KR100880392B1 - Method for measuring photoplethysmogram - Google Patents

Abstract

A pulse wave detecting method using a portable phone is provided to enable a user to check his/her health condition by storing pulse-based data in a memory of the portable phone and managing various data stored in the memory through software installed in the portable phone. After a skin tissue of the human body in which the blood flow is changed is located in a camera lens part(20) and a flash(10) which is adjacent to the camera lens part, the light is irradiated on the skin tissue. Data about changes in amount of light corresponding to the light irradiation and the change of the blood flow is collected by using pixels of an image sensor(22) equipped inside the camera lens part. The light change data is constructed in the type of time series data to be utilized as pulse wave data.

Description

Pulse wave detection method using a mobile phone {Method for measuring Photoplethysmogram}

The present invention relates to a pulse wave detection method using an image sensor and a flash mounted on a portable communication device.

By contracting and expanding the heart, blood is pushed along the arteries. Due to the flow of blood, the expansion and relaxation of blood vessels are repeated. This is commonly referred to as a pulse, and the pulse phenomena represented as a graph is called a pulse wave. In general, the pulse rate of adults is 60 to 80 times per minute, and the younger the age, the greater the 120 to 140 times per minute. The magnitude of the pulse is the height of the pulse wave and is related to the volume of blood released from the heart. The greater the activity of the heart, the faster blood flows to the arteries, the faster the pulse and the higher the pulse wave.

Typical methods for measuring pulse waves include recording volume changes of organs or extremities associated with cardiac output, recording impedance changes, and detecting blood flow changes in an optical manner. Of these, optical methods are frequently used because of their convenience.

Such pulse wave can clinically identify abnormalities such as heart, vascular system, pump function, and vascular hardening, and detect pulsation time intervals to determine the degree of activation of sympathetic and parasympathetic nerves. It can also be used to determine a person's stress state.

Therefore, in the related art, a pulse wave detection device has been developed to add a pulse wave detection device to a portable communication device so that the general person can easily examine such symptoms in daily life.

However, a method for detecting a pulse wave based on a conventional portable communication device was possible by separately providing a light source and a light receiving element in addition to the portable communication device.

In addition, there was a method in which a separate circuit for pulse wave detection is implemented in the battery pack, and a method of transmitting data to the mobile phone using an external connection connector of the mobile phone. It is pointed out that it is necessary to carry additional equipments and sensor cables other than mobile phones, and to increase manufacturing costs due to additional equipments and hassle of measuring process.

Accordingly, the present invention has been proposed to solve the above problems, and an object of the present invention is to detect a pulse wave without providing an additional device for measuring the pulse wave in a pulse wave detection method using a portable communication device. The present invention provides a pulse wave detection method using a mobile phone.

In addition, another object of the present invention, by storing the pulse wave-based data in the memory of the portable communication device using a mobile phone, and manages the various data stored in the memory through the software installed in the portable information communication device, the user conveniently To provide a way to manage your health status.

In addition, another object of the present invention is to detect the pulse wave by simply touching the user's finger to the mobile phone and to store the measured data in the memory of the portable information communication device, the remote server by wired / wireless communication, or The present invention provides a method that can be transferred to a computer terminal and managed by software installed in the computer terminal and can be consulted by a specialist if necessary.

Objects of the present invention as described above, in the pulse wave detection method using a portable communication device equipped with a flash and a camera lens portion, the skin tissue of the human body in which the blood flow is changed to a flash adjacent to the camera lens portion and the camera lens portion A light irradiation step of positioning and irradiating light, collecting light quantity change data according to the light irradiation and blood flow change by using pixels of the image sensor provided inside the camera lens unit, and constructing the light quantity change data as time series data It is achieved by a pulse wave detection method using a mobile phone, characterized in that it comprises the step of utilizing as pulse wave data.

According to the pulse wave detection method using a mobile phone according to the present invention, there is no need for an additional device other than the mobile phone in detecting the pulse wave, thereby reducing the manufacturing cost, and the user can easily maintain his or her health state regardless of time and place. There is an advantage to check.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the elements of each drawing, it should be noted that the same elements are denoted by the same reference numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a view showing a state of collecting the pulse wave of the subject with a mobile phone in the pulse wave detection method using a mobile phone according to an embodiment of the present invention, Figure 2 is a view showing a conventional conventional mobile phone having a camera function, 3 is a diagram illustrating an hourly index of image data generated by a lens unit of a mobile phone.

On the other hand, Figure 4 is a view showing the time series data constructed by incorporating the hourly index of Figure 3, Figure 5 is a graph showing the absorption coefficient of deoxyhemoglobin, oxyhemoglobin, water according to the frequency of light for explaining the present invention 6 is a schematic block diagram illustrating a pulse wave detection method using a mobile phone according to an embodiment of the present invention.

And, Figure 7 is a view showing an example of the pulse wave detection method using a mobile phone according to another embodiment of the present invention, when the mobile phone does not have a flash showing the state of collecting a pulse wave by providing a separate light emitting unit, 8 is a view showing an example of a pulse wave detection method using a mobile phone according to another embodiment of the present invention, it is a view showing an embodiment of detecting a pulse wave in a mobile phone that can be rotated 360 ° based on the hinge.

Preferably, the present invention provides a method for detecting a pulse wave using a portable communication device, that is, the image sensor 22 of the flash unit 10 and the camera lens unit 20 provided in the mobile phone 200.

The portable communication device may be variously selected by those skilled in the art, and an example thereof may include a mobile phone 200 equipped with the flash 10 and the camera lens unit 20 shown in FIG. 1. That is, the mobile phone 200 having the camera function and equipped with the flash 10 can be any species. However, the present invention is not limited thereto, but the camera lens unit 20 is provided, but it is shown in FIG. 7 so that the pulse wave can be detected even when there is no flash 10, which will be described below.

The mobile phone 200 having a camera function is provided with a camera lens unit 20, and the camera lens unit 20 is equipped with an image sensor 22. The type of the image sensor 22 includes a metal oxide semiconductor (MOS) or a charge coupled device (CCD), and whether the CCD or the MOS type image sensor receives light, the amount of light incident on each pixel is converted into an electrical signal. It is a device to convert. Therefore, the present invention is based on the common feature of the image sensor that the image sensor of the camera converts the amount of light incident on each pixel into an electrical signal.

With such a setting, a pulse wave detection method using a mobile phone according to the present invention will be described.

The peripheral portion of the human body (hereinafter referred to as the finger 100) is brought into close contact with the camera lens 20 and the flash 10 adjacent to the camera lens 20. Then, when the flash 10 is operated, light is irradiated to the finger 100, and the light is reflected into the pixel of the image sensor 22 provided in the camera lens unit 20 by reflecting or passing through the finger 100. .

The flash 10 usually uses white light, and white light is light having a wide frequency component in the light spectrum band. In the case of projecting white light into skin tissue, most of green light and blue color that have a high frequency of light are absorbed by blood, and red color which is a slow frequency component is relatively low in absorption. The series is shown. This will be described with reference to the graph of FIG. 5 illustrating this. Figure 5 shows the absorption coefficient according to the frequency of light ① oxyhemoglobin (OxyHb; Oxygen hemoglobin), ② DeoxyHb (DeoxyHb; deoxidation hemoglobin), ③ water.

The fact that the absorption coefficient of light at a particular frequency is large means that it absorbs a lot of light at that frequency. On the other hand, when white light is transmitted through blood, most of light having a wavelength longer than 900 nm is absorbed by water, which is a basic component of blood in FIG. 5, and light having a wavelength shorter than 700 nm is also absorbed by hemoglobin. .

Therefore, it can be seen that the region between 700 nm and 900 nm is absorbed less and the transmittance is good. For this reason, when white light is projected onto the skin tissue, most of the frequency components are absorbed by the tissues internally, and the light from the 700 nm to 900 nm frequency components is mainly transmitted. That is, the blood plays a role of filtering the frequency band. This is why the light that penetrates the skin, which is known empirically, is reddish. Most of the high frequency components (ie, blue green) are absorbed, so the components become very weak in transmitted light. We are looking at the frequency components of light that are relatively less absorbed.

If the volume of blood in the path of the skin tissue through which the light from the flash passes is constant, the amount of light transmitted is also constant because the amount absorbed is the same. However, the blood flow in the skin tissue is changing due to the heartbeat, and the blood flow in the light passing zone is also changed by the heartbeat. Since the amount of light absorbed by the change of blood flow changes in proportion to the amount of blood flow, the amount of incident light is constant, thereby reflecting the temporal dynamic characteristics of the change in the amount of light in the skin tissue during transmission.

That is, it is the relationship between the amount of transmitted light = the amount of incident light and the amount of absorbed light. When the amount of absorbed light changes in time, the amount of transmitted light appears. That is, the amount of transmitted light decreases as the blood flow increases, and the amount of transmitted light increases when the amount of blood flow decreases.

On the other hand, the flash 10 may be appropriately selected according to the purpose of application of the time the light is irradiated to the finger 100 for the image sensor 22 for detecting a change in the amount of light in accordance with the change in the blood flow flowing through the finger (100). have. For the purpose of detecting the time interval between pulses for a short time, it may be possible for at least two or three seconds when the pulse appears at least twice. On the other hand, when the purpose of detecting the pulse wave is to detect the rate of heart rate variability for the purpose of stress testing, the operation should not be stopped for more than one minute.

Here, the blood permeability measurement of the light is to measure the amount of blood flowing into the finger (that is, the volume change of the blood flow), so it is not limited to the wavelength of 660nm and 940nm for detecting oxygen saturation, which has been used in the past, The change can be detected.

On the other hand, when light having a change in the amount of light flows into the pixel of the image sensor 22, the image formed on the pixel of the image sensor 22 is a situation that the object is within the focal length of the lens, so the image is seen to be blurred, the object Shape information of the object is not secured. Since the pixel of the image sensor 22 receives the transmitted light through the finger as the subject, the change in the blood flow rate through the finger, that is, the amount of light transmitted through the pulse, can be measured.

Therefore, since the present invention aims to detect a change in the amount of light caused by a change in the blood flow rate through the finger, the blurred image is not an obstacle in achieving the object of the present invention.

Hereinafter, a process of generating pulse wave data while sampling image data will be described in detail.

The overall steps are shown in FIG. In this section, the image sensor acquires the light quantity signal from the image sensor in chronological order, and the pixel area of the image sensor It is a step of detecting a change in the amount of light. This process is shown in detail in FIG. 3. The image data for which the light quantity information of any one or more pixels is required is defined as the intensity (i, j) of the pixel width i-th and vertical j-th of the image sensor 22 as the intensity of the image sensor 22. In the microcomputer (MCU), the light quantity signal is secured and discrete sampling is performed in time. In addition, when time index n is introduced to express Intensity (i, j, n) on the time axis, time series data as shown in FIG. 4 can be obtained.

Each of the discrete data points of FIG. 4 is a signal showing the temporal change of the light transmitted through the finger to the image sensor, which corresponds to the pulse wave signal that enables the change of blood flow.

On the other hand, although the intensity (i, j, n) is the result of discrete pulse signal detection directly, the amount of light changes for each pixel according to the arrangement of the finger 100, the flash 10 and the image sensor 22 Differences can occur. That is, the width of change in the amount of light may be large at the points 1 and 2, and the change in the amount of light may be small at the points 50 and 30. In other pixels, no discriminating signal change may be observed.

Therefore, in order to detect the pulse wave signal more efficiently, the measurement is not guaranteed only by the output signal of any one pixel. Therefore, a processor is required to select a pixel having a large signal intensity from among the plurality of pixels, which is referred to as the “pixel of FIG. 6. Processor ".

For example, the pixel processing unit may select a pixel having the largest variation in the amount of light from among the pixels. That is, a method of selecting a pixel that outputs the largest change by comparing the width of the signal change between the pixels. For example, if a pixel having a width of 100 and a height of 20 has the largest change amount of light, discrete time series data of intensity (100, 20, n) is used as a pulse wave signal. Alternatively, a method of using all of the pixels in which light quantity changes occur due to light irradiation and blood flow changes may be used. Examples thereof include using an average of light amount changes of all pixels, that is, the following formula (1).

Where i is the horizontal point of the pixel, j is the vertical point of the pixel, and n is the light amount change time.

Finally, the pulse wave data generated in the above process may be stored in a memory by the pulse wave data utilization unit of FIG. 6, may be displayed on a screen, and may be transmitted using an external wired / wireless communication function of a mobile phone. It may be delivered to a signal processor for performing peak detection of waveforms, heart rate calculation per minute, and the like.

On the other hand, only a camera is built in some portable communication devices and there is no flash. In this case, as shown in FIG. 7, when a user uses a separate light emitting unit 11, a pulse wave detection environment is established. An example of the light emitting unit 11 may include a light emitting diode.

Meanwhile, the present invention compares the time series data with normal data previously stored in a microcomputer (MCU) provided in a portable communication device and outputs it to a display unit (LCD) so that the user's health state can be easily and conveniently checked. Could be.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

1 is a view showing a state of collecting the pulse wave of the subject by the mobile phone in the pulse wave detection method using a mobile phone according to an embodiment of the present invention,

2 is a view showing a conventional conventional mobile phone,

3 is a view showing a time-based index of the image data generated by the lens unit of the configuration of the mobile phone,

4 is a diagram illustrating time series data constructed by integrating the hourly indexes of FIG. 3;

Figure 5 is a graph showing the absorption coefficient of deoxyhemoglobin, oxyhemoglobin, water according to the frequency of light for explaining the present invention,

6 is a schematic block diagram illustrating a pulse wave detection method using a mobile phone according to an embodiment of the present invention;

7 is a view showing an example of a pulse wave detection method process using a mobile phone according to another embodiment of the present invention,

8 is a view showing an example of a pulse wave detection method process using a mobile phone according to another embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

10: Flash 11: Light Emitting Part

20: camera lens unit 21: lens

22: Image sensor 100: finger

200: cell phone

Claims (3)

In the pulse wave detection method using a portable communication device equipped with a flash 10 and a camera lens unit 20, A light irradiation step (S100) of placing the skin tissue of the human body whose blood flow is changed in the camera lens unit 20 and the flash 10 adjacent to the camera lens unit 20 and irradiating light; Collecting the light quantity change data according to the light irradiation and blood flow change by the pixel of the image sensor 22 provided in the camera lens unit 20, constructing the light quantity change data as time series data to use as pulse wave data To include (S200); including, The light quantity change data is made using at least one pixel having the largest change in light quantity according to light irradiation and blood flow change, or a pixel in which light quantity change occurs due to light irradiation and blood flow change calculated by the following equation. Pulse wave detection method using a mobile phone, characterized in that the overall average of the.

Where i is the horizontal point of the pixel, j is the vertical point of the pixel, and n is the light change time. delete delete

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