in an embodiment of the present invention, the control unit detects a DC component signal corresponding to the force data through the force sensor, detects an AC component signal corresponding to the PPG signal through the photodiode, And estimates the blood pressure based on the DC component signal and the detected AC component signal.

In addition, in the embodiment of the present invention, the sensor unit may be inclined at a predetermined angle with respect to the center line of the body part.

Further, in the embodiment of the present invention, the body portion may further include a wing portion on which the force sensor, the light emitting diode and the photodiode are mounted, and a close adjustment portion, and the control portion controls the close adjustment portion, And the degree of protrusion from the body portion is adjusted.

According to an embodiment of the present invention, the body part further includes an angle adjusting part, and the control part controls the angle adjusting part to adjust the angle formed by the wing part with respect to the body part.

Further, in the embodiment of the present invention, the distance between the photodiode and the light emitting diode is 3 mm to 6 mm.

In the embodiment of the present invention, the control unit sets a predetermined threshold value for the force data, and processes the PPG signal in response to the force data falling below the set threshold value .

Further, in an embodiment of the present invention, the control unit starts the blood pressure monitoring in any one of the user's subjective angle mode and the user's subjective angle mode.

According to an embodiment of the present invention, there is one or more of the following effects.

First, unlike the conventional cuff-type blood pressure diagnostic device for diagnosing hypertension, the user can measure the blood pressure without feeling uncomfortable by using the non-pressure method through the earphone.

Secondly, since the small-sized ear-type type that is embedded in the body of the earphone is used, the blood pressure can be measured while moving, and the blood pressure can be measured in parallel with daily life.

Third, since the blood pressure that can be measured once can be continuously measured, it is possible to provide various medical services due to sudden fluctuation. Furthermore, the risk of cardiovascular disease due to BPV (Blood Pressure Variability) can be predicted.

1 is a view for explaining a site where a user's blood pressure is monitored through earphones for blood pressure monitoring according to an embodiment of the present invention.
2 is a block diagram of an earphone for blood pressure monitoring according to an embodiment of the present invention.
3 is a cross-sectional view of a sensor portion of an earphone for blood pressure monitoring according to an embodiment of the present invention.
4 is a sectional view of a sensor part of an earphone for blood pressure monitoring according to an embodiment of the present invention.
5 is a diagram illustrating a method of detecting a PPG signal by a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention.
FIG. 6 is a view illustrating a structure in which a sensor portion of an earphone for blood pressure monitoring according to an embodiment of the present invention is provided in a body portion.
7 is a view illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention is provided in a body part.
8 is a view illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention is provided in a body part.
9 is a diagram illustrating a signal quality index according to a distance between a photodiode and a light emitting diode of an earphone for blood pressure monitoring.
10 is a graph showing PPG signals for respective wavelengths according to changes in pressure sensed by a force sensor of an earphone for blood pressure monitoring according to an embodiment of the present invention.
11 is a view showing a blood pressure value estimated by an earphone through a force sensor for blood pressure monitoring according to an embodiment of the present invention.
12 shows a time domain graph of the PPG signal.
FIG. 13 is a flowchart illustrating a blood pressure monitoring method of an earphone according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or similar elements, and redundant description thereof will be omitted. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , ≪ / RTI > equivalents, and alternatives.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

[Anti-tragus area and PPG signal]

1 is a view for explaining a site where a user's blood pressure is monitored through earphones for blood pressure monitoring according to an embodiment of the present invention.

Blood pressure can be measured at various parts of the body, such as the ear, wrist, brachial artery of the elbow, finger, carotid artery of the neck, and plantar artery of the heel. However, since the signal qualities of the blood pressures measured at the respective body parts are different from each other, the method of estimating the blood pressure from the measured signals may be different. An earphone for blood pressure monitoring according to an embodiment of the present invention provides a method of monitoring blood pressure in a user's ear.

First, referring to FIG. 1, a portion where an earphone for blood pressure monitoring monitors a blood pressure of a user will be described. The ear of the human user (user) is largely divided into the outer ear, middle ear and inner ear. Fig. 1 shows the external appearance. The external teeth are a triangular fossa, a crus of helix, an ear bead, an intertragic notch, an anti-tragus, -helix) and auricle (helix).

In particular, anti-tragus is more vascular than other sites. Therefore, the earphone according to the embodiment of the present invention is designed to detect a photoplethysmography (PPG) signal for estimating the blood pressure from the transitional region through the sensor unit.

Photoplethysmography (PPG) signals refer to pulse wave signals measured in peripheral blood vessels when blood ejected during ventricular systole is delivered to peripheral blood vessels. The photoelectric pulse wave (PPG) signal is measured using the optical characteristics of the living tissue.

2 is a block diagram of an earphone for blood pressure monitoring according to an embodiment of the present invention. The earphone 200 for blood pressure monitoring according to an embodiment of the present invention includes a body 210, a sensor 220, a communication unit 230, and a controller 240.

The body part 210 forms the body of the earphone 200 according to the embodiment of the present invention and may have various shapes. The body portion 210 may include additional components for the earphone 200 to be in close contact with the ear migration region. In this regard, it will be described later in detail in FIG. 7 to FIG.

The sensor unit 220 includes a force sensor 221, a photodiode 223, and a light emitting diode 222, and is provided on the body portion. The sensor unit 220 detects the PPG signal from the ear-to-ear region of the user. Meanwhile, the sensor unit 220 may further include a printed circuit board 224.

The communication unit 230 may include one or more modules that enable communication between the earphone 200 and the external device 300 according to an embodiment of the present invention. In addition, the communication unit 230 may include one or more modules that connect the earphone 200 to one or more networks.

The controller 240 is coupled to the body 210, the sensor 220 and the communication unit 230 of the earphone 200 according to the embodiment of the present invention and controls the sensor unit 220 and the communication unit 230 And processes the PPG signal detected from the ear-versus-migrated region of the user.

The external device 300 may be a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation device, a slate PC, A tablet PC, an ultrabook, a wearable device (e.g., a smartwatch, a glass glass, a head mounted display (HMD)), and the like.

Meanwhile, the earphone for blood pressure monitoring according to the embodiment of the present invention may be interlocked with the service system (not shown) through the communication unit 230. The service system can provide a warning message and feedback to the user by comparing the blood pressure data of the other user with the blood pressure data of the user.

[Sensor part of GENERAL TYPE]

3 is a cross-sectional view of a sensor portion of an earphone for blood pressure monitoring according to an embodiment of the present invention. More specifically, FIG. 3 shows a structure of a sensor portion of an earphone capable of sensing a PPG signal in a body part excluding an ear.

3, the sensor unit 220 of the earphone for monitoring blood pressure according to the embodiment of the present invention includes a force sensor 221, a light emitting diode 222, (Photo diode, 223). The force sensor 221, the light emitting diode 222, and the photodiode 223 are coupled to a printed circuit board (PCB) 224 to receive power required for driving.

The control unit 240 determines whether the earphone is in close contact with the ear of the user (more specifically, the large-size ear) through the force data sensed from the force sensor 221. The earphone according to the embodiment of the present invention can obtain an optimal PPG signal for blood pressure monitoring when it is brought into close contact with the transitional region at a pressure within a predetermined range. The correlation between the force data and the PPG signal will be described in detail later with reference to FIG. 10 to FIG.

The light emitting diode 222 is an element for converting electrical energy into light energy. The sensor unit 200 according to the embodiment of the present invention includes at least one light emitting diode 222.

Referring to FIG. 3 (b), the light emitting diode 222 according to the embodiment of the present invention may include at least two light emitting diodes that emit light of different wavelengths.

For example, the light emitting diode 222 may include a first light emitting diode 222-1 and a second light emitting diode 222-2 that emit light having a wavelength of 400-700 nm corresponding to visible light, And a third light emitting diode 222-3 emitting light corresponding to a wavelength of 700 nm or more.

The present invention provides a multi-wavelength based blood pressure monitoring method because the optical characteristics of a living tissue such as absorption and reflection of light are changed according to wavelengths. This will be described later in detail with reference to FIG.

The photodiode 223 is an element that converts light energy into electrical energy, and detects light to generate an electrical signal. Light generated in the light emitting diode 222 is absorbed and reflected by a living body tissue (for example, a parasite) and is detected by the photodiode 223.

The distance between the light emitting diode 222 and the photodiode 223 of the sensor unit 220 according to the embodiment of the present invention affects the quality of the PPG signal sensed by the photodiode 223. Therefore, the light emitting diode 222 and the photodiode 223 need to maintain an optimum distance. This will be described later in detail with reference to FIG.

[Sensor part of EAR TYPE]

4 is a sectional view of a sensor part of an earphone for blood pressure monitoring according to an embodiment of the present invention. More specifically, Fig. 4 is a diagram showing the structure of a sensor portion of an earphone capable of sensing a PPG signal in the ear (e.

Referring to FIG. 4A, the sensor unit 220 of the earphone for blood pressure monitoring according to the embodiment of the present invention is provided with a predetermined angle with respect to the longitudinal center line 211 of the body part (not shown) . This is for the sensor part 220 of the earphone 200 to come into close contact with the ear-to-ear area, and the predetermined angle is, for example, about 15 to 75 degrees.

The earphone according to the embodiment of the present invention detects the PPG signal from the ear migration region through the photodiode 223 because the ear canal migration region has more blood vessels distributed than the other regions as described above.

Referring to FIG. 4B, the photodiode 223 of the earphone sensor unit 220 according to the embodiment of the present invention is located in a first region corresponding to about 15 to 75 degrees in the transverse direction, The force sensor 221 of the unit 220 is located in the second region except for the first region.

The distance between the light emitting diode 222 and the photodiode 223 of the sensor unit 220 according to the embodiment of the present invention affects the quality of the PPG signal sensed by the photodiode 223. Therefore, the light emitting diode 222 and the photodiode 223 need to maintain an optimum distance.

Therefore, the photodiode 223 and the light emitting diode 222 according to the embodiment of the present invention may be disposed at intervals of 3.2 mm to 5.6 mm. In addition, the force sensor 221 is disposed as close as possible to the photodiode 223. The quality of the PPG signal according to the distance between the light emitting diode 222 and the photodiode 223 will be described later in detail with reference to FIG.

[Multi-wavelength based feature extraction]

5 is a diagram illustrating a method of detecting a PPG signal by a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention. Referring to FIGS. 3 to 4 together, a method of detecting the PPG signal by the sensor unit will be described with reference to FIG.

As described above with reference to FIGS. 3 to 4, the earphone sensor unit 220 according to the embodiment of the present invention includes at least one light emitting diode 222-1 to 222-3. Since the optical characteristics of living tissues such as absorption and reflection of light are changed depending on the wavelength, the earphone according to the embodiment of the present invention provides a multi-wavelength-based blood pressure monitoring method, It is possible to estimate the blood pressure by detecting difficult hemodynamic information.

FIG. 5 (a) is a view showing the penetration depth of light emitted by the light emitting diode 222 to the skin tissue by wavelength. Referring to FIG. 5 (a), the blue light penetrates to the epidermis, the green light penetrates to the dermis, the yellow wavelength penetrates into the dermal artery, and the red wavelength It can be seen that the light penetrates to the harpy. In other words, it can be seen that the long wavelength light is transmitted to the deeper region of the skin tissue.

FIG. 5 (b) is a diagram comparing the depths of the red light and the green light penetrating the skin tissue. Referring to FIG. 5 (b), it can be seen that the light (? 1) at the green wavelength penetrates into the capillary and the light (? 2) at the red wavelength penetrates into the small artery and the artery. The sensor unit of the earphone according to the embodiment of the present invention includes a plurality of light emitting diodes to emit light of a plurality of wavelengths so that hemodynamic information that is difficult to detect at a single wavelength can be detected to estimate the blood pressure.

On the other hand, referring to Table 1 below, it can be seen that the average blood pressure is different for each type of blood vessel. More specifically, it can be seen that the average blood pressure decreases as the diameter of the blood vessel decreases through [Table 1]. Since the mean blood pressure is different depending on the type of blood vessel as well as the wavelength, the blood pressure shows different pulse wave morphology at the time of pressure / decompression depending on the body part to be measured.

blood vessel Mean blood pressure (mmHg) aorta 100 artery 100 to 40 Capillary 60 to 40 Pulmonary artery 18 ~ 15 Pulmonary vein 10 to 8 vein 10 ~ 2 Vena cava 2 to 5

In consideration of various factors described above, the earphone for blood pressure monitoring according to an exemplary embodiment of the present invention may include a method of estimating a user's blood pressure from a PPG signal measured in an ear-to-migrate region through multi-wavelength based monitoring .

[ The sensor unit  Close contact structure]

FIG. 6 is a view illustrating a structure in which a sensor portion of an earphone for blood pressure monitoring according to an embodiment of the present invention is provided in a body portion. More specifically, Fig. 6 is a view showing the body portion of the earphone viewed from the side.

The body portion 210 of the earphone according to the embodiment of the present invention includes a wing portion 212. A force sensor 221, a light emitting diode 222, and a photodiode 223, which are components of the sensor unit 220, are mounted on the wing portion 212. 4, the photodiode 223 and the light emitting diode 222 according to the embodiment of the present invention are spaced by a distance of 3.2 mm to 5.6 mm. The force sensor 221 is disposed on the photodiode 223, As shown in FIG.

As described above with reference to FIG. 3, when the earphone according to the embodiment of the present invention is closely attached to the transitional region at a pressure within a predetermined range, an optimal PPG signal for blood pressure monitoring can be obtained.

The wing portion 212 according to the embodiment of the present invention may be inclined by 10 degrees with respect to the transverse center line 213 of the body portion 210. [ The wing portion 212 also transmits a force to a surface joining the inner surface of the wing portion 212 when the user wears the earphone to the ear. The force sensor 221 according to the embodiment of the present invention is provided on the joining surface. That is, the wing portion 212 has an ergonomic structure that automatically transmits force to the force sensor 221 according to whether the user wears it.

Meanwhile, the wing portion 212 according to the embodiment of the present invention may include a flexible printed circuit board 224 therein. The wing portion 212 ensures an optimum signal-to-noise ratio when the distance between the light emitting diode 222 and the photodiode 223 is 5 mm or less.

It is preferable that the distance a between the wing portion 212 and the skin contact surface of the user, for example, the bimetal according to the embodiment of the present invention is maintained at 1.5 mm to 3.0 mm. In this case, if the distance between the light emitting diode 222 and the photodiode 223 is b, the length of the optical path can be calculated as shown in Equation (1) below.

7 is a view illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention is provided in a body part. More specifically, FIG. 7 is a view showing that the sensor unit is brought into close contact with the large-displacement region with appropriate pressure by using the close-fitting adjustment unit provided on the body portion. 7 (a) to 7 (b) are views showing the body part 210 of the earphone from a side view.

The control unit 240 controls the close adjustment unit 270 to adjust the degree to which the wing portion 212 is closely attached to the ear migration region. More specifically, the degree to which the wing portion 212 protrudes from the body portion 210 by the close adjustment portion 270 can be adjusted. 7A and 7B, the distance d at which the wing portion 212 protrudes from the body portion 210 can be variably adjusted.

For example, it can be seen that the protrusion of the wing portion 212 is set higher in FIG. 7 (b) than in FIG. 7 (a) and protruded further from the body portion 210. In FIGS. 7A and 7B, the degree of close contact of the close-contact adjusting unit 270 is shown to be four, but it may be designed to be adjusted in further steps or continuously.

The earphone according to the embodiment of the present invention can obtain the PPG signal having the optimum signal quality index by adjusting the degree to which the sensor unit 220 is closely attached. When the sensor unit 220 according to the embodiment of the present invention is brought into close contact with the large-transitional region, the pressure is closer to zero. This will be described later in detail with reference to FIG.

The control unit 240 of the earphone according to the embodiment of the present invention detects the DC component signal through the force sensor 221 and outputs the DC component signal to the photodiode 223. In the state where the sensor unit 220 is ideally in close contact with the large- Lt; RTI ID = 0.0 > AC < / RTI > In addition, the control unit 240 can more accurately estimate the blood pressure value of the user based on the detected DC component signal and AC component signal.

8 is a view illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention is provided in a body part. More specifically, FIG. 8 is a view showing that the sensor portion is accurately positioned in the transitional region using the angle adjusting portion provided in the body portion. 8 (a) is a view showing a side view of the body portion 210 of the earphone, and FIGS. 8 (b) to 8 (d) are views showing the body portion 210 of the earphone from above.

In general, earphones are designed using anatomical structures for use in a variety of shapes of ears. However, due to your anatomical differences, the inclination of migration may be different for each individual. Therefore, the sensor unit 220 according to the embodiment of the present invention may include the angle adjusting unit 280. [

The control unit 240 according to the embodiment of the present invention can optimize the angle of the sensor unit 220 according to the anatomical structure by rotating the wing unit 212 by controlling the angle adjusting unit 280. [

For example, in FIG. 8A, the body 210 of the earphone further includes an angle adjuster 280 as well as the close adjuster 270. The controller 240 of the earphone according to the embodiment of the present invention controls the angle adjuster 280 to adjust the angle formed by the wing 212 with respect to the body 210 as shown in Figures 8A to 8C Can be adjusted differently.

Further, the earphone according to the embodiment of the present invention can monitor whether or not the wing portion 212 is properly adhered to the large migration region through an external device (for example, a smart phone) connected through the communication portion 230 have.

[Experimental data]

9 is a diagram illustrating a signal quality index according to a distance between a photodiode and a light emitting diode of an earphone for blood pressure monitoring.

4, the distance between the light emitting diode 222 and the photodiode 223 in the sensor part 220 of the earphone for blood pressure monitoring according to the embodiment of the present invention is sensed by the photodiode 223 It affects the quality of the PPG signal. Therefore, the light emitting diode 222 and the photodiode 223 need to maintain an optimum distance.

9 represents the distance between the photodiode 223 and the light emitting diode 222, and the vertical axis represents the signal quality index indicating the quality of the PPG signal. As shown in FIG. 9, when the distance between the photodiode 223 and the light emitting diode 222 is 3.2 mm to 5.6 mm, the signal quality index indicates 0.8 or more.

More specifically, when the distance between the photodiode 223 and the light emitting diode 222 is 3.2 mm or less, the photodiode 223 has more light coming directly through the subcutaneous tissue than the light reflected from the blood vessel, . On the other hand, when the distance between the photodiode 223 and the light emitting diode 222 is 5.6 mm or more, the amount of light reflected from the blood vessel decreases as the photodiode 223 moves away from the light emitting diode 222, The index drops.

The distance between the photodiode 223 and the light emitting diode 222 may be designed to be 3.2 mm to 5.6 mm in the earphone sensor unit 220 according to the embodiment of the present invention. Accordingly, the earphone for blood pressure monitoring according to the embodiment of the present invention can acquire a PPG signal having a signal quality index of 0.8 or more.

10 is a graph showing PPG signals for respective wavelengths according to changes in pressure sensed by a force sensor of an earphone for blood pressure monitoring according to an embodiment of the present invention. The horizontal axis of FIG. 10 represents the time and the vertical axis represents the pressure sensed by the force sensor 221.

Referring to FIG. 10, it can be seen that the pressure sensed by the force sensor 221 is 0.55 N or more in the interval of 0 to 12 seconds. The large pressure sensed by the force sensor 221 means that the pressure of the skin (large diaphragm) contacting the force sensor 221 is large. PPG signals are not well detected because the large pressure on the capillaries of the large esophagus interferes with the flow of blood in the blood vessels. Therefore, it can be seen that the quality of the PPG signal using the green, red, and infrared LEDs deteriorates in the interval of 0 to 12 seconds in FIG.

On the other hand, it can be seen that the PPG signal using the green, red, and infrared light emitting diodes is detected in the interval of 12 to 45 seconds when the pressure sensed by the force sensor 221 becomes 0.55N or less. Also, as shown in FIG. 10, it can be seen that the quality of the PPG signal using the green light emitting diode and the infrared light emitting diode is higher than that of the PPG signal using the red light emitting diode in the interval of 12 to 45 seconds.

Therefore, the threshold value of the force data sensed by the force sensor 221 of the earphone for blood pressure monitoring according to the embodiment of the present invention can be set to 0.55N. That is, the control unit 240 may be designed to set a predetermined threshold value (for example, 0.55 N) for the force data, and to process the PPG signal in response to the force data falling below the set threshold value.

On the other hand, the PPG signal is not detected well even though the pressure sensed by the force sensor 221 is 0.55 N or less because the force sensor 221 is not in close contact with the transitional region and the SNR is lowered due to the ambient light . It can be confirmed that the PPG signal is not detected in the section after 45 seconds in FIG.

11 is a view showing a blood pressure value estimated by an earphone through a force sensor for blood pressure monitoring according to an embodiment of the present invention.

The PPG signal is a relative value without a unit since the intensity of the light reflected by the blood vessel distribution, skin color, ambient light noise, the degree of contact of the photodiode with the skin, and the light intensity of the LED vary. Therefore, the blood pressure monitoring method according to the related art uses a method of estimating the change in blood pressure by calibrating the measured PPG signal after receiving the reference blood pressure value, since the blood pressure should be estimated only with the PPG signal as a relative value.

In contrast, the earphone for blood pressure monitoring according to the embodiment of the present invention can measure the absolute value of the pressure applied by the sensor unit 220 to the major transitional region through the force sensor 221.

Referring to FIG. 11A, the DC component signal 1110 is measured in the force sensor 221 in a state in which the sensor unit 220 is ideally in close contact with the large-displacement region. The control unit 240 can analyze the AC component signal 1120 measured by the photodiode 223 together with the DC component signal 1110 to more accurately estimate the blood pressure value.

11 (b) shows the phase and amplitude of the DC component signal 1110 and the AC component signal 1120 of FIG. 11 (a) corrected by the ensemble average method. According to the embodiment of the present invention, a blood pressure value corresponding to one cycle can be estimated every 20 seconds.

[ PPG  Method for estimating blood pressure from signal]

The factors for estimating blood pressure are classified into pulse wave signal and physiological factors. Physiological factors include factors such as age, sex, height and weight. The pulse wave signal factor is again divided into morphological factor, frequency factor and time-frequency factor. The morphological factors are classified into time domain analysis, frequency domain analysis, and time-frequency domain analysis.

12 shows a time domain graph of the PPG signal. More specifically, the morphological factors of the PPG signal, particularly time domain analysis, will be described in detail with reference to FIG.

The control unit 240 preprocesses the PPG signal obtained through the photodiode 223. 12 shows a preprocessed PPG signal 1210 corresponding to one cycle of a pulse wave. Next, the control unit 240 first differentiates the preprocessed PPG signal 1210. Next, the control unit 240 second-differentiates the first-differentiated PPG signal 1220. Finally, the control unit 240 detects a fiducial point from the second-order differentiated PPG signal 1230.

Meanwhile, the controller 240 of the earphone for blood pressure monitoring according to the embodiment of the present invention can use a Windkessel Model to estimate the blood pressure of the user from the detected PPG signal. The Windkessel model models changes in PPG signal with changes in vessel shape and pressure due to blood flow. The preprocessed PPG signal 1210 shown in Fig. 12 is a signal in which the forward wave and the reflected wave are superimposed, and the PPG signal of the blood pressure within the normal range and the PPG signal of the blood pressure outside the normal range appear morphologically different.

The control unit 240 of the earphone for blood pressure monitoring according to the embodiment of the present invention detects the reference points a to g from the second order differentiated PPG signal 1230 shown in FIG.

The controller 240 of the earphone for monitoring the blood pressure according to the embodiment of the present invention models the blood pressure of the user through the analysis of the time domain or the amplitude domain of the reference points a to g shown in FIG. Compare.

[FLOW CHART]

FIG. 13 is a flowchart illustrating a blood pressure monitoring method of an earphone according to an embodiment of the present invention. More specifically, referring to FIG. 13, a monitoring method in the case where the user is in the awake state and the non-awake state with respect to the blood pressure monitoring will be described.

The controller 240 of the earphone for monitoring the blood pressure according to the embodiment of the present invention starts monitoring blood pressure in either the user's subjective angle mode or the user's subjective angle mode.

In the user awakening mode, the control unit 240 determines whether or not to start monitoring the blood pressure according to step 1310. For example, the controller 240 may start monitoring the blood pressure in response to an input of a predetermined button included in the earphone according to the embodiment of the present invention.

If there is no input for blood pressure monitoring, the controller 240 controls the controller 220 to maintain the sleep mode in which the sensor unit 220 is not operated according to step 1311. If there is an input for blood pressure monitoring, the control unit 240 initializes the sensor unit 220 according to step 1312.

On the other hand, in the user non-awake mode, the controller 240 immediately initializes the sensor unit 220 according to step 1320 without determining whether the blood pressure monitoring is started as in step 1310.

If the sensor unit 220 is initialized to acquire the PPG signal in accordance with step 1312 or step 1320, the controller 240 determines whether the quality of the obtained PPG signal is equal to or greater than a preset value according to step 1330. At this time, the above-described signal quality index in Fig. 9 can be used. For example, the control unit 240 may determine that the quality of the PPG signal is equal to or greater than a preset value when the signal quality index is 0.8 or more.

If the quality of the obtained PPG signal is less than a preset value, the controller 240 outputs a message requesting re-wearing of the earphone according to step 1331. The message may be output as a voice message or a vibrate message.

On the other hand, if the quality of the obtained PPG signal is equal to or greater than a predetermined value, the controller 240 monitors the operation of the user according to steps 1340 and 1341 and outputs a message informing the blood pressure measurement period.

According to step 1350, the control unit 240 determines whether the user is in a stable state. More specifically, since it is difficult to monitor the blood pressure through the PPG signal measurement in a situation where the user is excessively moving (for example, during exercise), the control unit 240 of the earphone for blood pressure monitoring according to the embodiment of the present invention, Is in a stable state.

If it is determined that the user is not in the stable state, the control unit 240 monitors the user operation again according to step 1340. If it is determined that the user is in the stable state, the control unit 240 starts measurement of the blood pressure according to step 1360. For the blood pressure measurement, the method described in Figs. 11 to 12 may be used.

When the blood pressure measurement is started, the control unit 240 detects the peripheral factors according to step 1361. Peripheral factors are factors that can affect blood pressure measurements, such as ambient light noise. Next, in accordance with step 1362, the control unit 240 determines whether the detected peripheral factors affect the measured blood pressure.

If it is determined that the detected peripheral factors have an influence on the measured blood pressure, the control unit 240 outputs a predetermined message according to step 1370. The message may be output as a voice message or a vibrate message.

If it is determined that the detected peripheral factors do not affect the measured blood pressure, the control unit 240 determines whether there is an abnormal blood pressure change based on the measured blood pressure according to step 1371.

If it is determined that there is an abnormal blood pressure change, the control unit 240 outputs a warning message according to step 1380. On the other hand, if it is determined that there is no abnormal blood pressure change, the control unit 240 stores the blood pressure data measured according to step 1381.

The present invention described above can be embodied as computer-readable codes on a medium on which a program is recorded. The computer readable medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of the computer readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, , And may also be implemented in the form of a carrier wave (e.g., transmission over the Internet). Also, the computer may include a control unit of the terminal. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

200: Earphone
210:
220:
230:
240:

Claims (10)

1. An earphone for blood pressure monitoring,
A body portion;
A sensor unit including a force sensor, a photodiode, and a light emitting diode;
A communication unit for wired / wireless communication with an external device; And
And a controller coupled to the body, the sensor, and the communication unit, for processing a PPG signal detected through the sensor unit to estimate a blood pressure of the user. The method according to claim 1,
Wherein,
Wherein the PPG signal is detected in an anti-tragus region of the user's ear through the photodiode. The method according to claim 1,
The light-
And at least two light emitting diodes for emitting light of different wavelengths. The method according to claim 1,
Wherein,
Detecting a DC component signal corresponding to the force data through the force sensor, detecting an AC component signal corresponding to the PPG signal through the photodiode, and based on the detected DC component signal and the detected AC component signal And the blood pressure is estimated. The method according to claim 1,
The sensor unit includes:
Wherein the earphone is inclined at a predetermined angle with respect to a center line of the body part. The method according to claim 1,
The body portion
Further comprising a wing portion and a close adjustment portion on which the force sensor, the light emitting diode, and the photodiode are mounted,
Wherein,
And controls the tightening adjusting unit to adjust the degree of protrusion of the wing portion from the body portion. The method according to claim 6,
The body portion
Further comprising an angle adjusting section,
Wherein,
And controls the angle adjusting unit to adjust an angle formed by the wing portion with respect to the body portion. The method according to claim 1,
Wherein the distance between the photodiode and the light emitting diode is 3 mm to 6 mm. 5. The method of claim 4,
Wherein,
Sets a predetermined threshold value for the force data, and processes the PPG signal in response to the force data falling below the set threshold value. The method according to claim 1,
Wherein,
Wherein the blood pressure monitoring is started in any one of the user's subjective angle mode and the user's subjective angle mode.

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