JP2009247679A - Pulse wave detection method and pulse wave detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse wave detection method and a pulse wave detector for obtaining desired pulse wave information without being influenced by a temperature condition. <P>SOLUTION: A pulse wave detection method for receiving light that has transmitted a finger out of light emitted toward the finger by a light emitting part 11 or light reflected by the finger at a light receiving part 12, converting the received light into an electric signal, and amplifying the electric signal by an amplifying part 14 to detect a pulse wave is provided with a table 40 which measures at least either a finger temperature or ambient temperature and associates the temperature with either the amount of light emitted from the light emitting part, light reception sensitivity of the light receiving part or the amplification degree of the received electric signal. The table is prescribed so that the lower the temperature is, the larger a light emitting amount becomes and the higher the light reception sensitivity and the amplification degree become. One of the light emitting amount, light reception sensitivity, or the amplification degree corresponding to the temperature is adopted with reference to the table to detect the pulse wave. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pulse wave detection method and a pulse wave detection device.

Conventionally, a pulse wave detection device capable of detecting and displaying pulse wave information such as a pulse wave and a pulse rate is known. The pulse wave detection device irradiates light toward a finger surface from a light emitting unit configured by, for example, an LED (Light Emitting Diode) or the like, while PD reflects light reflected from a finger (blood vessel) or transmitted through the finger. By receiving light with a light receiving unit configured by (Photo Diode) or the like, a change in blood volume can be detected as a change in the amount of received light, and a pulse wave or a pulse rate can be detected based on the detection result ( For example, see Patent Document 1).
JP-A-9-108192

  By the way, when it is going to detect the pulse wave of a fingertip using the pulse wave detection apparatus of the patent document 1 mentioned above, the blood vessel (fingertip) (temperature of a fingertip (body temperature) or the surrounding temperature where a to-be-measured person is located). As the state of the capillaries) changes, the blood flow changes and the amplitude of the pulse wave changes. If the amplitude of the pulse wave changes, when the CPU provided in the apparatus uses the detected pulse wave signal for calculation, the pulse wave signal cannot be used for calculation, and desired pulse wave information can be obtained. There was no problem.

  Therefore, the present invention provides a pulse wave detection method and a pulse wave detection device that can obtain desired pulse wave information without being affected by temperature conditions.

  In order to solve the above-described problem, the pulse wave detection method according to the present invention receives light transmitted through the finger or reflected by the finger from light emitted from the light emitting unit toward the finger. In the pulse wave detection method for detecting the pulse wave by converting the received light into an electrical signal and amplifying the electrical signal, measure at least one of the temperature of the finger and the ambient temperature, and the temperature, A table that associates at least one of the light emission amount of the light from the light emitting unit, the light receiving sensitivity of the light receiving unit, and the amplification degree of the received electric signal, and the table emits light as the temperature decreases. The amount of light, the light receiving sensitivity, and the amplification degree are defined to be high, and the light emission amount corresponding to the temperature, the light receiving sensitivity, and the amplification degree are adopted with reference to the table. Shi It is characterized by detecting the pulse wave.

In the present invention, when the finger temperature or the ambient temperature is lowered, the capillary of the fingertip is contracted and the blood flow is reduced, so that the amplitude of the pulse wave is reduced, while the finger temperature or the ambient temperature is increased, This is based on the knowledge that the amplitude of the pulse wave is increased because the capillary at the fingertip is expanded and the blood flow is increased.
By configuring as described above, when detecting a pulse wave, at least one of the temperature of the finger and the surrounding temperature is measured, for example, the temperature stored in the storage unit of the pulse wave detection device, and light emission Referring to a table that associates at least one of quantity, light sensitivity, and amplification degree, pulse wave detection is performed after adopting at least one of light emission quantity, light sensitivity, and amplification degree corresponding to the temperature. By doing so, a pulse wave having a desired amplitude can be obtained.
That is, based on the above-described knowledge, the table setting values are set such that the lower the temperature, the higher the light emission amount, the light reception sensitivity and the amplification degree (the higher the temperature, the smaller the light emission amount, the light reception sensitivity and the amplification degree. Therefore, it is possible to reliably obtain pulse wave information having a desired amplitude without being affected by temperature conditions.

  In addition, the pulse wave detection device according to the present invention can receive a light emitting unit that emits light toward the finger, and light that is transmitted from the light emitting unit or reflected by the finger. A temperature sensor for measuring at least one of the temperature of the finger and the ambient temperature, the temperature detected by the temperature sensor, and the light emitting unit. A table for associating at least one of the light emission amount of the light, the light receiving sensitivity of the light receiving unit, and the amplification degree of the electric signal converted from the light detected by the light receiving unit, the lower the temperature is, the lower the temperature is The light emission amount, the light reception sensitivity, and the amplification degree are defined to be high, and based on the information in the table, a light emission amount adjustment unit that adjusts the light emission amount, and a light reception sensitivity that adjusts the light reception sensitivity Adjustment And it is characterized in that it comprises at least one of amplification degree adjusting unit that adjusts the amplification degree.

With this configuration, when detecting a pulse wave, the temperature sensor measures at least one of the temperature of the finger and the surrounding temperature. For example, the temperature stored in the storage unit of the pulse wave detection device Referring to a table that associates at least one of light emission amount, light reception sensitivity, and amplification degree, light emission after adopting at least one of light emission amount, light reception sensitivity, and amplification degree corresponding to the temperature A pulse wave having a desired amplitude can be obtained by adjusting the amount adjusting unit, the light receiving sensitivity adjusting unit, and the amplification degree adjusting unit and detecting the pulse wave.
That is, the set values of the table are defined such that the lower the temperature, the higher the light emission amount, the light reception sensitivity and the amplification degree (the higher the temperature, the smaller the light emission amount, the light reception sensitivity and the amplification degree). Therefore, it is possible to reliably obtain pulse wave information having a desired amplitude without being affected by temperature conditions.

Furthermore, in the pulse wave detection device according to the present invention, the temperature sensor accommodates the light emitting unit and the light receiving unit, and is provided on a surface of the sensor case on which the finger can be placed. It is characterized by being.
With this configuration, when a finger is placed on the sensor case in order to detect a pulse wave, the temperature of the finger can be measured by the temperature sensor substantially simultaneously. Therefore, the pulse wave can be detected after setting at least one of the light emission amount, the light receiving sensitivity, and the amplification degree based on the temperature of the finger to be detected at the time of detecting the pulse wave. As a result, a pulse wave having a desired amplitude can be obtained.

According to the pulse wave detection method of the present invention, when detecting a pulse wave, at least one of the temperature of the finger and the surrounding temperature is measured, for example, the temperature stored in the storage unit of the pulse wave detection device And a table associating at least one of light emission amount, light reception sensitivity and amplification degree, and adopting at least one of light emission amount, light reception sensitivity and amplification degree corresponding to the temperature, By detecting the wave, there is an effect that a pulse wave having a desired amplitude can be obtained.
That is, the set values of the table are defined such that the lower the temperature, the higher the light emission amount, the light reception sensitivity and the amplification degree (the higher the temperature, the smaller the light emission amount, the light reception sensitivity and the amplification degree). Therefore, there is an effect that it is possible to reliably obtain pulse wave information having a desired amplitude without being affected by temperature conditions.

  Next, an embodiment of a pulse wave detection device according to the present invention will be described with reference to FIGS.

(Pulse wave detector)
FIG. 1 is a schematic block diagram of the pulse wave detection device.
As shown in FIG. 1, the pulse wave detection device 10 receives a light emitting unit 11 that irradiates light on the finger F, and light that receives reflected light that is a part of the light emitted from the light emitting unit 11 to the finger F. Unit 12, filter unit 13 that extracts a pulse wave band from the electrical signal obtained by converting the light obtained by light receiving unit 12, and the amplitude of the waveform with respect to the signal value (waveform) that has passed through filter unit 13 An output unit 16 for displaying pulse wave information such as a pulse wave waveform from a calculation result by the CPU 15, a CPU 15 for receiving the signal from the amplification unit 14 and executing various calculations, and the like. An input unit 17 for giving various setting conditions, a storage unit 18 composed of a RAM for storing pulse wave data converted into a digital signal, a table described in detail later, and the CPU 15 Supply the clock It comprises an oscillation unit 19, a.

FIG. 2 is a side view showing a state where a finger is placed on the sensor unit.
As shown in FIG. 2, the sensor unit 21 is arranged in a box-shaped sensor case 22 and a component storage space 23 configured inside the sensor case 22, and includes a light emitting unit 11 made of, for example, an LED and a PD. A light receiving unit 12. In addition, the length along the longitudinal direction of the finger in the sensor case 22 is formed with a length substantially equal to the first joint of the finger.

  A translucent plate 26 made of a glass plate or the like is disposed on the upper surface 22a of the sensor case 22. The light emitting unit 11 and the light receiving unit 12 are attached to the component housing space 23 side of the translucent plate 26, and the finger F Can emit light and receive the reflected light. Further, a temperature sensor 31 for measuring the temperature of the finger F that detects a pulse wave is provided on the upper surface 22a of the sensor case 22. By placing the finger F on the temperature sensor 31, the temperature of the finger F can be measured.

  Returning to FIG. 1, the pulse wave detection device 10 includes a light emission amount adjusting unit 32 that adjusts the light emission amount of light emitted from the light emitting unit 11, and a light reception sensitivity that adjusts the light reception sensitivity when the light receiving unit 12 receives light. An adjustment unit 33 and an amplification degree adjustment unit 34 that adjusts the amplification degree by which the amplitude of the waveform is increased or decreased with respect to the signal value (waveform) by the amplification unit 14 are provided.

  The storage unit 18 also has a table 40 that associates the temperature of the finger F with the amount of light emitted from the light emitting unit 11, the light receiving sensitivity received by the light receiving unit 12, and the waveform amplification level at the amplification unit 14. Stored in advance.

FIG. 3 is a schematic configuration diagram of the table 40.
As shown in FIG. 3, in the table 40, for example, when the temperature of the finger F is 30 ° C., the light emission amount, the light receiving sensitivity, and the amplification factor are set to 1. That is, when the temperature of the finger F is 30 ° C., the CPU 15 receives the signal (waveform) obtained through the filter unit 13 as a pulse wave signal without adjusting the light emission amount, the light receiving sensitivity, and the amplification degree. It becomes.

  When the temperature of the finger F is less than 30 ° C., the capillary of the fingertip contracts and the blood flow decreases as the temperature decreases, so the amplitude of the pulse wave decreases. Therefore, it is specified that the light emission amount, the light receiving sensitivity, and the coefficient of amplification become larger than 1 as the temperature of the finger F becomes lower.

  On the other hand, when the temperature of the finger F exceeds 30 ° C., the capillary blood vessels at the fingertip dilate and the blood flow increases as the temperature increases, and the amplitude of the pulse wave increases. Accordingly, it is specified that the light emission amount, the light receiving sensitivity, and the coefficient of amplification become smaller than 1 as the temperature of the finger F increases.

(Function)
Next, the effect | action which detects the pulse wave of a finger | toe with the pulse wave detection apparatus 10 is demonstrated.
As shown in FIG. 2, when the finger F is brought into close contact with the upper surface 22 a of the sensor case 22, the finger F comes into contact with the translucent plate 29 and is arranged to come into contact with the temperature sensor 31.

  At this time, the temperature of the finger F is measured by the temperature sensor 31. When the temperature of the finger F is measured by the temperature sensor 31, the table 40 is referred to and at least one coefficient of the light emission amount, the light receiving sensitivity, and the amplification degree corresponding to the temperature is adopted.

  For example, when adjusting the light emission amount, the light emission amount adjustment unit 32 adjusts the light emission amount based on the coefficient of the light emission amount corresponding to the temperature of the finger F, and the light emission unit 11 adjusts the light emission amount with the adjusted light emission amount. F is irradiated with light.

  Further, when adjusting the light receiving sensitivity, the light receiving sensitivity adjustment unit 33 adjusts the light receiving sensitivity based on the coefficient of the light receiving sensitivity corresponding to the temperature of the finger F, and the light receiving sensitivity after the light receiving unit 12 adjusts the light receiving sensitivity. The light reflected from the finger F is received.

  Similarly, when adjusting the amplification degree, the amplification degree adjustment unit 34 adjusts the amplification degree based on the amplification factor coefficient corresponding to the temperature of the finger F, and the signal (waveform) passing through the filter unit 13 is adjusted. ), The amplitude of the waveform is adjusted using the adjusted amplification degree.

  FIG. 4 is an image diagram of the pulse wave shape obtained when the light emission amount, light reception sensitivity, and amplification degree are fixed (fixed) without using a table, and FIG. 5 is a light emission amount, light reception sensitivity, and amplification using the table. It is an image figure of the pulse wave shape obtained when the degree is adjusted. 4 and 5, the horizontal axis represents time, and the vertical axis represents the output value from the amplifying unit (only the AC component).

  As shown in FIG. 4, when all of the light emission amount, the light receiving sensitivity, and the amplification degree are fixed, when the temperature of the finger F is an appropriate temperature (for example, 30 ° C.), a pulse wave with a desired amplitude is obtained. A shape is obtained (see FIG. 4B). However, when the temperature of the finger F is low (for example, less than 30 ° C.), the capillary of the fingertip contracts and the blood flow decreases, so the amplitude of the pulse wave is small (see FIG. 4A). .

  If the amplitude of the pulse wave becomes too small in this way, the pulse wave may not be accurately recognized depending on the processing resolution of the apparatus. Further, in the case where the obtained waveform is binarized based on a certain threshold, if the amplitude is too small, binarization processing may not be performed.

  On the other hand, when the temperature of the finger F is high (for example, when it exceeds 30 ° C.), the capillary of the fingertip dilates and blood flow increases, so that the amplitude of the pulse wave is large (FIG. 4 (c) )reference).

  Thus, if the amplitude of the pulse wave becomes too large, the processing range of the apparatus may be exceeded. That is, there is a case where the top of the detected waveform of the pulse wave is crushed and an accurate pulse wave cannot be obtained.

  On the other hand, as shown in FIG. 5, at least one of the light emission amount, the light receiving sensitivity, and the amplification degree can be adjusted, and by adjusting the coefficient according to the temperature of the finger F, it is not affected by the temperature condition. It becomes possible to obtain pulse wave waveforms having substantially the same amplitude.

  That is, when the temperature of the finger F is low, the pulse wave amplitude is adjusted so that the pulse wave amplitude is increased by increasing the light emission amount, the light receiving sensitivity, and the amplification factor. On the other hand, when the temperature of the finger F is high, the pulse wave amplitude is adjusted so that the amplitude of the pulse wave is reduced by decreasing the light emission amount, the light receiving sensitivity, and the amplification factor.

  The light emitting amount adjustment of the light receiving sensitivity and amplification factor may be previously set or adjusted beforehand which items to be measured when measuring the pulse wave from the input unit 17 of pulse wave measuring device 10 The user may input and set. Further, only one or two of the light emission amount, the light receiving sensitivity, and the amplification degree may be adjustable, or all items may be adjustable. That is, it is only necessary to adjust at least one of the light emission amount, the light receiving sensitivity, and the amplification degree so that a pulse wave having a desired amplitude can be detected.

  According to the pulse wave detection device 10 of the present embodiment, the temperature sensor 31 that measures the temperature of the finger F is disposed on the upper surface 22a of the sensor case 22, and the temperature detected by the temperature sensor 31 and the light from the light emitting unit 11 are measured. A table 40 is provided for associating the light emission amount, the light receiving sensitivity of the light receiving unit 12, and the amplification degree of the electric signal obtained by converting the light detected by the light receiving unit 12. Further, the table 40 is defined so that the light emission amount, the light receiving sensitivity, and the amplification degree are higher (larger) as the temperature of the finger F is lower, and the light emission amount is adjusted based on the information in the table 40. A light emission amount adjusting unit 32, a light receiving sensitivity adjusting unit 33 for adjusting the light receiving sensitivity, and an amplification degree adjusting unit 34 for adjusting the amplification degree are provided.

  With this configuration, when detecting the pulse wave, the temperature of the finger F is measured by the temperature sensor 31, and the temperature stored in the storage unit 18 of the pulse wave detection device 10, the light emission amount, the light receiving sensitivity, With reference to the table 40 that associates the amplification degree, at least one of the light emission amount, the light reception sensitivity, and the amplification degree corresponding to the temperature is adopted, and then the light emission amount adjustment unit 32, the light reception sensitivity adjustment unit 33, and A pulse wave having a desired amplitude can be obtained by adjusting the amplitude adjustment unit 34 and detecting the pulse wave.

  That is, the setting values of the table 40 are defined such that the light emission amount, the light reception sensitivity, and the amplification degree increase as the temperature decreases (the light emission amount, the light reception sensitivity, and the amplification degree decrease as the temperature increases). Therefore, it is possible to reliably obtain pulse wave information having a desired amplitude without being affected by temperature conditions.

  Furthermore, since the temperature sensor 31 is disposed on the upper surface 22a of the sensor case 22, when the finger F is placed on the sensor case 22 to detect a pulse wave, the temperature of the finger F can be measured by the temperature sensor 31 almost simultaneously. . Therefore, the pulse wave can be detected after setting at least one of the light emission amount, the light receiving sensitivity, and the amplification degree based on the temperature of the detection target finger F at the time of detecting the pulse wave. As a result, a pulse wave having a desired amplitude can be obtained.

  The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. That is, the specific shapes, configurations, numerical values, and the like given in the present embodiment are merely examples, and can be changed as appropriate.

For example, in the present embodiment, the case of a reflection type pulse wave detection device has been described. However, the present invention can be similarly applied to a transmission type pulse wave detection device.
In this embodiment, the temperature of the finger is measured with the temperature sensor and the amount of light emission is adjusted according to the temperature. However, the ambient temperature (air temperature) is measured with the temperature sensor, You may make it adjust the light emission amount etc. according to temperature. In this case, the appropriate temperature may be set to 25 ° C., for example, and adjusted depending on whether the temperature is lower or higher than the appropriate temperature.

It is a schematic block diagram of a pulse wave detection device in an embodiment of the present invention. It is a side view when a finger | toe is mounted in the sensor unit in embodiment of this invention. It is an image figure of the table in embodiment of this invention. It is an image figure of the output result of a pulse wave when the amount of luminescence, light reception sensitivity, and amplification degree in the embodiment of the present invention are fixed. It is an image figure of the output result of the pulse wave when adjusting the emitted light amount, the light reception sensitivity, and the amplification degree in the embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Pulse wave detection apparatus 11 ... Light emission part 12 ... Light-receiving part 22 ... Sensor case 22a ... Upper surface (surface) 31 ... Temperature sensor 40 ... Table F ... Finger

Claims (3)

Of the light emitted toward the finger from the light emitting unit, the light transmitted through the finger or the light reflected by the finger is received by the light receiving unit, and the received light is converted into an electric signal and the electric signal is amplified to obtain a pulse. In a pulse wave detection method for detecting a wave,
Measure at least one of the finger temperature and the ambient temperature,
A table that associates the temperature with at least one of the amount of light emitted from the light emitting unit, the light receiving sensitivity of the light receiving unit, and the amplification degree of the received electrical signal;
The table is defined such that the lower the temperature, the higher the light emission amount, the light receiving sensitivity and the amplification degree,
A pulse wave detection method, wherein the pulse wave is detected by referring to the table and adopting at least one of the light emission amount, the light receiving sensitivity and the amplification degree corresponding to the temperature. A light emitting unit that emits light toward the finger;
In the pulse wave detection device comprising: a light receiving unit capable of receiving light transmitted through the finger or light reflected from the finger among the light emitted from the light emitting unit;
A temperature sensor for measuring at least one of the temperature of the finger and the ambient temperature is disposed;
At least one of the temperature detected by the temperature sensor, the amount of light emitted from the light-emitting unit, the light-receiving sensitivity of the light-receiving unit, and the amplification degree of the electrical signal converted from the light detected by the light-receiving unit, It has a corresponding table,
The table is defined such that the lower the temperature, the higher the light emission amount, the light receiving sensitivity and the amplification degree,
Based on the information in the table, at least one of a light emission amount adjustment unit that adjusts the light emission amount, a light reception sensitivity adjustment unit that adjusts the light reception sensitivity, and an amplification degree adjustment unit that adjusts the amplification degree is provided. A pulse wave detection device characterized by comprising:   3. The temperature sensor according to claim 2, wherein the temperature sensor is provided on a surface of the sensor case on which the finger can be placed while housing the light emitting unit and the light receiving unit. Pulse wave detector.

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