JP2006102261A - Photoelectric type sphygmomanometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sphygmomanometer for which power consumed in a light emitting element is reduced. <P>SOLUTION: In the sphygmomanometer for measuring a blood pressure by detecting pulse waves by using the light emitting element and a light receiving element, the light emitting element is made to flicker at a prescribed frequency or the light emitting level of the light emitting element is varied at the prescribed frequency. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sphygmomanometer that measures blood pressure by detecting pulsation using a photoelectric element.

  A sphygmomanometer using a photoelectric element generally belongs to the oscillometric method, and is a device that detects pulsation associated with compression and release of an artery. In a sphygmomanometer using a photoelectric element, there are methods of detecting cuff vibration caused by pulsation by the photoelectric element or detecting pulsation from a change in the amount of absorbed light due to the volume of the blood vessel. The former is called the cuff vibration method, and the latter is called the volume vibration method (see Non-Patent Document 1).

Usually, a light emitting diode (LED) or a semiconductor laser is used as the light emitting element, both of which are driven by a constant current source circuit to emit continuous light and measure blood pressure. The required drive current is, for example, several tens of mA in the case of LEDs. The components that consume the most power in the sphygmomanometer are a pump for pumping air to a cuff that compresses the artery and a valve for decompressing the exhaust gas. Therefore, the driving current of the light emitting element is comparable to these.
Kenichi Yamakoshi, et al. “Biological Sensors and Measurement Devices” pp. 44-48 Corona Corporation 2000

  In recent years, the importance of ABPM (Ambulatory Blood Pressure Measurement), which measures blood pressure throughout the day, several times a day, is being recognized rather than the conventional sporadic blood pressure measurement. The ABPM sphygmomanometer needs to be small and light enough to operate continuously for 24 hours and be portable. A sphygmomanometer using a photoelectric element is suitable for measuring the blood pressure of a peripheral artery because there is no adverse effect even if the cuff is small. Therefore, it is suitable for downsizing of the sphygmomanometer. It will be a powerful method for the total. However, due to the large driving current of the light emitting element, the battery has to be enlarged.

  That is, in the prior art, the light emitting element is driven by a DC power supply. Therefore, if the light emitting element requires power consumption equivalent to that of a pump or a valve, the method of measuring blood pressure using a photoelectric element is The power consumption is increased by about 1.5 times compared to a method of measuring blood pressure by detecting a pulse wave. In the case where the driving current of the light emitting element is 50 mA and one minute is required for one blood pressure measurement, 240 mAh is required only for the light emitting element in order to perform measurement for 24 hours at intervals of 5 minutes. Although this depends on the driving voltage, it is about 1/3 of the capacity of an ultra-small lithium ion battery mounted on a digital camera or the like. Therefore, as described above, the battery is increased in size, which is a factor that prevents the sphygmomanometer from being reduced in size.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a sphygmomanometer that reduces power consumed in a light emitting element.

  In the sphygmomanometer that measures blood pressure by detecting a pulse wave using a light emitting element and a light receiving element, the above-described problem is caused to cause the light emitting element to flash and emit light at a predetermined frequency, or to set a light emission level of the light emitting element to a predetermined level This can be solved by varying the frequency.

  The sphygmomanometer may include a function of performing PWM control on the drive circuit of the light emitting element and means for setting a duty ratio in PWM control. The blinking or light emission level fluctuation frequency may be 100 Hz or more.

  The electrical signal output from the light receiving element may be extracted at a timing synchronized with the blinking of the light emitting element or the light emission level fluctuation, and a pulse wave may be detected from the extracted signal. An electric signal output from the light receiving element may be digitized, and a pulse wave may be detected from the digitized signal.

  Furthermore, a pulse wave amplitude detecting means for detecting the amplitude of the pulse wave, and means for changing the light emission level or the light emission intensity amplitude of the light emitting element according to the magnitude of the pulse wave amplitude detected by the pulse wave amplitude detecting means. Also good. The present invention is also a program for causing a sphygmomanometer that measures blood pressure by detecting a pulse wave using a light emitting element and a light receiving element to execute processing, and the light emitting element flashes at a predetermined frequency. Or a program for causing the sphygmomanometer to execute a procedure for changing the light emission level of the light emitting element at a predetermined frequency.

  According to the present invention, since the light emitting element is caused to blink or light and dark, the driving power consumed by the light emitting element can be reduced. Therefore, the battery capacity can be reduced, and as a result, the sphygmomanometer can be downsized.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the present embodiment, in an ear-type sphygmomanometer including a light emitting element and a light receiving element, the power consumed in the light emitting element is reduced by causing the light emitting element to blink. Hereinafter, a basic configuration of the ear blood pressure monitor in the present embodiment will be described, and then a configuration for causing the light emitting element to blink and emit light will be described.

(Basic configuration of ear blood pressure monitor)
First, the structure of the auricle and the names of each part related to the description of the ear type blood pressure monitor of the present embodiment will be described with reference to the auricle structure diagram shown in FIG.

  An auricle is a so-called ear and is a general term for the entire ear shown in FIG. Each part of the auricle is referred to as a tragus 1, a tragus 2, an auricle 3, an auricle 4, an auricle 5, a leg 6, an auricle leg 7, and a concha cavity 8. In the present application, the “inner side of the tragus” refers to the side of the concha cavity 8 of the tragus 1 in FIG. “Outside of tragus” refers to the side of tragus 1 opposite to concha cavity 8 in FIG. The ear including the pinna and the external auditory canal is called the outer ear. Further, the temporal region around the auricular root is referred to as the outer ear periphery, and the “ear part” in the present specification and the claims is a part including the outer ear and the outer ear periphery. In addition, there are branch arteries under the pinna and external auditory canal, and there is a superficial temporal artery in the temporal region around the base of the pinna, especially in the surface of the skin around the tragus and extending upwards. To do. These are all useful parts for pulse wave measurement (blood pressure measurement).

  2A and 2B are diagrams showing a configuration example of the measurement unit 30 of the ear sphygmomanometer according to the present embodiment, where FIG. 2A is a front view and FIG. 2B is a plan view. 2A and 2B, 31 is a first arm, 32 is a second arm, 33 and 34 are cuffs, 35 is a support shaft, 36 is an air tube, 37 is a signal line, and 40 is a variable distance. A mechanism 41 is a rotation mechanism, and the cuff 33 accommodates a photoelectric sensor composed of a light emitting element and a light receiving element.

  The measurement unit 30 is connected to an air tube 36 for sending and exhausting air to each of the cuffs 33 and 34 and a signal line 37 for sending and receiving signals to the photoelectric sensor. The air tube 36 and the signal line 37 are connected to each other. Each passes through the first arm 31 and the second arm 32, and is drawn out to the outside at the other end. A destination connected by the air tube and the signal line is a main body in which an air supply / exhaust system and an electronic circuit system are accommodated in one casing.

  The measuring unit 30 includes a first arm 31, a second arm 32, and a support shaft 35, and one end of each of the first arm 31 and the second arm 32 is connected to the support shaft 35. In addition, the measuring unit 30 includes, for example, a portion where each of the first arm 31 and the second arm 32 is connected to the support shaft 35, or the support shaft 35, and the first arm 31 and the second arm 32 are connected to each other. A distance variable mechanism that adjusts the distance between the opposite ends is provided.

In the configuration example of the measurement unit 30 shown in FIG. 2A, the support shaft 35 and the first arm 31 are used as a variable mechanism that varies the distance between the surfaces of the first arm 31 and the second arm 32 facing each other. The first arm 31 and the second arm 32 have a function of adjusting the distance between the surfaces facing each other by changing the angle α shown in FIG. Here, the mechanism for changing the angle of the distance variable mechanism 40 may be any of a mechanism for adjusting the angle of the support shaft 35 and the first arm 31 with a screw, or a mechanism for using both friction and screw fixing. Further, as a mechanism for adjusting the distance between the other ends of the first arm 31 and the second arm 32 facing each other, a mechanism for expanding and contracting the length of the support shaft 35 may be used. 2A includes a rotation mechanism 41 that moves the first arm 31 in the rotation direction around the support shaft 35 at the connection portion between the first arm 31 and the support shaft 35. The rotation mechanism 41 has a function of varying an angle β formed by the direction of the first arm 31 and the direction of the second arm 32 as viewed from the axial direction of the support shaft 35 shown in FIG. Note that the rotation mechanism 41 is optional.
The measurement unit 30 has a function of detecting pulse wave information by bringing cuffs 33 and 34 into contact with a part of the projections of the auricle of the human body, for example, both sides of the tragus 1 of the auricle. FIG. 3 shows an example of mounting the ear blood pressure monitor on the auricle. In FIG. 3, the measurement unit 30 is attached to the tragus 1 so as to be in contact with both sides, the cuff 33 provided in the first arm 31 is outside the tragus 1, and the cuff 34 provided in the second arm 32 is the tragus 1. Mounted in contact with the inside. Since a part of the second arm 32 and the cuff 34 are inside the tragus 1, they are indicated by broken lines.

Here, when the cuffs 33 and 34 are brought into contact with both sides of the tragus 1, the distance between the cuffs is changed by the distance variable mechanism 40 to change the distance between the opposing surfaces of the first arm 31 and the second arm 32. Thus, the position of contact between the cuff 33 and the cuff 34 is adjusted to an appropriate position by changing the angle β shown in FIG. In addition, when attaching the measurement part 30 to a tragus like this example, mounting | wearing stability is bad only by pinching an tragus with the cuffs 33 and 34. FIG. Therefore, when the cuff 34 is attached in contact with the inside of the tragus 1, a sponge material or the like that substantially fills the space between the second arm 32 and the concha 3 is integrated with the back side of the second arm 32. Provided. As a result, the measurement unit 30 is supported at multiple points so that the cuff portion contacts the surface of the tragus and at the same time the sponge material fits in the concha 3, and the entire measurement unit 30 is stably attached to the ear.
As shown in FIG. 3, the main body section detects a pressure part that sends air to the cuff to inflate, a decompression part that exhausts air from the inflated cuff at a constant rate and decompresses the cuff, and detects the pressure inside the cuff. An air system composed of a pressure detecting unit, a light emitting circuit for driving the light emitting element, a pulse wave circuit for detecting a pulse wave signal obtained by irradiating the light emitting element with an artery, and a control unit for controlling the pulse wave circuit are provided in one casing. It is mounted with high density and is large enough to fit into a breast pocket. The main unit further includes a display unit, a storage unit, a time management unit, and a battery.

  FIG. 4 shows an example of a photoelectric sensor installed in the cuff. As shown in FIG. 4, a light emitting element 61 and a light receiving element 62 are installed on the surface where the cuff 33 is in contact with the tragus 1, and incident light obtained by causing the light emitted from the light emitting element 61 to enter the tragus 1 is inside the tragus 1. The scattered light 66 is received by the light receiving element 62. Here, the light receiving element 62 is installed at a position where the incident light incident on the tragus 1 from the light emitting element 61 receives the scattered light 66 scattered in the tragus 1.

  With such a light emitting / receiving element pair, it is possible to detect a waveform due to vascular vibration generated in conjunction with expansion / contraction of the heart, a so-called pulse wave. Then, in the process of detecting the pulse wave, the tragus 1 is pressed by the cuffs 33 and 34, and the blood flow of the blood vessel is gradually reduced from the state where the blood flow of the blood vessel is stopped. If the pulse wave corresponding to the pulsation of the blood vessel is measured as a pulse wave signal, the blood pressure can be measured from the pulse wave signal.

  In FIG. 4, the light emitting element 61 and the light receiving element 62 are not necessarily set on the expansion surface of the cuff 33, but by fixing the light emitting element 61 and the light receiving element 62 on the expansion surface of the cuff 33, When the pressure is applied to the tragus 1 by inserting air into the tragus 1 and when the pressure applied to the tragus 1 is reduced by removing the air from the cuff 33 and the cuff 34, the cuff 33 and the light emitting element 61, and the cuff 55 and the light receiving element 62. Since the positional relationship between the cuff 34, the light emitting element 61, and the light receiving element 62 is stabilized, the pulse wave is detected with higher accuracy, and the blood pressure is measured more accurately from the detected pulse wave. can do.

  In FIG. 4, a pair of a light emitting element and a light receiving element is arranged in the cuff 33 so as to detect light scattered in the reflection direction of the irradiation light, but the light emitting element is placed in the cuff 34 in the cuff 33. A light-receiving element may be disposed in the transmission type to detect light scattered in the transmission direction of irradiation light. Further, in both types, it is possible to appropriately set the arrangement such as reversing the positions of the light emitting element and the light receiving element.

  FIG. 5 shows the relationship between the cuff pressure 74 applied by the cuffs 33 and 24, the pulse wave signal 75 corresponding to the pulsation of the blood vessel, and the blood pressure waveform 70. In FIG. 5, the blood pressure changes as a whole gently swells while showing a sawtooth waveform due to the motion of the heart as indicated by the blood pressure waveform 70. The blood pressure waveform 70 is shown for explaining the principle of blood pressure measurement, and can be measured by a precise blood pressure measuring instrument inserted into the blood vessel.

  The cuff pressure 74 shown in FIG. 5 is obtained by gradually removing air from the cuff from a state in which air is inserted into the cuff and pressure is applied to the tragus 1 so that the blood flow is stopped. It shows how the cuff pressure is gradually reduced over time. FIG. 5 shows the pulse wave waveform measured as the pulse wave signal 75 in the process of decreasing the cuff pressure 74. As shown in FIG. 5, when the cuff pressure 74 is sufficiently high, the blood flow stops and the pulse wave signal 75 hardly appears. However, as the cuff pressure 74 decreases, the pulse wave signal 75 becomes a small triangle. Appears as a wavy waveform. The point in time when the pulse wave signal 75 appears is shown as S1 point 76. Further, when the cuff pressure 74 is lowered, the amplitude of the pulse wave signal 75 increases and reaches the maximum value at the point S 2 77. Further, when the cuff pressure 74 is lowered, the amplitude of the pulse wave signal 75 gradually decreases, and then the upper end becomes a constant value and shows a flat state. After a slight time delay, the lower end of the pulse wave signal 75 Is also converted to a constant value, but the point in time at which the value at the lower end of the pulse wave signal 75 changes to a constant value is indicated by S3 point 78. In the above process of decreasing the cuff pressure 74, the value of the cuff pressure 74 corresponding to the S1 point 76 is the maximum blood pressure 71, the value of the cuff pressure 74 corresponding to the S2 point 77 is the average blood pressure 72, and S3 It is known that the value of the cuff pressure 74 corresponding to the point 78 is the minimum blood pressure 73.

  As described above, the pulse wave signal 75 changes and shows a unique shape in the process of reducing the cuff pressure 74 from a pressure high enough to stop blood flow in the blood vessel. If the shape of the pulse wave signal 75 corresponding to is stored, it is determined from the pulse wave signal 75 measured at an arbitrary time point which position between the maximum blood pressure and the minimum blood pressure corresponds to the blood pressure value at the time of measurement. can do. The pulse wave signal 75 shows particularly remarkable waveform changes at the S1 point 76 corresponding to the maximum blood pressure 71, the S2 point 77 corresponding to the average blood pressure 72, and the S3 point 78 corresponding to the minimum blood pressure 73. It is also possible to memorize the characteristics of the waveform changes and to measure the blood pressure from the characteristics of the waveform changes. For example, when the cuff pressure 74 is controlled so that the pulse wave signal 75 always has the maximum value when the S2 point 77 corresponding to the average blood pressure 72 having the maximum amplitude of the pulse wave signal 75 is measured, The mean blood pressure 72 can be measured. Based on the same principle, it is possible to continuously measure the maximum blood pressure 71 and the average blood pressure 72. The above is an example in which the systolic blood pressure and the systolic blood pressure are obtained by detecting the volume pulse wave by the photoelectric sensor.

  Further, as the ear sphygmomanometer in the present embodiment, in addition to the ear sphygmomanometer that measures blood pressure by sandwiching a part of the auricle with the arm as described above, a measuring unit is provided in the external auditory canal as shown in FIG. An ear-type sphygmomanometer may be inserted. The measurement part of the sphygmomanometer shown in FIG. 1 includes a hollow frame 15, a holding part 16 that holds the hollow frame 15 in the ear canal, and a sensing part 17 attached to the hollow frame 15. FIG. 6 shows a state in which the holding portion 16 is attached to the outer ear 11. In the production of the holding portion, for example, the shape of the outer ear 11 and the ear canal 12 of the measurement subject is molded with a polymeric resin impression material or the like, and the entire shape is made with, for example, a silicone resin based on this mold. A hollow portion for securing a passage is cut out to form a frame 15 and a sensing unit 17 is installed. The sensing unit includes a light emitting element 171, a light receiving element 172, and a pressure generating mechanism 173, and is connected to the main body as shown in FIG. 3 by an air tube, a signal line, or the like. In this sphygmomanometer, blood pressure is measured by pressing an artery of the ear canal. The principle of measuring blood pressure is the same as that of the sphygmomanometer shown in FIG.

  Moreover, as shown in FIG. 7, you may provide the suspension part 18 which suspends the holding | maintenance part 16 to the outer ear 11. As shown in FIG. The shape of the suspension portion 18 may be a shape that surrounds the auricle 10 toward the back of the head as shown in FIG. 7A, or a shape that surrounds the face side of the auricle 10 as shown in FIG. It may be circular or linear.

  Further, instead of providing the main body and the measurement unit separately in each of the above-described ear-type blood pressure monitors, as shown in FIG. 8, the main body and the measurement unit can be configured integrally. In this case, an air tube that connects the main body and the measurement unit is not necessary. FIG. 8 shows an example of a type that is inserted into the ear canal. However, the blood pressure monitor shown in FIG. 3 can be configured such that the main body unit and the measurement unit are integrated by attaching the main body unit to the arm. Is possible.

(Reducing power consumption of light emitting elements)
Next, a configuration for reducing the power consumption of the light emitting element in the ear blood pressure monitor will be described. In the embodiment described here, the power consumption of the light emitting element is reduced by blinking light emission or changing the light emission level (brightness / darkness fluctuation). The human pulse is about 0.5 Hz to 1.5 Hz at rest, although there are individual differences. On the other hand, in a normal electronic sphygmomanometer, the A / D converted pulse wave signal is digitally processed by a microprocessor (MPU). Therefore, the pulse wave data stored in the MPU is sampling data stored at a certain time interval. The sampling frequency may theoretically be at least 10 times the pulse wave frequency, but is generally implemented at about 100 Hz (10 msec interval). Therefore, for example, if a correct pulse wave signal can be detected in synchronization with the sampling timing, the light emitting element does not need to emit light continuously, and only needs to emit light when necessary. Thus, it can be seen that a pulse wave signal necessary for blood pressure calculation can be obtained while the light emitting element is caused to blink. In each of the following embodiments, a specific configuration for obtaining a pulse wave signal necessary for blood pressure calculation while causing the light emitting element to blink and emit light will be described.

  For example, when the light emitting element is made to emit light with a rectangular PWM (Pulse Width Modulation) signal, the current consumption is almost equal to the duty ratio (one pulse width) compared to DC light emission. The ratio of the H level portion to the ratio) times. That is, if the ratio of light emission to extinction is 1: 9, the current consumption is about 1/10 of continuous driving. This relationship does not depend on the PWM drive frequency.

(Example 1)
FIG. 9 shows a block diagram of a portion related to light emission and light reception in the sphygmomanometer of the first embodiment. The configuration shown in FIG. 9 includes a light emitting element driving circuit 80, a light emitting element 81, a light receiving element and photoelectric conversion circuit 82, and a filter circuit / amplifier circuit 83.

  In the configuration shown in FIG. 9, a pulse signal having a frequency f of 100 Hz or higher and a duty ratio d is input to the light emitting element driving circuit 80, and the light emitting element driving circuit 80 causes the light emitting element 81 to emit pulses. The light received by the light receiving element 82 is converted into an electric signal by photoelectric conversion, and is input to the filter circuit / amplifier circuit 83. The waveform is appropriately shaped and amplified, and the pulse wave signal is converted into a control unit (for example, a microprocessor (MPU), hereinafter). The control unit will be described as an MPU). Then, the MPU determines the blood pressure value based on the input pulse wave signal. As in this embodiment, driving the light emitting element at a frequency sufficiently faster than Shannon's theorem with respect to the maximum frequency of the pulse wave signal means that the pulse wave signal is quantized by a sample and hold circuit, and a PAM wave (Pulse Amplitude This is equivalent to (Modulation). Therefore, if the filter circuit is a low-pass filter or a band-pass filter suitable for the pulse wave frequency and f is sufficiently large, an analog signal equivalent to that of continuous light can be obtained as an output signal.

  In each embodiment, in order to cause the light emitting element to blink and emit light, a drive signal supplied from the MPU to the light emitting circuit (light emitting element driving circuit) is controlled. The light emitting element drive circuit supplied with the drive signal changes the light emission level of the light emitting element in accordance with the drive signal. The fluctuation of the light emission level is a pulse, for example, a rectangular wave pulse. As described above, the blinking control and the pulse wave signal calculation are performed by the same MPU.

  The drive signal is, for example, a PWM signal as described above, and its duty ratio can be appropriately changed by setting. For example, a duty ratio is input from an operation unit provided in the main body, the duty ratio is stored in a storage unit, and a control unit (MPU) generates and outputs a drive signal by referring to the duty ratio. The duty ratio can be set.

  Further, the light emitting element may not be “flashing” but may be changed in intensity of light emission. In this case, the intensity of the light emission level is repeated at a predetermined cycle according to the drive signal.

(Example 2)
FIG. 10 is a block diagram of a portion related to light emission and light reception in the sphygmomanometer according to the second embodiment. 10 includes a light emitting element driving circuit 80, a light emitting element 81, a light receiving element and photoelectric conversion circuit 82, a sample / hold circuit 84, and a filter circuit / amplifier circuit 83. In the configuration shown in FIG. 10, the light emitting element and the sample and hold circuit (SH circuit) 84 are driven by a signal synchronized by the MPU to extract a pulse wave signal.

  FIG. 11 shows the concept of pulse wave signal waveform extraction in the second embodiment. In the example of FIG. 11, a phototransistor 85 is used as a specific example of the light receiving element, and a pulse wave signal is extracted from the output signal of the phototransistor by the amplifier circuit 86 with an S−H function. As shown in FIG. 11, the voltage of each pulse signal after photoelectric conversion is sampled and held by a sample and hold circuit 86 driven by a signal synchronized with the light emitting element drive signal, whereby a pulse wave is extracted. I understand that.

  In this embodiment, a sample and hold circuit is used and driven by a signal synchronized with the light emitting element drive signal. Therefore, an accurate pulse wave signal is extracted even if the emission frequency f is lower than that in the first embodiment. Is possible.

(Example 3)
In FIG. 12, the block diagram of the part which concerns on light emission and light reception in the blood pressure meter of Example 3 is shown. In this embodiment, an A / D conversion circuit 87 is provided as shown in FIG. 12, and a signal after photoelectric conversion is input to the A / D conversion circuit 87 and digitized (quantized) in the A / D conversion circuit 87. The digital signal is output to the MPU (or digital signal processor (DSP)), and the MPU (or digital signal processor (DSP)) performs digital operations such as amplification and filtering to generate a pulse wave. Extract ingredients. The A / D conversion circuit 87 is driven in a cycle synchronized with the light emitting element drive signal.

  Alternatively, the A / D conversion circuit 87 is driven at a frequency sufficiently faster than the light emitting element driving frequency without synchronizing the A / D conversion circuit 87 with the light emitting element driving signal. Here, the sufficiently fast frequency is equal to or higher than the Nyquist frequency, but is not equal to or higher than twice the light emitting element driving frequency, but is equal to or higher than twice the maximum frequency of the frequency component included in the driving signal. That is, instead of extracting a pulse wave signal at the stage of A / D conversion from the photoelectric signal pulsed by pulse driving, the pulse waveform itself is completely extracted and filtered at the stage of digital signal processing in the MPU or the like. Amplification operation is performed to extract the pulse wave.

(Example 4)
In this embodiment, the amplitude of a pulse wave signal obtained before blood pressure measurement, that is, before cuff pressure application is detected, and from the result, a) the level of the light emitting element drive signal or Amplitude, b) The gain of the photoelectric conversion circuit is adjusted.

  As shown in FIG. 5, in the blood pressure measurement process, the pulse wave amplitude becomes maximum when the cuff pressure becomes equal to the average blood pressure. The amplitude of the pulse wave signal must not exceed the range that can be handled by the circuit. If the amplitude of the pulse wave signal is too small, the accuracy of blood pressure measurement is deteriorated. Therefore, for example, when the maximum level of the pulse wave amplitude is 2V, the amplitude before pressure application is set to 0.5V. Since these values vary depending on the measurement site of the human body and individual differences, it may be obtained empirically, or the maximum amplitude level is detected when the cuff pressure is increased, and the circuit is adjusted before the cuff pressure is reduced. May be.

  FIG. 13 shows a configuration example for detecting the maximum amplitude level and feeding it back to the light emission and light reception circuits. In the example of FIG. 13, the light emitting element driving circuit, the light emitting element, the light receiving element, the photoelectric conversion circuit, the filter circuit / amplifier circuit have the same configuration as that shown in FIG. 9, and the maximum amplitude level is detected in this embodiment. For this purpose, a pulse wave amplitude detector 88 is added.

  In the configuration of FIG. 13, the MPU is notified of the maximum amplitude level detected by the pulse wave amplitude detector 88, and the MPU controls the light emitting element driving circuit or the photoelectric conversion circuit according to the maximum amplitude level.

  Specifically, if it is a light emitting element driving circuit (FIG. 14A), the level and amplitude of the driving signal are adjusted. In the case of a photoelectric conversion circuit, an analog switch 89 is provided as shown in FIG. 14B, and a resistance selection signal is input to the analog switch to select an appropriate resistance value of the photocurrent-voltage conversion resistor. To do. For example, if a large resistance value is selected, the photoelectric conversion gain increases. Of course, you may use these together.

  Since this embodiment causes the light emitting element to emit light at an appropriate pulse level, it is also effective in reducing power consumption.

  By using the methods described so far, the light emitting element driving current in the photoelectric sphygmomanometer can be greatly reduced, and when driven by a battery, the battery size and weight can be reduced. This makes it possible to reduce the size and weight of a sphygmomanometer that must always be carried, such as a 24-hour sphygmomanometer, and to improve the portability. In addition, when combined with an ear sphygmomanometer whose sensor part is extremely small, the advantages of the ear sphygmomanometer can be demonstrated to the maximum, and both 30 million and 40 million hypertensive patients in Japan It can contribute to the reduction, and in the future, it can contribute to the prevention of lifestyle-related diseases, so it is possible not only to reduce the burden of health insurance premiums but also to support the healthy lifestyle of the people. The present invention is not limited to the ear-type blood pressure monitor, and can be effectively applied to any blood pressure monitor as long as the blood pressure monitor requires a reduction in size and weight.

  In addition, you may implement | achieve the process of the main-body part in embodiment described so far using a program. In this case, the program is stored in the storage unit, and the control unit (corresponding to the CPU of the computer) executes the program to control the operation of the light emission drive circuit and extract the pulse wave signal described so far. A process for calculating the blood pressure value is executed. For example, the program is stored in a readable / writable memory, and is executed in the main body by setting the memory in the sphygmomanometer. In addition to the above, a floppy (registered trademark) disk, a CD-ROM, or the like can be used as a recording medium for storing the program.

  The present invention is not limited to the above-described embodiments, and various modifications and applications can be made within the scope of the claims.

It is a structural diagram of the auricle. It is a figure which shows the structural example of the measurement part 30 of an ear | style blood pressure meter. It is a figure which shows the example of mounting | wearing with the auricle of this ear-type blood pressure monitor, and the structure of a main-body part. It is a figure which shows an example of the photoelectric sensor installed in a cuff. It is a figure which shows the relationship between the cuff pressure 74, the pulse wave signal 75 corresponding to the pulsation of the blood vessel, and the blood pressure waveform 70. It is a figure which shows the other example of the measurement part of an ear | style blood pressure meter. It is a figure which shows the example of the holding | maintenance part of a measurement part. It is a figure which shows the example at the time of uniting a measurement part and a main-body part. It is a block diagram of the part which concerns on light emission and light reception in the sphygmomanometer of Example 1. FIG. It is a block diagram of the part which concerns on light emission and light reception in the blood pressure meter of Example 2. FIG. It is a conceptual diagram of the pulse wave signal waveform extraction in Example 2. It is a block diagram of the part which concerns on light emission and light reception in the blood pressure meter of Example 3. FIG. This is a configuration example for detecting the maximum amplitude level and feeding back to the light emission and light reception circuits. It is a figure for demonstrating light emission level adjustment and gain adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tragus, 2 Pairs, 3 Conchas, 4 Pairs, 5 Collars, 6 Collars, 7 Collars, 8 Conchasal cavity 31 First arm, 32 Second arm, 33, 34 Cuff 35 support shaft, 36 air tube, 37 signal line, 40 distance variable mechanism, 41 rotating mechanism, 61 light emitting element, 62 light receiving element 10 pinna, 11 outer ear, 12 ear canal, 15 frame, 16 holding part, 17 sensing part, 18 Suspension part 80 Light emitting element drive circuit, 81 Light emitting element, 82 Light receiving element and photoelectric conversion circuit, 83 Filter circuit / amplifier circuit, 84 Sample hold circuit, 85 Phototransistor, 96 Amplification circuit with SH function, 87 A / D conversion circuit, 88 pulse wave amplitude detector

Claims (32)

In a sphygmomanometer that measures blood pressure by detecting a pulse wave using a light emitting element and a light receiving element,
A sphygmomanometer, wherein the light emitting element is caused to blink at a predetermined frequency, or the light emission level of the light emitting element is varied at a predetermined frequency.   The sphygmomanometer according to claim 1, further comprising a control unit configured to control the blinking or light emission level fluctuation caused by the light emitting element to be a rectangular wave pulse.   The sphygmomanometer according to claim 2, wherein the control unit has a function of performing PWM control on a drive circuit of the light emitting element, and includes a unit that sets a duty ratio in PWM control.   The sphygmomanometer according to any one of claims 1 to 3, wherein a frequency of the blinking or the fluctuation of the light emission level is 100 Hz or more.   The electrical signal output from the said light receiving element is extracted at the timing synchronized with the timing of the blink of the said light emitting element or the light emission level, and a pulse wave is detected from the extracted signal. The blood pressure monitor according to item.   The sphygmomanometer according to any one of claims 1 to 3, wherein an electric signal output from the light receiving element is digitized and a pulse wave is detected from the digitized signal.   A pulse wave amplitude detecting means for detecting the amplitude of the pulse wave, and means for changing the light emission level or the intensity of the light emission intensity according to the magnitude of the pulse wave amplitude detected by the pulse wave amplitude detecting means. Item 7. The blood pressure monitor according to any one of Items 1 to 6.   The sphygmomanometer according to any one of claims 1 to 7, wherein the sphygmomanometer is an ear sphygmomanometer that measures blood pressure by pressing a part of blood vessels in an ear.   The ear sphygmomanometer has two arms each having a cuff, the blood pressure is measured by sandwiching a part of the ear part between the two arms and pressing a part of the blood vessel of the ear part by the cuff. Item 9. The blood pressure monitor according to Item 8.   The sphygmomanometer according to claim 8, wherein the ear sphygmomanometer has a shape suitable for attachment to the outer ear or the ear canal, and includes a sensing unit for measuring blood pressure by pressing a blood vessel in the ear canal.   The sphygmomanometer according to claim 8, wherein a part of the ear part is a part of the outer ear.   The sphygmomanometer according to claim 11, wherein a part of the outer ear is a part of an auricle.   The sphygmomanometer according to claim 12, wherein a part of the pinna is a tragus.   The sphygmomanometer according to claim 11, wherein a part of the outer ear is an ear canal.   The sphygmomanometer according to claim 8, wherein a part of the ear is around the outer ear.   The sphygmomanometer according to claim 15, wherein the periphery of the outer ear is a temporal region around the base of the auricle. The sphygmomanometer according to claim 16, wherein the temporal region around the base of the auricle is the temporal region around the tragus.
A method of controlling a sphygmomanometer in a sphygmomanometer that measures blood pressure by detecting a pulse wave using a light emitting element and a light receiving element,
A method comprising the steps of causing the light emitting element to flash and emit light at a predetermined frequency, or changing a light emission level of the light emitting element at a predetermined frequency.   The method according to claim 18, wherein the step includes a control step of controlling the sphygmomanometer so that the blinking or light emission level fluctuation by the light emitting element becomes a pulse of a rectangular wave.   The method according to claim 19, wherein the control step includes a step of PWM control of a drive circuit of the light emitting element.   21. The method according to any one of claims 18 to 20, wherein a frequency of the blinking or emission level fluctuation is set to 100 Hz or more.   21. The method according to claim 18, further comprising: extracting an electrical signal output from the light receiving element at a timing synchronized with a blinking timing of the light emitting element or a light emission level, and detecting a pulse wave from the extracted signal. The method according to any one of the above.   21. The method according to claim 18, further comprising the step of digitizing an electrical signal output from the light receiving element and detecting a pulse wave from the digitized signal.   A pulse wave amplitude detecting step for detecting the amplitude of the pulse wave, and further changing the emission level of the light emitting element or the amplitude of the emission intensity according to the magnitude of the pulse wave amplitude detected by the pulse wave amplitude detecting step. 24. A method according to any one of claims 18 to 23. A program for causing a sphygmomanometer to measure blood pressure by detecting a pulse wave using a light emitting element and a light receiving element,
A program for causing the sphygmomanometer to execute a procedure for causing the light emitting element to blink and emit light at a predetermined frequency, or to change the light emission level of the light emitting element at a predetermined frequency.   26. The program according to claim 25, wherein the sphygmomanometer is caused to execute the procedure so that the blinking or light emission level fluctuation by the light emitting element becomes a pulse of a rectangular wave.   27. The program according to claim 26, wherein the processing is performed by PWM control of a drive circuit of the light emitting element.   The program according to any one of claims 25 to 27, wherein the frequency of the blinking or the change in the light emission level is set to 100 Hz or more.   The sphygmomanometer executes a procedure for extracting an electrical signal output from the light receiving element at a timing synchronized with a blinking timing of the light emitting element or a light emission level, and detecting a pulse wave from the extracted signal. The program according to any one of 25 to 27.   The program according to any one of claims 25 to 27, wherein the electrical signal output from the light receiving element is digitized, and the procedure for detecting a pulse wave from the digitized signal is executed by the sphygmomanometer.   A procedure for causing the sphygmomanometer to perform a pulse wave amplitude detection procedure for detecting a pulse wave amplitude, and changing a light emission level or a light emission intensity amplitude of the light emitting element according to the detected pulse wave amplitude. The program according to any one of claims 25 to 30, wherein the program is executed.   32. A computer-readable recording medium on which the program according to any one of claims 25 to 31 is recorded.

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