WO2022249907A1

WO2022249907A1 - Pulse wave measuring device

Info

Publication number: WO2022249907A1
Application number: PCT/JP2022/020288
Authority: WO
Inventors: 亨志牟田
Original assignee: 株式会社村田製作所
Priority date: 2021-05-27
Filing date: 2022-05-13
Publication date: 2022-12-01
Also published as: JPWO2022249907A1

Abstract

A pulse wave measuring device (11A) comprises: a pulse wave sensor (12) that measures pulse waves; a housing (13) containing the pulse wave sensor (12); and protruding sections (15, 15) which each have, on a housing (13) surface which is around the pulse wave sensor (12) and sandwiching the pulse wave sensor (12), a width (W) equal to or smaller than a width (W1) of the sensing section of the pulse wave sensor (12), the protruding sections protruding at an interval (L2) which is smaller than the length (L1) of the distal segment of a finger held over the pulse wave sensor (12).

Description

Pulse wave measuring device

The present invention relates to a pulse wave measuring device that incorporates a pulse wave sensor and measures a person's pulse wave.

Conventionally, as this type of pulse wave measuring device, for example, there is an arm-mounted measuring device disclosed in Patent Document 1.

This arm-mounted measuring device includes a pulse detector, electrodes for detecting electrocardiograms with which a fingertip placed on the pulse detector contacts, and a finger regulating part that regulates the orientation of the fingertip with respect to the pulse detector and the electrodes. . The finger regulating part is composed of a tip side projection part for regulating the position of the tip side of the fingertip by contacting the tip side of the fingertip, and a side projection part for regulating the position of both sides of the fingertip by contacting both side parts of the fingertip.

JP-A-2002-165768

However, in the arm-worn measuring device disclosed in the conventional patent document 1, as shown in FIG. For a person whose fingertip 4 is narrower than the space between the fingertips 4, the fingertips 4 play between the

side projections

3, 3, and the fingertips 4 become wider in the width direction between the

side projections

3, 3. It leans to one side of the direction. Therefore, there is a possibility that the protective glass 5 of the pulse detector 1 will not be completely covered with the pad of the fingertip 4 and the protective glass 5 will be partially exposed. In this case, if the size of the gap formed in the exposed portion of the protective glass 5 fluctuates due to vibration or the like, the amount of light incident on the light receiving element of the pulse detector 1 through this gap fluctuates, resulting in noise in the photoplethysmogram measurement. , which causes the waveform of the photoplethysmogram measured by the pulse detector 1 to be distorted.

Conversely, as shown in FIG. There is a possibility that the fingertip 4 may float without contacting the protective glass 5 without completely entering. Further, as shown in FIG. 1(c), if the height of the tip-side protrusion 6 that regulates the position of the tip of the fingertip 4 is high, the tip of the tip-side protrusion 6 from the side A of the tip-side protrusion 6 may reach the fingertip. , there is a possibility that the fingertip 4 will float without contacting the protective glass 5 . If the fingertip 4 is even slightly lifted from the protective glass 5 in this manner, the pulse wave detector 1 cannot accurately measure the pulse wave.

The present invention was made to solve such problems,
a pulse wave sensor that measures a pulse wave;
A housing containing a pulse wave sensor,
On the surface of the housing around the pulse wave sensor sandwiching the pulse wave sensor, each having a width equal to or smaller than the width of the sensing part of the pulse wave sensor, at intervals smaller than the length of the distal joint of the finger held over the pulse wave sensor A pulse wave measuring device is configured by including a protruding part provided to protrude.

In order to stably measure the pulse wave, it is necessary that the pad of the fingertip is in close contact with the surface of the housing that covers the pulse wave sensor. By simply guiding and regulating the pulse wave sensor, the pulse wave measurer himself touches the sensor position with the fingertip and recognizes whether the pad of the fingertip is in close contact with the surface of the housing covering the pulse wave sensor. I didn't. However, according to this configuration, there is a pulse wave sensor between the protrusions provided at intervals smaller than the length of the distal node of the finger held over the pulse wave sensor, and the position of the fingertip is recognized by the sensation of the fingertip touching the protrusion. Because it is configured, the pulse wave measurer himself/herself confirms and recognizes whether the fingertip is at the sensor position and the pad of the fingertip is in close contact with the surface of the housing that covers the pulse wave sensor. . Therefore, unlike the conventional art, the possibility that the fingertips do not touch the surface of the housing covering the pulse wave sensor and float is reduced.

Also, according to this configuration, the fingertip is positioned not by the outer shape of the finger, but by arranging the pad of the fingertip between the protrusions, so it can be done regardless of the thickness of the fingertip. Therefore, as in the past, by touching the surface of the housing that covers the pulse wave sensor with a thin fingertip biased against the sensor position, the fingertip cannot cover the pulse wave sensor and a part is exposed and a gap occurs. Also, thick fingertips do not stick to the surface of the housing that covers the pulse wave sensor and float.

In addition, since the pulse wave measurer recognizes the protrusion from the outer shell of the protrusion, if the width of the protrusion is large, the recognition position of the protrusion may be shifted from the sensor position. Since the width of is equal to or smaller than the width of the sensing portion of the pulse wave sensor, the influence of the positional deviation is small. In addition, since the distance between the protrusions is smaller than the length of the distal joint of the finger held over the pulse wave sensor, the positions of each protrusion can be clearly identified by simultaneously touching the separated protrusions with the pad of the distal joint, which is sensitive to touch. can recognize.

Therefore, according to the present invention, the possibility that the fingertip cannot cover the pulse wave sensor or float from the pulse wave sensor as in the conventional art is reduced, and the pulse wave measurer himself places the fingertip at the sensor position. It is possible to provide a pulse wave measuring device that can be brought into close contact and accurately measure a pulse wave without distortion.

It is a figure explaining the subject of the conventional pulse wave measuring device. 1 is a diagram showing a pulse wave measuring device according to a first embodiment of the present invention; FIG. FIG. 4 is a diagram for explaining a close contact state between the pulse wave measuring device and a finger according to the first embodiment; FIG. 4 is a diagram for explaining directivity angles of a light-emitting element and a light-receiving element in a pulse wave sensor that constitutes the pulse wave measuring device according to the first embodiment; FIG. 4 is a diagram for explaining finger size measurement points referred to in determining the size of protrusions and the like that constitute the pulse wave measuring device according to each embodiment. FIG. 10 is a diagram showing a pulse wave measuring device according to a second embodiment of the present invention; FIG. 10 is a diagram for explaining a close contact state between the pulse wave measuring device and a finger according to the second embodiment; FIG. 10 is a diagram showing a pulse wave measuring device according to a third embodiment of the present invention; FIG. 11 is a diagram for explaining a close contact state between the pulse wave measuring device and a finger according to the third embodiment;

Next, a form for implementing the pulse wave measuring device of the present invention will be described.

FIG. 2(a) is a plan view of the pulse wave measuring device 11A according to the first embodiment of the present invention, and FIG. 2(b) is a cutaway view of the pulse wave measuring device 11A along line II in FIG. 2(a). 11A is a lateral cross-sectional view of the pulse wave measuring device 11A as seen from the arrow direction. FIG. In this embodiment, the case where the pulse wave measuring device 11A is incorporated in a smart phone will be described, but mobile phones, smart watches, portable or stationary (installation) game machines, pulse oximeters, and pulse wave measuring devices It can be similarly incorporated in a blood pressure estimation device, a blood sugar level estimation device, and a fatigue stress measurement device.

The pulse wave measuring device 11A is configured with a pulse wave sensor 12, a housing 13, a protective cover 14, and projecting

protrusions

15,15. The housing 13 is a housing of the smart phone in which the pulse wave measuring device 11A is incorporated, and contains the pulse wave sensor 12 therein. The pulse wave sensor 12 is composed of a photoelectric pulse wave sensor having an LED (light emitting diode) 12a as a light emitting element in a light emitting part and a PD (photo diode) 12b as a light receiving element in a light receiving part, and measures a pulse wave.

In this embodiment, a photoelectric pulse wave sensor will be described as an example of the pulse wave sensor 12, but a piezoelectric pulse wave sensor can also be used in the same way. However, when pulse wave sensor 12 is a piezoelectric pulse wave sensor, pulse wave sensor 12 may be exposed without a protective cover covering pulse wave sensor 12 . If the protective cover is soft such as a resin film, the pulse wave sensor 12 may be covered with the protective cover, but if the protective cover is hard, the pulse wave cannot be detected, so the pulse wave sensor 12 needs to be exposed. There is In addition, the light emitting element of the light emitting part and the light receiving element of the light receiving part constituting the sensing part of the pulse wave measuring device 11A are not limited to the LED 12a and PD 12b. A phototransistor or the like may be used. Further, the pulse wave sensor 12 may be configured by regarding the camera and the flash built in the smart phone as the light receiving element and the light emitting element of the photoelectric pulse wave sensor, respectively.

The light-emitting portion is an area where light is emitted by the LED 12a, and the light-receiving portion is an area where light can be received by the PD 12b. A light-emitting element normally emits pulsed light at about 10 to 1000 Hz. The pulse wave sensor 12 converts the light received by the light receiving element into an electric signal, and performs amplification, filtering, and AD conversion. Sampling of the digital signal that has undergone AD conversion is performed in accordance with the light emission timing of the light emitting element. The sampled digital signal is sent to an MCU or the like of a smart phone in which the pulse wave sensor 12 is incorporated.

The MCU obtains a pulse waveform (PPG waveform) based on the input digital signal, and obtains information such as pulse rate, autonomic nerve function, oxygen saturation, blood pressure, and blood sugar level from the obtained PPG waveform. In order to calculate the oxygen saturation, PPG waveforms measured with light-emitting elements of multiple wavelengths such as red light and near-infrared light are required. In addition, a clear PPG waveform is required for calculating autonomic nerve function, blood pressure, and blood sugar level. In particular, blood pressure and blood sugar levels are calculated using a phenomenon in which the PPG waveform changes minutely due to changes in blood pressure and blood sugar levels, so a PPG waveform with a good S/N ratio and no distortion is required.

Although one LED 12a and one PD 12b are illustrated, a plurality of each may be used to form the light emitting element and the light receiving element. Also, the light emitting element may be composed of a plurality of LEDs having different emission wavelengths. Emission wavelengths are generally green, which is strongly absorbed by living organisms, red, which is often used in pulse oximeters, and near-infrared wavelengths.

The LED 12a and PD 12b are usually sealed with a transparent resin. In addition, since the light directly entering the PD 12b from the LED 12a without passing through the skin significantly lowers the light receiving sensitivity, a light shielding wall 12c is formed between the LED 12a and the PD 12b. Since the pulse wave sensor 12 is touched by a finger, the light emitting part and the light receiving part are covered with a transparent protective cover 14 made of glass, acrylic, polycarbonate, or the like to prevent dirt adhesion, waterproofing, and wear resistance. Protective cover 14 is provided on the surface of housing 13 that covers built-in pulse wave sensor 12, but may be omitted.

A pair of protruding

portions

15, 15 are provided on the surface of the housing 13 around the pulse wave sensor 12 sandwiching the pulse wave sensor 12, and have a width w equal to or smaller than the width W1 of the sensing portion of the pulse wave sensor 12. It has a hemispherical shape. 3(a) and 3(b), the

protrusions

15, 15 have a width w smaller than the width W2 of the finger 16 held over the pulse wave sensor 12, and are shown in FIG. 3(c). As shown, the finger 16 protrudes at a distance L2 that is less than the distal segment length L1. This interval L2 is the distance between the highest points of the

protrusions

15,15. The projecting

portions

15, 15 are arranged along the longitudinal direction of the finger 16 to be measured, as shown in FIG. 2(a). In addition, although the light-emitting portion and the light-receiving portion are arranged along the direction in which the projecting

portions

15, 15 are arranged in FIG.

3(a) and 3(b) are cross-sectional views of the pulse wave measuring device 11A on which the finger 16 is placed, viewed from the fingertip side of the finger 16, and FIG. It is a vertical cross-sectional view of the placed pulse wave measuring device 11A. In FIG. 3, parts that are the same as or correspond to those in FIG.

Also, in this embodiment, the finger 16 is described as the index finger, but the finger 16 is not limited to the index finger, and may be another finger. The

projections

15, 15 may be shaped like a cone or a triangular pyramid, but it is desirable to round the corners of the projections so as not to hurt the finger 16 when pressed. In addition, although a shape such as a cylinder or a rectangular parallelepiped may be used, if the side surface is nearly vertical and angular, there is a risk that the fingertip will be caught and the pad of the finger 16 will float from the pulse wave sensor 12. The sides should be slanted rather than vertical.

In addition, the

projections

15, 15 are higher than the thickness of the epidermis layer of the skin on the pad of the finger 16, and have a height h equal to or lower than the sum of the thickness of the epidermis layer and the dermis layer of the skin on the pad of the finger 16. have. In addition, the projecting

portions

15, 15 have a width w or a length L (see FIG. 2(a)) that is larger than the distance between the tactile points of the skin on the pad of the finger 16, It is provided at an interval L2 larger than the point discrimination threshold. Moreover, the projecting

portions

15, 15 are arranged outside the directivity angle θ of the photoelectric pulse wave sensor 12, as shown in FIG. FIG. 4 is a longitudinal sectional view of the pulse wave measuring device 11A showing the directivity angle θ. The angle at which the intensity of the light emitted from the LED 12a of the light-emitting portion is half of the maximum (usually the center of light emission) is generally called the directivity angle. Further, the angle at which the sensitivity of light incident on the PD 12b of the light receiving portion is half of the maximum (usually the light receiving center) is also called the directivity angle.

If the

protrusions

15, 15 are within the directivity angle θ, the light reflected and scattered by the

protrusions

15, 15 does not pass through the skin of the finger 16 and directly enters the PD 12b. reduce the sensitivity of Therefore, the projecting

portions

15, 15 are arranged so as not to fall within the directivity angle θ. However, since the intensity of the light is only reduced to half at the directivity angle θ, the projecting

parts

15, 15 should be separated from the edges of the light emitting part and the light receiving part so as not to enter an angle where the intensity of the light is close to 0. should be placed. When the directivity angle θ increases, stray light, which is light that directly enters the PD 12b without passing through the skin of the finger 16 from the LED 12a, and disturbance light are more likely to enter the PD 12b. There is a risk that the ratio will decrease. In order to reduce the incidence of stray light and disturbance light on the PD 12b, it is effective to reduce the opening area of the light emitting unit and light receiving unit, and to form a lens in the opening of the light emitting unit and light receiving unit. A decrease in the amount of light emitted from the light emitting element and an increase in the thickness of the pulse wave sensor 12 are caused.

As for the size of the light-emitting part and the light-receiving part, when measuring the pulse wave at the tip of the index finger 16, it is suitable that the width and length are within the range of 1 to 10 mm, and preferably within the range of 2 to 6 mm. If the size of the light emitting part or the light receiving part is larger than this, it will not be possible to cover it with the pad of the finger 16, and the light from the LED 12a of the light emitting part will leak, or the disturbance light will enter the PD 12b of the light receiving part, resulting in the pulse wave measurement signal. causes a decrease in the S/N ratio. Conversely, if the size of the light emitting portion and the light receiving portion are smaller than this, the amount of light emitted by the LED 12a and the amount of light received by the PD 12b are reduced, which also causes a reduction in the S/N ratio of the pulse wave measurement signal.

In addition, although each width w of the protruding

portions

15, 15 is set smaller than the width W2 of the finger 16 in this embodiment as described above, the minimum width W2 of the distal joint of the index finger 16 of Japanese people is The width W2 of the distal joint of the female index finger 16 is the smallest. From the human body size and shape database of AIST (National Institute of Advanced Industrial Science and Technology) (reference URL; https://www.airc.aist.go.jp/dhrt/hand/data/list.html), the second The average value of the width Wa of the distal joint of the finger (index finger) shown in FIG. 5(a) is 13.8 mm. The minimum value of the second finger distal joint width Wa is 11.7 mm (=13.8−3×0.7), considering the dispersion of three times the standard deviation of 0.7 of the statistical data. Therefore, assuming that the distal joint width Wa of the second finger is the width W2 of the distal joint of the index finger 16, the width W2 of the distal joint of the index finger 16 of about 99.7% of Japanese women is 11.7 mm or more. Also, as the width W1 of the sensing portion of the pulse wave sensor 12, the width W3 (see FIGS. 3A and 3B) at which the belly of the index finger 16 contacts the pulse wave sensor 12 is larger than the width W2 of the distal joint. 6 mm or less is desirable because it becomes small. Therefore, the width w of each of the protruding

portions

15, 15 is set to be smaller than the minimum value of 11.7 mm of the width W2 of the distal joint of the index finger 16. However, in order to be equal to or smaller than the width W1 of the sensing portion, the width w is 6 mm or less. is set to

However, the smaller the size of each of the

protrusions

15, 15, the better. be. The skin density of Merkel's discs and Meissner's corpuscles, which are tactile receptors, is about 30 pieces/cm ² , and the average interval between them is about 2 mm. is set greater than 2 mm. Therefore, it is desirable that each width w of the

projections

15, 15 is 2 to 6 mm.

Further, each height h of the

projections

15, 15 is set higher than the thickness of the epidermis layer of the skin of the finger 16, which is the measurement site, as described above, and the thickness of the epidermis layer is 0.2 to 0.3 mm. Since it is a degree, it is set to 0.2 mm or more. Further, each height h of the protruding

portions

15, 15 is set equal to or lower than the sum of the thickness of the epidermis layer and the dermis layer of the skin of the finger 16, which is the measurement site, as described above. is about 2 mm, although it varies depending on the site. Therefore, it is desirable that each height h of the

protrusions

15, 15 is 0.2 to 2 mm.

The distance L2 between the projecting

portions

15, 15 is set smaller than the length L1 of the distal joint of the index finger 16 as described above. Since there is no quantity, 1/3 of the length of the index finger 16, for which there is a length statistic, is taken as the distal segment length. The minimum length of the index finger 16 of the Japanese is that of Japanese women. The average value of the length La of the second finger (index finger) of Japanese women shown in FIG. The minimum value of the second finger length La is 56.0 mm (=66.5−3×3.5), taking into account the scattering that is three times the standard deviation of 3.5 of the statistical data. Assuming that ⅓ of the second finger length La is the length L1 of the distal joint of the index finger 16, the length L1 of the distal joint of the index finger 16 is 18.7 mm (≈56.0÷3).

Therefore, the distance L2 between the projecting

portions

15, 15 is set to be smaller than 18.7 mm, but since the fingertips are difficult to contact the projections such as the projecting

portions

15, 15, 15 mm or less is suitable. . Further, the distance L2 between the

projections

15, 15 is set larger than the two-point discrimination threshold, which is the minimum distance at which two points can be felt on the skin, as described above. is 2 to 3 mm. Therefore, the distance L2 between the projecting

portions

15, 15 is suitable to be 3 to 15 mm.

In addition, the directivity angle θ of the light-emitting portion and the light-receiving portion in the photoelectric pulse wave sensor 12 varies depending on the structure of the light-emitting portion and the light-receiving portion, but about 30° to 60° is suitable. Therefore, the distance L3 (see FIG. 4) by which the projecting

portions

15 and 15 are separated from the respective edges of the light emitting portion and the light receiving portion is , 0.35 mm (=0.2×tan60°) or more.

For stable measurement of the pulse wave, it is necessary that the pad of the fingertip of the finger 16 is in close contact with the surface of the housing 13 that covers the pulse wave sensor 12 and that the contact pressure does not fluctuate. In particular, if there is a gap between the finger 16 and the surface of the housing 13 covering the pulse wave sensor 12, noise superimposed on the pulse wave measurement signal increases, causing distortion of the pulse wave waveform. In the conventional pulse wave measuring device, the fingertip is simply guided and restricted to the sensor position by the finger restricting part, and the pulse wave measurer himself/herself touches the sensor position with the fingertip and the pad of the fingertip covers the pulse wave sensor. It was not configured to recognize whether or not it is in close contact with the surface of the housing.

However, according to the pulse wave measuring device 11A according to the present embodiment, the pulse wave sensor 12 is positioned between the protruding

portions

15, 15 provided at an interval L2 smaller than the distal segment length L1 of the finger 16 held over the pulse wave sensor 12. The position of the fingertip is recognized by the sensation of the fingertip of the finger 16 touching the

projections

15 , 15 . Therefore, the pulse wave measurer himself or herself checks and recognizes whether or not the fingertip is at the sensor position and the pad of the fingertip is in close contact with the surface of the housing 13 covering the pulse wave sensor 12 . Therefore, the possibility that the fingertip of the finger 16 floats without contacting the surface of the housing 13 covering the pulse wave sensor 12 as in the conventional art is reduced.

Further, according to the pulse wave measuring device 11A of the present embodiment, the positioning of the fingertip is not performed by the outer shape of the finger 16, but by placing the pad of the fingertip between the

projections

15, 15. It can be done regardless of thickness. Therefore, as in the prior art shown in FIG. 1(a), the thin fingertip 4 is biased against the sensor position and touches the pulse wave sensor 1, so that the fingertip 4 cannot cover the pulse wave sensor 1 and is partially exposed. As shown in FIG. 3( a ), the tip of the thin finger 16 completely covers the pulse wave sensor 12 . In addition, as in the prior art shown in FIG. 1(b), the thick fingertip 4 does not come into close contact with the surface of the housing 2 covering the pulse wave sensor 1 and does not float, and as shown in FIG. 3(b), The fingertips of the thick fingers 16 are brought into close contact with the surface of the housing 13 .

In addition, since the pulse wave measurer recognizes the

protrusions

15 and 15 by the outer contours of the

protrusions

15 and 15, the larger the width w of each of the

protrusions

15 and 15 is, the more the recognition position of the

protrusions

15 and 15 is detected by the sensor. There is a possibility that it will shift out of position. However, in the pulse wave measuring device 11A according to the present embodiment, the width w of each of the

protrusions

15, 15 is equal to or smaller than the width W1 of the sensing portion of the pulse wave sensor 12, so the influence of positional deviation is small. In addition, since the distance L2 between the

protrusions

15 and 15 is smaller than the length L1 of the distal joint of the finger 16 held over the pulse wave sensor 12, each separated

protrusion

15 and 15 is sensitive to touch with the belly of the distal joint finger 16. The positions of the

protrusions

15, 15 can be clearly recognized by touching them at the same time.

Therefore, according to the pulse wave measuring device 11A according to the present embodiment, the fingertip 4 may not be able to cover the pulse wave sensor 1 as in the conventional art, or may float from the surface of the housing 2 covering the pulse wave sensor 1. The pulse wave measurement device 11A can be provided, in which the pulse wave measurement person can bring the fingertip of the finger 16 into close contact with the sensor position and accurately measure the pulse wave without distortion.

Further, when the pad of the finger 16 contacts the surface of the housing 13 covering the pulse wave sensor 12, each width w of the

projections

15, 15 is large, and the pressing force of the finger 16 against the

projections

15, 15 is strong, Blood flow to the finger 16 is blocked along the outline of the projecting

portions

15 , 15 . If the width w of the

protrusions

15, 15 is larger than the width W2 of the finger, the blood flow will be obstructed over the entire width of the finger 16, and the pulse wave cannot be detected on the fingertip side from the

protrusions

15, 15. put away. However, according to the pulse wave measuring device 11A of the present embodiment, each

projection

15, 15 has a width w smaller than the width W2 of the finger 16, and both sides of each

projection

15, 15 have blood flow. A pulse wave can be detected at the fingertip of finger 16 because there is an unobstructed area.

In addition, the skin has an epidermis layer and a dermis layer from the surface side, and sensory receptors including tactile receptors are in the dermis layer but not in the epidermis layer. Therefore, with the pulse wave measuring device 11A according to the present embodiment, the

projections

15 and 15 each have a height h that is higher than the thickness of the epidermal layer of the skin on the pad of the finger 16, so that the skin of the fingertip is When the surface of the housing 13 covering the is touched, the

projections

15, 15 reach the depth of the dermis layer, so that the fingertips are reliably touching the

projections

15, 15. It can be detected by receptors.

Further, when the height h of the projecting

portions

15, 15 increases, the pressure applied from the projecting

portions

15, 15 to the fingertips becomes stronger, and the blood flow in the fingertips is likely to be obstructed, and the pulse wave sensor 12 cannot detect the pulse wave. it gets harder. In addition, there is a risk that the pads of the fingertips may be lifted from the pulse wave sensor 12 by being obstructed by the

protrusions

15 , 15 . If the height h of the protruding

portions

15, 15 is further increased, the protruding

portions

15, 15 will not be buried in the pads of the fingertips, and the pads of the fingertips will float above the surface of the housing 13 covering the pulse wave sensor 12. According to the pulse wave measuring device 11A according to the present embodiment, the

projections

15, 15 have a height equal to or lower than the sum of the thickness of the epidermis layer and the dermis layer of the skin on the pad of the finger 16. Adverse effects can be suppressed. Furthermore, the

protrusions

15, 15 have a height equal to or lower than the sum of the thickness of the epidermis layer and the dermis layer of the skin on the pad of the finger 16, and have a height h higher than the thickness of the epidermis layer. Therefore, it is possible to reliably detect the contact of the fingertip of the finger 16 with the projecting

portions

15, 15 while suppressing the above-described adverse effects.

Also, if the outer shapes of the protruding

portions

15, 15 are smaller than the distance between the tactile points of the skin on the pad of the finger 16, there is a possibility that the contact may not be detected by the tactile points depending on the position of the protruding

portions

15, 15 touching the pad of the finger 16. There is However, according to the pulse wave measuring device 11A according to the present embodiment, the

projections

15, 15 have respective outlines larger than the distance between the tactile points of the skin on the pad of the finger 16, so that the

projections

15, 15 and the finger 16 can be reliably detected by tactile points on the skin.

Further, if the distance L2 between the

protrusions

15, 15 is smaller than the two-point discrimination threshold of the skin on the pad of the finger 16, the pulse wave measurer will find that the

protrusions

15, 15 are provided with the interval L2 therebetween. , the position of the pulse wave sensor 12 may not be recognized accurately. However, according to the pulse wave measuring device 11A according to the present embodiment, the

protrusions

15, 15 are provided at an interval L2 that is larger than the two-point discrimination threshold of the skin on the pad of the finger 16, so that between the

protrusions

15, 15 By feeling the provided interval L2, the position of the pulse wave sensor 12 provided between the

projections

15, 15 can be correctly recognized.

Further, according to the pulse wave measuring device 11A according to the present embodiment, the protruding

portions

15, 15 each have a substantially hemispherical shape, and the edges of the protruding ends of the protruding

portions

15, 15 are not angular. 15 will not stick in your finger and feel pain. Also, if the side surfaces of the protruding

portions

15, 15 stand up nearly vertically, there is a risk that the fingertips will be caught by the protruding

portions

15, 15 and the pad of the finger 16 will float from the surface of the housing 13 that covers the pulse wave sensor 12. There is, but there is no such thing. Further, since the protruding

portions

15, 15 are substantially hemispherical, even if the fingertips are pressed against the protruding

portions

15, 15 from the lateral direction, the fingertips do not get caught on the protruding

portions

15, 15, and the fingertips can be moved from the fingertips to the protruding portions. It is difficult to apply force to 15,15. Furthermore, since the protruding

portions

15, 15 are frequently touched, if the protruding

portions

15, 15 have corners, they are likely to be worn. no corners. Therefore, the protruding

portions

15, 15 are hard to apply force and have no corners, so that the wear thereof can be effectively suppressed.

Further, in the pulse wave measuring device 11A according to this embodiment, the pulse wave sensor 12 is a photoplethysmographic sensor. A photoelectric pulse wave sensor is more advantageous than a piezoelectric pulse wave sensor in reducing the size of a measuring device. It returns to the pulse wave sensor 12 and becomes stray light, causing a decrease in the S/N ratio of the pulse wave measurement signal. However, according to the pulse wave measuring device 11A according to the present embodiment, since the

protrusions

15 and 15 are arranged outside the directivity angle θ of the pulse wave sensor 12, light is not scattered by the

protrusions

15 and 15. , stray light does not occur. Therefore, the size of the pulse wave measuring device 11A can be reduced without lowering the S/N ratio of the pulse wave measuring signal.

FIG. 6(a) is a plan view of the pulse wave measuring device 11B according to the second embodiment of the present invention, and FIG. 6(b) is a cutaway view of the pulse wave measuring device 11B along line II-II in FIG. 6(a). 11B is a horizontal cross-sectional view of the pulse wave measuring device 11B as seen from the arrow direction. FIG. 7 is a longitudinal sectional view of pulse wave measuring device 11B on which finger 16 is placed. In FIGS. 6 and 7, the same or corresponding parts as those in FIGS. 2 and 3(c) are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the housing 13 in which the pulse wave measuring device 11B is incorporated has a protective cover longer in the longitudinal direction than the protective cover 14 in the pulse wave measuring device 11A on the surface of the housing 13 covering the built-in pulse wave sensor 12. 14', and

projections

15, 15 in the pulse wave measuring device 11B are provided on the surface of this transparent protective cover 14'. Other configurations of the pulse wave measuring device 11B are the same as those of the pulse wave measuring device 11A according to the first embodiment.

According to the pulse wave measuring device 11B according to the second embodiment, between the protective cover 14' covering the pulse wave sensor 12 and the

projections

15, 15, the protective cover 14 and the housing 13 in the pulse wave measuring device 11A There are no boundaries 17, 17 (see FIG. 2(a)) between them, and there are no slight steps or gaps. Therefore, according to the pulse wave measuring device 11B according to the second embodiment, the pulse wave measuring person can clearly recognize the positions of the

protrusions

15, 15 without being confused by the

boundaries

17, 17, and the first The same effects as those of the pulse wave measuring device 11A according to the embodiment of .

In addition, in this embodiment, by providing a protective cover 14 'on the upper part of the pulse wave sensor 12, the protective cover 14' is provided on the surface of the housing 13, but the protective cover 14' is attached to the housing 13 It may be a structure.

FIG. 8(a) is a plan view of the pulse wave measuring device 11C according to the third embodiment of the present invention, and FIG. 8(b) is a cutaway view of the pulse wave measuring device 11C along line III-III in FIG. 8(a). 11C is a horizontal cross-sectional view of the pulse wave measuring device 11C as seen from the arrow direction. 9(a) and 9(b) are cross-sectional views of the pulse wave measuring device 11C on which the finger 16 is placed, viewed from the fingertip side of the finger 16, and FIG. 11C is a vertical cross-sectional view of the pulse wave measuring device 11C placed. FIG. In FIGS. 8 and 9, the same or corresponding parts as those in FIGS. 2 and 3 are denoted by the same reference numerals, and descriptions thereof are omitted.

In this embodiment,

finger restricting portions

18, 18 are provided to restrict movement of the finger 16 in a direction perpendicular to the arrangement direction of the projecting portions 15', 15'. The

finger restraint portions

18, 18 sandwich both sides of the projecting portions 15', 15' provided at the interval L2 at a distance wider than the contact width W3 of the finger 16 with the surface of the housing 13, and the projecting portions 15', 15 ' is protruded along the arrangement direction of '. The distance L2 between the

protrusions

15, 15 in each of the first and second embodiments was the distance between the highest points of the

protrusions

15, 15, but in this embodiment, the protrusions 15', The interval L2 between 15' is the distance between the highest points in the center of the pulse wave sensor 12 side since the highest point of each protrusion 15', 15' is not one point.

Unlike the

protrusions

15, 15, the protrusions 15', 15' do not have a generally hemispherical shape, but have a generally semi-cylindrical shape. In this embodiment, connecting

portions

19, 19 are provided between projecting portions 15′, 15′ and

finger restricting portions

18, 18, and projecting portions 15′, 15′,

finger restricting portions

18, 18 and connecting portion 19 are provided. , 19 are integrally formed on the surface of the housing 13 at the same height h. Other configurations of the pulse wave measuring device 11C are the same as those of the pulse wave measuring device 11A according to the first embodiment.

The distance L4 between the

finger regulating portions

18, 18 is set wide so that the finger 16 does not run over the

finger regulating portions

18, 18 even if the finger 16 is thick as shown in FIG. 9(b). Therefore, between the

finger restricting portions

18, 18, a recess is formed along the shape of the finger 16, and the position of the finger 16 held over the pulse wave sensor 12 is roughly restricted by this recess.

The maximum width W2 of the distal joint of the index finger 16 of Japanese men is the width W2 of the distal joint of the index finger 16 of Japanese men. From the human body size/shape database of AIST, the average value of the width Wa of the distal joint of the second finger (index finger) of Japanese males shown in FIG. 5(a) is 15.6 mm. The maximum value of the second finger distal joint width Wa is 18.3 mm (=15.6+3×0.9), taking into account the dispersion of three times the standard deviation of 0.9 of the statistical data. Therefore, assuming that the distal joint width Wa of the second finger is the width W2 of the distal joint of the index finger 16, the width W2 of the distal joint of the index finger 16 of about 99.7% of Japanese men is 18.3 mm or more.

Therefore, in order to prevent both sides of the finger 16 from riding on the

finger regulating portions

18 and 18 and the pad of the finger 16 from floating from the surface of the housing 13 covering the pulse wave sensor 12, the distance between the

finger regulating portions

18 and 18 is L4 is set to 10 mm, for example. As the height h of the

finger restraint portions

18, 18 increases, the space L4 between the

finger restraint portions

18, 18 needs to be widened. ' are integrated at the same height h. Therefore, the height h of the

finger restricting portions

18, 18 is also set to 0.2 to 2 mm, which is the same as the projecting

portions

15, 15, and the distance L4 between the

finger restricting portions

18, 18 is the same as that of the projecting

portions

15, 15, is set to 10 mm, for example.

According to the pulse wave measuring device 11C of the present embodiment, the movement of the finger 16 in the direction perpendicular to the arrangement direction of the projecting portions 15', 15' is roughly restricted by the

finger restricting portions

18, 18, and the finger restricting portion Protrusions 15', 15' are arranged at locations sandwiched by 18, 18 with an interval L2 therebetween. Therefore, the pulse wave measurer can recognize the rough position of the fingertip of the finger 16 with the

finger restraints

18, 18, and then recognize the accurate position of the pulse wave sensor 12 with the projections 15', 15'. , the position of the pulse wave sensor 12 can be quickly recognized, and the same effects as those of the pulse wave measuring device 11A according to the first embodiment can be obtained.

In the above-described third embodiment, the projections 15', 15' have a substantially semi-cylindrical shape. Alternatively, it may have a substantially hemispherical shape. In this case, the protruding portions 15', 15' are separated from the connecting

portions

19, 19. As shown in FIG.

Further, in each of the above-described embodiments, the

protrusions

15, 15, 15', 15' are arranged one by one on each side of the pulse wave sensor 12, but the present invention is limited to this. Alternatively, a plurality of sensors, for example, two sensors, for example, four sensors in total, may be arranged on each side of the pulse wave sensor 12 . In this case, by considering a mass of a plurality of protrusions arranged on each side of the pulse wave sensor 12 as one and applying each of the above embodiments, the same as each of the above embodiments Action and effect are exhibited.

11A, 11B, 11C... pulse wave measuring device 12... pulse wave sensor 12a... LED (light emitting element)
12b... PD (light receiving element)
12c... Light shielding wall 13... Housing 14... Protective cover 15, 15'... Protruding part 16... Finger (index finger)
17... Boundary 18... Finger regulation part 19... Connection part

Claims

a pulse wave sensor that measures a pulse wave;
A housing containing the pulse wave sensor;
On the surface of the housing around the pulse wave sensor sandwiching the pulse wave sensor, each having a width equal to or smaller than the width of the sensing part of the pulse wave sensor, and the distal joint of the finger held over the pulse wave sensor A pulse wave measuring device comprising: projections that project at intervals smaller than the length of the pulse wave measuring device.
The pulse wave measuring device according to claim 1, wherein the protrusion has a width smaller than the width of the finger.
The pulse wave measuring device according to claim 1 or 2, wherein the projection has a height higher than the thickness of the epidermal layer of the skin on the pad of the finger.
4. The projection according to any one of claims 1 to 3, wherein the projection has a height equal to or lower than the sum of the thickness of the epidermis layer and the dermis layer of the skin on the pad of the finger. Pulse wave measuring device.
The pulse wave measuring device according to any one of claims 1 to 4, wherein the protruding portion has an outer shape larger than the distance between the tactile points of the skin on the pad of the finger.
The pulse wave measuring device according to any one of claims 1 to 5, wherein the protrusions are provided at the intervals that are larger than the two-point discrimination threshold of the skin on the pad of the finger.
The pulse wave measuring device according to any one of claims 1 to 6, wherein the protruding portion has a substantially hemispherical shape.
The pulse wave sensor according to any one of claims 1 to 7, wherein the pulse wave sensor is a photoplethysmogram sensor, and the projecting portion is arranged outside the directional angle of the photoplethysmogram sensor. wave measuring device.
Both sides of the projection provided at the interval are sandwiched by a distance wider than the contact width of the finger with the surface of the housing, and are provided so as to project along the arrangement direction of the projection, and the arrangement of the projection 9. The pulse wave measuring device according to any one of claims 1 to 8, further comprising a finger restricting portion that restricts movement of the finger in a direction perpendicular to the direction.
10. The housing is provided with a transparent protective cover on the surface of the housing that covers the built-in pulse wave sensor, and the projecting portion is provided on the surface of the protective cover. The pulse wave measuring device according to any one of 1.