United States Patent 19
`Kondo et al.
`
`54 PULSE-VAVE MEASURINGAPPARATUS
`(75) Inventors: Yutaka Kondo; Katsuyuki Honda,
`both of Suwa; Hiroshi Odagiri;
`Takeshi Ono, both of Chiba, all of
`Japan
`73) Assignees: Seiko Epson Corporation, Tokyo;
`Seiko Instruments, Inc., Chiba, both of
`Japan
`
`(21) Appl. No.: 692,897
`22 Filled:
`Jul. 30, 1996
`30
`Foreign Application Priority Data
`Aug. 4, 1995
`JP
`Japan .................................... 7-19983
`Oct. 20, 1995
`JP
`Japan .................................... 7-273240
`Oct. 20, 1995
`(JP)
`Japan .................................... 7-273241
`(51) Int. Cl. ... A61B 5/02
`52 U.S. Cl. .......................... 600/502; 600/344; 600/503;
`600/310
`58) Field of Search ..................................... 128/633, 639,
`128/664-667, 687-690; 600/310,323, 344,
`503. 502, 473-480
`
`56
`
`References Cited
`U.S. PATENT DOCUMENTS
`... 128/690
`4,280,506 7/1981 Zurcher ...
`... 128/687
`4,332,258
`6/1982 Arai et al. ...
`4.425,921
`1/1984 Fujisaki et al. ......................... 128/690
`4,807,639 2/1989 Shimizu et al. .
`4,825,872 5/1989 Tan et al. .
`4,971,062 11/1990 Hasebe et al. .......................... 128/664
`5,080,098
`1/1992 Willett et al. ...
`... 128/633
`5,125,403
`6/1992 Culp ....................................... 128/633
`
`
`
`III US005766131A
`
`11) Patent Number:
`45) Date of Patent:
`
`5,766,131
`Jun. 16, 1998
`
`... 128/666
`5.224,478 7/1993 Sakai et al. ....
`...... 128/666
`5,452,717 9/1995 Branigan et al.
`5,511,546 4/1996 Hon. ........................................ 128/666
`
`FOREIGN PATENT DOCUMENTS
`2583 282 2.986 France.
`1909 882 9/1970 Germany.
`2 052051 1/1981 United Kingdom.
`
`Primary Examiner-Lee S. Cohen
`Assistant Examiner-David M. Ruddy
`Attorney, Agent, or Firm-Michael T. Gabrik
`57
`ABSTRACT
`To achieve a pulse wave measuring apparatus whereby the
`sensor unit can be easily and consistently worn against the
`skin surface. a wristwatch type pulse wave measuring appa
`ratus is comprised as follows. Specifically, light transmit
`tance plate 34 is disposed on the outside surface side of LED
`31 and phototransistor 32 in sensor unit 30. Outside surface
`341 of light transmittance plate 34, which is pressed against
`the finger, projects above the reference surface, which is
`outside surface 361 of sensor frame 36 surrounding light
`transmittance plate 34. Two body ground terminals 38
`contacting the finger surface when light transmittance plate
`34 is pressed tight to the finger are disposed around light
`transmittance plate 34; the body ground terminals 38 also
`project above the reference surface. However, the position of
`outside surfaces 381 of body ground terminals 38 is lower
`than the outside surface 341 of light transmittance plate 34.
`A supporter-like sensor unit holding band is used to hold
`sensor unit 30 on the finger. A thick material such as that
`used in diving wet suits is used for the sensor unit holding
`band, and comprises a middle layer of foam rubber.
`
`19 Claims, 32 Drawing Sheets
`
`1
`
`APPLE 1009
`
`

`

`US. Patent
`U.S. Patent
`
`Jun.16, 1998
`Jun. 16, 1998
`
`Sheet 1 of 32
`Sheet 1 of 32
`
`5,766,131
`5,766,131
`
`F.G. 1A
`
`
`
`
`
`40
`
`FIG. 1B
`FIG._1B
`
`2
`
`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 2 of 32
`
`5,766,131
`
`12.----- -----
`12 O'CLOCK ? 105
`
`\Y
`
`f 11
`
`
`
`
`
`
`
`3
`
`

`

`US. Patent
`U.S. Patent
`
`Jun. 16, 1998
`Jun. 16, 1998
`
`Sheet 3 of 32
`Sheet 3 of 32
`
`5,766,131
`5,766,131
`
`
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`

`U.S. Patent
`
`Jun.16, 1998
`
`Sheet 4 of 32
`
`5,766,131
`
`
`
`5
`
`

`

`
`
`6
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jun. 16, 1998
`Jun. 16, 1998
`
`Sheet 6 of 32
`Sheet 6 of 32
`
`5,766,131
`5,766,131
`
`
`
`
`
`7
`
`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 7 of 32
`
`5,766,131
`
`RELATIVE
`INTENSITY
`(%)
`
`35O
`FIG.8
`
`4OO
`
`450
`500
`550
`WAVELENGTH (nm)
`
`600
`
`650
`
`
`
`(%)
`
`100
`
`RELATIVE
`SENSTIVITY
`(%)
`so
`
`360 400
`FIG.10
`
`500
`
`600
`700
`8OO
`WAVELENGTH (nm)
`
`900
`
`8
`
`

`

`U.S. Patent
`U.S. Patent
`
`
`
`Sheet 8 of 32
`
`5,766,131
`5,766,131
`
`
`
`Jun. 16, 1998
`
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`U.S. Patent
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`WLSAYO-GINON
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`Jun. 16, 1998
`
`Sheet 9 of 32
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`5,766,131
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`US. Patent
`U.S. Patent
`
`Jun. 16, 1998
`Jun. 16, 1998
`
`5,766,131
`
`
`
`Sheet 10 of 32
`Sheet 10 of 32
`
`5,766,131 FIG._14A
`
`11
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jun. 16, 1998
`Jun. 16, 1998
`
`Sheet 11 of 32
`
`5,766,131
`5,766,131
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`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 12 of 32
`
`5,766,131
`
`60
`
`INCIDENT
`LIGHT
`TRANSMITANCE
`(%)
`
`1.5
`1.0
`: 0.5
`0
`: DISTANCE FROM
`CORNEUM SIGACE's
`FIG. 17A EPIDERMS
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`ABSORPTION
`COEFFICENT
`(1/cm.mM)
`
`FIG.17B
`
`3OO 400 50O 600 7OO 800 900 OOO
`WAVELENGTH (nm)
`
`13
`
`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 13 of 32
`
`5,766,131
`
`RELATIVE
`INTENSITY
`% 50
`
`4OO
`FIG. 18
`
`450
`
`500
`
`550
`600
`WAVELENGTH (nm)
`
`650
`
`700
`
`750
`
`
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`
`RELATIVE
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`
`2OO
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`400
`600
`WAVELENGTH (nm)
`
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`
`14
`
`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 14 of 32
`
`5,766,131
`
`38t 381
`FINGER
`
`
`
`
`
`36D
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`36
`
`34
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`RESIDUAL
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`FIG.21A
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`PRESSURE FROM LIGHT
`TRANSMITTANCE PLATE 34.
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`FIG.21B
`
`15
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`

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`
`U.S. Patent
`U.S. Patent
`
`
`
`Jun. 16, 1998
`
`Sheet 15 of 32
`
`5,766,131
`5,766,131
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`U.S. Patent
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`
`
`Jun. 16, 1998
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`Sheet 16 of 32
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`5,766,131
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`U.S. Patent
`U.S. Patent
`
`Jun. 16, 1998
`Jun. 16, 1998
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`Sheet 17 of 32
`Sheet 17 of 32
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`5,766,131
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`U.S. Patent
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`
`Jun. 16, 1998
`Jun. 16, 1998
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`Sheet 18 of 32
`Sheet 18 of 32
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`5,766,131
`5,766,131
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`U.S. Patent
`U.S. Patent
`
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`
`Jun. 16, 1998
`
`Sheet 19 of 32
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`U.S. Patent
`U.S. Patent
`
`Jun. 16, 1998
`Jun. 16, 1998
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`Sheet 20 of 32
`Sheet 20 of 32
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`5,766,131
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`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 21 of 32
`
`5,766,131
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`22
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`

`

`Jun.16, 1998
`Jun. 16, 1998
`
`Sheet 22 of 32
`Sheet 22 of 32
`
`5,766,131
`5,766,131
`
`U.S. Patent
`U.S. Patent
`
`
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`
`23
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`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 23 of 32
`
`5,766,131
`
`FIG. 32A
`
`
`
`FIG.32B
`
`24
`
`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 24 of 32
`
`5,766,131
`
`FIG.33A
`
`
`
`FIG.33E3
`
`25
`
`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 25 of 32
`
`5,766,131
`
`DIMENSION
`K-A->
`
`415
`425
`
`
`
`4 16
`
`4f
`
`4ff / 417
`
`430 N418 N 412
`473
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`K-B
`
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`DIMENSION
`42
`
`42
`
`FIG.34A
`
`FIG.34B
`
`44
`
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`
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`
`FIG.34D
`
`26
`
`

`

`416,426DIMENSION
`
`FIG._35D
`
`
`
`415,425 44
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`
`U.S. Patent
`Jun. 16, 1998
`41 rE ,430
`
`43
`
`Sheet 26 of 32
`
`5,766,131
`
`FIG._35C
`
`FIG._35B
`
`416,426
` 415,
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`DIMENSION
`
`FIG._35A
`
`27
`
`

`

`US. Patent
`U.S. Patent
`
`
`
`Jun. 16, 1998
`Jun. 16, 1998
`
`Sheet 27 of 32
`Sheet 27 of 32
`
`5,766,131
`5,766,131
`
`51m
`55™/m60m65™m70™%m75™m
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`28
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`

`

`U.S. Patent
`
`Jun. 16, 1998
`
`30
`
`38
`
`
`
`5,766,131
`Sheet 28 of 32
`Total sensor
`area = approx.
`144mm2
`Glass area =
`pprox. 40mm?
`
`34
`
`FIG. 37
`
`
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`FIG.42A
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`FIG.42B
`
`29
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jun. 16, 1998
`
`Sheet 29 of 32
`
`5,766,131
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`U.S. Patent
`U.S. Patent
`
`Jun. 16, 1998
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`Sheet 30 of 32
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`5,766,131
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`Jun. 16, 1998
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`U.S. Patent
`U.S. Patent
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`Jun. 16, 1998
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`Sheet 32 of 32
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`

`

`1.
`PULSEWAVE MEASURINGAPPARATUS
`
`5,766,131
`
`2
`phototransistor from external light, this structure in fact
`results in less contact with the finger. This then results in
`variations in the detection sensitivity.
`OBJECTS OF THE INVENTION
`Therefore it is an object of the present invention to
`overcome the aforementioned problems.
`It is another object of the present invention to provide a
`pulse wave measuring apparatus capable of detecting the
`pulse signal with good sensitivity by enabling the sensor unit
`to be easily worn against the skin surface of, for example,
`the finger in a consistently stable condition.
`SUMMARY OF THE INVENTION
`To achieve a pulse wave measuring apparatus capable of
`detecting the pulse signal with good sensitivity by enabling
`the sensor unit to be easily worn against the skin surface of.
`for example, the finger in a consistently stable condition, a
`pulse wave measuring apparatus according to the present
`invention comprises a sensor unit comprising a light emit
`ting element for emitting light to the finger, wrist, or other
`body surface, a receptor element for detecting the light
`emitted from the light emitting element and reflected back
`from the body surface, and a light transmittance plate
`disposed on the body surface side of the receptor element
`and light emitting element such that the outside surface of
`the light transmittance plate is pressed tight to the body
`surface. A main unit comprises a data processing means for
`obtaining such pulse information as the pulse count based on
`the pulse signal detection result supplied from the sensor
`unit. A sleeve-like sensor unit holding band is provided that
`is elastic in at least the circumferential direction, and is used
`to wear and hold the sensor unit against the body surface
`such that the light transmittance plate is tight to the body
`surface.
`It should be noted that the body surfaces referenced herein
`shall not be limited to the surface of a finger or wrist, and
`may be any body surface, including the ankles or arm, where
`a pulse signal can be detected and the sensor unit can be held
`securely by means of a supporter-like sensor unit holding
`band.
`Unlike the conventional method whereby the belt tight
`ness must be adjusted with the surface fastener each time the
`sensor unit is put on, the sensor unit of the present invention
`can be pressed against the finger with appropriate force by
`simply fitting the sensor unit holding band to the finger if the
`sensor unit holding band has been sized appropriately to the
`finger because the sensor unit is held to a finger by means of
`a supporter-like sensor unit holding band with the pulse
`wave measuring apparatus according to the present inven
`tion. The method of the invention also prevents formation of
`gaps between the body surface and the sensor unit. The pulse
`signal detection sensitivity is therefore also consistently
`high.
`If the outside surface of the sensor unit surrounding the
`light transmittance plate is the reference surface, it is pref
`erable according to the present invention for the outside
`surface of the light transmittance plate to be exposed above
`this reference surface. Because the outside surface of the
`light transmittance plate covering the receptor element and
`light emitting element projects above that part of the sensor
`unit surrounding the light transmittance plate with this
`construction, the body surface is held tight to the entire
`outside surface of the light transmittance plate. This tight fit
`also remains stable when the body pressure against the light
`transmittance plate varies as a result of body movement.
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates to a pulse wave measuring
`apparatus used to obtain the pulse rate, for example, by
`optically detecting a pulse signal. The invention more spe
`cifically relates to a structural technology for the pulse signal
`detection part of the pulse wave measuring apparatus.
`2. Description of the Related Art
`Optical devices are one type of pulse wave information
`measuring apparatus capable of measuring and displaying
`the pulse rate and other types of pulse wave information.
`Optical pulse wave measuring apparatuses typically expose
`the surface of a finger with light emitted from an LED, and
`detect the light reflected back from the blood vessels near the
`surface using, for example. a phototransistor to detect the
`change in reflected light quantity as representative of the
`change in blood volume. This detection result is then used to
`measure the pulse count and other parameters.
`As shown in FIGS. 42A and 42B. light transmittance
`plates 34C and 34D are provided on the skin-surface side of
`LEDs 31C and 31D and phototransistors 32C and 32D with
`this type of pulse wave information measuring apparatus.
`The outside surface side 341C and 341D of the light
`transmittance plates 34C and 34D is then pressed against the
`finger to detect the pulse signal. If the surfaces surrounding
`light transmittance plates 34C and 34D are reference sur
`faces 361C and 361D, outside surfaces 341C and 341D of
`light transmittance plates 34C and 34D are either on the
`same plane as reference surfaces 361C and 361D or are
`recessed therefrom.
`When a pulse wave detector thus constructed is assembled
`and used as the sensor unit, the sensor unit is held pressed
`against the skin by a surface fastening belt using a hook and
`loop-like material, such as Velcrocs, similar to a conven
`tional blood pressure gauge.
`The problem with this design is that when the sensor unit
`is worn on the finger by pressing the sensor unit against the
`finger, wrapping a belt around the finger and sensor unit, and
`securing the belt with the surface fastener part thereof, the
`pressure applied between the sensor unit and finger must be
`adjusted by adjusting the belt tension each time the sensor
`unit is put on. This is because if the belt is too loose, external
`light may penetrate to the phototransistors through the gap
`between the belt and the finger. If this light reaches the
`sensor unit, it may not be possible to accurately measure the
`pulse signal.
`Another problem with this method of securing the sensor
`unit with a surface fastener is that the force pressing the
`sensor unit against the finger varies each time the sensor unit
`is put on. As a result, the detection sensitivity tends to vary,
`It is therefore necessary when measuring the pulse rate to
`adjust the belt tension (tightness) and sensor-finger pressure
`by actually detecting the pulse signal to determine the fit
`obtaining optimum detection sensitivity. A certain amount of
`time and trouble is therefore required between preparing for
`pulse wave measurements and making the actual measure
`ments.
`Various sensor unit constructions were also studied by
`evaluating the detection sensitivity and data reliability. It
`was found that while disposing light transmittance plates
`34C and 34D recessed from the reference surface 361D or
`on the same plane as the reference surface 361C is appar
`ently more effective in terms of shielding the LED and
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`In addition, because the outside surface of the light
`transmittance plate projects from the part surrounding the
`light transmittance plate, the contact area between the light
`transmittance plate and body surface can be assured to a
`certain degree, and the force pressing the sensor unit to the
`body surface can be easily controlled.
`Moreover, residual blood in the blood vessels pressurized
`by the light transmittance plate is purged from that area
`when the light transmittance plate is pressed against the skin,
`As a result, the signal detected by the receptor element is
`minimally affected by residual blood in the blood vessels.
`The detection sensitivity of the pulse signal detected by the
`receptor element is therefore high, and the reliability of the
`obtained data is high. Less pressure between the light
`transmittance plate and body surface is thus needed to
`achieve consistently high sensitivity, and there is therefore
`less discomfort from wearing the sensor unit.
`When the outside surface of the light transmittance plate
`is flat in the present invention, the body surface can be
`pressed evenly against the entire outside surface of the light
`transmittance plate.
`When the outside surface of the light transmittance plate
`is a convex surface, pressure is applied to the light trans
`mittance plate by simply holding the outside surface of the
`light transmittance plate lightly against the body surface.
`and positive contact between the body surface and outside
`surface of the light transmittance plate can therefore be
`improved.
`Abody ground terminal contacting the body surface when
`the light transmittance plate is tight to the body surface may
`also be provided according to the present invention on the
`outside surface of the sensor unit surrounding the light
`transmittance plate. The outside surface of the body ground
`terminal in this case preferably projects from the reference
`surface to a position lower than the outside surface of the
`light transmittance plate. When the skin is then pressed
`against the light transmittance plate, the body positively
`contacts the body ground terminal. The body ground termi
`nal also does not inhibit tight contact between the body and
`the outside surface of the light transmittance plate because
`the outside surface of the body ground terminal is positioned
`lower than the outside surface of the light transmittance
`plate.
`The sensor unit holding band in the present invention is
`preferably made from, for example, a material having a
`foam rubber layer, or from a material with a polyurethane
`layer. More specifically, if a thick material such as that used
`for diving wet suits and having a foam rubber layer or
`polyurethane layer is used for the sensor unit holding band,
`external light will not pass through the sensor unit holding
`band to the sensor unit even when the band is stretched to
`hold the sensor unit in place. Gaps will also not develop
`when the sensor unit holding band becomes wet because the
`dimensional stability of the band is good. It is therefore
`possible to stably detect the pulse signal without being
`affected by external light.
`When the sensor unit holding band is made from a thick
`material having a foamrubber layer or polyurethane layer as
`described above, the band is preferably covered on both
`inside circumferential and outside circumferential surfaces
`with a stretchable fabric.
`The inside and outside circumferential surfaces of the
`sensor unit holding band are also preferably covered with
`stretchable fabric of different colors. This makes it simple to
`identify the inside and outside of the sensor unit holding
`band.
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`The sensor unit holding band is further preferably manu
`factured from sheet-like strips fastened together at the edges
`thereof. The sensor unit holding band thus comprised does
`not result in unnecessary surface roughness, and is therefore
`more resistant to penetration by external light.
`When the sensor unit holding band is manufactured from
`sheet-like strips fastened together at the edges thereof, a tape
`is preferably applied with adhesive to cover the seam
`between the edges of the strips. When this sensor unit
`holding band is then worn on the finger, there is no discom
`fort from the seam contacting the finger. Covering the seam
`with a tape helps to completely eliminate unevenness in the
`seam, thereby improving light-tightness and making the
`band more resistant to external light.
`A sensor unit slipping prevention means preventing the
`position of the sensor unit from shifting inside the sensor
`unit holding band is also preferably disposed to the sensor
`unit holding band or sensor unit. The slipping prevention
`means keeps the sensor unit from shifting inside the sensor
`unit holding band and from falling out of the sensor unit
`holding band.
`When, for example, the main unit and sensor unit are
`connected by a connector cable, the sensor unit slipping
`prevention means of the present invention may use an elastic
`body of which both ends are fastened to the inside circum
`ference of the sensor unit holding band. Specifically, when
`the cable is passed between this elastic body and the inside
`circumference of the sensor unit holding band, the position
`of the sensor unit can be fixed by fastening with the elastic
`body that part of the cable near the connection between the
`cable and sensor unit,
`The sensor unit slipping prevention means of the present
`invention may further use a protrusion provided on the
`sensor unit projecting in the direction opposite the light
`transmittance plate, and catching the inside circumferential
`surface of the sensor unit holding band.
`The sensor unit holding band of the invention further
`preferably comprises a fingerhold extending in the length
`wise direction from the end of the band. It is therefore
`possible using the fingerhold to pull the sensor unit holding
`band on to the base of the finger, and the sensor unit holding
`band can be easily worn at the base of the finger even when
`the overall length of the sensor unit holding band itself is
`short.
`The sensor unit holding band and sensor unit of the
`present invention are preferably comprised so that the load
`applied from the sensor unit to the body surface ranges from
`1.0 gf/mm to 2.8 gfilmm per unit area of the light trans
`mittance plate when the sensor unit is fixed to the body
`surface. The pulse signal detection sensitivity is high under
`these conditions because the force exerted by the sensor unit
`on the body surface is appropriate.
`The sensor unit holding band and sensor unit in the
`present invention are preferably comprised to allow dis
`placement between 2.0 mm and 3.0 mm from the position
`whereat the sensor unit is disposed without applying any
`load to the body surface, to the position whereat the light
`transmittance plate is fixed tight to the body surface by the
`sensor unit holding band. The pulse signal detection sensi
`tivity is high under these conditions because the force
`exerted by the sensor unit on the body surface is appropriate.
`The sensor unit holding band in this case is preferably
`manufactured from a material having a foam rubber layer or
`a material with a polyurethane layer.
`A projection for focusing on the light transmittance plate
`the force of the sensor unit holding band pressing the sensor
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`unit against the body surface is also preferably disposed on
`the side of the sensor unit opposite the light transmittance
`plate. When the projection is provided and the sensor unit is
`worn on the finger by the sensor unit holding band, the force
`of the sensor unit holding band pushing the sensor unit into
`the finger is focused on the light transmittance plate, thereby
`making it easier to regulate the load applied from the sensor
`unit to the body surface. It is therefore easier to design the
`sensor unit holding band and sensor unit to apply the
`optimum force from the sensor unit to the body surface.
`If a wrist band for wearing the main unit on the wrist, and
`a cable connecting the main unit with the sensor unit, are
`further provided, a wristwatch-type pulse wave measuring
`apparatus that can be used to measure the pulse while
`running can also be provided according to the present
`invention.
`Other objects and attainments together with a fuller
`understanding of the invention will become apparent and
`appreciated by referring to the following description and
`claims taken in conjunction with the accompanying draw
`IngS.
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`FIG. 16 is a cross-sectional view showing the connector
`piece shown in FIGS. 14A and B mounted on the connector
`shown in FIG. 15;
`FIG. 17A is a graph of the relationship between optical
`wavelength and the optical transmittance of the skin, and
`FIG. 17B shows the relationship between optical wave
`length and the light absorbance of various types of hemo
`globin;
`FIG. 18 is a graph showing the emissions spectrum of a
`GaP LED that can be used in the pulse wave measuring
`apparatus in FIGS. 1A and B;
`FIG. 19 is a graph of the light reception characteristics of
`a GaAsP phototransistor used in the pulse wave measuring
`apparatus in FIGS. 1A and B;
`FIGS. 20A-1, 20A-2, 20B-1 and 20B-2 illustrate the
`effect of improving contact between the finger and light
`transmittance plate in the sensor unit used in the pulse wave
`measuring apparatus in FIGS. 1A and B;
`FIGS. 21A-21B illustrate the effect of reducing the effects
`of residual blood on the signal detected by the phototrans
`istor in a sensor unit used in the pulse wave measuring
`apparatus in FIGS. 1A and B:
`FIG. 22 is a graph of the evaluation results of the
`relationship between the sensor unit pressure on the finger
`and the levels of the AC signal and DC signal detected by the
`phototransistor in a pulse wave measuring apparatus as
`shown in FIGS. 1A and B in which the light transmittance
`plate is recessed from the reference surface 0.2 mm for
`comparison;
`FIG. 23 is another graph of the evaluation results (the
`relationship between the sensor unit pressure on the finger
`and the levels of the AC signal and DC signal detected by the
`phototransistor) shown in FIG.22 obtained in a separate test
`under the same basic conditions using a pulse wave mea
`suring apparatus as shown in FIGS. 1A and B in which the
`light transmittance plate is recessed from the reference
`surface 0.2 mm for comparison;
`FIG. 24 is a graph of the relationship obtained from the
`results shown in FIG.22 between the sensor unit pressure on
`the finger and the ratio of the AC signal to DC signal
`detected by the phototransistor;
`FIG. 25 is a graph of the evaluation results of the
`relationship between the sensor unit pressure on the finger
`and the levels of the AC signal and DC signal detected by the
`phototransistor in a pulse wave measuring apparatus as
`shown in FIGS. 1A and B in which the light transmittance
`plate projects 0.25 mm from the reference surface according
`to the preferred embodiment;
`FIG. 26 is another graph of the evaluation results (the
`relationship between the sensor unit pressure on the finger
`and the levels of the AC signal and DC signal detected by the
`phototransistor) shown in FIG. 25 obtained in a separate test
`under the same basic conditions using a pulse wave mea
`suring apparatus as shown in FIGS. 1A and B in which the
`light transmittance plate projects 0.25 mm from the refer
`ence surface according to the preferred embodiment;
`FIG. 27 is a graph of the relationship obtained from the
`results shown in FIG.25 between the sensor unit pressure on
`the finger and the ratio of the AC signal to DC signal
`detected by the phototransistor;
`FIG. 28 is a cross-sectional view of a separate sensor unit
`that can be used in the pulse wave measuring apparatus
`shown in FIGS. 1A and B;
`FIG. 29 is a cross-sectional view taken along line I-I in
`FIG. 4 of the sensor unit used in a pulse wave measuring
`
`BRIEF DESCRIPTION OF THE DRAWTNGS
`In the drawings wherein like reference symbols refer to
`like parts:
`FIGS. 1A and B show the overall configuration and use of
`a pulse wave information measuring apparatus according to
`the first embodiment of the present invention;
`FIG. 2 is a plan view of the main unit of the pulse wave
`measuring apparatus shown in FIGS. 1A and B;
`FIG. 3 is a side view showing of the main unit of the pulse
`wave measuring apparatus shown in FIGS. 1A and B from
`the three o'clock direction of a wristwatch;
`FIG. 4 is a plan view of the sensor unit used in the pulse
`wave measuring apparatus shown in FIGS. 1A and B;
`FIG. 5 is a cross-sectional view taken along line I-I in
`FIG. 4;
`FIG. 6 is a cross-sectional view taken along line II-II in
`FIG. 4;
`FIG. 7 is a cross-sectional view taken along line III-IIT
`in FIG. 4;
`FIG. 8 is a graph showing the emissions spectrum of an
`InGaN blue LED used in the pulse wave measuring device
`apparatus in FIGS. 1A and B;
`FIG. 9 is a graph of the light reception characteristics of
`an InCap phototransistor used in the pulse wave measuring
`device apparatus in FIGS. 1A and B;
`FIG. 10 is a graph of the light reception characteristics of
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`a filtered phototransistor unit used in the pulse wave mea
`suring device apparatus in FIGS. 1A and B;
`FIG. 11 illustrates the operation of the sensor unit in the
`pulse wave measuring device apparatus in FIGS. 1A and B
`when worn on a finger;
`55
`FIG. 12 is a functional block diagram of the data pro
`cessing circuit used in the pulse wave measuring apparatus
`shown in FIGS. 1A and B;
`FIG. 13 is a schematic diagram of electrical connections
`of a connector in the pulse wave measuring apparatus shown
`in FIGS. 1A and B;
`FIGS. 14A and B are diagrams of the connector piece
`used in the connecting means of the pulse wave measuring
`apparatus shown in FIGS. 1A and B;
`FIG. 15 is a diagram of the connector used in the
`connecting means of the pulse wave measuring apparatus
`shown in FIGS. 1A and B;
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`apparatus in accordance with a second embodiment of the
`present invention;
`FIG. 30 is a cross-sectional view taken along line II-IT
`in FIG. 4 of the sensor unit used in a pulse wave measuring
`apparatus in accordance with the second embodiment of the
`invention;
`FIG. 31 is a cross-sectional view taken along line III-IIT
`in FIG. 4 of the sensor unit used in a pulse wave measuring
`apparatus in accordance with the second embodiment of the
`invention:
`FIG. 32A is a perspective view of the sensor unit holding
`band used in a pulse wave measuring apparatus according to
`the second embodiment of the invention, and FIG. 32B is a
`perspective view of the sensor unit holding band when
`viewed from an upside down position;
`FIG. 33A is a perspective view of the sensor unit holding
`band shown in FIGS. 32A and 32B inverted from the
`condition shown in FIG. 32A, and FIG.33B is a perspective
`view of the sensor unit holding band shown in FIGS. 32A
`and 32B inverted from the condition shown in FIG. 32B;
`FIGS. 34A-34D are plan views of the sheet-like strips
`from which the sensor unit holding band shown in FIGS.
`32A and 32B is manufactured;
`FIG. 35A is a rear view of the sensor unit holding band
`shown in FIGS. 32A and 32B, FIG. 35B is a left side view
`thereof.