US007209775B2
`
`a2) United States Patent
`US 7,209,775 B2
`(10) Patent No.:
`(45) Date of Patent:
`Apr. 24, 2007
`Baeet al.
`
`
`(54) EAR TYPE APPARATUS FOR MEASURING A
`BIO SIGNAL AND MEASURING METHOD
`THEREFOR
`
`(75)
`
`Inventors: Sang-kon Bae, Seoul (KR); Gil-won
`Yoon, Seoul (KR); Jong-youn Lee,
`Yongin-si (KR)
`
`(73) Assignee: Samsung Electronics Co., Ltd.,
`Suwon-si, Gyeonggi-do (KR)
`
`4/2002 Imaiet al.
`6,371,925 BL
`5/2002 Kuuselaetal.
`6,396,416 Bl
`.......... 600/300
`9/2002 Cosentino et al.
`6,454,705 BL*
`6,816,741 B2* 11/2004 Diab occ: 600/324
`2002/0029000 Al
`3/2002 Ohsaki etal.
`2002/0042558 Al*
`4/2002 Mendelson .....ceceee 600/323
`2003/0036685 Al
`2/2003 Goodman
`2003/0163054 AL*
`8/2003 Dekker veces 600/502
`
`*)
`
`Notice:
`
`1)
`y
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 298 days.
`
`FOREIGN PATENT DOCUMENTS
`
`CN
`
`1 206 461
`
`1/1999
`
`(21)
`
`Appl. No.: 10/824,387
`
`(22)
`
`Filed:
`
`Apr. 15, 2004
`
`(65)
`
`(30)
`
`Prior Publication Data
`
`US 2004/0225207 Al
`
`Nov.11, 2004
`
`Foreign Application Priority Data
`
`(Continued)
`OTHER PUBLICATIONS
`
`Medical Science Series, Design of Pulse Oximeters,, Webster, J.G.,
`Editor, pp. 40-55,.
`
`May 9, 2003
`
`(KR) ween 10-2003-0029365
`
`Primary Examiner—Eric Winakur
`Assistant Examiner—Etsub Berhanu
`
`(51)
`
`(52)
`
`(58)
`
`(56)
`
`Int. Cl.
`A6IB 5/00
`
`(2006.01)
`(2006.01)
`A6IB 5/02
`(2006.01)
`A6IB 5/08
`US. Cleee 600/340; 600/323; 600/324;
`600/502; 600/529
`Field of Classification Search................ 600/322,
`600/323, 324, 340, 379
`See application file for complete search history.
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,002,060 A *
`5,673,692 A
`6,078,829 A *
`6,080,110 A
`6,109,782 A
`6,361,501 Bl
`
`3/1991
`10/1997
`6/2000
`6/2000
`8/2000
`3/2002
`
`......eceeeeeeeeeeeeeee 600/484
`Nedivi
`Schulze et al.
`Uchida etal.
`Thorgersen
`Fukuraetal.
`Amanoetal.
`
`be teeeeeeeeees 600/310
`
`(74) Attorney, Agent, or Firm—Lee & Morse, P.C.
`
`(57)
`
`ABSTRACT
`
`An apparatus for measuring a bio signal including a bio
`signal measurement unit, which is insertable into an ear to
`be in close contact with an internal surface of the ear, the bio
`signal measurement unit having a photo plethysmography
`(PPG) measurement module for radiating light of different
`wavelengths onto the internal surface of the ear, detecting
`light transmitted through the ear, and outputting a PPG
`signal including bio information, a control unit having a
`PPG signal processor for generating the bio information
`using the PPG signal measured by the PPG measurement
`module, and an output unit for displaying the bio informa-
`tion generated from the control unit.
`
`49 Claims, 14 Drawing Sheets
`
`MICROPHONE
`
`
`
`MODULE
`
`
`SOUND
`
`PROCESSOR
`
`590
`
`DISPLAY
`TEMPERATURE
`
`
`TRANSMITTER
`UNIT
`PROCESSOR
`
`TEMPERATURE
`MEASUREMENT
`
`MODULE
`
`520
`
`PPG
`
`PPG SIGNAL
`
`MEASUREMENT
`PROCESSOR
`
`
`
` Apple Inc.
`APL1150
`U.S. Patent No. 8,942,776
`
`550
`
`
`
`001
`
`Apple Inc.
`APL1150
`U.S. Patent No. 8,942,776
`
`001
`
`

`

`US 7,209,775 B2
` Page 2
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`
`0 770 349
`5-504084
`06-233745
`9-122083
`10-033511
`63-84520
`11-56827
`11-178803
`11-511301
`
`5/1997
`7/1993
`8/1994
`5/1997
`2/1998
`4/1998
`3/1999
`7/1999
`9/1999
`
`JP
`JP
`JP
`JP
`KR
`KR
`wo
`wo
`wo
`
`2001-344678
`2002-027051
`2002-078690
`2002-224050
`10-353380
`10/2002-0011730
`WO 91/11956
`WO 96/23442
`WO 96/41498
`
`* cited by examiner
`
`12/2001
`1/2002
`3/2002
`8/2002
`11/2000
`2/2002
`8/1991
`8/1996
`12/1996
`
`002
`
`002
`
`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 1 of 14
`
`US 7,209,775 B2
`
`FIG.
`
`1
`
`(PRIOR ART)
`
`11
`
`150
`
`120
`
`LIGHT. RECEIVER
`
`
`
`
`
`
`130
`
`
`
`SIGNAL
`PROCESSOR
`
`140
`
`DISPLAY/
`SOUND UNIT
`
`FIG. 2 (PRIOR ART)
`
`003
`
`

`

`U.S. Patent
`
`(LUVwold)§“DI
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`Apr. 24, 2007
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`|LINNI||Av1dSI0|;{1
`
`Sheet 2 of 14
`
`SSIT1S¢IM!JOVAYSLNI||-uaUnsvaN|eee||iviAGO|
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`LINNNOLLVOINNWAODLINA
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`YIYNSVIN
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`US 7,209,775 B2
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`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 3 of 14
`
`US 7,209,775 B2
`
`FIG. 4 (PRIOR ART)
`
`VOLTAGE
`GENERATOR
`
`AMPLIFIER
`
`PULSE
`
`401
`
`
`
`
`
`
`SHAPER ELECTRODES
`
`406
`
`
`
`
`NTERFACE
` Cc = 4
`|
`
`312
`
`oO
`
`405
`
`PULSE
`COUNTER
`
`FIG.5SA
`
`500
` UNIT
`
`590
`
`
`
`DISPLAY
`UNIT
`
`
`
` TEMPERATURE
`
`MEASUREMENT
`
`
`550
`MODULE
`
`CONTROL
`
`
` PPG
`
`MEASUREMENT
`
`
`MODULE
`
`
`
`005
`
`005
`
`

`

`U.S. Patent
`
`Apr. 24, 2007
`
`Sheet 4 of 14
`
`US 7,209,775 B2
`
`FIG.5B
`
`
`
`006
`
`006
`
`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 5 of 14
`
`US 7,209,775 B2
`
`FIG. 6
`
`SOUND
`PROCESSOR
`
`590
`
`DISPLAY
`
`TRANSMITTER
`
`
`
`
`UNIT TEMPERATURE
`
`
`
`MEASUREMENT
`MODULE
`
`920
`
`PPG
`MEASUREMENT
`
`
`MODULE
`
`
`
`
`PPG SIGNAL
`PROCESSOR
`
`FIG. 7
`
`
` AMPLIFIER
`
`
`570
`
`FILTER
`
`A/D
`CONVERTER
`
`TEMPERATURE
`MEASUREMENT
`MODULE
`
`565
`
`TRANSMITTER
`
`007
`
`007
`
`

`

`U.S. Patent
`
`Apr. 24, 2007
`
`Sheet 6 of 14
`
`US 7,209,775 B2
`
`__jo—!JOYNOSaounos|waunanv||JHOM—soLHON
`TWNOIS
` YOSS390Ud
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`Adog
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`
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`1uVdqoojd
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`1aSS3A
`
`008
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`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 7 of 14
`
`US 7,209,775 B2
`
`
`
`
`
`
`
`
`PEAK
`DETECTOR
`
`
`
`920
`
`AC
`DETECTOR
`
`DC
`DETECTOR
`
`930
`
`
`
`OXYGEN
`SATURATION
`DETECTOR
`
`
`
`
`
`REFLECTION
`COEFFICIENT
`DETECTOR
`
`
`
`009
`
`009
`
`

`

`U.S. Patent
`
`Apr. 24, 2007
`
`Sheet 8 of 14
`
`US 7,209,775 B2
`
`FIG
`
`. 10
`
`ALISNALNI
`
`WAVELENGTH (2m)
`
`11
`
`FIG. (%)
`
`NOISSINSNVUL
`
`WAVELENGTH (ym)
`
`010
`
`010
`
`
`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 9 of 14
`
`US 7,209,775 B2
`
`FIG. 12
`
`
`
`OUTPUT[mV]
`
`100
`80
`60
`40
`20
`0
`TEMPERATURE['C] @T amb.=25['C]
`
`FIG. 13
`
`
`
`LIGHTINTENSITY(1)
`
`
` AMOUNT OF
`
`
`HEART BEAT PERIOD
`
`
`ABSORBED
`LIGRT
`
`VARIATION OF TRANSMITTED LIGHT
`INTENSITIES DUE TO ARTERIAL
`PULSATILE COMPONENTS (AC)
`
`
`
`
`AMOUNT
`AMOUNT OF
`
`
`OF LIGHT
`{TRANSMITTED LIGHT
`
`
`
`TRANSMITTED LIGHT INTENSITY QUE
`TO NON=PULSATILE COMPONENTS (DC)
`
`
`
`Ip
`
`0
`
`TIME. (SEC)
`
`011
`
`~--t----
`
`1
`I
`‘
`o
`
`it i|
`
`|
`|
`|
`
`{{t1
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`
`{'
`
`011
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`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 10 of 14
`
`US 7,209,775 B2
`
`FIG. 14
`
`BAND-—PASS FILTER PPG DATA COLLECTED
`FOR PREDETERMINED PERIOD OF TIME
`
`S1410
`
`DIFFERENTIATE FILTERED SIGNAL AND
`FIND INFLECTION POINT AT WHICH SLOPE
`CHANGES FROM POSITIVE TO NEGATIVE
`
`STORE INFLECTION POINT AS PEAK WHEN
`INFLECTION POINT VALUE EXCEEOS
`THRESHOLD VALUE
`
`CALCULATE AVERAGE OF TIME DIFFERENCES
`BETWEEN PEAKS
`
`CALCULATE PULSE RATE BY DIVIDING 60
`SECONDS BY AVERAGE TIME DIFFERENCE
`
`END
`
`$1420
`
`$1430
`
`$1440
`
`51450
`
`012
`
`

`

`U.S. Patent
`
`Apr. 24, 2007
`
`Sheet 11 of 14
`
`US 7,209,775 B2
`
`FIG. 154
`
`1216
`
`830
`
`1591
`
`1968 2548
`
`126
`
`463
`
`”oO
`
`0.2
`
`
`
`AUSNSLNILHONM
`
`1318
`
`1693
`
`2069
`
`931
`
`205
`
`561
`
`neaeaeaeaeyeoee
`
`013
`
`013
`
`
`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 12 of 14
`
`US 7,209,775 B2
`
`FIG. 15B
`
`INTENSITY (
`
`||(t{
`
`LIGHT
`
`4000
`
`{f |
`
`3000
`
`1000 | 2000
`
`!!I |
`
`0
`
`014
`
`014
`
`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 13 of 14
`
`US 7,209,775 B2
`
`FIG. 16A
`
`PPG SIGNAL
`
`0
`
`i000
`
`2000
`
`3000
`
`4000
`
`5000
`
`6000
`
`7000
`
`8000
`
`FIG. 16B
`RESPIRATION SIGNAL
`
`j000.
`
`2000
`
`3000
`
`4000
`
`5000
`
`6000
`
`7000
`
`#8000
`
`14
`
`“1.16
`
`412
`
`4.25
`
`1
`
`FIG. 17A
`BAND—PASSFILTERED PPG
`
`0.2
`
`0
`
`1000
`
`«2000
`
`493000
`
`4000
`
`5000
`
`6000
`
`7000
`
`8000
`
`015
`
`015
`
`

`

`U.S. Patent
`
`Apr.24, 2007
`
`Sheet 14 of 14
`
`US 7,209,775 B2
`
`FIG. 17B
`
`HIGH—PASS FILTERED RESPIRATION SIGNAL
`
`0.01
`
`0.005
`
`-0.005
`1800
`
`OO —Fo00
`
`2000
`
`«3000-4000
`
`~«s000
`
`6000
`
`7000
`
`6000
`
`FIG. 18
`
`1815
`
`1825
`
`016
`
`016
`
`

`

`US 7,209,775 B2
`
`1
`EAR TYPE APPARATUS FOR MEASURING A
`BIO SIGNAL AND MEASURING METHOD
`THEREFOR
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates to an ear type apparatus for
`measuring a bio signal and a measuring methodtherefor.
`Moreparticularly, the present invention relates to an ear type
`apparatus for measuring a bio signal, such as temperature,
`respiration, pulse, and oxygen saturation, which can mini-
`mize a motion artifact caused by a subject’s motion, and a
`measuring method therefor.
`2. Description of the Related Art
`When a human body is in an abnormal state, various
`changes may occur such as an increase in blood pressure, an
`increase in pulse rate, an increase in body temperature, or a
`change in an electric potential occurring during a heartbeat,
`which may be measured by an electrocardiogram. Among
`these changes, the increase in body temperature is the most
`representative sign of an abnormal state of a human body
`and is thus generally measured during a patient diagnosis in
`hospitals or general medical
`institutions. Conventionally,
`body temperature is measured using a mercury thermometer.
`Recently, various ear type thermometers for measuring a
`body temperature,i.e., inner body temperature withoutinflu-
`ence from external temperature, have been developed. In
`operation, such an ear type thermometer detects an amount
`of infrared rays emitted from an eardrum at an internal body
`temperature and converts the detected amountof infrared
`rays into a temperature value. The ear type thermometeris
`advantageous in that a measurement time is short and the
`body temperature can be conveniently measured by inserting
`the ear type thermometer into an ear.
`A pulse indicates a dynamic extension of an artery that
`can be felt by a finger. Since the dynamic extension of an
`artery is due to a contraction of the heart, a heart rate, 1.e.,
`a heart’s contraction rate, can be inferred from a pulserate.
`When a humanbodyis infected by a disease, the pulse rate,
`rhythm, or strength changes even when the human bodyis
`ina stable status. Accordingly, a person’s state of health can
`be checked by measuringthe pulse rate, rhythm,or strength.
`Further, oxygen saturation indicates an amountofarterial
`blood (SpO,) in which oxygenis saturated. Oxygen satura-
`tion is measured to test a pulmonary function, estimate a
`concentration of oxygen in blood during oxygen therapy at
`home, or diagnose asthma and pulmonary emphysema.
`Humanrespiration is a process of discharging waste gas,1.e.,
`carbonic acid gas, from a human bodyandproviding oxygen
`to the humanbody. A human lung accommodates air coming
`from outside, emits carbonic acid gas, and absorbs oxygen.
`A pulmonary artery discharges carbonic acid gas collected
`throughout
`the human body through pulmonary alveoli
`using a difference in air pressure during exhalation. Con-
`versely, blood in a pulmonary vein absorbs oxygen from
`inhaled air and then circulates to the heart. When respiration
`is unstable, a supply of oxygen is interrupted, which dete-
`riorates the functions of a body’s organs.
`In particular,
`oxygen saturation directly relates to an amount of oxygen
`supplied to the organs and thus provides very useful infor-
`mation regarding metabolism.
`FIG. 1 shows an example of a conventional ear type
`thermometer for measuring body temperature. The ear type
`thermometer shown in FIG. 1 includes a housing 150 having
`a probe 110 through which infrared rays pass, a light
`receiver 120 that receives infrared rays emitted from at least
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`one area from among a human eardrum andperipheral areas
`of the eardrum through the probe 110, a signal processor 130
`that calculates a temperature from an output of the light
`receiver 120, and a display/sound unit 140 that displays the
`temperature.
`Thelight receiver 120 includes a condenser device, which
`condensesinfrared rays passing through the probe 110, and
`an infrared receiver device, which is disposed to receive the
`infrared rays condensed by the condenser device to receive
`infrared rays emitted from at least one area from among the
`eardrum and the peripheral areas of the eardrum.
`Disadvantageously, the conventional ear type thermom-
`eter shown in FIG. 1 is a separate device that has to be
`additionally carried by a user. Moreover, a tip of the probe
`110 of the thermometer needs to be in close contact with an
`internal surface of a subject’s ear in order to accurately
`measure the subject’s body temperature. However, when
`another person measures a subject’s body temperature, the
`contact between the thermometer and the internal surface of
`
`the ear cannot be adjusted effectively. Although the subject
`can directly adjust the contact when measuring his own body
`temperature, the subject must remove the thermometer from
`the ear to view the display unit to check a measured value
`and verify whether the measurement has been accurately
`performed. Accordingly, this thermometeris not appropriate
`for self-diagnosis and is thus usually used when another
`person measures a subject’s body temperature.
`In order to apply such a conventional ear type thermom-
`eter to a remote medical treatment, since a measured value
`needs to be transmitted via a separate transmission appara-
`tus, an interface is required. Accordingly,
`it is difficult to
`monitor results of the measurement frequently or for an
`extended period of time.
`FIG. 2 shows an example of a conventional mobile
`apparatus that is capable of measuring a bio signal. The
`exemplary mobile apparatus shown in FIG.2 is a portable
`communication terminal, which allows a function of a heart
`to be diagnosedor obesity to be tested based on a heart rate
`and a bodyfat rate, which are detected from a user’s body.
`This apparatus eliminates an inconvenience of carrying a
`separate apparatus solely for measuring bio information.
`Electrodes 2a, 26, 2c, and 2d are attached to an outer surface
`of a mobile communication terminal in order to measure a
`user’s bio information.
`FIG. 3 is a block diagram of the conventional mobile
`apparatus shown in FIG. 2. A portable communication
`terminal 300 includes a communication terminal module
`320 and a bio-information measurement module 310 to
`provide dual functionality of voice communication and bio
`information measurement. The communication terminal
`module 320 includes a transceiver 326 as a user interface
`unit, a display unit 321, such as a liquid crystal display
`(LCD), allowing communication of character information,
`and an input unit 322 such as a keypad. The input unit 322
`is used by a user to operate or control the portable commu-
`nication terminal 300. Communication of information can
`
`be implemented by wireless transmission and reception of
`data via a wireless communication unit 323. A memory unit
`324 stores information regarding the user of the portable
`communication terminal 300 and data necessary for the
`operation of the central controller 325.
`The bio-information measurement module 310 includes a
`body fat measurer 311 and a heart rate measurer 312. An
`interface unit 313 performs data interface between the
`portable communication terminal 300 and an external elec-
`tronic apparatus, for example, a removable bio-information
`measurement module.
`
`017
`
`017
`
`

`

`US 7,209,775 B2
`
`4
`whichis insertable into an ear to be in close contact with an
`
`internal surface of the ear, the bio signal measurement unit
`having a photo plethysmography (PPG) measurement mod-
`ule for radiating light of different wavelengths onto the
`internal surface of the ear, detecting light
`transmitted
`through the ear, and outputting a PPG signal including bio
`information, and further having a plurality of electrodes for
`outputting the PPG signal, an earphone having a speaker for
`outputting sound and a plurality of electrodes on an outer
`surface to be connected to the plurality of electrodes of the
`bio signal measurement unit
`to receive the PPG signal
`output from the bio signal measurementunit, a control unit
`having a PPG signal processor for receiving the PPG signal
`through the electrodes of the earphone and generating bio
`information using the PPG signal and a sound processor for
`outputting a soundsignalto the earphone, and an output unit
`for displaying the bio information generated from the con-
`trol unit.
`
`Preferably, the PPG measurement module includesa light
`source unit for radiating light onto the internal surface of the
`ear and a photodetector for detecting light radiated onto the
`internal surface of the ear and then transmitted through the
`ear. The light source unit may includea first light source for
`radiating light of a first wavelength onto the internal surface
`of the ear, and a secondlight source for radiating light of a
`second wavelength onto the internal surface of the ear,
`wherein the first and second wavelengths are different.
`Preferably,
`the PPG signal processor includes a peak
`detector for detecting peaks of the PPG signal and a signal
`processor for generating the bio information using values of
`the peaks. The signal processor may include a pulse detector
`for calculating a time interval between the peaks to measure
`a pulse rate. The signal processor may include a respiration
`detector for band-pass filtering the PPG signal to measure a
`respiration frequency. The signal processor may include a
`reflection coefficient detector for detecting an AC compo-
`nent and a DC component from each of PPGsignals detected
`at different wavelengths and measuring reflection coefti-
`cients and an oxygen saturation detector for detecting oxy-
`gen saturation in blood using a ratio between the reflection
`coefficients of the different wavelengths.
`The PPGsignal processor may further include an ampli-
`fier for amplifying the PPG signal anda filter for removing
`noise components from the PPG signal amplified by the
`amplifier and then outputting the PPG signal to the peak
`detector.
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`3
`FIG. 4 is a detailed block diagram of the heart rate
`measurer 312. The heart rate measurer 312 includes a
`
`voltage generator 401, electrodes 402, an amplifier 403, a
`pulse shaper 404, a pulse counter 405, and an interface unit
`406. When the electrodes 402 of the voltage generator 401,
`which are attached to a main body of the portable commu-
`nication terminal 300, are in close contact with a part of a
`subject’s body, for example, right and left hands, a voltage
`change signal dueto the heart’s beat is detected. The voltage
`changesignal is amplified by the amplifier 403, for example,
`a differential amplifier. The amplified voltage change signal
`is converted to a pulse signal by the pulse shaper 404. The
`pulse signal is counted by the pulse counter 405 to obtain a
`heart rate. An output signal of the pulse counter 405 is a
`digital signal and is input to the interface unit 406. The
`central controller (325 of FIG. 3) displays the heart rate on
`the display unit 321 and transmits it through the wireless
`communication unit 323. Voltage measurement electrodes
`used to measure body fat in the body fat measurer 311 are
`also used as the electrodes 402.
`Disadvantageously, such a conventional portable commu-
`nication terminal for measuring bio information using elec-
`trodes is influenced by a motion artifact caused by a force
`pressing the electrodes and is sensitive to contamination of
`the electrodes or the skin since the electrodes directly
`contact the skin. When the electrodes are exposed outside
`the communication terminal, they are easily damaged or
`contaminated.
`
`To obtain bio information, such as oxygen saturation, a
`component in blood needs to be detected. Accordingly, a
`methodof applying signals showing different characteristics
`according to concentrations of oxidized hemoglobin and
`reduced hemoglobin and obtaining the bio information using
`a difference between the signals is usually used. In conven-
`tional methods, however, since one electrode cannot apply
`different types of signals, bio information beyond a pulse
`rate cannot be appropriately measured.
`
`SUMMARY OF THE INVENTION
`
`The present invention provides an apparatus for measur-
`ing a bio signal, which is convenient
`to carry, can be
`adjusted to be correctly positioned at a body part to be
`measured by a subject himself, and can transmit measured
`bio information without requiring a separate transmitter,
`thereby facilitating long-term monitoring. In addition, the
`apparatus can obtain pulse and respiration information and
`simultaneously measure oxygen saturation using changes in
`absorptance of light having at least two different wave-
`lengths. The present invention further provides a method for
`measuring a bio signal.
`According to a feature of an embodiment of the present
`invention, there is provided an apparatus for measuring a bio
`signal including a bio signal measurement unit, which is
`insertable into an ear to be in close contact with an internal
`surface ofthe ear, the bio signal measurement unit having a
`photo plethysmography (PPG) measurement module for
`radiating light of different wavelengths onto the internal
`surface ofthe ear, detecting light transmitted through theear,
`and outputting a PPG signal including bio information, a
`control unit having a PPG signal processor for generating
`the bio information using the PPG signal measured by the
`PPG measurement module, and an output unit for displaying
`the bio information generated from the control unit.
`According to another feature of an embodiment of the
`present invention, there is provided an apparatus for mea-
`suring a bio signal including a bio signal measurementunit,
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`further
`the bio signal measurement unit
`Preferably,
`includes a temperature measurement module for sensing
`infrared rays radiated from a body and outputting an elec-
`trical signal corresponding to the sensed infrared rays, and
`wherein the control unit further includes a temperature
`processor for calculating a body temperature using the
`electrical signal output from the temperature measurement
`module. The temperature measurement module may include
`a waveguide installed near an eardrum for guiding infrared
`rays radiated from the eardrum anda light receiver sensing
`the infrared rays guided by the waveguide and converting
`the infrared rays to the electrical signal. The waveguide may
`be made of a material that can reflect infrared rays. The
`temperature processor may include an amplifier for ampli-
`fying the electrical signal received from the temperature
`measurement module, a filter for removing noise from the
`amplified electrical signal, and an analog-to-digital con-
`verter for converting the electrical signal to a digital signal.
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`US 7,209,775 B2
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`5
`The output unit may be a liquid crystal display apparatus.
`Further,
`the output unit may be a liquid crystal display
`apparatus of a mobile communication terminal or a compact
`disc player.
`The bio information unit may further include a mobile
`communication terminal through which the bio information
`generated from the control unit is wirelessly transmitted to
`a predetermined medicalinstitution.
`Accordingtostill another feature of an embodimentof the
`present invention, there is provided a method of measuring
`a bio signal using an ear type bio signal measurement
`apparatus including a bio signal measurement unit, which is
`insertable into an ear to measurea bio signal, a control unit
`for generating bio information using the measured bio
`signal, and an output unit for outputting the bio information,
`the method including (a) receiving infrared rays radiated
`from an eardrum and measuring a body temperature using
`the bio signal measurement unit, (b) radiating light having
`different wavelengths onto an internal surface of an ear,
`which is in close contact with the bio signal measurement
`unit,
`to measure a photo plethysmography (PPG) signal
`including bio information and measuring at least one bio
`signal from among the group consisting of oxygen satura-
`tion, a pulse rate, and a respiration frequency, using the PPG
`signal, and (c) outputting the at least one bio signal mea-
`sured in (a) and (b), wherein (a) and (b) are simultaneously
`performed.
`Preferably, (b) includes (b1) radiating the light having the
`different wavelengths onto the internal surface of the ear,
`receiving the light transmitted through the ear, and output-
`ting the PPG signal, using a PPG measurement module
`included in the bio signal measurement unit having a side
`thereof in close contact with the internal surface of the ear;
`(b2) detecting peaks of the PPG signal; and (b3) generating
`bio information using the detected peaks.
`Preferably, (b3) includes detecting an AC component and
`a DC component from each of PPG signals detected at the
`different wavelengths and measuring reflection coefficients
`of the different wavelengths, and calculating oxygen satu-
`ration in blood using a ratio between the reflection coeffi-
`cients of the different wavelengths. Preferably, (b3) includes
`band-pass filtering the PPG signal to detect a respiration
`frequency. In addition, (b2) may include band-pass filtering
`the PPG signal collected for a predetermined period of time,
`detecting an inflection point by differentiating the filtered
`PPGsignal, and storing the inflection point as a peak when
`the inflection point has a value exceeding a predetermined
`threshold value.
`Preferably, (b3) may include measuring a pulse rate using
`a time interval between peaks of the PPG signal. The output
`unit may be a liquid crystal display apparatus of a mobile
`communication terminal, and (c) may further include wire-
`lessly transmitting the bio signals measured in (a) and (b) to
`a predetermined medical
`institution through the mobile
`communication terminal.
`According to yet another feature of an embodimentof the
`present invention, there is provided a recording medium
`having recorded therein a program for executing the above-
`described method in a computer.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and other features and advantages of the
`present invention will become more apparent to those of
`ordinary skill in the art by describing in detail preferred
`embodiments thereof with reference to the attached draw-
`
`ings in which:
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`6
`FIG. 1 shows an example of a conventional ear type
`thermometer for measuring body temperature;
`FIG. 2 shows an example of a conventional mobile
`apparatus that is capable of measuring a bio signal;
`FIG. 3 is a block diagram of a conventional mobile
`apparatus as shown in FIG.2;
`FIG.4 is a detailed block diagram of a conventional heart
`rate measurer as shown in FIG.3;
`FIG. 5A is block diagram of an apparatus for measuring
`a bio signal according to a first embodimentof the present
`invention;
`FIG. 5B shows an example in which an apparatus for
`measuring a bio signal according to an embodimentof the
`present invention is applied to a mobile apparatus;
`FIG.6 is a block diagram showing a control unit as shown
`in FIG. 5A;
`FIG.7 is a detailed block diagram showing a temperature
`processor as shown in FIG.6;
`FIG. 8 is a detailed block diagram showing a photo
`plethysmography (PPG) measurement module and a PPG
`signal processor as shown in FIG.6;
`FIG. 9 is a detailed block diagram showing a signal
`processor as shown in FIG.8;
`FIG. 10 is a graph of intensity of radiant energy of a black
`body versus wavelength;
`FIG. 11 is a graph showing a transmission characteristic
`of a sensorfilter;
`FIG.12 is a graph showing a temperature characteristic of
`a sensor;
`FIG. 13 is a conceptual diagram of a measured PPG
`waveform;
`FIG. 14 is a flowchart of a method of measuring a pulse
`rate according to an embodimentof the present invention;
`FIG. 15A is a diagram showing a detected pulse signal;
`FIG. 15B illustrates a method of detecting respiration
`according to an embodiment of the present invention;
`FIGS. 16A and 16B show a PPGsignaland a respiration
`signal, respectively, which are simultaneously measured;
`FIGS. 17A and 17B, respectively, show a respiration
`signal detected using a PPG signal anda respiration signal
`obtained by high-passfiltering the respiration signal shown
`in FIG. 16B; and
`FIG. 18 illustrates a schematic diagram of an apparatus
`for measuring a bio signal according to a second embodi-
`ment of the present invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`Korean Patent Application No. 2003-29365, filed on May
`9, 2003, and entitled: “Ear Type Apparatus for Measuring a
`Bio Signal and Measuring Method Therefor,” is incorpo-
`rated by reference herein in its entirety.
`The present invention will now be described more fully
`hereinafter with reference to the accompanying drawings, in
`which preferred embodiments of the invention are shown.
`The invention may, however, be embodiedin different forms
`and should not be construed as limited to the embodiments
`
`set forth herein. Rather, these embodiments are provided so
`that this disclosure will be thorough and complete, and will
`fully convey the scope ofthe invention to those skilled in the
`art. Like reference numerals refer to like elements through-
`out.
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`FIG. 5A is block diagram of an apparatus for measuring
`a bio signal according to a first embodimentof the present
`invention. FIG. 5B shows an example in which an apparatus
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`US 7,209,775 B2
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`7
`for measuring a bio signal according tothe first embodiment
`of the present invention is applied to a mobile apparatus.
`Referring to FIG. 5A, the apparatus according tothefirst
`embodimentof the present invention includes a bio signal
`measurement unit 500, which is insertable into an ear to
`measure a bio signal; a control unit 550, which calculates bio
`information using the bio signal measured by the bio signal
`measurement unit 500; and a display unit 590, which dis-
`plays the bio information on a screen for a user. The bio
`signal measurement unit 500 includes a temperature mea-
`surement module 510, which measures body temperature
`using infrared rays radiated from an internal surface of an
`ear, and a photo plethysmography (PPG) measurement mod-
`ule 520, which is installed on an outer surface of the bio
`signal measurement unit 500 to closely contact the internal
`surface of the ear and measure a PPG signal.
`Referring to FIGS. 5A and 5B, the bio signal measure-
`ment unit 500 can be easily inserted into the ear dueto its
`shape. The PPG measurement module 520is installed at the
`outer surface of the bio signal measurement unit 500 to
`closely contact the ear surface. The temperature measure-
`ment module 510 is installed in the bio signal measurement
`unit 500 at a position that will be in relatively close
`proximity to an eardrum. The bio signal measurement unit
`500 may have a same shape as an earphone 530, as shown
`in FIG. 5B. However, since it is preferable that the tem-
`perature measurement module 510 is positioned near the
`eardrum so thatit can effectively sense infrared rays radiated
`from the eardrum, it is preferable to shape the bio signal
`measurement unit 500 as a conical frustum and to dispose
`the temperature measurement module 510 at a top of the
`conical frustum-shaped bio signal measurement unit 500.
`The temperature measurement module 510 includes a
`waveguide 511 guiding infrared rays near the eardrum to the
`bio signal measurement unit 500 and a light receiver 513
`implemented by an infrared sensorto sensethe infrared rays
`input through the waveguide 511.
`For the display unit 590, a separate display apparatus or
`a display apparatus includedin an existing apparatus can be
`used. In the example shown in FIG. 5B, a mobile apparatus
`is used as the display unit 590. The display unit 590 may be
`implemented by a liquid crystal display (LCD) of a mobile
`communication terminal (as shown in FIG. 5B), a personal
`digital assistant (PDA), a compact disc player, or the like.
`When a mobile communication terminal is used, bio infor-
`mation can be transmitted to a predetermined medicalinsti-
`tution, so that remote examination can be performed. Here-
`inafter, it is assumed that a mobile apparatus is used for the
`display unit 590.
`In FIG. 5B, the control unit 550 is shown separate from
`the bio signal measurement unit 500. The control unit 550
`calculates bio information using a signal received from the
`bio signal measurement unit 500 and outputs the bio infor-
`mation to the display unit 590. When a mobile apparatusis
`used for the display unit 590, the control unit 550 can be
`installed within the mobile apparatus. When the control unit
`550 is separately installed outside the mobile apparatus, it
`can be provided with a jack, which can be connectedto the
`earphone 530, as shown in FIG. 5B, so that the control unit
`550 controls a sound signal output from the mobile appa-
`ratus and outputs the sound signal to the earphone 530.
`FIG. 6 is a block diagram showing the control unit 550
`shown in FIG. 5A. The control unit 550 includes a tempera-
`ture processor 570, which converts a signal detected by the
`infrared sensor of the temperature measurement module 510
`to a temperature value; a PPG signal processor 580, which
`generates measurement values of a pulse rate, a respiration
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`8
`frequency, and oxygen saturation using the PPG signal
`measured by the PPG measurement module 520; and a
`transmitter 565, which selectively transmits an output signal
`from the temperature processor 570 and an output signal
`from the PPGsignal processor 580 to the mobile apparatus
`according to a selection signal of the mobile apparatus used
`for the display unit 590. When the earphone 530, which can
`output a sound signal from the mobile apparatus,
`is con-
`nected to the control unit 550, the control unit 550 further
`includes a sound processor 560, which re