JP7394646B2 - blood pressure measuring device - Google Patents

Description

The present invention relates to a blood pressure measuring device.

In recent years, electronic devices such as mobile terminals have been developed that have healthcare functions that measure a user's blood pressure, heart rate, and the like. For example, U.S. Pat. No. 5,900,301 discloses a personal handheld computing device that measures blood pressure. Further, Patent Document 2 discloses a biological information detection device that can improve waterproof performance.

Special table 2016-511667 publication International Publication No. 2016/031221

Since blood pressure is one of the important vital sign information representing the circulatory dynamics of a living body, blood pressure measurement is useful for understanding the state of health. There are two types of blood pressure measurement methods in practice: non-invasive blood pressure measurement methods and invasive blood pressure measurement methods. As a method of non-invasive blood pressure measurement, there are many electronic blood pressure monitors on the market that use an oscillometric method that pressurizes the upper arm or wrist with a cuff and detects vibrations of the cuff caused by pulse waves.

Oscillometric methods include a decompression measurement method in which a cuff attached to the upper arm or wrist is quickly pressurized to a predetermined pressure, and then the pressure is gradually reduced while detecting vibrations of the cuff caused by pulse waves. There is a linear pressurization measurement method (also called iNIBP (registered trademark)) in which a pulse wave is detected during pressurization and the pressurization of the living body is stopped when the systolic blood pressure can be measured. In the latter linear pressurization measurement method, pressurization of the living body can be stopped when the systolic blood pressure can be measured, so there is no need to pressurize the living body to a uniform pressure as in the decompression measurement method. Therefore, blood pressure measurement can be performed in a shorter time than in the case of pressurizing a living body to a predetermined pressure as in the reduced pressure measurement method.

The oscillometric method pressurizes a living body in this way and measures blood pressure from the pulse wave at the pressurized area. It is also possible to measure the blood pressure value from the pulse wave of the patient. Therefore, for example, if a photoplethysmographic sensor and a pressure sensor are provided in an electronic device such as a smartphone that is carried on a daily basis, the user of the electronic device can easily measure blood pressure.

However, in the oscillometric method, the pressure applied to the living body needs to follow a predetermined pressure pattern. However, it is not easy to adjust the pressure force of the fingertips so as to follow a predetermined pressure pattern by adjusting the force of the fingertips. In addition, photoplethysmographic sensors are sometimes installed on the back of electronic devices such as smartphones, but since the photoplethysmographic sensor installed on the back is difficult for the subject to see, the tip of the finger is placed at the position of the photoplethysmographic sensor. It becomes difficult to match. If the position of the fingertip applying pressure is shifted from the photoplethysmographic sensor, it will no longer be possible to apply pressure with the fingertip along the pressure pattern.

One aspect of the disclosed technology is to provide a blood pressure measuring device that can easily apply pressure with a fingertip along a predetermined pattern defined for blood pressure measurement.

One aspect of the disclosed technology is exemplified by the following blood pressure measuring device. This blood pressure measuring device includes a first sensor that is placed on the back side of a housing and that acquires biological information from a fingertip that comes into contact with the device, and a second sensor that detects the pressure exerted by the fingertip on the first sensor. an elastic member that applies an elastic force to the pressing fingertip in accordance with the rotation of the housing around one end of the housing, and a detection value of the second sensor that satisfies a predetermined pressing pattern. and a measuring section that measures blood pressure based on the biological information acquired by the first sensor.

The disclosed technology makes it possible to easily apply pressure with a fingertip along a predetermined pattern defined for blood pressure measurement.

FIG. 1 is a diagram illustrating the appearance of a blood pressure measuring device according to an embodiment viewed from the side. FIG. 2 is a diagram illustrating the appearance of a smartphone used in the embodiment. FIG. 3 is a diagram illustrating an example of the hardware configuration of a smartphone used in the embodiment. FIG. 4 is a diagram illustrating an example of processing blocks of a smartphone used in the embodiment. FIG. 5 is a diagram explaining a method of measuring blood pressure using the oscillometric method. FIG. 6 is a diagram showing an example of a pressure pattern in the linear pressure measurement method. FIG. 7 is a first diagram illustrating how the blood pressure measuring device is used in the embodiment. FIG. 8 is a second diagram illustrating how the blood pressure measuring device is used in the embodiment. FIG. 9 is a diagram illustrating the relationship between the angle at which the casing is rotated and the elastic force of the coil spring in the embodiment. FIG. 10 is a diagram showing an example of a guidance screen displayed by the guidance section in the embodiment. FIG. 11 is a first diagram showing an example of a blood pressure measurement flow of the blood pressure measurement device according to the embodiment. FIG. 12 is a second diagram showing an example of the blood pressure measurement flow of the blood pressure measurement device according to the embodiment. FIG. 13 is a diagram showing how the comparative example is used. FIG. 14 is a first diagram showing variations of the auxiliary stand. FIG. 15 is a second diagram showing variations of the auxiliary stand.

<Embodiment>
The blood pressure measuring device according to the embodiment includes, for example, the following configuration. The blood pressure measuring device according to the embodiment includes:
a first sensor that is placed on the back side of the housing and acquires biometric information from a fingertip that comes in contact;
a second sensor that detects the pressure exerted by the fingertip on the first sensor;
an elastic member that applies an elastic force to the pressing fingertip in accordance with the rotation of the housing around one end of the housing;
a guide unit that guides whether the detected value of the second sensor satisfies a predetermined pressurization pattern;
A measurement unit that measures blood pressure based on the biological information acquired by the first sensor.

The elastic member is not limited as long as it can exert an elastic force corresponding to the rotation of the housing, and examples thereof include a spring, rubber, and the like. The biological information acquired by the first sensor is not limited as long as it can be used for blood pressure measurement, and is, for example, a pulse wave. The first sensor is, for example, a photoplethysmogram sensor that irradiates a fingertip with light and obtains a pulse wave based on the reflected light. In this blood pressure measuring device, the first sensor acquires biological information from the fingertip while the fingertip pressurizes the first sensor and rotates the housing, and the biological information acquired by the first sensor Based on this, blood pressure is measured, for example, by oscillometric methods. Here, the elastic member applies an elastic force to the fingertip according to the rotation, thereby making up for the pressure insufficient in blood pressure measurement using the oscillometric method. In this blood pressure measuring device, the guide section indicates whether or not the detected value of the second sensor satisfies the predetermined pressurization pattern, thereby instructing pressurization according to the predetermined pattern specified for blood pressure measurement. This can be done easily with a sharp tip. Furthermore, since the person being measured for blood pressure can visually check the degree of pressure applied by the fingertip as the inclination of the housing, it becomes easier to apply pressure in accordance with a predetermined pattern defined for blood pressure measurement.

Here, the guide unit moves along the predetermined pressure pattern based on the elapsed time since the fingertip starts applying pressure to the first sensor and the detected value of the second sensor. Informs whether pressurization is being performed or not. The predetermined pressurization pattern can be represented by a function of time and pressure. Therefore, the guide section guides whether or not pressurization is being performed in accordance with a predetermined pressurization pattern, based on the elapsed time since the start of pressurization and the detected value of the second sensor. be able to.

The blood pressure measuring device according to this embodiment may have the following features. The guide unit includes a tilt sensor that detects the tilt of the casing, and the guide unit detects the tilt of the casing and the pressure that pressurizes the first sensor when pressurization is performed in accordance with the predetermined pressure pattern. Based on the correspondence relationship, it is determined whether the predetermined pressure pattern is satisfied. Since the elastic force applied by the elastic member to the fingertip changes linearly, when pressure is applied along a predetermined pressure pattern, the inclination of the housing and the pressure applied to the first sensor are It is thought that there is a correspondence relationship. Here, the correspondence relationship can be a table or a function. This blood pressure measuring device performs pressurization according to a predetermined pressurization pattern based on whether or not the inclination detected by the inclination sensor and the detected value of the second sensor satisfy such a correspondence relationship. We can tell you if there are any.

The blood pressure measuring device according to this embodiment may have the following features. The guide unit calculates an appropriate pressure to be applied to the first sensor from the inclination detected by the inclination sensor based on the correspondence relationship, and calculates an appropriate pressure to be applied to the first sensor based on the correspondence relationship, and determines that the difference between the appropriate pressure and the detected value of the second sensor is allowable. If it is outside the range, it is determined that the predetermined pressure pattern is not satisfied. For example, if the fingertip deviates from the first sensor, the difference between the appropriate pressure and the value detected by the second sensor becomes large and falls outside the allowable range. By having such features, the present blood pressure measuring device can indicate that pressurization is not being performed in accordance with a predetermined pressurization pattern due to, for example, a fingertip being displaced from the first sensor.

An embodiment in which the blood pressure measuring device described above is implemented using a smartphone will be described with reference to the drawings. FIG. 1 illustrates the external appearance of a blood pressure measuring device according to an embodiment when viewed from the side. The blood pressure measuring device 500 illustrated in FIG. 1 includes a smartphone 100 and an auxiliary stand 200. Hereinafter, in this specification, the direction from the auxiliary stand 200 to the smartphone 100 will be referred to as the +Y direction, and the direction from the smartphone 100 to the auxiliary stand 200 will also be referred to as the -Y direction. Furthermore, the right direction in FIG. 1 is referred to as the +X direction, and the left direction is also referred to as the -X direction.

Smartphone 100 is a portable information processing device. The smartphone 100 includes a plate-shaped housing 110, as illustrated in FIG. A display 1 is provided on the front of the housing 110.
13 is provided, and a photoplethysmographic sensor 121 and a pressure sensor 122 are provided on the back surface. The photoplethysmographic sensor 121 and the pressure sensor 122 are provided to overlap in the thickness direction of the housing 110. That is, the pressure sensor 122 is provided at a position where it can detect the pressure that presses the photoplethysmographic sensor 121. The smartphone 100 is placed on the auxiliary stand 200 with the back surface on which the photoplethysmographic sensor 121 is provided facing the base 201 of the auxiliary stand 200 . The lower end of the smartphone 100 is supported by a support portion 202 of an auxiliary stand 200 so as to be rotatable within a predetermined range. The back surface of the smartphone 100 is connected to the base 201 by a coil spring 203 at a position closer to the upper end of the smartphone 100 than the photoplethysmographic sensor 121 and the pressure sensor 122 .

The auxiliary stand 200 includes a base 201, a support portion 202, and a coil spring 203. The base 201 is a rigid, plate-shaped member. The support portion 202 protrudes from the +X direction end of the base 201 in the +Y direction, and supports one end of the housing 110 of the smartphone 100 so as to be rotatable within a predetermined range. The end of the coil spring 203 in the +Y direction is connected to the back of the smartphone 100, and the end in the -Y direction is connected to the base 201. Note that in FIG. 1, the angle between the base 201 and the smartphone 100 is defined as an angle θ.

FIG. 2 illustrates an example of the appearance of the smartphone used in the embodiment as seen from one side (the front side appearance) and the other side (the back side appearance). In FIG. 2, the front side and the back side of the smartphone 100 are alternately arranged and illustrated by arrows. Smartphone 100 has a plate-shaped housing 110. As illustrated in FIG. 1, the distance (thickness) between the front surface and the rear surface of the housing 110 is short compared to the external dimensions of the front surface or the rear surface. In FIG. 2, it is assumed that the upper side of the paper is the upper side of the casing 110, and the lower side of the paper is the lower side of the casing 110.

As shown in FIG. 2, a display 113 is provided on the front surface of the housing 110. A speaker 111 is provided at a central position above the display 113. A telephone microphone 112 is provided at the center of the lower side of the display 113. For example, a touch panel is provided to overlap the display 113.

A photoplethysmographic sensor 121 and a pressure sensor 122 are provided on the back surface of the housing 110. The positions where the photoplethysmographic sensor 121 and the pressure sensor 122 are provided are, for example, when the housing 110 is grasped with one hand and the fingertip F of the grasped hand is extended toward the photoplethysmographic sensor 121. This is a position that reaches the photoplethysmographic sensor 121 from diagonally below the photoplethysmographic sensor 121. The photoplethysmographic sensor 121 detects the pulse wave of the fingertip F that is in contact with the photoplethysmographic sensor 121 . The pressure sensor 122 detects the pressure that the fingertip F applies to the photoplethysmographic sensor 121.

FIG. 3 is a diagram illustrating an example of the hardware configuration of a smartphone used in the embodiment. The smartphone 100 includes a central processing unit (CPU) 101, a main memory section 102, an auxiliary memory section 103, a communication section 104, a speaker 111, a microphone for telephone calls 112, a display 113, a photoplethysmographic sensor 121, and a pressure sensor 122. The CPU 101, the main storage section 102, the auxiliary storage section 103, the communication section 104, the speaker 111, the telephone microphone 112, the display 113, the photoplethysmographic sensor 121, and the pressure sensor 122 are interconnected by a connection bus.

The CPU 101 is also called a microprocessor unit (MPU) or a processor. The CPU 101 is not limited to a single processor, and may have a multiprocessor configuration. Further, a single CPU 101 connected through a single socket may have a multi-core configuration. At least a part of the processing executed by the CPU 101 is executed by a processor other than the CPU 101, for example, a Digital Signal Processor (DS
P), a dedicated processor such as a Graphics Processing Unit (GPU), a numerical calculation processor, a vector processor, or an image processing processor. Furthermore, at least part of the processing executed by the CPU 101 may be executed by an integrated circuit (IC) or other digital circuit. Furthermore, at least a portion of the CPU 101 may include an analog circuit. Integrated circuits include large scale integrated circuits (LSIs), application specific integrated circuits (ASICs), and programmable logic devices (PLDs). The PLD includes, for example, a field-programmable gate array (FPGA). CPU 101 may be a combination of a processor and an integrated circuit. The combination is called, for example, a microcontroller unit (MCU), a system-on-a-chip (SoC), a system LSI, a chipset, or the like. In the smartphone 100, the CPU 101 loads the program stored in the auxiliary storage unit 103 into the work area of the main storage unit 102, and controls peripheral devices through execution of the program. Thereby, the smartphone 100 can perform processing that meets a predetermined purpose. The main storage unit 102 and the auxiliary storage unit 103 are recording media that can be read by the smartphone 100.

The main storage unit 102 is exemplified as a storage unit directly accessed by the CPU 101. The main storage unit 102 includes Random Access Memory (RAM) and Read
Contains only memory (ROM).

The auxiliary storage unit 103 stores various programs and various data on a recording medium in a readable and writable manner. The auxiliary storage unit 103 is also called an external storage device. The auxiliary storage unit 103 stores an operating system (OS), various programs, various tables, and the like. The OS includes a communication interface program that exchanges data with an external device connected via the communication unit 104. External devices include, for example, other information processing devices and external storage devices connected via a computer network or the like. Note that the auxiliary storage unit 103 may be, for example, part of a cloud system that is a group of computers on a network.

The auxiliary storage unit 103 is, for example, an erasable programmable ROM (EPROM), a solid state drive (SSD), a hard disk drive (HDD), or the like. Further, the auxiliary storage unit 103 is, for example, a Compact Disc (CD) drive device, a Digital Versatile Disc (DVD) drive device, a Blu-ray (registered trademark) Disc (BD) drive device, or the like. Further, the auxiliary storage unit 103 may be provided by Network Attached Storage (NAS) or Storage Area Network (SAN).

The communication unit 104 is, for example, an interface with a computer network that communicably connects the information processing device. The communication unit 104 communicates with an external device via a computer network.

The speaker 111 is a sound source that outputs sound. The speaker 111 outputs sounds such as the voice of the other party during a phone call using the smartphone 100 . The telephone microphone 112 is a microphone mainly used for telephone calls. The telephone microphone 112 receives sound input such as a user's voice during a telephone call using the smartphone 100 .

The display 113 displays data processed by the CPU 101 and data stored in the main storage unit 102. The display 113 is, for example, a cathode ray tube (CRT) display, a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence (EL) panel, or an organic EL panel.

The photoplethysmographic sensor 121 is a sensor that acquires a pulse wave from the fingertip F. The photoplethysmographic sensor 121 receives reflected light of the light irradiated onto the fingertip F, and acquires a pulse wave based on the received reflected light. The light source that irradiates the fingertip F with light may be integrated with the photoplethysmographic sensor 121 or may be a separate body. The light source is, for example, a light emitting diode (LED).

The pressure sensor 122 is a sensor that detects pressure applied to a detection surface. The pressure sensor 122 is provided so as to overlap the photoplethysmographic sensor 121 with its detection surface facing the photoplethysmographic sensor 121 . Tilt sensor 123 detects the tilt of smartphone 100. For example, the tilt sensor 123 detects the direction of gravitational acceleration, and detects the tilt of the smartphone 100 based on the detected direction of the gravitational acceleration.

<Processing block of smartphone 100>
FIG. 4 is a diagram illustrating an example of processing blocks of a smartphone used in the embodiment. The smartphone 100 includes a pressure detection section 11, a guide section 12, and a measurement section 13. The smartphone 100 executes processing as each part of the smartphone 100, such as the pressure detection unit 11, the guide unit 12, and the measurement unit 13, by having the CPU 101 execute a computer program that is executable and deployed in the main storage unit 102. do.

The pressure detection unit 11 detects the pressure exerted by the fingertip F on the photoplethysmographic sensor 121 based on the detected value of the pressure sensor 122 . The guide unit 12 determines whether the pressure applied to the photoplethysmographic sensor 121 by the fingertip F satisfies a pressure pattern stored in the auxiliary storage unit 103 in advance. Further, the guide unit 12 may display a guide screen that guides whether the pressure applied to the photoplethysmographic sensor 121 by the fingertip F satisfies the pressure pattern. The measurement unit 13 measures blood pressure based on the pulse wave that the photoplethysmographic sensor 121 acquires from the fingertip F.

Blood pressure measurement device 500 measures blood pressure using an oscillometric method. Here, the oscillometric method will be briefly explained. For example, in the oscillometric method using a cuff, an air bag called a cuff is wrapped around a limb such as an upper arm. Air is pumped into a cuff that is placed around a limb to increase pressure (also referred to as cuff pressure). The blood pressure value is calculated using a phenomenon in which an oscillation component (oscillation) due to arterial pulsation is superimposed on the cuff pressure when the cuff pressure is increased to a systolic blood pressure or higher and then reduced.

FIG. 5 is a diagram explaining a method of measuring blood pressure using the oscillometric method. FIG. 5 shows the relationship between the Korotkoff sounds and oxygenation waveforms observed when a living body is gradually pressurized and the pressurizing force. Korotkoff sound is a sound generated by turbulence that occurs within an artery where external pressure is applied when a living body is pressurized or depressurized. In the traditional auscultation method, the pressure when the Korotkoff sounds occur is the diastolic blood pressure, and the pressure when the Korotkoff sounds disappear is the systolic blood pressure. Further, the oxidation waveform is a waveform of vibration generated in a portion to which external pressure is applied.

The oscillometric method uses the characteristic that when pressurizing or depressurizing a living body, the vibration component (oscillation) due to the pulsation of the artery that occurs in the area where external pressure is applied gradually increases, reaches its maximum amplitude, and then decreases again. This is the blood pressure measurement method used. In the oscillometric method, the blood pressure value is calculated from the correlation between the amplitude of the oxidation waveform and the change in pressurization force instead of the Korotkoff sound. That is, the pressure at which the amplitude of the oxygenation waveform becomes the largest is the average blood pressure. Several methods have been proposed for calculating systolic blood pressure and diastolic blood pressure, but one example is to multiply the maximum point by a predetermined constant (for example, 0.5) as the threshold for systolic blood pressure, and then calculate the maximum point. There is a method in which a value multiplied by a predetermined constant (for example, 0.7) is set as the threshold for the diastolic blood pressure, and the cuff pressure corresponding to the point where the envelope of the pulse wave amplitude intersects each threshold is set as the respective blood pressure value.

Since the oscillometric method is such a measurement method, blood pressure cannot be measured correctly if the pressure applied to the living body is unstable. For example, there may be sudden changes in the pressure applied to the living body, changes in the pressure applied to the living body may be excessively slow, temporary fluctuations in depressurization during the process of gradual pressurization, or gradual depressurization. If there is a temporary fluctuation in pressure during the process, errors may occur in the detection of the pressure pulse waveform, which may result in false detection of the maximum amplitude of the oxygenation waveform, which may reduce the accuracy of blood pressure measurement. There is.

Therefore, in the blood pressure measurement device 500, a pattern of changes in the pressure force to be applied to the fingertip F is stored in advance in the auxiliary storage unit 103 of the smartphone 100 as a pressure pattern. FIG. 6 is a diagram showing an example of a pressure pattern in the linear pressure measurement method. In FIG. 6, the correspondence between the elapsed time after the start of measurement and the pressure due to pressurization of the fingertip F is illustrated. In the blood pressure measuring device 500, the correspondence between the elapsed time from the start of measurement and the pressure due to the pressurization of the fingertip F is stored in advance in the auxiliary storage unit 103 as a pressurization pattern, as illustrated in FIG. Note that the photoplethysmographic sensor 121 included in the smartphone 100 can be applied to either a linear pressurization measurement method or a decompression measurement method as long as it uses an oscillometric method. Blood pressure measuring device 500 employs a linear pressurization measurement method. However, the blood pressure measurement device 500 is not limited to the linear pressurization measurement method, but may also employ a decompression measurement method.

When measuring blood pressure, a reference pulse wave is measured to determine the resting heart rate, etc. used to calculate the systolic and diastolic blood pressures, and then the diastolic blood pressure and systolic blood pressure are measured while changing the pressurizing force on the living body. Periodic blood pressure measurements are taken. Therefore, as shown in FIG. 6, the pressurization pattern set on the smartphone 100 includes a constant pressure section (B-C in FIG. 6) for measuring the reference pulse wave, as well as diastolic blood pressure and systolic pressure. In order to measure the diastolic blood pressure, a section (CD in FIG. 6) in which the pressurizing force is gradually increased is prepared. Then, when the photoplethysmographic sensor 121 is pressurized with the fingertip F along this pressurization pattern, the measurement unit 13 measures blood pressure based on the pulse wave obtained from the photoplethysmographic sensor 121. I can do it.

A method of using the blood pressure measuring device 500 having the above configuration will be explained. FIGS. 7 and 8 are diagrams illustrating how the blood pressure measuring device in the embodiment is used. Further, in FIGS. 7 and 8, the force that acts when pressurizing the photoplethysmographic sensor 121 with the fingertip F is illustrated by an arrow. 7 and 8, L is the length of the smartphone 100 in the longitudinal direction, and _L2 is the length from the lower end of the smartphone 100 to the photoplethysmographic sensor 121. In addition, N ₁ is the vertical force from the base 201 to the smartphone 100 , N ₂ is the force that the fingertip F presses the photoplethysmogram sensor 121 (the force that the fingertip F pushes up the smartphone 100 ), and E is the elasticity due to the coil spring 203 exemplify power. m exemplifies the mass of the smartphone 100. Further, the angle θ is an example of the angle formed between the base 201 and the smartphone 100, as in FIG.

FIG. 7 is a diagram illustrating the state of the blood pressure measuring device according to the embodiment at the time of starting blood pressure measurement. In the state illustrated in FIG. 7, the smartphone 100 is supported by the fingertip F so that the length of the coil spring 203 is the natural length. In other words, in the state shown in FIG. 7, the photoplethysmographic sensor 121 is pressurized by the fingertip F so that the length of the coil spring 203 becomes the natural length. That is, in the state shown in FIG. 7, the coil spring 203 has its natural length, so the elastic force E is zero.

In FIG. 7, since the moments in the rotational direction around the lower end of the smartphone 100 as the central axis are balanced, the following equation (1) holds true.

According to the above equation (1), the force N ₂ with which the fingertip F presses the photoplethysmographic sensor 121 is determined by the following equation (2).

When blood pressure is measured by the blood pressure measuring device 500, blood pressure is measured by the oscillometric method by pressurizing the photoplethysmographic sensor 121 with the fingertip F from the state shown in FIG. In the blood pressure measuring device 500, the smartphone 100 is rotatably supported by the auxiliary stand 200, so when the fingertip F presses the photoplethysmographic sensor 121, the smartphone 100 rotates in accordance with the pressing force. FIG. 8 is a diagram illustrating a state in which the smartphone is rotated by Δθ from the state in FIG. 7 in the embodiment. In FIG. 8, since the moments in the rotational direction around the lower end of the smartphone 100 as the central axis are balanced, the following equation (3) holds true.

According to the above equation (3), the force N ₂ with which the fingertip F presses the photoplethysmographic sensor 121 is determined by the following equation (4).

In equation (4), the elastic force E of the coil spring 203 is calculated by the following equation (5), assuming that the spring constant of the coil spring 203 is k, and the displacement of the coil spring 203 when the smartphone 100 is rotated by Δθ is ΔX. It is determined.

Here, the mass m of the smartphone 100 is 0.15 kg, the gravitational acceleration g is 9.8 kg/s ² , the length L in the longitudinal direction of the smartphone is 0.15 m, and the length from the lower end of the smartphone 100 to the photoplethysmographic sensor 121 Assume that the length L ₂ is 0.12 m and the spring constant k of the coil spring 203 is 70 N/m. For example, if the coil spring 203 is at its natural length when the angle θ is 15 degrees, the force N ₂ with which the fingertip F presses the photoplethysmographic sensor 121 is determined by the above equation (2) as shown in the following equation (6). determined.

Furthermore, when the photoplethysmographic sensor 121 is pressurized with the fingertip F so that the angle θ becomes 15 degrees to 20 degrees (so that Δθ becomes 5 degrees), the elastic force E of the coil spring 203 is calculated by the above formula (5 ) is determined as shown in the following equation (7).

When the photoplethysmographic sensor 121 is pressurized with the fingertip F so that the angle θ is from 15 degrees to 20 degrees (so that Δθ is 5 degrees), the force applied to the fingertip F is expressed by the above formula (4). is determined as shown in the following equation (8).

Furthermore, when the photoplethysmographic sensor 121 is pressurized with the fingertip F so that the angle θ changes from 15 degrees to 45 degrees (so that Δθ becomes 30 degrees), the elastic force E of the coil spring 203 is calculated by the above formula (5 ) is determined as shown in the following equation (9).

When the photoplethysmographic sensor 121 is pressurized with the fingertip F so that the angle θ is from 15 degrees to 45 degrees (so that Δθ is 30 degrees), the force applied to the fingertip F is expressed by the above formula (2). is determined as shown in the following equation (10).

According to equations (6) and (10), when the angle θ is changed from 15 degrees to 45 degrees, the force that the coil spring 203 applies to the fingertip F changes from 91 g to 690 g. If the elastic force of the coil spring 203 changes linearly in this range as illustrated in FIG. 9, the force applied to the fingertip F will increase by 0.2 N (20 g) each time the angle θ increases by 1 degree. By employing the coil spring 203 in the blood pressure measuring device 500, the elastic force of the coil spring 203 can compensate for the insufficient pressure for blood pressure measurement by the oscillometric method when the photoplethysmographic sensor 121 is only pressurized by the fingertip F.

Here, the guide unit 12 may display a guide screen on the display 113 that guides whether the pressure applied by the fingertip F is in accordance with the pressure pattern based on the tilt of the smartphone 100 detected by the tilt sensor 123. good. FIG. 10 is a diagram showing an example of a guidance screen displayed by the guidance section in the embodiment. FIG. 10(a) illustrates a guide screen that guides measurement preparation. On the guidance screen that guides measurement preparation, the user is instructed to press the photoplethysmographic sensor provided on the back of the smartphone 100 with the fingertip F and lift the smartphone 100 with the fingertip F to a position where the coil spring 203 has its natural length. Along with the guide text, an arrow image that schematically shows the angle of the smartphone 100 at the time of starting the measurement is displayed. When the angle of the smartphone 100 reaches the angle at the start of measurement, the guide unit 12 displays a guide screen for guiding the start of measurement, as illustrated in FIG. 10(b).

(c) and (d) of FIG. 10 illustrate guidance screens that guide the user during measurement. The guidance screen illustrated in FIGS. 10(c) and 10(d) schematically shows the position of the smartphone 100 that rotates according to the pressure applied by the fingertip F, and an arrow indicating a preferable position of the smartphone 100. That is, the guide unit 12 displays the guide screens illustrated in FIGS. 10(c) and 10(d) so that the pressure applied to the photoplethysmographic sensor 121 by the fingertip F follows the pressure pattern. invite. The person to be measured applies pressure to the photoplethysmographic sensor 121 with the fingertip F in accordance with a pressurization pattern preferable for blood pressure measurement by rotating the smartphone 100 so as to match the position of the arrow on the guide screen. It becomes easier to do. When the angle of the smartphone 100 reaches the angle at the end of the measurement, the guide unit 12 displays a guide screen for guiding the end of the measurement, as illustrated in FIG. 10(e).

The blood pressure measuring device 500 stores the correspondence relationship between the angle detected by the tilt sensor 123 and the appropriate pressure when the photoplethysmographic sensor 121 is pressurized along the pressurization pattern in the auxiliary storage section of the smartphone 100. 103 may be stored. In this case, if the appropriate pressure associated with the angle detected by the inclination sensor 123 and the pressure that pressurizes the photoplethysmographic sensor 121 detected by the pressure detection unit 11 are equal, the guide unit 12 It may be determined that the position where the photoplethysmogram sensor 121 is pressurized matches the position of the photoplethysmogram sensor 121. Furthermore, if the appropriate pressure associated with the angle detected by the inclination sensor 123 is different from the magnitude of the pressure that pressurizes the photoplethysmographic sensor 121 detected by the pressure detection unit 11, the guide unit 12 It may be determined that the position where F pressurizes and the position of the photoplethysmographic sensor 121 are shifted. When the guide unit 12 determines that the position where the fingertip F applies pressure and the position of the photoplethysmogram sensor 121 are misaligned, the guide unit 12 may guide the person to that effect.

Note that the guide unit 12 may make the determination by taking into account the error in the angle detected by the tilt sensor 123. For example, if the error of the tilt sensor 123 is ±1 degree, the elastic force E may have an error in the range of ±20 g. Therefore, the guide unit 12 sets an allowable range in consideration of this error, and makes sure that the difference between the pressure detected by the pressure detector 11 and the appropriate pressure associated with the angle detected by the tilt sensor 123 is within the allowable range. In some cases, it may be determined that the fingertip F is correctly pressurizing the photoplethysmographic sensor 121. Furthermore, if the difference between the pressure detected by the pressure detection unit 11 and the appropriate pressure associated with the angle detected by the inclination sensor 123 is outside the allowable range, the guide unit 12 detects that the fingertip F is detected by the photoplethysmogram. It may be determined that the position is deviated from the sensor 121.

11 and 12 are diagrams showing an example of a blood pressure measurement flow of the blood pressure measurement device according to the embodiment. An example of a blood pressure measurement flow of the blood pressure measurement apparatus 500 will be described below with reference to FIGS. 11 and 12.

At T1, the person to be measured attaches the smartphone 100 to the auxiliary stand 200, as illustrated in FIG. That is, the person to be measured rotatably attaches the lower end of the smartphone 100 to the support section 202 and connects one end of the coil spring 203 to the back of the smartphone 100.

At T2, the guide unit 12 of the smartphone 100 displays a guide screen on the display 113 to guide the start of measurement. For example, when the guide unit 12 receives an instruction to start blood pressure measurement from the subject, it may display a guide screen on the display 113 to guide the start of the measurement. The guidance screen for guiding the start of measurement is, for example, the screen illustrated in FIG. 10(a).

At T3, the guide unit 12 detects the angle θ between the smartphone 100 and the base 201 based on the detected value of the tilt sensor 123. If the detected angle θ is the measurement start position (YES at T4), the process proceeds to T5. If the detected angle θ is not the measurement start position (NO at T4), the process at T4 is repeated.

At T5, measurement of blood pressure by the measurement unit 13 is started. The measurement unit 13 starts acquiring the pulse wave detected by the photoplethysmogram sensor 121. The measurement unit 13 continuously acquires pulse waves until the end of the measurement at T11 in order to measure blood pressure using the oscillometric method.

At T6, the guide unit 12 displays a guide screen on the display 113 that guides the application of pressure to the photoplethysmogram sensor 121 by the fingertip F during measurement. The guidance screen for guiding pressurization is, for example, the screen illustrated in FIGS. 10(c) and 10(d). The person to be measured applies pressure to the photoplethysmographic sensor 121 with the fingertip F in accordance with the guidance screen displayed on the display 113 to guide the pressurization.

At T7, the pressure detection unit 11 detects the pressure applied to the photoplethysmogram sensor 121 based on the detected value of the pressure sensor 122. At T8, the guide unit 12 detects the angle θ between the smartphone 100 and the base 201 based on the detected value of the tilt sensor 123. Further, at T8, the guide unit 12 obtains the appropriate pressure corresponding to the angle θ based on the correspondence stored in the auxiliary storage unit 103.

At T9, the guide unit 12 determines whether the pressurization of the photoplethysmogram sensor 121 by the fingertip F is appropriate based on the pressure detected at T7 and the appropriate pressure acquired at T8. For example, if the difference between the pressure detected at T7 and the appropriate pressure acquired at T8 is within the allowable range, the guide unit 12 determines that the pressurization by the fingertip F is appropriate. Further, for example, if the difference between the pressure detected at T7 and the appropriate pressure acquired at T8 is outside the allowable range, it is assumed that the fingertip F is deviated from the photoplethysmographic sensor 121. Therefore, if the difference between the pressure detected at T7 and the appropriate pressure acquired at T8 is outside the allowable range, the guide unit 12 determines that the pressure applied by the fingertip F is not appropriate. If the pressure applied by the fingertip F is appropriate (YES at T9), the process proceeds to T10. If the pressure applied by the fingertip F is not appropriate (NO at T9), the process proceeds to T12.

At T10, the guide unit 12 determines whether the angle θ between the smartphone 100 and the base 201 is the measurement end position. The guide unit 12 detects the angle θ between the smartphone 100 and the base 201 based on the detected value of the tilt sensor 123. If the detected angle θ matches the measurement end angle stored in advance in the auxiliary storage unit 103, the guide unit 12 determines that the measurement has ended. If the measurement is completed (YES at T10), the process proceeds to T11. If the measurement is not completed (NO at T10), the process proceeds to T6.

At T11, the guide unit 12 displays a guide screen on the display 113 to guide the end of the measurement. The guide screen for guiding the end of the measurement is, for example, the screen illustrated in FIG. 10(e). Further, at T11, the measurement unit 13 calculates the blood pressure value of the subject based on pulse wave information continuously acquired from the photoplethysmographic sensor 121 from T5 to T11. The measurement unit 13 displays the calculated blood pressure value on the display 113.

At T12, the guide unit 12 displays a message on the display 113 informing that the fingertip F has shifted from the photoplethysmographic sensor 121. Thereafter, the process proceeds to T7.

<Actions and effects of embodiments>
In blood pressure measurement using the smartphone 100 equipped with the photoplethysmographic sensor 121, as in the comparative example illustrated in FIG. Another possible method is to press the However, it is very difficult to apply pressure to the photoplethysmographic sensor 121 along the pressure pattern using such a method because the force applied to the fingertip F cannot be visually confirmed. Moreover, since the photoplethysmographic sensor 121 is provided on the back of the smartphone 100, even if the fingertip F is displaced from the photoplethysmographic sensor 121, it is difficult for the person to be measured to notice the displacement of the fingertip F.

In the blood pressure measurement device 500 according to the embodiment, the smartphone 100 rotates in response to the pressurization of the photoplethysmographic sensor 121 by the fingertip F, so that the degree of pressure applied by the fingertip F can be changed depending on the rotation of the smartphone 100. It can be visually observed by the measurer. Therefore, the person to be measured can check the degree of pressure applied to the photoplethysmographic sensor 121 by the fingertip F by visually observing the rotation of the smartphone 100, and the photoplethysmographic sensor 121 is applied along the pressure pattern. It becomes easy to pressurize. Furthermore, in the blood pressure measuring device 500 according to the embodiment, the guide unit 12 displays the guide screen illustrated in FIG. It becomes even easier to pressurize.

Furthermore, in the blood pressure measuring device 500 according to the embodiment, the guide unit 12 determines whether the fingertip F is connected to the photoplethysmographic sensor based on the appropriate pressure corresponding to the inclination detected by the inclination sensor 123 and the pressure detected by the pressure sensor 122. It is determined whether or not it deviates from 121, and if it is determined that it deviates, a notification to that effect is provided. Therefore, according to the blood pressure measuring device 500 according to the embodiment, the person to be measured can easily understand that the fingertip F is displaced from the photoplethysmographic sensor 121.

In the blood pressure measuring device 500 according to the embodiment, the smartphone 100 rotates by pressurizing the photoplethysmographic sensor 121 with the fingertip F. If the smartphone 100 is simply rotated with the fingertip F in this way, there is a possibility that the pressure applied by the fingertip F will not reach a pressure suitable for the oscillometric method. In the blood pressure measurement device 500, by employing the coil spring 203, insufficient pressure can be compensated for.

<Modified example>
In the embodiment, the guide unit 12 uses guide screens illustrated in FIGS. 10(c) and 10(d) to guide the application of pressure by the fingertip F. May be omitted. That is, as described above, the blood pressure measuring device 500 according to the embodiment allows the person to be measured to check the degree of pressure applied by the fingertip F by visually observing the rotation of the smartphone 100. Therefore, even if the guide screen illustrated in FIGS. 10(c) and 10(d) is omitted, the blood pressure measuring device 500 allows pressurization to be performed in accordance with the pressure pattern more easily than in the comparative example illustrated in FIG. 13. be able to. Note that when the guidance screen illustrated in FIGS. 10(c) and 10(d) is omitted, if the pressure applied by the fingertip F does not follow the pressure pattern, the guide unit 12 displays a message to that effect on the measured object. All you need to do is output a message to guide the person.

In the embodiment, the correspondence between the angle detected by the tilt sensor 123 and the magnitude of the force expected to be applied to the fingertip F is stored in the auxiliary storage unit 103 of the smartphone 100, but this correspondence may be realized in any format. may be done. Such a correspondence relationship may be, for example, a table that associates the angle detected by the tilt sensor 123 with the magnitude of the force expected to be applied to the fingertip F on a one-to-one basis. Further, for example, such a correspondence may be a function that calculates the magnitude of the force expected to be applied to the fingertip F based on the angle detected by the inclination sensor 123.

In the embodiment, the smartphone 100 includes the tilt sensor 123, but the tilt sensor 123 may be omitted. In such a case, the guide unit 12 may determine whether or not pressurization is being performed in accordance with the pressurization pattern based on the elapsed time from the start of measurement and the pressure detected by the pressure sensor 122.

Although the blood pressure measuring device 500 according to the embodiment uses the auxiliary stand 200 that connects the coil spring 203 to the back of the smartphone 100, the auxiliary stand used by the blood pressure measuring device 500 may have other shapes. 14 and 15 are diagrams showing variations of the auxiliary stand. (a) of FIG. 14 is a perspective view of an auxiliary table according to the first modification, and (b) of FIG. 14 is a side view of the auxiliary table according to the first modification. (a) of FIG. 15 is a perspective view of an auxiliary table according to the second modification, and (b) of FIG. 15 is a side view of the auxiliary table according to the second modification. In FIGS. 14 and 15, the smartphone 100 is also illustrated so that the manner of use can be confirmed.

An auxiliary stand 200a according to a first modification illustrated in FIG. 14 includes a base 201a, a support plate 202a, and a spring hinge 203a. The base 201a and the support plate 202a are rotatably connected by a spring hinge 203a. The support plate 202a is a plate material that supports the smartphone 100. The support plate 202a includes an upper end support part 2021a that holds the upper end of the smartphone 100, and a lower end support part 2022a that supports the lower end of the smartphone 100. The support plate 202a is further provided with an opening 2023a at a position corresponding to at least the photoplethysmographic sensor 121 of the smartphone 100 supported by the support plate 202a. A coil spring is provided inside the spring hinge 203a so that an elastic force acts in the direction in which the support plate 202a and the base 201a close (towards the back of the smartphone 100 supported by the support plate 202a).

The auxiliary stand 200b according to the second modified example illustrated in FIG. 15 includes a base 201b, a support plate 202b, and a spring hinge 203b. In the auxiliary stand 200b, by making the width direction of the support plate 202b narrower than the support plate 202a of the auxiliary stand 200a according to the first modification, the fingertip F can be attached to the photoplethysmographic sensor 121 even if the opening 2023a is omitted. It can be pressurized. By narrowing the width direction of the support plate 202b, the upper end support part 2021b, the lower end support part 2022b, and the spring hinge 203b are also narrower in the width direction than the upper end support part 2021a, the lower end support part 2022a, and the spring hinge 203a of the auxiliary stand 200a. It's getting narrower. In both the auxiliary stand 200a and the auxiliary stand 200b, the spring hinge 203a and the spring hinge 203b can apply elastic force to the finger tip F like the coil spring 203 according to the embodiment. Therefore, the blood pressure measuring device 500 can also employ an auxiliary stand 200a or an auxiliary stand 200b instead of the auxiliary stand 200.

The embodiments and modifications disclosed above can be combined.

100, 100a...Smartphone 101...CPU
102... Main memory section 103... Auxiliary memory section 104... Communication section 110... Housing 111... Speaker 112... Microphone for calling 113... Display 121... Photoplethysmogram Sensors 200, 200a, 200b... Auxiliary stand 201, 201a, 201b... Base 202... Support part 202a, 202b... Support plate 2021a, 2021b... Upper end support part 2022a, 2022b... Lower end support part 2023a...Opening part 203...Coil spring 500...Blood pressure measuring device

Claims (5)

Auxiliary stand and
a plate-shaped casing whose lower end is rotatably supported by the auxiliary base with its back surface facing the auxiliary base;
a first sensor that is disposed on the back surface of the housing and acquires a pulse wave from a fingertip in contact with the first sensor;
a second sensor that is arranged to overlap with the first sensor and detects the pressure exerted by the fingertip on the first sensor;
On the back surface of the housing, one end is connected to the upper end side of the housing than the first sensor and the second sensor, the other end is connected to the auxiliary stand, and the upper end of the housing an elastic member that applies an elastic force in a direction from the back surface toward the auxiliary base to the pressing fingertip in response to rotation of the casing around the lower end in a direction away from the auxiliary base ;
a processor housed in the housing;
The processor includes:
Informing whether the detected value of the second sensor satisfies a predetermined pressurization pattern ,
measuring blood pressure based on the pulse wave acquired by the first sensor ;
Blood pressure measuring device. The processor applies pressure along the predetermined pressure pattern based on the elapsed time since the fingertip started applying pressure to the first sensor and the detected value of the second sensor. to inform you whether or not the
The blood pressure measuring device according to claim 1. The housing includes a tilt sensor that detects a tilt of the housing,
The processor determines the predetermined pressurization pattern based on the correspondence between the inclination of the casing and the appropriate pressure for pressurizing the first sensor when pressurization is performed in accordance with the predetermined pressurization pattern. Determine whether or not it satisfies
The blood pressure measuring device according to claim 1. The correspondence relationship includes a function between the inclination of the casing and the pressure that pressurizes the first sensor,
The processor determines that the predetermined pressurization pattern is not satisfied when the tilt detected by the tilt sensor and the detected value of the second sensor do not satisfy the function.
The blood pressure measuring device according to claim 3. The processor includes:
Calculating the appropriate pressure to be applied to the first sensor from the tilt detected by the tilt sensor based on the correspondence relationship,
determining that the predetermined pressurization pattern is not satisfied when the difference between the appropriate pressure and the detected value of the second sensor is outside an allowable range;
The blood pressure measuring device according to claim 3 or 4.

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