Description
BODY FAT MEASUREMENT DEVICE
Technical Field
[0001] The present invention relates to a body fat measurement device, and more
particularly, to a body fat measurement device of a type which performs measurement by
wrapping a belt around the abdomen of a subject.
Background Art
[0002] A body fat measurement device of a type which performs measurement by
wrapping a belt around the abdomen of a subject has high measurement accuracy compared
to a body fat measurement device of a built-in type, in weighing scales, or the like, and is
used in periodic examinations, and the like. A visceral fat measurement device which uses
this measurement method, namely, an abdominal impedance method, has been proposed
before by the present applicants in Patent Document 1.
[0003] In the abdominal impedance method described in Patent Document 1, a pair of
current application electrodes are placed on the front and back of the subject, more
specifically, on the center of the subject's abdomen (navel) and the center of the subject's
back (spine), and a current is passed in the front/rear direction through the subject's abdomen.
Furthermore, a pair of voltage measurement electrodes are placed on the subject at staggered
positions in the front and back of the body (the sides of the subject), and the abdominal
impedance is calculated from the voltage between the voltage measurement electrodes when
a uniform current is passed from the current application electrodes. An amount of visceral fat
is measured from this abdominal impedance.

[0004] Moreover, in the abdominal impedance method described in Patent Document 1,
the subcutaneous fat thickness is measured separately, and the amount of visceral fat is
corrected by this measured subcutaneous fat thickness. By this means, the effects due to
difference in the subcutaneous fat thickness are eliminated and the measurement accuracy of
the amount of visceral fat is improved. In Patent Document 1, desirably, an optical sensor is
used as subcutaneous fat thickness measurement means.
[0005] In this way, a sensor, or the like, for measuring parameters other than the
abdominal impedance such as the subcutaneous fat thickness, are attached to the subject's
body, apart from the current application electrodes and the voltage measurement electrodes.
Signal wires are extracted from the electrodes and the sensor and are connected to a
measurement device. A current is supplied to the current application electrodes by the
measurement device, and the amount of visceral fat is measured from the voltages detected
by the voltage measurement electrodes and the sensor, and the subcutaneous fat thickness.
[0006] In this way, if a sensor for measuring parameters other than the abdominal
impedance is attached to a subject's body, apart from current application electrodes and
voltage measurement electrodes which are used in order to measure abdominal impedance,
then it is necessary to connect a large number of signal wires between the subject and the
measurement device, and therefore the arrangement of the signal wiring becomes
complicated, usability becomes worse, and the cost of the signal cables increases.
[0007] Therefore, from the viewpoint of usability and cost, it is desirable to connect the
electrodes and sensor with the measurement device by using a multi-core cable in which a
plurality of core wires are bunched together inside a single insulating coating. More
specifically, it is desirable to form the core wires for the current application electrodes and
the voltage measurement electrodes, and the core wire for the another measurement means, in
an integrated fashion inside the same insulating coating.

[0008] In a body fat measurement device of a type which is built into weighing scales,
for example, the impedance is measured, for example, between the legs of a subject standing
on the scales, or between electrodes gripped by the subject's hands or in contact with the
user's feet. Therefore, the impedance measurement path becomes long, as a result of which
the measurement impedance becomes several hundred Ω, for example.
[0009] On the other hand, in a device which measures the amount of body fat from the
abdominal impedance, the impedance is measured across a short distance between the
subject's sides, and is one several hundredth of the impedance in a measurement device built
into a weighing scales, while the measurement voltage is only several mV.
[0010] Therefore, if a multi-core cable is used and the core wires for the current
application electrodes and the voltage measurement electrodes, and a core wire for another
measurement means are bunched inside a single insulating coating, then the wire-to-wire
capacitance and unwanted radiation from the core wire for the other measurement means has
a great effect on the weak measurement voltage. Consequently, the accuracy of the voltage
measurement declines and there is a risk that the measurement accuracy of the abdominal
impedance will decline.
[0011 ] Patent Document 1: Japanese Patent Application Publication No. 2007-151619
Summary of the Invention
[0012] It is an object of the present invention to provide a body fat measurement device
which is capable of reducing the risk of decline in the measurement accuracy of abdominal
'impedance, when calculating an amount of body fat from an abdominal impedance.
[0013] The body fact measurement device according to one aspect of the present
invention is a body fat measurement device, including: a belt which is wrapped around an
abdomen of a subject; a plurality of electrodes which are provided on the belt and contact a

body surface of the subject: a current application unit which passes a predetermined current
between a pair of electrodes of the plurality of electrodes; a first measurement unit which
measures a voltage between another pair of electrodes, of the plurality of electrodes, while
the current is passed between the pair of electrodes by the current application unit; a
calculation unit which calculates an abdominal impedance of the subject on the basis of the
voltage measured by the first measurement unit and calculates an amount of body fat of the
subject by using the calculated abdominal impedance; a second measurement unit which
acquires a parameter other than the abdominal impedance and outputs a signal indicating the
measured parameter to the calculation unit; a cable in which a first core wire which connects
between at least one of the current application unit and the pair of electrodes, and the first
measurement unit and the other pair of electrodes, and a second core wire which connects the
second measurement unit and the calculation unit are provided inside a same insulating
coating; and an isolating unit which can shut off the connection between the second core wire
and the calculation unit, wherein the calculation unit shuts off the connection between the
second core wire and the calculation unit by the isolating unit, during measurement of the
abdominal impedance, acquires the voltage measured by the first measurement unit while the
connection is shut off, and calculates the abdominal impedance on the basis of the acquired
voltage.
Brief Description of the Drawings
[0014] [Fig. 1] Fig. 1 is a perspective diagram of a belt-type body fat measurement
device relating to one embodiment of the present invention.
[Fig. 2] Fig. 2 is a perspective diagram showing a state of use of a body fat
measurement device shown in Fig. 1.

[Fig. 3] Fig. 3 is a diagram for describing the principles of measuring body fat by an
impedance method.
[Fig. 4] Fig. 4 is a diagram for describing a method of measuring abdominal
circumference.
[Fig. 5] Fig. 5 is an enlarged view of Fig. 4.
[Fig. 6] Fig. 6 is a block diagram showing an electrical composition of the body fat
measurement device shown in Fig. 1.
[Fig. 7] Fig. 7 is a diagram showing a schematic view of the wiring of lead wires in the
body fat measurement device shown in Fig. 1.
[Fig. 8] Fig. 8 is a flowchart showing one example of the operation of the body fat
measurement device 1 shown in Fig. 1.
[Fig. 9] Fig. 9 is a flowchart showing one example of the operation of the body fat
measurement device 1 shown in Fig. 1.
[Fig. 10] Fig. 10 is a flowchart showing one example of the operation of the body fat
measurement device 1 shown in Fig. 1.
[Fig. 11] Fig. 11 is a waveform diagram for describing a method of judging an
electrode contact defect (in a normal situation).
[Fig. 12] Fig. 12 is a waveform diagram for describing a method of judging an
electrode contact defect (error mode 1).
[Fig. 13] Fig. 13 is a waveform diagram for describing a method of judging an
electrode contact defect (error mode 2).
[Fig. 14] Fig. 14 is a waveform diagram for describing a method of judging an
electrode contact defect (error mode 3-1).
[Fig. 15] Fig. 15 is a waveform diagram for describing a method of judging an
electrode contact defect (error mode 3-2).

[Fig. 16] Fig. 16 is a waveform diagram for describing a method of judging an
electrode contact defect (error mode 4).
[Fig. 17] Fig. 17 is a block diagram showing the electrical composition of a belt-type
body fat measurement device relating to a further embodiment of the present invention.
Mode for Carrying Out the Invention
[0015] (First Embodiment)
Fig. 1 is a perspective diagram of a belt-type body fat measurement device 1 relating to
one embodiment of the present invention. Fig. 2 is a perspective diagram showing a state of
use of the body fat measurement device 1. This body fat measurement device 1 is broadly
constituted by a belt 3 which is wrapped around the abdomen 2a of a subject 2, a plurality of
electrodes 11 to 14 which contact the surface 2b of the abdomen 2a of the subject 2, an
abdominal circumference meter 4 which is attached to the belt 3, a wire concentrator 5, and a
main body 6 which is disposed separately from the belt 3. This body fat measurement device
1 is used in medical examinations, and the like, and measures the amount of body fact of a
subject 2 by using an abdominal impedance method. In the body fat measurement device 1,
one of, for example, three types of belt of sizes S, M and L, and equipment attached to the
belts (abdominal circumference meter 4, wire concentrator 5, etc.), is selected in accordance
with the waist size of the subject, and is used by connection to the common main body 6.
Alternatively, respective belts 3 of different sizes and equipment attached to the belts may be
connected simultaneously to the main body 6.
[0016] Fig. 3 is a diagram for describing the principle of measuring body fat by the
abdominal impedance method described above. To give a simple illustration, a cross-
sectional view of the abdomen 2a of a person (subject 2) perpendicular to the axis (a
horizontal cross-section) can be depicted as shown in Fig. 3. More specifically, inside the

subcutaneous fat 2A, there is muscle tissue 2B and visceral fat 2C accumulates inside this
muscle tissue 2B. Here, a pair of current application electrodes 11, 12 are provided on the
center of the abdomen (navel) 2c of the subject 2 and the center of the back (spine position)
2d of the subject 2, and when a predetermined current is passed between these electrodes 11,
12, equipotential lines occur in virtual front/back symmetry in the abdomen 2a due to the
passage of the current, as shown by the broken lines in Fig. 3. In this case, the ends of the
equipotential lines which pass through the portion of the visceral fact 2C appear at the sides
2e of the subject 2. Therefore, when voltage detection electrodes 13,14 are placed in contact
with the front and rear of a side 2e of the subject 2, the potential difference generated in the
portion of the visceral fat 2C can be detected by the voltage detection electrodes 13, 14 as a
detection voltage V.
[0017] It is known that, in general terms, the product obtained by multiplying the
detection voltage V by the total cross-sectional area of the abdomen 2a is proportional to the
area of the visceral fat. In practice, taking the constant current that is passed to be I and
taking the detection voltage to be V, then the resistance (impedance) R of the visceral fat 2C
can be determined from Formula (1) below. Desirably, the resistance (impedance) R of the
visceral fat 2C is read out from a previously created look-up table in association with other
parameters (information) such as gender, weight, abdominal circumference, subcutaneous fat
thickness, and the like, and the amount of body fat is determined by carrying out appropriate
interpolation calculations, and the like. Below, the resistance (impedance) R of the visceral
fat 2C is called the "abdominal impedance" R.
Abdominal impedance R = V/I ... (1)
[0018] More specifically, the greater the amount of visceral fat 2C, the greater the
abdominal impedance R. The relationship between the abdominal impedance R and the
amount of body fat varies depending on parameters indicating physical quantities, such as the

subject's body weight and abdominal circumference, and parameters indicating the subject's
gender.
[0019] Therefore, a look-up table which associates body fat values with combinations of
various parameters, such as abdominal impedance R, gender, weight, abdominal
circumference, and the like, is determined in advance by experimentation, for instance, and
then stored in a memory 615 which is described below. A control microcomputer 611, also
described below, then acquires various parameters such as the abdominal impedance R,
gender, weight, abdominal circumference, and the like, and obtains the amount of body fat
stored in association with these parameters in the look-up table stored in the memory 615, as
the amount of body fat of the subject. In this way, by determining the amount of body fat
using parameters other than the abdominal impedance R, in addition to the abdominal
impedance R, the calculation accuracy of the amount of body fat is improved.
[0020] The look-up table is not necessarily limited to an example which associates a
body fat amount with a combination of respective parameters, such as the abdominal
impedance R, gender, weight, abdominal circumference, and the like. The look-up table may
also associate the body fat amount with the abdominal impedance R, or may associate the
body fat amount with a combination of a portion of the parameters of abdominal impedance
R, gender, weight and abdominal circumference, or may include parameters other than
gender, weight and abdominal circumference.
[0021] Returning to Fig. 1 and Fig. 2, therefore, the belt 3 is constituted by a base side
buckle 31, a slit portion 32 connected to this, and a belt-shaped portion 33 connected to this.
A surface fastener (a hook section, for example) 31a is attached to the front surface of the
buckle 31, and a surface fastener (a loop section, for example) 33b which corresponds with
the surface fastener 31a is attached to the rear surface of the free end 33a of the belt portion
33. By applying strong pressure to the surface fastener 3 la and the surface fastener 33b, it is

possible to wrap the belt 3 tightly around the abdomen 2a of a subject 2 having any girth.
Here, the surface fasteners 31a and 33b are a pair of so-called mechanical fasteners consisting
of hooks and loops, in which, when pressed strongly together, the hook section and loop
section interlock and become difficult to separate, and when pulled strongly apart, the
interlocking is released and the hook section and loop section can be peeled apart.
[0022] As shown in Fig. 2, a buckle 31 is arranged at a position of the center of the
abdomen (navel) 2c on the surface 2b of the subject 2, and the belt 3 is wrapped in a
clockwise direction and the surface fastener (loop section) 33b on the free end 33a is attached
to the surface fastener (hook section) 31a on the buckle 31. In this way, it is possible to fix
the belt 3 to the abdomen 2a of the subject 2, as shown in Fig. 2 and Fig. 4. Furthermore, by
this means, the current application electrode 11 provided on the rear surface of the buckle 31
(the first current application electrode) makes contact with a position in the center of the
abdomen (navel) 2c on the surface 2b of the subject 2.
[0023] The slit portion 32 connects with the buckle 31, and an electrode sheet 35 is
attached to a portion of the inside of an opening 32a of the slit portion 32, which corresponds
with the side 2e of the subject 2. The electrode sheet 35 is constituted by attaching voltage
detection electrodes 13, 14 consisting of gel electrodes to a flexible plastic sheet coated with
adhesive. Therefore, the voltage detection electrodes 13, 14 are not fixed to the belt 3, and
hence it is possible to provide the voltage detection electrodes 13, 14 accurately at a position
on the side 2e of the subject 2, for subjects 2 having different abdominal circumferences.
Furthermore, even if the voltage detection electrodes 13, 14 are not pressed against the
subject 2 by the belt 3, the voltage detection electrodes 13, 14 adhere to the subject 2 with a
uniform adhesive force, and therefore stable voltage detection can be achieved.
[0024] In the belt-shaped portion 33 which connected with the slit portion 32, an
abdominal circumference meter 4 is fitted into the base end 33c side. A current application

electrode 12 (second current application electrode) which opposes the current application
electrode 11 is provided on the rear surface of this abdominal circumference meter 4. The
user, such as a subject 2 or an examination technician, wraps the belt 3 around the subject 2
as described above, and then slides the abdominal circumference meter 4 so to position the
meter in the center of the abdomen, as shown in Fig. 4. By this means, it is possible to
dispose the current application electrodes 11, 12 in opposing fashion on the subject 2, at the
center of the abdomen (navel) 2c and at the center of the back (spine) 2d. The current
application electrodes 11,12 correspond to one example of a pair of electrodes.
[0025] Furthermore, in the belt-shaped portion 33, an indicator mark which shows the
abdominal circumference by means of magnetic strips, slits, or the like, is embedded in the
base end 33c side, and the abdominal circumference is measured by means of the indicator
mark being read by a measuring unit 16 (see Fig. 6) which is built into the abdominal
circumference meter 4. More specifically, when the current application electrode 12 has been
arranged at a position at the center of the subject's back (spine) 2d, as described above, the
length from the current application electrode 11 embedded in the buckle 31 to the current
application electrode 12 is determined via the slit portion 32. The length A from the current
application electrode 11 to the current application electrode 12 which is determined in this
way is measured by means of the measuring unit 16 reading out the indicators embedded in
the belt-shape portion 33. The measuring unit 16 is then able to determine the abdominal
circumference by multiplying the measured length A by two.
[0026] The measuring unit 16 corresponds to one example of a second measuring unit.
The second measuring unit is not limited to one which measures the abdominal
circumference, and may be a unit which measures other parameters, such as the subcutaneous
fat thickness, or the like.

[0027] Moreover, as shown in Fig. 1 and Fig. 4, an indicator mark 33d which indicates
the abdominal circumference is provided visibly on the belt-shape portion 33, in such a
manner that a user (technician, or the like) can measure the abdominal circumference directly.
An indicator arrow 4b is also provided in an opening 4a of the abdominal circumference
meter 4 through which the belt-shape portion 33 passes. In accordance with this, as depicted
in enlarged view in Fig. 5, indicator marks 32b indicating the abdominal circumference are
also formed in the slit portion 32. By aligning an indicator mark 35a attached to the electrode
sheet 35 with the position on the indicator marks 32b of the value read out by the indicator
• arrow 4b of the abdominal circumference meter 4, the voltage detection electrodes 13, 14 are
easily registered in position in such a manner that a prescribed position of the side 2e of the
subject 2, in other words, the center between the voltage detection electrodes 13, 14 is
situated at a position one half of the length from the current application electrode 11 to the
current application electrode 12. The voltage detection electrodes 13, 14 correspond to one
example of another pair of electrodes.
[0028] On the other hand, a wire concentrator 5 is suspended by a cord 5a from the slit
portion 32. Single-core lead wires 21, 22, 23 from the current application electrode 11 and
the two voltage detection electrodes 13, 14 and five-core lead wires 24, 25, 26, 27, 28 from
the abdominal circumference meter 4 are connected to the wire concentrator 5 by a connector,
or the like. The wire concentrator 5 concentrates these lead wires 21 to 28 into a single cable
29 with an insulating coating, and connects to the main body 6. In this way, by uniting the
lead wires 21 to 28 into a single cable 29, usability is improved and costs can be reduced.
[0029] Fig. 6 is a block diagram showing an electrical composition of the body fat
measurement device 1 shown in Fig. 1. The main body 6 comprises a main board (circuit
board) 61, an operation control board (circuit board) 62, a board (circuit board) 63 for
selecting belts of three types of sizes S, M and L, a display panel 64, and a USB interface

board (USB board) 65. The main board 61 is connected to an external personal computer 7,
or the like, via a USB interface board 65. By this means, information about the amount of
body fat measured by the main board 61 is sent to the personal computer 7, and measurement
results can be compiled and recorded by the personal computer 7, and the detailed settings in
the main board 61, and the like, can be established from the personal computer 7.
[0030] In Fig. 6, a belt 3 and equipment attached to the belt 3 are depicted. Furthermore,
the belts of three types of the sizes S, M, L have a common electrical composition, and
therefore the belt 3, the cable 29 and the connector 30 shown in Fig. 6 relating to each of the
belts.
[0031] A power key 621, a visceral fat measurement key 622, an abdominal
circumference measurement key 623 and man and woman selection keys 624, 625 are
provided on the operation control board 62. Indicators (LEDs) 626 to 630 which light up
respectively in response to the operation of the keys 621 to 625 are provided. Similarly, keys
631 to 633 are provided on the belt selection board 63 in order to select which of the three
types of belt S, M, L is to be used in measurement. The indicators LEDs 634 to 636 light up
respectively in response to the operation of the keys 631 to 633. The display panel 64 is
made from a liquid crystal display device, or the like.
[0032] The main board 61 is constituted by a control microcomputer 611, a current
application block 612, a voltage measurement block 613, a belt communication block 614, a
memory (EEPROM) 615, a buzzer 616, variable resistors RS1, RS2, RM1, RM2, RL1, RL2,
a dummy internal resistance R0, and connectors 61S, 61M, 61L.
[0033] The control microcomputer 611 corresponds to one example of a calculation unit,
a contact judgment unit, an adjustment unit and a drive unit.
[0034] The connectors 61S, 61M and 61L are provided respectively for each of the belts
3 of three types, S, M, L, and the connectors 30 provided on the ends of the cables 29 from

the wire concentrators 5 of the respective belts 3 are attached respectively to the connectors
61S, 61M, 61L. The connectors 61S, 61M, 61L and the connectors 30 are formed so that,
structurally, they can only be fitted into the corresponding connector. Here, in a physical
examination, or the like, a large number of subjects are examined, and therefore the
connectors 30 of the belts 3 of three sizes are left fitted to the respectively corresponding
connectors 61S, 61M, 61L and can be selected by the keys 631 to 633, thereby increasing
examination efficiency.
[0035] The connectors 61S, 61M, 61L and the connectors 30 have at least an 8-pin
composition so as to correspond to the cables 29 from the wire concentrator 5, and firstly,
variable resistors RS1, RM1, RL1 are connected in series to any of the lines connecting the
lead wires 21, 24 to the current application electrodes 11, 12, and similarly, variable resistors
RS2, RM2, RL2 are connected in series to any of the lines connecting to the lead wires 22, 23
from the voltage detection electrodes 13,14.
[0036] The variable resistors RS1, RM1, RL1, RS2, RM2, RL2 and the control
microcomputer 611 correspond to one example of a fluctuation suppression unit.
[0037] On the other hand, the current application block 612 which is one example of a
current application unit, is constituted by a frequency generating circuit 6121, a constant
current circuit 6122, and multiplexers 6123, 6124. At the start of a visceral fat measurement
operation, the control microcomputer 611 starts a frequency generating circuit 6121, and
generates a pulse wave at 100 kHz, for example. In response to this pulse wave, the constant
current circuit 6122 generates a corresponding alternating constant current, for example, a 1
mA constant current pulse. The current direction of this constant current pulse is set by a
multiplexer 6123 to either a forward direction from the current application electrode 11 to the
current application electrode 12, or a reverse direction from the current application electrode
12 to the current application electrode 11, and the constant current pulse is output to the

selected belt, S, M or L, by a multiplexer 6124. The constant current pulse described above
is applied between the current application electrodes 11, 12 of the selected belt via the
variable resistor and connector corresponding to the selected belt, of the variable resistors
RS1, RM1, RL1 and connectors 61S, 61M, 61L, and via the connector 30 and the lead wires
21,24.
[0038] Furthermore, the voltage measurement block 613 which is one example of the
first measurement unit comprises a multiplexer 6131, a differential amplification circuit 6132,
a half-wave rectifying circuit 6133, an amplification circuit 6134, and an analog/digital
converter 6135. The voltage detected between the voltage detection electrodes 13, 14 of the
belt 3 is input to the multiplexer 6131 via the variable resistors RS2, RM2, RL2, from the
lead wires 22, 23, and the connector 30 and connectors 61S, 61M, 61L, and the voltage
output of the belt which is the measurement object, in other words, the detection voltage, is
selected by the multiplexer 6131. The selected detection voltage is amplified by the
differential amplification circuit 6132, rectified by the half-wave rectification circuit 6133,
and then amplified by the amplification circuit 6134, converted to digital data by the
analog/digital converter 6135, and input to the control microcomputer 611, whereby the
amount of body fat can be calculated.
[0039] Moreover, the belt communication block 614 comprises a multiplexer 6141, and
a switch 6142. One of the connectors 61S, 61M, 61L is selected by a switching operation of
the multiplexer 6141, and the lines (connector pins) connected to the lead wires 25 to 28 in
the selected connector are connected to the control microcomputer 611 via the switch 6142.
By this means, the control microcomputer 611 and the control microcomputer 161 of the
measurement unit 16 are able to communicate with each other via the connectors 61S, 61M,
61L, the connectors 30, and the lead wires 25 to 28. Of the lead wires 25 to 28, two wires are
signal wires between the control microcomputers 611, 161, one wire is a power supply wire,

and the remaining wire is a GND wire. The switch 6142 functions as an isolating unit. The
switch 6142 is formed, for example, by using a plurality of transistors which are introduced
respectively in series with the power wires corresponding to the lead wires 25 to 28, the GND
wire and the signal wires. The transistors of the switch 6142 are switched on and off by the
control microcomputer 611.
[0040] Fig. 7 shows a schematic view of the relationship between the current application
block 612, the voltage measurement block 613, the belt communication block 614, and the
lead wires 21 to 28 described above. In Fig. 7, in order to simplify the illustration, the
multiplexers 6123, 6124, 6131, 6141, the variable resistors RS1, RS2, RM1, RM2, RL1, RL2,
and so on, are not depicted.
[0041] The switch 6142 is not limited to an electrical switch which can be controlled to
open and close electrically, such as a transistor or other semiconductor element, or a relay
switch, or the like, and may also be a mechanical switch which can be operated manually. In
the case of an electrical switch, it is possible to shut off the lead wires 25 to 28 automatically
without the subject being aware, by controlling the opening and closing of the switch 6142 by
the control microcomputer 611. Moreover, if a manual mechanical switch is used as the
switch 6142, then it is possible to shut off the lead wires 25 to 28 at low cost.
[0042] The measurement unit 16 of the abdominal circumference meter 4 comprises a
sensor 162 which performs abdominal circumference measurement, such as reading out
magnetic strips or slits as described above, by receiving a supply of power from the main
body 6, a control microcomputer 161 which controls the operation of the sensor 162, and a
memory for calculation processing (EEPROM) 163. The control microcomputer 161
performs serial communication with the control microcomputer 611 via the lead wires 26,27.
By this means, the abdominal circumference measurement data is output from the control

microcomputer 161 to the control microcomputer 611 via the lead wires 26, 27, as a serial
communication signal.
[0043] Next, the operation of the body fat measurement device 1 which is composed as
described above will be explained. Fig. 8 and Fig. 9 are flowcharts showing one example of
the operation of the body fat measurement device 1 shown in Fig. 1. In the flowchart
described below, the same operations are labeled with the same step numbers and repeated
description thereof is omitted. In the body fat measurement device 1 composed as described
above, when the power key 621 is operated on the operation control board 62, a power supply
is input to the body fat measurement device 1.
[0044] When the man or woman selection keys 624, 625 are operated, a man/woman
selection is performed, and information indicating the gender of the subject 2 is output to the
control microcomputer 611 from the selection keys 624, 625. The corresponding indicator
(LED) 629, 630 is lit up by the control microcomputer 611. In this way, information
indicating the gender of the subject 2 is acquired by the control microcomputer 611 (step S1).
[0045] Furthermore, when the visceral fat measurement key 622 is operated, the control
microcomputer 611, which is one example of a calculation unit, lights up the corresponding
indicator (LED) 627. The control microcomputer 611 then switches the multiplexers 6124,
6131 to the connector 61S, 61M, 61L corresponding to the belt selected by the keys 631 to
633, in accordance with an algorithm stored in a memory 615 consisting of a non-volatile
EEPROM, or the like (step S2).
[0046] The control microcomputer 611 drives the current application block 612 and the
voltage measurement block 613 as described above, and carries out measurement of the
abdominal impedance.
[0047] More specifically, the control microcomputer 611 firstly turns the switch 6142
off, in other words, turns off the transistors which constitute the switch 6142 (step S3). By

this means, the connection between the lead wires 25 to 28 which are one example of second
core wires and the calculation unit is shut off.
[0048] Next, 1 is substituted for the variable i by the control microcomputer 611 (step
S4). A current I in the forward direction is passed between the current application electrodes
11, 12 by the current application block 612, in accordance with the control signal from the
control microcomputer 611 (step S5).
[0049] Thereupon, the voltage between the voltage detection electrodes 13, 14 while the
forward-direction current I is passing between the current application electrodes 11, 12 is
measured as a measurement result Zl(i) by the voltage measurement block 613 (step S6).
[0050] Next, a current I is passed in the reverse direction between the current
application electrodes 11, 12, by the current application block 612, in accordance with a
control signal from the control microcomputer 611 (step S7).
[0051] Thereupon, the voltage between the voltage detection electrodes 13, 14 during
the passing of the reverse-direction current I between the current application electrodes 11,12
is measured as the measurement result Z2(i) by the voltage measurement block 613 (step S8).
[0052] Here, when the measurement result Zl(i) and the measurement result Z2(i) are
measured, the switch 6142 turns off and the connection between the lead wires 25 to 28,
which are one example of second core wires, and the control microcomputer 611 is shut off.
If it is supposed that the connection between the lead wires 25 to 28 (second core wires) and
the control microcomputer 611 is not shut off, then the lead wires 21, 24 (first core wires)
which connect the current application block 612 and the current application electrodes 11,12,
and the lead wires 22, 23 (first core wires) which connect the voltage measurement block 613
and the voltage detection electrodes 13, 14 become coupled to the lead wires 25 to 28 due to
line-to-line capacitance, as a result of which a circuit is formed which links the power source
of the control microcomputer 611 to which the lead wires 25 to 28 are connected, the circuit

ground (GND), and the signal line, with the current application block 612 and the voltage
measurement block 613, by means of the line-to-line capacitance.
[0053] Therefore, noise generated by the control microcomputer 611 is superimposed on
the lead wires 21, 24 and the lead wires 22, 23, and there is risk of decline in the
measurement accuracy of the measurement result Zl(i) and the measurement result Z2(i).
[0054] However, the body fat measurement device 1 shown in Fig. 1 carries out
measurement of the measurement result Zl(i) and the measurement result Z2(i) in a state
where the switch 6142 is turned off and the connection between the lead wires 25 to 28 and
the control microcomputer 611 is shut off, and therefore the noise generated by the control
microcomputer 611 is not superimposed on the lead wires 21, 24 and the lead wires 22, 23,
and the measurement accuracy of the measurement result Zl(i) and the measurement result
Z2(i) is improved.
[0055] Thereupon, the control microcomputer 611 calculates an average value Z(i) of
the measurement result Zl(i) and the measurement result Z2(i) (step S9). The measurement
result Zl(l), the measurement result Z2(l) and the average value Z(l) indicate first
measurement values for the measurement result Z1, the measurement result Z2 and the
average value Z; the measurement result Zl(2), the measurement result Z2(2) and the average
value Z(2) indicate second measurement values for the measurement result Zl, the
measurement result Z2 and the average value Z; and the measurement result Zl(i), the
measurement result Z2(i) and the average value Z(i) indicate ith measurement values for the
measurement result Zl, the measurement result Z2 and the average value Z. Furthermore, if
there is no need to specify the number of measurements in particular, then the notation,
measurement result Zl, measurement result Z2 and average value Z, is used.
[0056] Next, the control microcomputer 611 checks whether or not the variable i has
reached a predetermined number of measurements N (step S10). If the variable i has not

reached the number of measurements N, then the control microcomputer 611 increments the
variable i by 1 (step S11) and transfers again to step S5. On the other hand, if the variable i
has reached the number of measurements N, then the control microcomputer 611 transfers to
step S12.
[0057] Here, in the measurement in steps S5 to S9, the measurement period is set to a
period during which measurement can be performed while the subject holds his or her breath,
for example, 6 seconds, and the measurement cycle, in other words, the cycle at which the
steps S5 to S9 are repeated, is set to 500 msec. The number of measurements N is set to 12
times. The control microcomputer 611 has an internal standby period during the first two
measurements in order to stabilize spike noise, and the like, and uses the measurement results
obtained in the remaining ten measurements. The first two measurements may not be
executed in steps S6 and S7. In one measurement, the control microcomputer 611 drives the
multiplexer 6123, successively performs two times of measurement by switching the current
application direction, and sets the average value of the respective average values in the
forward and reverse directions as the measurement value. Of the ten average value data thus
obtained, the two largest values and the two smallest values are excluded, and the remaining
six average values are used as the detection voltage V for calculating the abdominal
impedance.
[0058] More specifically, the control microcomputer 611 defines the detection voltage
V as the average of the six average values Z remaining after the largest value, the next largest
value, the smallest value and the next smallest value have been removed from the average
values Z(3) to Z(12) (step S12).
[0059] Thereupon, the control microcomputer 611 judges whether or not the state of
contact of the current application electrodes 11,12 and the voltage detection electrodes 13,14
on the surface of the subject 2 is good (step S13), and adjusts the contact balance in

accordance with requirements (step S14). The judgment regarding the state of contact (step
S13) and the adjustment of the contact balance (step S14) are described hereinafter.
[0060] Next, the control microcomputer 611 calculates the abdominal impedance R by
using Formula (1) given above (step S21).
[0061] Thereupon, the control microcomputer 611 corrects the abdominal impedance R
on the basis of the resistance value measurement results of the internal resistance R0 (step
S22). More specifically, the control microcomputer 611 switches the multiplexers 6124,
6131 to the internal resistance R0 side of the dummy, supplies the current I to the internal
resistance R0 by means of the current application block 612, and measures the voltage
between the respective ends of the internal resistance R0, as the detection voltage V, by
means of the voltage application block 613. The control microcomputer 611 measures the
resistance value of the internal resistance R0, by dividing the detection voltage V obtained in
this way, by the current I, to calculate the resistance value of the internal resistance R0.
[0062] The resistance value of the internal resistance R0 is set previously to 1 Ω, for
example, as a reference. The resistance value of the internal resistance R0 is measured within
one second, for instance, and of the measurement values obtained in two measurements at an
interval of 500 msec apart as described above, the first data is discarded in order to remove
spike noise, and the like, and the second data is used as the internal resistance value.
[0063] The resistance value of the internal resistance R0 changes with temperature. The
control microcomputer 611 then compares the resistance value of the internal resistance R0
measured in this way with a measurement value upon shipment, which is stored in the
memory 615, and the differential value dR therebetween is calculated. A look-up table
showing associations between the amount of change of the abdominal impedance R with
respect to the temperature and the differential value dR is determined previously by
experimentation and stored in the memory 615. The control microcomputer 611 refers to the

look-up table in order to acquire the amount of change stored in association with the
differential value dR, as a correction value, and corrects the abdominal impedance R by
adding or subtracting this correction value to or from the abdominal impedance R calculated
at step S21. By this means, the variation in the measurement value with temperature is
corrected and the measurement accuracy of the abdominal impedance R is improved.
[0064] If the abdominal circumference measurement key 623 is not operated when the
visceral fat measurement key 622 is operated (NO at step S23), then the control
microcomputer 611 transfers to step S26 without carrying out abdominal circumference
measurement.
[0065] On the other hand, if the abdominal circumference measurement key 623 is
operated (YES at step S23), then after the measurement of the abdominal impedance R
described above, the control microcomputer 611 switches the multiplexer 6141 to the
connector corresponding to the selected belt, of the connectors 61S, 61M, 61L. The switch
6142 is then turned on, in other words, the respective transistors constituting the switch 6142
are turned on (step S24).
[0066] The control microcomputer 611 communicates with the control microcomputer
161 of the measurement unit 16, causes the measurement unit 16 to measure the abdominal
circumference, and receives data indicating the measurement result for the abdominal
circumference from the measurement unit 16 (step S25).
[0067] Thereupon, when gender information due to the selection of the man/woman
selection keys 624, 625 has been acquired, when data about the height and weight of the
subject 2 has been input from the personal computer 7, and when a abdominal circumference
measurement result has been obtained, then the control microcomputer 611 uses this
respective data to refer to the look-up table stored in the memory 615 and acquire an amount
of body fat associated with these parameters (step S26).

[0068] The calculation result for the amount of body fat thus obtained is displayed on
the display panel 64 by the control microcomputer 611, and is also sent to the personal
computer 7 (step S27). During this measurement, an error judgment operation such as that
described in detail hereinafter is also carried out, and if there is not judged to be an error, then
the measurement value is taken to be valid.
[0069] As shown in Fig. 10, in step S6a, the voltage V between the voltage detection
electrodes 13, 14 during the passage of the forward-direction current I between the current
application electrodes 11, 12 is measured by the voltage measurement block 613, and the
control microcomputer 611 may calculate a first abdominal impedance by V/I, from the
voltage V obtained in this way, and may set the first abdominal impedance calculated in this
way as the measurement result Z1 (i).
[0070] Furthermore, in step S8a, the voltage V between the voltage detection electrodes
13, 14 during the passage of the reverse-direction current I between the current application
electrodes 11, 12 is measured by the voltage measurement block 613, and the control
microcomputer 611 may calculate a second abdominal impedance by V/I from the voltage V
obtained in this way and may set the second abdominal impedance calculated in this way as
the measurement result Z2(i).
[0071] A composition may be adopted in which, at step S12a, the control
microcomputer 611 takes the abdominal impedance R to be the average value of the six
average values Z which remain when the largest value, the next largest value, the smallest
value and the next smallest value are excluded from the average values Z(3) to Z(12), and
does not execute step S21.
[0072] In this way, the measurement results Zl, Z2 and the average value Z may be
voltage values as shown in Fig. 8, or may be impedance values as shown in Fig. 10.

[0073] Furthermore, an example is described in which, in steps S5 to SI 1, the
measurement results Z1, Z2 and the average value Z are obtained a plurality of times, but it is
also possible to acquire the measurement results Zl, Z2 and the average value Z one time and
to set this average value Z directly as the detection voltage V.
[0074] Moreover, in steps S12, S12a, the average value of the average values Z(l) to
Z(N) may be set as the detection voltage V or the abdominal impedance R.
[0075] Furthermore, an example is described in which the detection voltage V and the
abdominal impedance R are determined by using an average value Z of measurement values
Zl, Z2, but it is also possible to determine only one of the measurement results Zl, Z2, and to
use this measurement result as the detection voltage V and the abdominal impedance R.
[0076] It should be noted that in the body fat measurement device 1, the control
microcomputer 611 turns off the switch 6142 when measuring the abdominal impedance as
described above by using the current application block 612 and the voltage measurement
block 613, thereby isolating the lead wires 25 to 28 for the measurement unit 16 which
performs abdominal circumference from the main body 6. If a size connector 30 is not
installed, then the function of an isolating unit is achieved by switching the multiplexer 6141
to a connector other than the connector of the belt which is the measurement object, and the
switch 6142 can be omitted. In this case, the multiplexer 6141 is one example of an isolating
unit.
[0077] By adopting this composition, in a body fat measurement device 1 of a belt type
which calculates an amount of body fat by taking account of other parameters, desirably,
gender, weight, abdominal circumference, and the like, in relation to the abdominal
impedance of the subject, it is possible to measure the abdominal circumference as described
above, which is another parameter that is different to the abdominal impedance and that can
assist the calculation of the amount of body fat, with the belt 3. In providing the

measurement unit 16 as a second measurement unit which performs measurement of the
abdominal circumference, even if, for the purpose of usability, costs, and the like, a cable 29
is used in which the lead wires 21, 24; 22, 23 which are first core wires that respectively
connect the current application block 612 and the voltage measurement block 613, which is a
first measurement unit, with the corresponding pairs of electrodes 11, 12; 13, 14, and the lead
wires 25 to 28 which are second core wires that connect the control microcomputer 161 of the
measurement unit 16 with the control microcomputer 611 to which the corresponding
measurement results are input, are provided inside the same insulating coating (are formed an
integrated fashion), a switch 6142 is provided between the lead wires 25 to 28 and the control
microcomputer 611, and the line-to-line capacitance of the lead wires 25 to 28 is isolated by
means of the switch 6142 during measurement of the abdominal impedance.
[0078] Consequently, if a further second measurement unit which is capable of
measuring a different parameter other than the abdominal impedance, that can assist in the
calculation of the amount of body fat, is provided on the same belt 3, it is also possible to
suppress decline in the measurement accuracy of the abdominal impedance, in other words,
the measurement accuracy of a very small voltage.
[0079] On the other hand, the measurement of the abdominal circumference by the
measurement unit 16 which forms a second measurement unit can be completed on the belt 3
side, in other words, can be carried out via the lead wires 25 to 28 without involving the main
body 6. However, if the measurement by the second measurement unit is affected by the
line-to-line capacitance of the lead wires 21, 24; 22, 23 which connect the current application
block 612 and the voltage measurement block 613 for measuring abdominal impedance with
the corresponding electrodes 11, 12; 13, 14, then an isolating unit should be provided in
similar fashion in order to shut off the current application block 612 and the voltage
measurement block 613 from the electrodes 11, 12; 13,14.

[0080] Moreover, the measurement unit 16 which is the second measurement unit is
able to measure the abdominal circumference, which is very important in the calculation of
an accurate amount of body fat, easily just by fitting the belt 3, through measuring the length
of the belt 3 that is in contact with the surface 2b of the subject, this length corresponding to
the abdominal circumference.
[0081] Furthermore, of the electrodes 11, 12; 13, 14, the pair of electrodes 11, 12 which
apply current, are situated at the center of the abdomen (navel) 2c of the subject 2, and at the
center of the back (spine) 2d of the subject, and consist of metal electrodes which are pressed
against the surface 2b of the subject 2 by the belt 3, whereas the other electrodes 13,14 which
detect a very weak voltage are gel electrodes which are stuck at front and rear positions of the
side 2e of the subject 2, through the opening 32a formed in the belt 3, and the positions of
this other pair of electrodes 13, 14 can easily be adjusted finely, variations due to difference
in the pressing force are eliminated, and uniform measurement conditions can be maintained
easily for each measurement operation.
[0082] Furthermore, in the current application block 612, the direction in which the
current flows is switched by the multiplexer 6123, a current is passed between the pair of
electrodes 11, 12 from the navel side to the back, and in reverse, from the back to the navel
side, and the control microcomputer 611 determines the abdominal impedance from the
average value of the two measurement results produced by the voltage measurement block
613, thus making it possible to improve the measurement accuracy of the abdominal
impedance and consequently also raising the measurement accuracy of the amount of body
fat.
[0083] Next, the judgment of whether or not the state of contact is good in step S13 will
be described. The control microcomputer 611 functions as a contact judgment unit which
judges fluctuation in the contact resistance between the electrodes 11 to 14 and the surface 2b

of the subject 2, in other words, whether or not the electrodes 11 to 14 are in good contact
with the surface 2b of the subject 2, from the measurement results of the measurement of the
abdominal impedance described above, by executing a control program which is stored in the
memory 615.
[0084] A buzzer 616 is installed as a warning generation unit on the main board 61, and
if an abnormality is judged, the control microcomputer 611 sounds the buzzer 616 and also
displays an error mode (the conditions relating to the abnormality) on the display panel 64.
Furthermore, the error mode may also be displayed on the personal computer 7. Below, the
details of each of a plurality of error modes are described in detail.
[0085] The control microcomputer 611 which serves as a contact judgment unit
functions as the first to fifth judgment unit.
[0086] Firstly, the control microcomputer 611 forming the first judgment unit judges an
error mode 1 as described below. More specifically, the control microcomputer 611 infers
the state of the contact resistance between the voltage detection electrodes 13, 14 and the
surface 2b of the subject from the average value Z of the two measurement results Z1, Z2
produced by the voltage measurement block 613 in response to the application of current in
the forward direction and reverse direction by the current application block 612.
[0087] If the average value Z is considerably smaller than a predetermined first
threshold value TH1, then it is judged that the voltage detection electrodes 13, 14 are floating,
in other words, that a defect has occurred in the contact between the two voltage detection
electrodes 13, 14 and the surface 2b.
[0088] If the voltage value is used as the average value Z, then the threshold value TH1
is 2.7 V, for instance, and if the abdominal impedance is used as the average value Z, then the
threshold value TH1 is 0.4 Ω, for instance. Taking the application of current in the forward
and reverse directions as one measurement, then if the conditions of the error mode 1 are

satisfied at least once in the average values Z(3) to Z(12) of the ten measurements as
described above, the control microcomputer 611 judges that a defect has occurred in the
contact between the voltage detection electrodes 13, 14 and the body surface 2b.
[0089] By this means, it is possible to provide an appropriate response in cases where,
for instance, the voltage detection electrodes 13, 14 are detached. Fig. 12 shows a detection
voltage waveform produced by the voltage measurement block 613 when floating occurs
between the voltage detection electrodes 13, 14, and Fig. 11 shows the detection voltage
waveform when all of the electrodes 11 to 14 are installed correctly. As is clear from Fig. 12,
when floating has occurred in the two voltage detection electrodes 13, 14, the two
measurement results Z1, Z2 appear as the noise floor.
[0090] Next, the control microcomputer 611 forming the second judgment unit carries
out judgment of error mode 2 as described below. More specifically, if the average value Z
obtained from the average value Z of the two measurement results Zl, Z2 is considerably
larger than a predetermined second threshold value TH2, then the control microcomputer 611
judges that a defect in the contact with the body surface 2b has occurred in either one of the
voltage detection electrodes 13, 14, for instance, that one of the voltage detection electrodes
13, 14 is not making adequate contact or has become disconnected, or that the skin has
become dry.
[0091] The threshold value TH2 is 4.5 V, for instance, when the voltage value is used as
the average value Z, and is 4.3 Ω, for instance, when the abdominal impedance is used as the
average value Z. If the condition of error mode 2 is satisfied at least once in the ten average
values Z(3) to Z(12), then the control microcomputer 611 judges that a defect has occurred in
the contact with the body surface 2b in either one of the voltage detection electrodes 13,14.
[0092] By this means, it is possible to judge that one of the voltage detection electrodes
13, 14 is detached. Fig. 13 shows a detection voltage waveform produced by the voltage

measurement block 613 in a state where one of the voltage detection electrodes 13, 14 is not
making adequate contact. As Fig. 13 reveals, if one of the voltage detection electrodes 13, 14
is not making adequate contact, then the two measurement results Z1, Z2 both become
extremely large.
[0093] Moreover, the control microcomputer 611 forming the third judgment unit
carries out judgment of the error mode 3 as described below. The control microcomputer 611
judges that a defect has occurred in the contact with the body surface 2b in one of the current
application electrodes 11,12, if one of the two measurement results Zl(i) and Z2(i) is smaller
than a first threshold value TH1' and the other measurement result is greater than a second
threshold value TH2'. In this case, if the condition of error mode 3 is satisfied in any set of
measurement results Zl(i), Z2(i) in the range of i = 3 to N, then it is judged that a defect has
occurred in the contact with the body surface 2b in one of the current application electrodes
11,12.
[0094] More specifically, in a state where the current application electrode 11 (one
electrode) is in contact with the center of the subject's abdomen (navel) 2c and the current
application electrode 12 (other electrode) is in contact with center of the subject's back
(spine) 2d, the control microcomputer 611 obtains a measurement result Zl by applying a
constant current pulse to the multiplexer 6123 which sets the current application electrode 11
on the abdomen center (navel) 2c side to a high level, in the first of the two measurements.
Thereupon, the control microcomputer 611 obtains a measurement result Z2 by applying a
constant current pulse which sets the current application electrode 12 on the back center
(spine) 2d side to a high level.
[0095] Thereupon, if Zl < TH1' and Z2 > TH2', then the control microcomputer 611
judges that the current application electrode 11 on the abdomen center (navel) 2c side is not
making adequate contact (error mode 3-1), and if Zl > TH2' and Z2 < TH1', then the control

microcomputer 611 judges that the current application voltage 12 on the back center (spine)
2d side is not making adequate contact (error mode 3-2).
[0096] The first judgment value TH1' and the second judgment value TH2' are
respectively 3.0 V and 4.5 V, for instance, when the voltage value is used for the
measurement results Z1, Z2, and are respectively 1.1 Ω and 4.3 Ω, for instance when the
impedance is used for the measurement results Zl, Z2. By this means, it is possible to judge
detachment of the current application electrodes 11, 12. The detection voltage waveform
produced by the voltage measurement block 613 in this case is shown in Fig. 14 (error mode
3-1) and Fig. 15 (error mode 3-2). As Fig. 14 and Fig. 15 clearly reveal, if the current
application electrodes 11, 12 do not make adequate contact, then a very large differential
appears between the two measurement results Zl, Z2.
[0097] Furthermore, the control microcomputer 611 forming the fourth judgment unit
carries out judgment of an error mode 4, as described below. The control microcomputer 611
judges the contact balance between the voltage detection electrodes 13, 14 from the
differential |Z1 - Z2| between the two measurement results Zl, Z2. More specifically, if the
differential |Z1 - Z2| is larger than a predetermined third threshold value TH3, then the
contact balance between the voltage detection electrodes 13, 14 is judged to be poor.
[0098] The threshold value TH3 is 0.5 V, for example, when the voltage value is used
for the measurement results Zl, Z3, and is 1.1 Ω, for example, when the impedance is used
for the measurement results Zl, Z2. The control microcomputer 611 judges that the contact
balance between the voltage detection electrodes 13, 14 is poor, among the ten measurement
results Zl(3) to (12) and Z2(3) to (12).
[0099] By this means, it is possible to judge that the balance of contact between the
voltage detection electrodes 13, 14 and the body surface 2b is poor, for example, that one of
the electrodes is detached. Fig. 16 shows a detection voltage waveform produced by a

voltage measurement block 613 in this case. As Fig. 16 reveals, if the contact balance of the
voltage detection electrodes 13, 14 is poor, then a difference occurs between the two
measurement results Z1, Z2.
[0100] Moreover, the control microcomputer 611 which forms a fifth judgment unit
carries out judgment of an error mode 5 as described below. Taking one sample to be the
average value Z of two measurement results Zl, Z2, of the ten samples obtained, the two
largest values and the two smallest values are excluded in steps S12, S12a, to leave six
samples, and if the maximum and minimum values of these six samples are greatly disparate
and the difference therebetween is greater than a predetermined fourth threshold value TH4,
then the control microcomputer 611 judges that the data has been disrupted due to irregular
breathing or body movements, or the like. If an impedance is used for the measurement
results Zl, Z2, then the fourth threshold value TH4 is 0.2 Ω, for example.
[0101] The judgment methods of the respective error modes described above are
summarized in Table 1 below.

[0102] As described above, at step S13, the control microcomputer 611 judges the state
of contact between the electrodes 11 to 14 and the body surface 2b of the subject 2, and if the

contact is defective, issues a warning to the user by, for instance, displaying the judgment
result on the display panel 64. In this way, the defective contact of the electrodes is reported
to the user, such as the subject or inspection technician, and a repeated measurement
operation is prompted, thereby making it possible to achieve accurate measurement reliably
by causing the user to adjust the belt 3 and the electrodes 11 to 14.
[0103] Furthermore, at step S14, if the visceral fat measurement key 622 is operated
again while a defective contact is being reported, then the control microcomputer 611 is able
to limit the extent of the decline in measurement accuracy by adjusting the variable resistors
RS2, RM2, RL2 in the voltage measurement block 613 so as to change the impedance of the
current path passing through the voltage detection electrodes 13, 14 in line with the
magnitude of the previously detected contact resistance, if the contact of the current
application electrodes 11, 12 is poor (error mode 3-1, 3-2) or if the contact balance between
the voltage detection electrodes 13,14 is poor (error mode 4).
[0104] Furthermore, if the contact of one of the voltage detection electrodes 13, 14 is
poor (error mode 2), then the control microcomputer 611 is able to limit the extent of decline
in the measurement accuracy by adjusting the resistance values of the variable resistors RSI,
RM1, RL1 in the current application block 612 so as to change the impedance of the current
path passing through the current application electrodes 11,12.
[0105] If the contact of the electrodes 11 to 14 is inadequate, as in error modes 2,3-1, 3-
2, 4, then fluctuation can be compensated for by means of the variable resistors RS1, RM1,
RL1; RS2, RM2, RL2, and in the case of a detached electrode (error mode 1), while the
control microcomputer 611 continues to issue a warning, it is reported via the display panel
64 or the personal computer 7 that compensation for the fluctuation is not possible.
Moreover, in the case of a measurement failure (error mode 5), it is possible to carry out
measurement again, without readjustments.

[0106] By adopting a composition of this kind, it is possible to correct the contact
resistance and suppress fluctuations by adjusting the variable resistors RS1, RM1, RL1; RS2,
RM2, RL2, if there is a problem with the contact resistance. By this means, it is possible to
reduce the extent of decline in the measurement accuracy, without refitting the electrodes to
the subject.
[0107] (Second embodiment)
Fig. 17 is a block diagram showing the electrical composition of a belt-type body fat
measurement device 1' relating to a further embodiment of the present invention. This body
fat measurement device 1' is similar to the body fat measurement device 1 shown in Fig. 6,
and corresponding parts are labeled with the same reference numerals and description thereof
is omitted here. The point to be noted is that in the body fat measurement device 1', an
actuator drive block 617 is provided instead of the variable resistors RS1, RM1, RL1
corresponding to the current application block 612 described above, in the main board 61' of
the main body 6'. In accordance with this, in the belt 3', actuators Al, A2 are provided on
the current application electrodes 11, 12.
[0108] The actuators Al, A2 are constituted by motors and drive mechanisms which
push the current application electrodes 11,12 embedded respectively in the buckle 31 and the
abdominal circumference meter 4 outwards toward the subject 2. Alternatively, if the voltage
detection electrodes 13, 14 are made from movable metal electrodes on the belt 3, then the
actuators Al, A2 may also be provided on the voltage detection electrodes 13, 14. On the
other hand, the actuator drive block 617 comprises a multiplexer 6172 which switches the
size of the belt 3', in a drive circuit 6171 which drives the motor in response to the drive
signal from the control microcomputer 611'.
[0109] The control microcomputer 611' carries out judgment of error modes 3-1, 3-2 at
step S13, and if it is judged that a contact defect has occurred between either of the current

application electrodes 11, 12 and the body surface 2b, then at step S14, the actuator on the
current application electrode side where a contact defect is judged to have occurred, of the
actuators Al, A2, is driven so as to adjust the state of contact of the current application
electrode. In this way, the contact between the current application electrodes 11,12 and the
body surface 2b is adjusted, and the fluctuation can be suppressed and the state of contact can
be improved. The control microcomputer 611' corresponds to one example of the drive unit.
[0110] The body fat measurement devices 1, 1' are described with respect to examples
in which belts 3 of a plurality of sizes S, M, L can be switched and connected, but it is not
particularly necessary to adopt a composition in which belts 3 of a plurality of sizes can be
switched. If there is one type of belt 3, then the multiplexers 2, 3, 4, 5 for belt switching are
not necessary.
[0111] The body fat measurement device according to one aspect of the present
invention includes: a belt which is wrapped around an abdomen of a subject; a plurality of
electrodes which are provided on the belt and contact the body surface of the subject; a
current application unit which passes a predetermined current between a pair of electrodes of
the plurality of electrodes; a first measurement unit which measures a voltage between
another pair of electrodes, of the plurality of electrodes, while the current is passed between
the pair of electrodes by the current application unit; a calculation unit which calculates an
abdominal impedance of the subject on the basis of the voltage measured by the first
measurement unit and calculates an amount of body fat of the subject by using the calculated
abdominal impedance; a second measurement unit which acquires a parameter other than the
abdominal impedance and outputs a signal indicating the measured parameter to the
calculation unit; a cable in which a first core wire which connects between at least one of the
current application unit and the pair of electrodes, and the first measurement unit and the
other pair of electrodes, and a second core wire which connects the second measurement unit

and the calculation unit are provided inside the same insulating coating; and an isolating unit
which can shut off the connection between the second core wire and the calculation unit,
wherein the calculation unit shuts off the connection between the second core wire and the
calculation unit by the isolating unit, during measurement of the abdominal impedance,
acquires the voltage measured by the first measurement unit while the connection is shut off,
and calculates the abdominal impedance on the basis of the acquired voltage.
[0112] According to the composition described above, the body fat measurement device
of a belt type comprises: a belt which is wrapped around the abdomen of a subject; a plurality
of electrodes which are provided on the belt and contact the body surface of the subject; a
current application unit which passes a predetermined current, for example, a high-frequency
pulse current, between a pair of electrodes of the plurality of electrodes, for example, at the
center of the abdomen (navel) of the subject and the center of the back (spine) of the subject;
a first measurement unit which measures the voltage between another pair of electrodes, of
the plurality of electrodes, for example, electrodes provided at the front and rear of a side
(flank) of the subject, while a current is passed between the pair of electrodes by the current
application unit; and a calculation unit which calculates an abdominal impedance of the
subject on the basis of the voltage measured by the first measurement unit, desirably by
taking account of other parameters, such as gender, weight, abdominal circumference, and the
like, and calculates an amount of body fat of the subject by using the calculation abdominal
impedance.
[0113] A second measurement unit which acquires a parameter other than the abdominal
impedance and outputs a signal indicating the measured parameter to the calculation unit is
provided on the belt, for example. In this, for the purpose of usability, costs, and the like, a
cable is used, in which first core wires which connect between at least one of the current
application u+nit and the pair of electrodes, and the first measurement unit and the other pair

of electrodes, and second core wires which connect the second measurement unit and the
calculation unit, are formed in an integrated fashion, for example, inside the same insulating
coating. An isolating unit which can shut off the connection between the second core wires
and the calculation unit is provided and the connection between the second core wires and the
calculation unit is shut off by the isolating unit so as to eliminate the line-to-line capacitance
of the second core wires, during the measurement of the abdominal impedance.
[0114] Consequently, if a second measurement unit capable of measuring a parameter
other than the abdominal impedance is provided on the same belt, it is possible to reduce the
risk of decline in the measurement accuracy of the abdominal impedance, in other words, the
measurement accuracy of a very small voltage, due to the line-to-line capacitance of the
second core wires. On the other hand, if there are effects due to the line-to-line capacitance
of the first core wires which connect the current application unit for measuring the abdominal
impedance with the electrodes corresponding to the first measurement unit during the
measurement by the second measurement unit, then in a similar fashion, an isolating unit
which shuts off the connection between the current application unit and the first measurement
unit and the electrodes should be provided.
[0115] Furthermore, desirably, the second measurement unit measures the abdominal
circumference of the subject as the parameter.
[0116] According to the composition described above, the abdominal circumference
which is a very useful parameter in improving the calculation accuracy of the amount of body
fat, in other words, the length of the belt which is in contact with the body surface of the
subject, can easily be measured by the second measurement unit, simply by fitting the belt.
[0117] Furthermore, desirably, the pair of electrodes are metal electrodes provided in
the center of the abdomen (navel) and the center of the back (spine) of the subject, and the

other pair of electrodes are gel electrodes which are attached to the front and rear sides of the
subject.
[0118] According to the composition described above, the pair of electrodes which
perform the current application are provided on the center of the abdomen (navel) and the
center of the back (spine) of the subject, and are constituted by metal electrodes which are
pressed against the body surface of the subject by the belt, whereas the pair of other
electrodes which detect a very weak voltage are gel electrodes which are attached to the front
and rear of a side of the subject.
[0119] Consequently, fine adjustment of the positions of the other pair of electrodes can
be carried out easily, and furthermore non-uniformities due to differences in the pressing
force are eliminated and the measurement conditions are kept uniform on each occasion.
[0120] The pair of electrodes may be metal electrodes which are provided in the center
of the abdomen and the center of the back of the subject, and the other pair of electrodes may
be metal electrodes which are attached to the front and rear sides of the subject.
[0121] Furthermore, desirably, the current application unit successively passes a current
in a forward direction and a current in a reverse direction, the forward direction and the
reverse direction being mutually opposite directions as the direction of a current passed
between the pair of electrodes is successively switched; and the calculation unit calculates the
abdominal impedance on the basis of an average value of respective measurement results of
voltages measured by the first measurement unit which correspond respectively to the
forward-direction current and the reverse-direction current while the connection is shut off.
[0122] According to the composition described above, the current application unit
passes a current successively from the navel side to the back and, in reverse, from the back to
the navel side, for instance, the first measurement unit carries out voltage measurement

during the plurality of passages of current, and the calculation unit determines the abdominal
impedance from the average value of the plurality of measurement results.
[0123] By this means, it is possible to raise the measurement accuracy of the abdominal
impedance, and consequently the measurement accuracy of the amount of body fat can be
raised.
[0124] Furthermore, the current application unit may successively pass a current in a
forward direction and a current in a reverse direction, the forward direction and the reverse
direction being mutually opposite directions as the direction of a current passed between the
pair of electrodes is successively switched; and the calculation unit may calculate a first
abdominal impedance as an impedance measurement result corresponding to the forward-
direction current, on the basis of the voltage measured by the first measurement unit which
corresponds to the forward-direction current while the connection is shut off, calculate a
second abdominal impedance as an impedance measurement result corresponding to the
reverse-direction current, on the basis of the voltage measured by the first measurement unit
which corresponds to the reverse-direction current while the connection is shut off, and
calculate the abdominal impedance on the basis of an average value of the first abdominal
impedance and the second abdominal impedance.
[0125] By this means, it is possible to raise the measurement accuracy of the abdominal
impedance, and consequently the measurement accuracy of the amount of body fat can be
raised.
[0126] Desirably, the body fat measurement device further comprises a contact
judgment unit which judges whether a contact between at least a portion of the plurality of
electrodes and the body surface of the subject is satisfactory or not.

[0127] According to this composition, if a contact defect has occurred between at least a
portion of the plurality of electrodes and the body surface of the subject, then it is possible to
detect that this contact defect has occurred.
[0128] Furthermore, desirably, the contact judgment unit comprises a first judgment unit
which judges that a defect has occurred in the contact of both of the other pair of electrodes,
when the average value is smaller than a predetermined first threshold value.
[0129] According to the composition described above, the first measurement unit
performs voltage measurement a plurality of times in accordance with the current application
unit switching the direction of the passed current, as described above, and the first judgment
unit infers the state of contact resistance between the other pair of electrodes, in other words,
the electrodes for voltage detection, and the body surface, from the average value of the
plurality of measurement results. If the average value is abnormally small, then it is judged
that a defect has occurred in the contact of both of the voltage detection electrodes.
[0130] Consequently, it is possible to respond appropriately, for instance, to the fact that
a voltage detection electrode has become detached.
[0131] Moreover, desirably, the contact judgment unit comprises a second judgment
unit which judges that a defect has occurred in the contact of one of the other pair of
electrodes, when the average value is greater than a predetermined second threshold value.
[0132] According to the composition described above, if the average value of the
plurality of measurement results is abnormally small as described above, then it is possible to
judge that both of the voltage detection electrodes are floating, whereas if the average value is
abnormally large, then the second judgment unit judges that a contact defect has occurred, for
instance, that one of the voltage detection electrodes is not making adequate contact, or is
disconnected, or that the skin is dry.

[0133] Furthermore, desirably, the contact judgment unit comprises a third judgment
unit which judges that a defect has occurred in the contact of one of the pair of electrodes, if
one of the measurement results corresponding respectively to the forward-direction current
and the reverse-direction current is less than a predetermined first judgment threshold value
and the other of the measurement results is greater than a second judgment threshold value
which is greater than the first judgment threshold value.
[0134] According to the composition described above, measurement is carried out a
plurality of times, as described above, and if the plurality of measurement results differ
greatly and one is smaller than a predetermined first threshold value while the other is greater
than a predetermined second threshold value, then the third judgment unit judges that a defect
has occurred in the contact between one of the pair of electrodes, in other words, one of the
pair of electrodes used to supply current, and the body surface.
[0135] Moreover, desirably, the third judgment unit judges that a defect has occurred in
the contact of one electrode of the pair of electrodes, when a first measurement result which
is the measurement result corresponding to the forward-direction current passed from the one
electrode to the other electrode of the pair of electrodes is smaller than the first judgment
threshold value, and a second measurement result which is the measurement result
corresponding to the reverse-direction current passed from the other electrode to the one
electrode is greater than the second judgment threshold value.
[0136] According to this composition, if a defect has occurred in the contact of one
electrode of the pair of electrodes, which is the electrode where the forward-direction current
flows out, then the occurrence of a contact defect in that electrode can be detected.
[0137] Furthermore, desirably, the third judgment unit judges that a defect has occurred
in the contact of the other electrode of the pair of electrodes, when a first measurement result
which is the measurement result corresponding to the forward-direction current passed from

one electrode to the other electrode of the pair of electrodes is greater than the second
judgment threshold value, and a second measurement result which is the measurement result
corresponding to the reverse-direction current passed from the other electrode to the one
electrode is smaller than the first judgment threshold value.
[0138] According to this composition, if a defect has occurred in the contact of the other
electrode of the pair of electrodes, which is the electrode on the side where the reverse-
direction current flows out, then the occurrence of a contact defect in that electrode can be
detected.
[0139] Moreover, desirably, the contact judgment unit comprises a fourth judgment unit
which judges that a balance of the other pair of electrodes is poor, when a difference between
the respective measurement results is greater than a predetermined third threshold value.
[0140] According to this composition, measurement is carried out a plurality of times, as
described above, and if the plurality of measurement results differ greatly and the difference
therebetween is greater than a predetermined third threshold value, then the fourth judgment
unit judges that the balance of contact between the other pair of electrodes, in other words,
the voltage detection electrodes, and the body surface, is poor, for instance, that one of the
electrodes is detached.
[0141] Moreover, desirably, the contact judgment unit comprises a fifth judgment unit
which acquires a plurality of average values of respective measurement results while the
connection is shut off, and judges that data is disrupted due to irregular breathing or body
movements, when a difference between the maximum value and the minimum value of the
plurality of average values is greater than a predetermined fourth threshold value.
[0142] According to the composition described above, when raising the measurement
accuracy of the abdominal impedance, which is a very small value, by carrying out sampling
a plurality of times, if the difference between the largest value and the smallest value is

abnormally large, then the fifth judgment unit judges that the data has been disrupted due the
occurrence of a defect in the electrode contact, as a result of irregular breathing, body
movements, or the like.
[0143] Furthermore, desirably, the body fat measurement device further comprises an
alarm generating unit which issues an alarm in accordance with the judgment result of the
contact judgment unit.
[0144] According to the composition described above, it is possible to issue an alarm by
the alarm generating unit, if it is judged by the first to fifth judgment units that there is a
defect in the state of contact between the electrodes and the body surface.
[0145] Consequently, the contact defect can be reported to a user, such as a subject or an
examination technician, or the like, and the user can be made to reattach the electrodes, or the
like, and thus carry out reliable and accurate measurement, easily.
[0146] Moreover, the body fat measurement device further comprises a fluctuation
suppression unit which suppresses fluctuation in contact resistance between at least a portion
of the electrodes and the body surface of the subject.
[0147] According to the composition described above, fluctuation occurs in the contact
resistance between the electrodes and the body surface of the subject, due to the belt fastening,
and the like. By providing means for suppressing this fluctuation, it is possible to detect the
detachment of electrodes, and the like, and to carry out highly accurate measurement.
[0148] Furthermore, desirably, the fluctuation suppression unit comprises a variable
resistor connected in series to at least a portion of the electrodes, and an adjustment unit
which adjusts a resistance value of the variable resistor; and the adjustment unit adjusts the
variable resistor connected to an electrode at which a contact defect is judged to have
occurred, when the contact judgment unit judges that a defect has occurred in the contact of
at least a portion of the electrodes.

[0149] According to the composition described above, when the state of contact
between an electrode and the body surface is judged to be defective by the first to fifth
judgment units, the fluctuation suppression unit adjusts the resistance value of the variable
resistor which is connected in series with the electrode judged to be defective.
[0150] Therefore, if there is a problem with the contact resistance, it is possible to
correct the contact resistance and to suppress fluctuation, by adjusting the variable resistance.
By this means, accurate measurement can be performed readily, without reattaching the
electrodes to the subject.
[0151] Moreover, the fluctuation suppression unit may comprise an actuator which
drives at least a portion of the electrodes and a drive unit which drives the actuator, and the
drive unit may adjust a state of contact by driving an electrode at which a contact defect is
judged to have occurred, by means of the actuator, when the contact judgment unit judges
that a defect has occurred in the contact of at least a portion of the electrodes.
[0152] According to the composition described above, if it is judged by the first to fifth
judgment units that there is a defect on the state of contact between an electrode and the body
surface, then the fluctuation suppression unit adjusts the contact resistance by driving the
actuator provided on the electrode judged to have an abnormality, so as to push or pull the
electrode, for instance.
[0153] Consequently, if there is a problem with the contact resistance, it is possible to
suppress fluctuation by driving the actuator to adjust the contact between the electrodes and
the body surface.
[0154] Furthermore, desirably, the isolating unit is an electrical switch.
[0155] According to the composition described above, by using an electrical switch such
as a semiconductor switch element, as the isolating unit, the signal wire can readily be shut
off automatically, without the subject being aware.

[0156] Moreover, in the body fat measurement device according to the present invention,
the isolating unit may be a mechanical switch.
[0157] According to the composition described above, it is possible to shut off the signal
wire at low cost, by using a mechanism switch that can be operated manually, as the isolating
unit.
[0158] The body fat measurement device according to the present invention is a belt-
type body fat measurement device in which, as described above, a plurality of electrodes are
placed in contact with a body surface of a subject, from a belt wrapped around the abdomen
of a subject, a predetermined current is passed by a current application unit between a pair of
electrodes at the center of the abdomen (navel) and the center of the back (spine) of the
subject, of the plurality of electrodes, the voltage generated at the front and rear of a side of
the subject during passage of the current is measured by a first measurement unit, a
calculation unit determines an abdominal impedance from the measurement result of the first
measurement unit, and an amount of body fat is calculated from the abdominal impedance, by
desirably taking account also of other parameters, such as gender, weight, abdominal
circumference, and the like, a second measurement unit which is capable of measuring
another parameter which is different to the abdominal impedance and which can assist in the
calculation of the amount of body fat being provided on the belt. In this, for the purpose of
usability and costs, and the like, if a cable is used, in which first core wires that respectively
connect the current application unit with a pair of electrodes corresponding to the first
measurement unit and second core wires which connect the second measurement unit with
the calculation unit to which the measurement result from the second measurement unit is
input, are provided inside the same insulating coating (are formed in an integrated fashion),
then an isolating unit is provided between the second core wires and the calculation unit, and

the line-to-line capacitance of the second core wires is isolated by this isolating unit during
measurement of the abdominal impedance.
[0159] Therefore, even if a second measurement unit which is capable of measuring
another parameter which is different to the abdominal impedance and which can assist in the
calculation of the abdominal impedance is provided on the same belt, it is still possible to
restrict decline in the measurement accuracy of the abdominal impedance, in other words, the
measurement accuracy of a very small voltage.
[0160] This application is based on Japanese Patent Application No. 2009-174648 filed
on 27th July 2009, the contents of which are hereby incorporated in the present application.
[0161] The concrete embodiments or examples given in the description of the
embodiments of the present invention are merely intended to clarify the technical contents of
the present invention and the present invention is not to be interpreted in a narrow sense as
limited to these examples only, but rather can be implemented with various modifications,
within the spirit of the invention and the claims which are indicated below.

Claims
1. A body fat measurement device, comprising:
a belt which is wrapped around an abdomen of a subject;
a plurality of electrodes which are provided on the belt and contact a body surface of
the subject;
a current application unit which passes a predetermined current between a pair of
electrodes of the plurality of electrodes;
a first measurement unit which measures a voltage between another pair of electrodes,
of the plurality of electrodes, while the current is passed between the pair of electrodes by the
current application unit;
a calculation unit which calculates an abdominal impedance of the subject on the basis
of the voltage measured by the first measurement unit and calculates an amount of body fat of
the subject by using the calculated abdominal impedance;
a second measurement unit which acquires a parameter other than the abdominal
impedance and outputs a signal indicating the measured parameter to the calculation unit;
a cable in which a first core wire which connects between at least one of the current
application unit and the pair of electrodes, and the first measurement unit and the other pair
of electrodes, and a second core wire which connects the second measurement unit and the
calculation unit are provided inside a same insulating coating; and
an isolating unit which can shut off a connection between the second core wire and the
calculation unit, wherein
the calculation unit shuts off the connection between the second core wire and the
calculation unit by the isolating unit, during measurement of the abdominal impedance,
acquires the voltage measured by the first measurement unit while the connection is shut off,
and calculates the abdominal impedance on the basis of the acquired voltage.

2. The body fat measurement device according to claim 1, wherein the second
measurement unit measures an abdominal circumference of the subject as the parameter.
3. The body fat measurement device according to claim 1 or 2, wherein the pair of
electrodes are metal electrodes provided in the center of the abdomen and the center of the
back of the subject, and the other pair of electrodes are gel electrodes which are attached to
front and rear sides of the subject.
4. The body fat measurement device according to claim 1 or 2, wherein the pair of
electrodes are metal electrodes provided in the center of the abdomen and the center of the
back of the subject, and the other pair of electrodes are metal electrodes which are attached to
front and rear sides of the subject.
5. The body fat measurement device according to any one of claims 1 to 4, wherein
the current application unit successively passes a current in a forward direction and a
current in a reverse direction, the forward direction and the reverse direction being mutually
opposite directions as the direction of a current passed between the pair of electrodes is
successively switched; and
the calculation unit calculates the abdominal impedance on the basis of an average
value of respective measurement results of voltages measured by the first measurement unit
which correspond respectively to the forward-direction current and the reverse-direction
current while the connection is shut off.
6. The body fat measurement device according to any one of claims 1 to 4, wherein

the current application unit successively passes a current in a forward direction and a
current in a reverse direction, the forward direction and the reverse direction being mutually
opposite directions as the direction of a current passed between the pair of electrodes is
successively switched; and
the calculation unit calculates a first abdominal impedance as an impedance
measurement result corresponding to the forward-direction current, on the basis of the
voltage measured by the first measurement unit which corresponds to the forward-direction
current while the connection is shut off, calculates a second abdominal impedance as an
impedance measurement result corresponding to the reverse-direction current, on the basis of
the voltage measured by the first measurement unit which corresponds to the reverse-
direction current while the connection is shut off, and calculates the abdominal impedance on
the basis of an average value of the first abdominal impedance and the second abdominal
impedance.
7. The body fat measurement device according to claim 5 or 6, further comprising a
contact judgment unit which judges whether a contact between at least a portion of the
plurality of electrodes and the body surface of the subject is satisfactory or not.
8. The body fat measurement device according to claim 7, wherein the contact judgment
unit comprises a first judgment unit which judges that a defect has occurred in the contact of
both of the other pair of electrodes, when the average value is smaller than a predetermined
first threshold value.
9. The body fat measurement device according to claim 7 or 8, wherein the contact
judgment unit comprises a second judgment unit which judges that a defect has occurred in

the contact of one of the other pair of electrodes, when the average value is greater than a
predetermined second threshold value.
10. The body fat measurement device according to any one of claims 7 to 9, wherein the
contact judgment unit comprises a third judgment unit which judges that a defect has
occurred in the contact of one of the pair of electrodes, when one of the measurement results
corresponding respectively to the forward-direction current and the reverse-direction current
is less than a predetermined first judgment threshold value and the other of the measurement
results is greater than a second judgment threshold value which is greater than the first
judgment threshold value.
11. The body fat measurement device according to claim 10, wherein the third judgment
unit judges that a defect has occurred in the contact of one electrode of the pair of electrodes,
when a first measurement result which is the measurement result corresponding to the
forward-direction current passed from the one electrode to the other electrode of the pair of
electrodes is smaller than the first judgment threshold value, and a second measurement result
which is the measurement result corresponding to the reverse-direction current passed from
the other electrode to the one electrode is greater than the second judgment threshold value.
12. The body fat measurement device according to claim 10 or 11, wherein the third
judgment unit judges that a defect has occurred in the contact of the other electrode of the
pair of electrodes, when a first measurement result which is the measurement result
corresponding to the forward-direction current passed from one electrode to the other
electrode of the pair of electrodes is greater than the second judgment threshold value, and a
second measurement result which is the measurement result corresponding to the reverse-

direction current passed from the other electrode to the one electrode is smaller than the first
judgment threshold value.
13. The body fat measurement device according to any one of claims 7 to 12, wherein the
contact judgment unit comprises a fourth judgment unit which judges that a balance of the
other pair of electrodes is poor, when a difference between the respective measurement
results is greater than a predetermined third threshold value.
14. The body fat measurement device according to anyone of claims 7 to 13, wherein the
contact judgment unit comprises a fifth judgment unit which acquires a plurality of average
values of respective measurement results while the connection is shut off, and judges that
data is disrupted due to irregular breathing or body movements, when a difference between
the maximum value and the minimum value of the plurality of average values is greater than
a predeterrnined fourth threshold value.
15. The body fat measurement device according to any one of claims 7 to 14, further
comprising an alarm generating unit which issues an alarm in accordance with the judgment
result of the contact judgment unit.
16. The body fat measurement device according to any one of claims 7 to 15, further
comprising a fluctuation suppression unit which suppresses fluctuation in contact resistance
between at least a portion of the electrodes and the body surface of the subject.
17. The body fat measurement device according to claim 16, wherein

the fluctuation suppression unit comprises a variable resistor connected in series to at
least a portion of the electrodes, and an adjustment unit which adjusts a resistance value of
the variable resistor; and
the adjustment unit adjusts the variable resistor connected to an electrode at which a
contact defect is judged to have occurred, when the contact judgment unit judges that a defect
has occurred in the contact of at least a portion of the electrodes.
18. The body fat measurement device according to claim 16, wherein
the fluctuation suppression unit comprises an actuator which drives at least a portion of
the electrodes and a drive unit which drives the actuator; and
the drive unit adjusts a state of contact by driving an electrode at which a contact defect
is judged to have occurred, by means of the actuator, when the contact judgment unit judges
that a defect has occurred in the contact of at least a portion of the electrodes.
19. The body fat measurement device according to any one of claims 1 to 18, wherein the
isolating unit is an electrical switch.
20. The body fat measurement device according to any one of claims 1 to 18, wherein the
isolating unit is a mechanical switch.


Abstract

A body fat measurement device, including: a plurality of electrodes which contact a body
surface of the subject; a current application unit which passes a current between a pair of
electrodes of the plurality of electrodes; a first measurement unit which measures a voltage
between another pair of electrodes, while current is passed between the pair of electrodes; a
calculation unit which calculates an abdominal impedance of the subject on the basis of the
voltage measured by the first measurement unit and calculates an amount of body fat of the
subject; a second measurement unit which outputs a signal indicating a parameter other than
the abdominal impedance; a cable in which a first core wire which connects between at least
one of the current application unit and the pair of electrodes, and the first measurement unit
and the other pair of electrodes, and a second core wire which connects the second
measurement unit and the calculation unit are provided inside a same insulating coating; and
an isolating unit which can shut off a connection between the second core wire and the
calculation unit; wherein the calculation unit calculates the abdominal impedance on the basis
of the voltage measured by the first measurement unit while a connection between the second
core wire and the calculation unit is shut off, during measurement of the abdominal
impedance.