JP2001212094A - Calibrator for measuring equipment for electrical characteristics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide calibrators for measuring equipment for electrical characteristics that promises accurate calibration even though electrical conductive gel sticks to electrical conductive clips that are connected to the electrodes attached to a subject's body, and it also sticks to connecting terminals of the calibrators. SOLUTION: Electrical conductive clips are connected to electrically conductive, superficial electrode attached to two fixed, superficial parts which are apart from each other on a subject's body. The signals for measurement are issued to the subject's body. The calibrator 110 for measuring equipment for electrical characteristics measures bioelectricity impedance by measuring electrical pressure generated between superficial parts of the subject's body. The calibrator 110 is provided with connecting terminals 112-115 where an electrical conductive clip 20 is connected and standard impedance element that are connected to the connecting terminals. Also, the connecting terminals 112-115 are made from electrically conductive materials whose quality is hard to be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calibrator of an electrical characteristic measuring device useful for estimating a body fat state and a body water distribution of a subject based on a bioelectrical impedance method. The present invention relates to a connection terminal of a calibrator to which a conductive clip connected to an electrode attached to a body is connected.

[0002]

2. Description of the Related Art The present inventor has applied for an apparatus using an M-sequence signal as a bioelectrical impedance measuring apparatus (Japanese Patent Laid-Open No. 10-14898). In that invention, 4
By performing a Fourier transform on the signal converted at the terminal A / D, bioelectric impedance at many frequencies is measured to calculate information on the amount of water inside and outside the cell.

[0003] The configuration of the invention described above will be described below. In recent years, to evaluate the body composition of humans and animals,
Research on the electrical properties of living organisms has been conducted. The electrical properties of living organisms vary significantly depending on the type of tissue or organ. For example, in humans, the electrical resistivity of blood is 150
While it is around Ω · cm, the electrical resistivity of bone and fat is 1 to 5 kΩ · cm. The electrical characteristics of the living body are called bioelectric impedance, and are measured by passing a small current between a plurality of electrodes attached to the body surface of the living body. The method of estimating the body water distribution, body fat percentage, body fat mass, etc. of the subject from the bioelectric impedance obtained in this way is called the bioelectric impedance method ("Bioelectric impedance method as a method for evaluating body composition", Baumga
rtner, RN, etc. Author, "Bioelectric impedance and its clinical application", Medical electronics and biotechnology, Hiroshi Kanai, 20 (3)
Jun 1982, "Estimation of body limb water distribution by impedance method and its application", Medical Electronics and Biotechnology, Makoto Haeno et al., 23 (6) 1985, "Long-term measurement of urinary bladder volume by impedance method" Ergonomics, written by Yasuo Kuchinomachi, 28 (3) 1992, etc.).

[0004] Bioelectric impedance is derived from the resistance of a living body to the current carried by ions in the body (resistance) and the reactance associated with various types of polarization processes created by cell membranes, tissue interfaces, or non-ionized tissue. Be composed. Capacitance, which is the reciprocal of reactance, causes a time delay in current rather than voltage, and creates a phase shift (phase shift). This value is the arctangent of the ratio of reactance to resistance (arctangent). It can be determined geometrically as a phase angle.

The bioelectric impedance Z, the resistance R, the reactance X and the electric phase angle φ depend on the frequency. At very low frequencies f _L , the bioelectrical impedance Z at the cell membrane-tissue interface is too high to conduct electricity. Thus, electricity flows only through the extracellular fluid and the measured bioelectrical impedance Z is purely a resistance R.

Next, as the frequency increases, the current penetrates the cell membrane, the reactance X increases, and the phase angle φ increases. The magnitude of the bioelectrical impedance Z is equal to the value of the vector defined by Z ² = R ² + X ² . The frequency at which both the reactance X and the phase angle φ are maximized is called a critical frequency f _C, and is one electrical characteristic value of a living body that is a conductive conductor. Above this critical frequency f _C , the cell membrane-tissue interface loses its capacitive capacity, and the reactance X decreases accordingly. At very high frequencies f _H , the bioelectrical impedance Z is again purely equivalent to the resistance R.

FIG. 8 is an electrical equivalent circuit diagram (equivalent circuit model) of the human body. In this figure, Cm represents the cell membrane capacity, and Ri and Re represent the intracellular fluid resistance and the extracellular fluid resistance, respectively. At low frequencies f _L , the current is mainly flowing in the extracellular space, and the impedance Z is equal to the extracellular fluid resistance Re. At high frequencies f _H , the current passes through the cell membrane completely, which is equivalent to the cell membrane capacitance Cm being substantially short-circuited.
Therefore, impedance Z at high frequency f _H is
It is equal to the combined resistance Ri · Re / (Ri + Re).

According to the method described above, the intracellular fluid resistance R
i and the extracellular fluid resistance Re can be determined, and based on these, the body fat status and body water distribution (intracellular fluid volume, extracellular fluid volume, etc.) of the subject such as body fat percentage, fat weight, lean body mass, etc. Volume and the total body water content).
The change in the body water distribution can be estimated from the change in the resistances Re and Ri. As a bioelectrical impedance measuring device that performs measurement / estimation of each of these parameters by injecting a small sine wave current of a plurality of frequencies arbitrarily selected into a living body and digitally processing the obtained signal, there is a special table. Hei 6
The thing described in 506854 is known.

In the conventional device described in the above publication, in addition to the complexity of the device configuration, minute sine-wave currents of a plurality of arbitrarily selected frequencies are injected into the living body at predetermined intervals, and the obtained signal is output. Processing takes a few seconds to complete all measurements. Therefore, there is a drawback that it is easily affected by breathing, pulse, etc. for the following reasons.

First, the effect of respiration will be described. As described above, it is known that the resistivity of fat is extremely large, but the electric impedance of air is also extremely large.
In addition, the bioelectric impedance is measured by flowing a small current between a plurality of electrodes mounted on the body surface of the human body as described above, and the electrodes are usually attached to the right hand and the right foot of the subject, respectively. Therefore, the current flows from the right arm to the upper right body to the lower right body to the right foot, and passes through the upper right body (right lung), which contains a lot of air. Further, the bioelectric impedance is affected by the cell membrane capacitance Cm (see FIG. 8), and this capacitance Cm changes due to respiration.

The bioelectrical impedance is related to hemodynamics, metabolic capacity, and the like, and is also closely related to blood flow. That is, the blood flow of the body is a part of the amount of water in the body, and changes according to expansion and contraction of the heart. On the other hand, bioelectric impedance changes according to the amount of water in the body. Therefore, the bioelectrical impedance must be measured in consideration of the blood flow that changes according to the expansion and contraction of the heart. However, in the above-described bioelectric impedance measuring apparatus, although there is a close relationship between the bioelectric impedance and the blood flow, the measurement is not performed in consideration of the blood flow, so that the apparatus is affected by the pulse. .

In order to reduce the influence of the pulse and respiration, it is conceivable to measure the bioelectric impedance continuously for a longer period than the pulse or respiration cycle. However, if current is continuously applied to the human body for a long time (for example, 1 second or more),
May cause harm to human body. That is, when a sine wave signal is used, there has been a problem that accurate bioelectric impedance, body fat amount, and body water amount cannot be measured.

In order to solve the above problems, it is necessary to measure the bioelectrical impedance in a very short time without being affected by a pulse or breathing. Instead, it is conceivable to use an impulse-like minute current containing many frequency components. However, in this method, for an extremely short time (for example, 0.1 μm).
In order to concentrate electric energy for about 2 sec., not only a circuit that generates a high voltage is required, but also a very large amount of energy is injected into the human body even in an extremely short time, so that there is no damage or burns. Depending on the danger of life, it is not practical.

To this end, a probe current consisting of an M-sequence code signal is passed through the body of the subject, the flowing current and the voltage between the electrodes are detected, and each of them is Fourier-transformed and converted into a voltage value for each frequency. , And calculates the bioelectrical impedance between the parts of the living body, and displays them. A coaxial cable is usually used as a connection cable for flowing a probe current through a living body and detecting a voltage between the flowing current and an electrode, and a conductive clip is connected to a distal end of the coaxial cable.

The bioelectrical impedance measuring apparatus causes an undesired error due to aging or temperature change, and needs to be calibrated periodically to maintain the measurement accuracy. The calibrator for that includes a connection terminal to which the conductive clip is connected and a reference impedance element connected to the connection terminal, and the connection terminal is
For example, it is configured by applying a gold plating or a nickel plating to a copper plate or a copper wire.

[0016]

By the way, the calibrator of the electric characteristic measuring apparatus having the above-mentioned structure has a connection terminal in which a copper plate or a copper wire is plated with gold or nickel, as described above. Calibration is performed by connecting a conductive clip. When the conductive clip is connected to an electrode attached to the body of the subject with a conductive gel, the conductive clip contains a sodium chloride solution (hereinafter, referred to as a NaCl solution). The gel may adhere to the electrode part. For this reason, the conductive gel adhered to the electrode portion may adhere to the connection terminal of the calibrator, and rust may be generated on the connection terminal. When rust is generated on the connection terminal as described above, there arises a problem that an electric resistance value changes and accurate calibration cannot be performed.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for measuring electrical characteristics, in which a conductive gel of an electrode attached to a subject's body adheres to a conductive clip. An object of the present invention is to provide a calibrator of an electrical property measuring device that can accurately calibrate even if the conductive gel adheres to a connection terminal of the calibrator when calibrating the device.

[0018]

In order to achieve the above object,
The calibrator of the electrical property measuring apparatus according to the present invention is configured such that a conductive clip is connected to an electrode conductively attached to a surface portion of the body of the subject, a measurement signal is applied to the body of the subject, and the surface portion of the body of the subject is A calibrator for an electrical property measuring device for measuring bioelectrical impedance by measuring a voltage value generated between the calibrator, the calibrator having a connection terminal to which the conductive clip is connected, and being connected to the connection terminal. Wherein the connection terminal is formed of a conductor which is hardly deteriorated.

In a preferred specific embodiment of the calibrator of the electric characteristic measuring apparatus according to the present invention, the conductor that is hardly deteriorated is formed of a stainless steel plate or wire. In addition, a metal having stabilization, such as aluminum, titanium, gold, and platinum, may be used. Further, the conductor that is hardly deteriorated is formed of a metal plate or a metal wire that is not plated. Here, it is formed of a single metal or several hundred μm thicker than a metal layer formed by plating.
and a metal layer having a thickness of at least m.

The calibrator of the electric characteristic measuring apparatus of the present invention having the above-described configuration is configured such that when the conductive clip is connected to the electrode attached to the body of the subject with the conductive gel, the conductive gel is connected to the electrode of the conductive clip. Even if the conductive gel adheres to the connecting part of the calibrator, it does not rust because the connecting terminal is made of a conductor that is hardly deteriorated.
The electric resistance value does not change. Therefore, the calibration of the electrical characteristic measuring device can be performed accurately. By forming the conductor forming the connection terminal from a metal plate or a metal wire that has not been plated, the calibration can be accurately performed without the plating being peeled off and the electrical resistance value not changing.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a calibrator for an electric characteristic measuring apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an electrical configuration of a bioelectrical impedance measuring device in which the calibrator of the present invention is used, and FIG. 2 is a schematic diagram schematically showing a use state of the measuring device shown in FIG. 1 and 2, a bioelectrical impedance measuring apparatus 100 of this example sends a probe current Ia as a measurement signal to a keyboard 1 and a body B of a subject, and thereby digitalizes voltage / current information obtained from the body B of the subject. A measurement processing unit 2 for processing and a CPU (central processing unit) for controlling various parts of the apparatus and calculating various quantities relating to bioelectric impedance, body fat and body water distribution of the human body based on the processing results of the measurement processing unit 2 Arithmetic processing unit)
3, a display unit 4 for displaying the bioelectric impedance, the body fat amount, the body water amount, etc. of the body B of the subject calculated by the CPU 3, a ROM 5 for storing a processing program of the CPU 3, and various data (for example, , A data area for temporarily storing the subject's height, weight, sex, the amount of extracellular fluid and intracellular fluid, etc.) and a RAM 6 in which a work area of the CPU 3 is set.

The keyboard 1 is used by a measurer to input a measurement start switch for instructing a start of measurement, a human body characteristic item such as height, weight, gender and age of the subject, and to measure a total measurement time T and a measurement interval t. The operation data of various keys supplied from the keyboard 1 is converted into key codes by a key code generation circuit (not shown),
Supplied to

The measurement processing unit 2 is attached to a PIO (parallel interface) 71, a measurement signal generator 72, a low-pass filter (hereinafter, referred to as LPF) 73, a coupling capacitor 74, and a predetermined part of the body. An output processing circuit including a surface electrode Hc; and surface electrodes Hp, Lp, and L that are also attached to a predetermined part of the body.
c, coupling capacitors 80a, 80b, 90, differential amplifier 81, I / V converter (current / voltage converter) 9
1. L consisting of an analog anti-aliasing filter
The input processing circuit includes PFs 82 and 92, A / D converters 83 and 93, and sampling memories (ring buffers) 84 and 94.

In the measurement processing section 2, the measurement signal generator 7
2 is equal to or more than 10 kΩ over the entire signal frequency range in which the output resistance is generated, and every time a signal generation instruction signal is supplied from the CPU 3 via the PIO 71 at a predetermined cycle t during the entire measurement time T, The longest linear code (maximal li
LPF7 that repeatedly generates the probe current Ia of the (near codes) series (M series) a predetermined number of times and uses the generated probe current Ia as a measurement signal to remove high-frequency noise.
3 and a coupling capacitor 74 that removes the DC component from flowing to the subject's body B so as not to flow to the surface electrode Hc.

The value of the probe current Ia is, for example, 500
８００800 μA. The supply period of the signal generation instruction signal matches the measurement interval t set by the measurer using the keyboard 1. Further, in this example, the number of repetitions of the probe current (measurement signal) Ia is 1 to 256 per signal generation instruction signal. The number of repetitions may be set arbitrarily by the measurer using the keyboard 1.
The number of repetitions increases as the number of repetitions increases. However, although it is a minute current, it may adversely affect the human body when continuously applied to the human body for a long time. Therefore, the number of repetitions is preferably 1 to 256.

As described in the section of "Prior Art", a small time interval (0.1
μsec), the energy is concentrated
The probe current using the series signal disperses the energy in about 1 msec even though it contains many frequency components, so it does not injure the living body and occurs at a time interval sufficiently shorter than the pulse or respiration cycle. So they are not affected. Furthermore, for example, in the case of a rectangular wave signal with a duty of 50%, the amplitude of the frequency spectrum is large at low frequencies and small at high frequencies, so that the frequency characteristic of the SN ratio deteriorates in the high frequency region, whereas the M-sequence signal is Since the amplitude of the frequency spectrum is substantially flat over the entire frequency range, the frequency characteristic of the SN ratio is also substantially flat. The details of the M-sequence signal are described in R. C.
Dixon, "Spread Spectrum Communication System" (P56-P89)
Please refer to.

As shown in FIG. 2, the surface electrode Hc is conductively attached to the right back part H of the subject at the time of measurement by an adhesive method. Therefore, the measurement signal (probe current)
Ia enters body B from the right hand part of the subject. The coupling capacitor 74 and the surface electrode Hc are connected by a coaxial cable 7a, and the shield of the coaxial cable 7a is grounded.

As shown in FIG. 2, the surface electrode Hc (first electrode) is conductively attached to the right back part H of the subject at the time of measurement by an adhesive method, and the surface electrode Lc (second electrode) is used. Is conductively attached to the right instep L by an adhesive method, and the measurement signal (probe current) Ia enters the body B from the right hand part of the subject. The surface electrode Hp (third electrode)
Electrode) is electrically conductively attached to the right back H of the subject by an adhesive method, and the surface electrode Lp (fourth electrode)
Is conductively attached to the right instep L by an adhesive method. At this time, the surface electrodes Hc and Lc are
It is attached to a part farther from the center of the human body than p and Lp.

Here, an adhesive system in which the surface electrode is conductively attached to the back part H and the foot part L of the subject will be described in detail with reference to FIGS. FIG. 3A is a perspective view of the upper surface side in a state where the conductive gel of the electrode sheet is separated,
4B is a perspective view of the lower surface side, FIG. 4 is a schematic perspective view of the conductive clip, and FIG. 5 is a perspective view of a state before the electrode sheet is attached to the back part H and the foot part L and connected by the conductive clip. is there. An electrode sheet 1 is provided on the back part H and the back part L of the subject.
0 is pasted. The electrode sheet 10 is made of a plastic sheet having a thickness of 50 μm or more, such as polyethylene terephthalate.
11 are formed and these contact pieces are bent upward. The electrode sheet 10 has electrodes 12, 12 formed on the lower surface at both ends in the longitudinal direction, and these electrodes are connected to contact pieces 11, 11.
Extends to Then, conductive gels 13 having adhesiveness are attached to the lower surfaces of the electrodes 12.
The conductive gels 13 contain a NaCl solution in order to obtain electrical conduction. The electrodes 12, 12 are formed, for example, by printing a conductive paste.

The contact pieces 11, 11 of the above-mentioned electrode sheet 10
As shown in FIG. 4, the conductive clip 20 connected to the main body 21 includes a main body 21 made of plastic, and pinching pieces 23, which are swingably supported by the main body 21 by shafts 22 and 22, respectively.
23, the two holding pieces are urged toward the main body 21 by a spring 24. Electrodes 25, 25 are located at portions of the main body facing the sandwiching pieces 23, 23, and cables 26, 26 are connected to these electrodes. Electrode part 2
The conductors 5 and 25 are made of a conductor that is hardly deteriorated. In this embodiment, the conductors 5 and 25 are made of a stainless steel wire having a diameter of about 1.5 mm, and slightly project from the surface of the main body 21. Moreover, you may comprise from the plate material of stainless steel.

The electrode portions 25, 25 may be formed of a non-plated metal plate as a conductor that is hardly deteriorated. For example, by using only a plate material such as silver, even if the conductive gel of the electrode sheet adheres, the plating is peeled off, the conduction state becomes unstable, and the contact resistance value does not fluctuate. Alternatively, the electrode portion may be formed of a plastic containing a conductive material such as carbon, and may be integrally injection-molded with the main body 21 by two-color molding.

As shown in FIG. 5, the electrode sheet 10 is adhered to the back part H and the back part L by conductive gels 13, 13, and the electrodes 12, 12 are connected to the back part H and the back part L. It becomes conductive. Connect the contact pieces 11 and 11 to the conductive clip 2
0 between the electrode portions 2
Electrical continuity is established between the connection pieces 5 and 25 and the contact pieces 11 and 11, and electrical continuity is established between the cables 26 and 26 and the back part H and foot part L. In FIG. 5A, the electrode 12 on the hand side corresponds to the surface electrode Hc, the cable 26 (7a) is connected, and the body B
Corresponds to the surface electrode Hp, and is connected to the cable 26 (7b). In FIG. 5B, the electrode 12 on the toe side corresponds to the surface electrode Lc, and the cable 26 (7d) is connected to the electrode 12 in the center direction of the body B.
Corresponds to the surface electrode Lp, to which the cable 26 (7c) is connected.

The conductive clip (first conductive clip) 20 of the back part H has two electrode parts 25 connected to the first and third electrodes, and the conductive clip (second conductive clip) of the foot part L. 20) has two electrode portions 25 connected to the second and fourth electrodes, and has two conductive clips 2
By connecting 0, 20 to the two electrode sheets 10, 10, conduction between the four surface electrodes and the cable can be achieved.

The differential amplifier 81 shown in FIG. 1 detects a potential (potential difference) between two surface electrodes Hp (third electrode) and Lp (fourth electrode). That is, the differential amplifier 81
When the probe current Ia is applied to the body B of the subject,
The voltage Vp between the right limb and the right hand of the subject is detected and input to the LPF 82. This voltage Vp is a voltage drop between the surface electrode Hp and the surface electrode Lp due to the bioelectric impedance of the body B of the subject.

The LPF 82 removes high frequency noise from the voltage Vp and supplies it to the A / D converter 83. LPF
The cutoff frequency 82 is lower than half the sampling frequency of the A / D converter 83. Thereby, aliasing noise generated in the A / D conversion processing by the A / D converter 83 is removed. The A / D converter 83 converts the noise-removed voltage Vp into a digital signal at a predetermined sampling cycle every time the digital conversion signal Sd is supplied from the CPU 3, and converts the digitized voltage Vp to the sampling cycle. The data is supplied to the sampling memory 84 every time.

As shown in FIG. 2, the surface electrode Lc is adhered to the right instep L of the subject by an adhesive method, and the surface electrode Lc and the coupling capacitor 90 (see FIG. 1) are coaxial. They are connected by a cable 7d, and the shield of the coaxial cable 7d is grounded. The I / V converter 91 detects a current flowing between the two surface electrodes Hc and Lc and converts the current into a voltage. That is, the I / V converter 91
When the probe current Ia is applied to the body B of the subject,
Detecting a probe current Ia flowing between the right limb of the subject,
After being converted to the voltage Vc, it is supplied to the LPF 92.

The LPF 92 removes high-frequency noise from the input voltage Vc and supplies it to the A / D converter 93.
The cutoff frequency of the LPF 92 is lower than half the sampling frequency of the A / D converter 93. In this case, A /
The aliasing noise generated in the A / D conversion processing by the D converter 93 is removed. The A / D converter 93 converts the noise-removed voltage Vc into a digital signal at a predetermined sampling cycle every time the digital conversion signal Sd is supplied from the CPU 3, and converts the digitized voltage Vc into a sampling cycle. The data is supplied to the sampling memory 94 every time.

The CPU 3 starts the measurement by the above-described measurement processing unit 2 according to the processing program stored in the ROM 5, and detects the detection voltage V at a predetermined sampling cycle.
After sampling p and Vc a predetermined number of times, control for stopping measurement and the following processing are performed. That is, CP
U3 first reads out the voltages Vp and Vc, which are functions of time, stored in the sampling memories 84 and 94 sequentially, and performs the Fourier transform processing on the voltages Vp (f) and Vc (f) (which are functions of frequency. After converting to f), averaging is performed to calculate bioelectric impedance Z (f) ｛= Vp (f) / Vc (f)｝ for each frequency.

Next, based on the obtained bioelectric impedance Z (f) for each frequency, the CPU 3 obtains an impedance locus D as shown in FIG. From the obtained impedance locus D, the bioelectric impedance R0 of the body B of the subject at a frequency of 0 and the bioelectric impedance R at a frequency of infinity are obtained.
∞ is calculated, and from the calculation result, the intracellular fluid resistance and the extracellular fluid resistance of the body B of the subject are calculated.

In the column of "Prior Art", cells in a human body tissue are represented by a simple electrical equivalent circuit (see FIG. 8), but in an actual human body tissue, cells of various sizes are irregular. , An electrical equivalent circuit close to the actual one is shown in FIG.
Is represented by a distributed constant circuit in which elements connected in series with a capacitor and a resistor having a time constant τ = Cmk · Rik (Re is extracellular fluid resistance, Rik is intracellular fluid of each cell) The resistance, Cmk, is the cell membrane capacity of each cell). Therefore,
In this embodiment, since an intracellular fluid resistance and an extracellular fluid resistance are determined by using an electrical equivalent circuit (see FIG. 7) that is close to actual, the impedance locus D of the human body is shown in FIG. Thus, the center is an arc raised above the real axis.

Next, the calculated intracellular fluid resistance and extracellular fluid resistance, and the height of the subject input from the keyboard 1,
Based on human body characteristic data such as weight, gender and age,
By making full use of the body composition estimation formula incorporated in the processing program in advance, the body fat percentage, fat weight,
The amount of lean body mass, the amount of intracellular fluid, the amount of extracellular fluid, and the sum of these amounts of body water (body fluid) are calculated. And
Each of the calculated data is displayed on a display unit 4 including a display controller and a display (for example, an LCD).

Here, the calibrator 110 of the bioelectrical impedance measuring device 100 will be described with reference to FIG. The calibrator 110 has a resistance value of 200 Ω, 500
A resistance element (not shown) of Ω is provided, and two resistance elements are connected to four connection terminals 112-1 protruding from the housing 111.
15. Ideally, the reference impedance element preferably has a flat temperature characteristic and an impedance value and a frequency characteristic equivalent to a bioelectric impedance of a human body. Two conductive clips 20, 20 are connected to the four connection terminals, and the conductive clips 2
The four electrode portions 25 of 0 and 20 are electrically connected to the four connection terminals 112 to 115, respectively.

The connection terminals 112 to 115 are formed of a conductor which is hardly deteriorated. In this example, the connection terminals 112 to 115 are formed of a stainless steel plate or a wire having a diameter of about 1.5 mm. Note that the connection terminals may be formed from a metal plate that is not plated. The distance between the connection terminals 112 and 113,
The distance between the connection terminals 114 and 115 is set substantially equal to the width of the main body 21 of the conductive clip 20. When the conductive clip 20 is positioned within the distance, the electrode portion 2
5 and each connection terminal are set so as to be in contact with each other. The conductive clip 20 is configured to be stably pressed by the sandwiching pieces 23, 23.

The operation of the thus-configured electric characteristic measuring apparatus of the present embodiment will be described below. First, prior to the measurement, as shown in FIG. 2, two surface electrodes Hc,
The electrode sheet 10 having Hp is placed on the right back part H of the subject.
An electrode sheet 10 having two surface electrodes Lp and Lc
To the right instep L of the subject, the conductive gel 13,
13 using an adhesive method. At this time, the electrode sheet 10 is attached such that the longitudinal direction of the electrode sheet 10 is directed to the hands and feet. Thus, the electrode on the tip of the back part H corresponds to the surface electrode Hc, and the electrode on the center side of the body B corresponds to the surface electrode Hp. The electrode at the toe of the instep portion L corresponds to the surface electrode Lc, and the electrode on the center side of the body B corresponds to the surface electrode Lp.

Next, the electrode sheet 10 and the bioelectrical impedance measuring device 100 are connected by the conductive clip 20. Opening the clip pieces 23 of the conductive clip 20, inserting the main body 21 between the contact pieces 11 of the electrode sheet 10, and closing the clip pieces 23, the electrode section 25 is opened.
And the electrode 12 of the contact piece 11 becomes conductive, and the contact piece 11,
The conductive clip 20 is fixed to 11. Since the electrode portion 25 is formed of a conductor that is hardly deteriorated, the electrode sheet 1
Even if the NaCl solution of the conductive gels 13 and 13 adheres,
It does not rust or deteriorate.

The measurer (or the subject himself) uses the keyboard 1 of the bioelectrical impedance measuring device 100 to
The human body characteristic items such as the height, weight, sex, and age of the subject are input, and the total measurement time T from the start of measurement to the end of measurement, the measurement interval t, and the like are set. Data and setting values input from the keyboard 1 are stored in the RAM 6.

Next, when the measurer (or the subject himself) turns on the measurement start switch of the keyboard 1, the CPU 3
Sends a signal generation instruction signal to the measurement signal generator 72 of the measurement processing unit 2 after performing a predetermined initial setting. As a result, the measurement signal generator 72 repeatedly generates the M-sequence probe current Ia a predetermined number of times, and outputs LP as the measurement signal.
F73, coupling capacitor 74, coaxial cable 7
a to the surface electrode Hc (see FIG. 2) affixed to the back H of the subject through a.
The measurement signal Ia of A flows through the body B of the subject from the surface electrode Hc, and the first measurement is started.

When the measurement signal Ia is applied to the subject's body B, the voltage Vp generated between the right limb to which the surface electrodes Hp and Lp are affixed in the differential amplifier 81 of the measurement processing unit 2.
Is supplied to the A / D converter 83 via the LPF 82. On the other hand, in the I / V converter 91, the surface electrode H
After the probe current Ia flowing between the right limb to which c and Lc are attached is detected and converted to the voltage Vc, the LPF 9
The signal is supplied to the A / D converter 93 through the second line. At this time, C
The PU 3 outputs an A / D converter 8 every sampling period.
The digital conversion signal Sd is supplied to 3,93.

The A / D converter 83 converts the voltage Vp into a digital signal every time the digital conversion signal Sd is supplied, and supplies the digital signal to the sampling memory 84. The sampling memory 84 sequentially stores the digitized voltage Vp. On the other hand, the A / D converter 93 converts the voltage Vc into a digital signal each time the digital converted signal Sd is supplied, and supplies the digital signal to the sampling memory 94. The sampling memory 94 sequentially stores the digitized voltage Vc.

The CPU 3 calculates the probe current (measurement signal) I
When the number of repetitions of “a” reaches a preset number, after performing control to stop the measurement, first, the voltages Vp, which are stored in the sampling memories 84 and 94 and are a function of time, as a function of time.
The voltages Vp (f) and Vc (f), which are functions of frequency, are sequentially read out and subjected to Fourier transform processing.
(F is a frequency), and after averaging, the bioelectrical impedance Z (f) ｛= Vp (f) /
Vc (f)} is calculated.

Next, the CPU 3 performs curve fitting based on the calculated bioelectrical impedance Z (f) for each frequency by a calculation method of the least squares method, and obtains an impedance locus D as shown in FIG. From the obtained impedance locus D, the body B of the subject
Of the bioelectric impedance R0 at the frequency 0 and the bioelectric impedance R∞ at the frequency of infinity (corresponding to the X coordinate value of the point where the arc of the impedance locus D intersects the X axis). Then, the intracellular fluid resistance and extracellular fluid resistance of the body B are calculated.

The CPU 3 executes a processing program in advance based on the calculated intracellular fluid resistance and extracellular fluid resistance, and human body characteristic data such as the height, weight, sex, and age of the subject input from the keyboard 1. The body fat percentage, fat weight, lean body mass, intracellular fluid volume, extracellular fluid volume, and the sum of these body water ( Volume). Then, the calculated data are stored in the RAM 6 and displayed on the display unit 4.

Next, the CPU 3 determines whether or not the total measurement time T has elapsed. If it is determined that the total measurement time T has elapsed, the CPU 3 terminates the subsequent measurement processing. After waiting for the time t corresponding to to elapse, the same measurement processing is started again. Then, the above process is repeated until the entire measurement time T has elapsed.

As described above, according to the configuration of this example, the probe current Ia is dispersed in energy of about 1 msec despite including many frequency components.
Since the amplitude of the frequency spectrum uses an M-sequence signal that is almost flat over the entire frequency range, it does not damage the living body and removes the effects of respiration and pulse in the measurement of body fat status and body water distribution. It is possible,
Good measurement of the SN ratio is possible over the entire frequency range. Further, the measurement signal can be generated only from the shift register and the plurality of logic circuits, so that the configuration becomes very simple.

Further, since the bioelectrical impedance at the infinite frequency can be obtained by using the curve fitting method based on the least squares method, the influence of stray capacitance and external noise can be avoided. The extracellular fluid resistance and the intracellular fluid resistance can be determined. Further, the surface electrodes Hc, Hp, Lp, Lc and the circuit elements 73,
Between the coupling capacitors 74 and 8.
Since the components 0a, 80b, and 90 are interposed, the DC component of the current flowing into the living body or the current flowing in the living body can be cut, which is safe for both the living body and the device.

Further, the output resistance of the measurement signal generator 72 is set to 10 kΩ over the entire range of the signal frequency.
At the same time, since the coupling capacitor 74 is interposed between the LPF 73 and the surface electrode Hc, the surface electrode Hc can be substantially regarded as a constant current source, and the probe current is determined by the bioelectric impedance (about 1 kΩ). I
The current value of a does not change, the maximum value of the current flowing through the living body is determined, and the living body is safe. Therefore, it is possible to more accurately and safely estimate the state of the body fat and the distribution of the body water of the subject.

When calibrating the bioelectrical impedance measuring apparatus 100, the connection terminals 112 to 11 of the calibrator 110 are used.
5 are connected to the conductive clips 20. That is, the conductive clips are located in the four connection terminals of the calibrator 110, and the two electrode portions 2 of the conductive clips 20, 20 are respectively provided.
5 and 25 are connected so as to conduct with each connection terminal. Then, measurement is performed according to the same measurement procedure as described above, and calibration is performed based on the known impedance values Z ₁ and Z ₂ and the impedance values Z ′ ₁ and Z ′ ₂ obtained by the measurement. It is desirable that the calibration be performed periodically to maintain the accuracy of the bioelectrical impedance measuring device 100.

At the time of this calibration, even if the conductive gel 13 of the conductive sheet 10 adheres to the electrode portion 25 of the conductive clip 20 and this conductive gel adheres to the connection terminals 112 to 115,
Since the connection terminal of the calibrator 110 is formed of a conductor that is hardly deteriorated, rust or the like does not occur, the electric resistance does not change, and the calibration can be performed accurately. If it is formed from a metal plate or a metal wire that has not been subjected to plating, there is no deterioration such as peeling of plating, and accurate calibration can be performed.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the design can be changed within the scope of the present invention. Even if there is, it is included in the present invention. For example, the bioelectrical impedance measuring device and the electrode attached to the body are configured to be connected by a coaxial cable,
The connection may be made using a normal conducting wire.

[0060]

As can be understood from the above description, in the calibrator of the electric characteristic measuring device of the present invention, the connection terminal to which the conductive clip is connected is formed of a conductor which is hardly deteriorated, and Even if the conductive gel of the electrode sheet attached to the part and the instep adheres to the connection terminal of the calibrator via the conductive clip, it does not deteriorate and the electrical resistance value does not change, Can be calibrated. In addition, by forming the conductor of the connection terminal from a metal plate or a metal wire that has not been plated, the calibration can be accurately performed without peeling off the plating.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a bioelectrical impedance measuring device using a calibrator of the present invention.

FIG. 2 is a diagram schematically showing a state of use of the bioelectrical impedance measuring device shown in FIG.

FIG. 3A is a perspective view of an upper surface side in a state where a conductive gel of an electrode sheet is separated, and FIG. 3B is a perspective view of a lower surface side.

FIG. 4 is a schematic perspective view of a conductive clip.

5A is a schematic perspective view showing a state before connection between a conductive clip and an electrode sheet on a back part, and FIG. 5B is a schematic view showing a state before connection between a conductive clip and an electrode sheet on a foot part. Perspective view.

FIG. 6 is a diagram showing an impedance locus of a human body.

FIG. 7 is a close-to-actual electrical equivalent circuit diagram of cells in a tissue of a human body.

FIG. 8 is a simplified electrical equivalent circuit diagram of cells in a tissue.

FIG. 9 is a schematic perspective view showing a use state of the calibrator of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Keyboard (human body characteristic data input means) 3 CPU (arithmetic means) 4 Display part (output means) 10 Electrode sheet 11 Contact piece 12 Electrode 13 Conductive gel 20 Conductive clip 23 Clipping piece 25 Electrode part 72 Measurement signal generator (Measurement Modulator (part of measurement signal supply unit) 73 LPF (part of measurement signal supply unit) 81 Differential amplifier (part of voltage measurement unit) 82 LPF (part of voltage measurement unit) 83) A / D converter (part of voltage measuring means) 84,94 Sampling memory (storage means) 91 I / V converter (part of current measuring means) 92 LPF (part of current measuring means) 100 Bioelectric impedance measuring device 110 Calibrator 112 to 115 Connection terminal Hc, Hp, Lc, Lp Surface electrode (first to fourth electrodes)

Claims (3)

[Claims] 1. A conductive clip is connected to an electrode conductively attached to a surface portion of a body of a subject, a measurement signal is applied to the body of the subject, and a voltage value generated between the surface portions of the body of the subject is measured. Thereby, a calibrator of the electrical property measuring device for measuring bioelectrical impedance, the calibrator includes a connection terminal to which the conductive clip is connected, and includes a reference impedance element connected to the connection terminal, A calibrator for an electrical characteristic measuring device, wherein the connection terminal is formed of a conductor that is hardly deteriorated. 2. The calibrator according to claim 1, wherein the conductor that is hardly deteriorated is formed of a stainless steel plate or wire. 3. The calibrator according to claim 1, wherein the conductor that is hardly deteriorated is formed of a metal plate or a metal wire that is not plated.