JP2012176063A - Measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate contact pressure acting on a body from an electrode portion by a simple structure.SOLUTION: The electrode portion 14 includes an electrode pair PA (electrode E1 and electrode E2) coming into contact with a measurement region of a subject and an electrode pair PB (electrode E3 and electrode E4). A control portion 22 computes impedance ZA[n] by a two-electrode method using the electrode pair PA and computes impedance ZB[n] by a four-electrode method using the electrode pair PA and the electrode pair PB, and computes a contact pressure index C[n] of the electrode portion 14 relative to the measurement region on the basis of a difference between the impedance ZA[n] and the impedance ZB[n].

Description

  The present invention relates to a technique for measuring biological information such as subcutaneous fat thickness.

  Conventionally, techniques for calculating biological information of a subject using bioelectrical impedance have been proposed. For example, in Patent Document 1, bioimpedance is calculated by bringing four electrodes formed on an electrode part (probe) into contact with the body of a subject, and the ratio (R) of resistance R and reactance X specified from the bioimpedance. / X) discloses a technique for calculating a subject's subcutaneous fat thickness.

JP 2010-259776 A

  However, since the subcutaneous fat is deformed according to the contact pressure (pressing force) acting from the electrode part, there is a possibility that an error occurs in the subcutaneous fat thickness calculated according to the bioimpedance. If a detector such as a pressure sensor that detects the contact pressure of the electrode part is used, it is possible to detect the suitability of the contact pressure acting on the body from the electrode part (for example, the presence or absence of deformation of subcutaneous fat). There is a problem that the configuration of the measuring apparatus becomes complicated due to the addition of the measuring instrument. In the above description, the measurement of the subcutaneous fat thickness is assumed, but the same problem may occur when measuring other biological information (for example, muscle thickness) that depends on the contact pressure of the electrode portion. In view of the above circumstances, an object of the present invention is to evaluate the contact pressure acting on the body from the electrode portion with a simple configuration.

  Means employed by the present invention to solve the above problems will be described. In order to facilitate the understanding of the present invention, in the following description, the correspondence between the elements of the present invention and the elements of the embodiments described later will be indicated in parentheses, but the scope of the present invention will be exemplified in the embodiments. It is not intended to be limited.

  The measurement apparatus of the present invention includes an electrode unit (for example, electrode unit 14) including a first electrode pair (for example, electrode pair PA) and a second electrode pair (for example, electrode pair PB) that are in contact with a subject's body (for example, measurement site 60). A first calculating means (for example, control unit 22) for calculating a first impedance (for example, impedance ZA [n]) by a two-electrode method using the first electrode pair, and a first electrode pair and a second electrode pair. Second calculation means (for example, control unit 22) for calculating the second impedance (for example, impedance ZB [n]) by the four-electrode method used, and a contact pressure index (for example, contact) according to the contact pressure of the electrode unit with respect to the body of the subject And an index calculating means (for example, the control unit 22) that calculates the pressure index C [n]) based on the difference between the first impedance and the second impedance. In the above configuration, according to the difference between the first impedance measured by the two-electrode method using the first electrode pair and the second impedance measured by the four-electrode method using the first electrode pair and the second electrode pair. The contact pressure index C [n] is calculated as an index of the contact pressure of the electrode part. Therefore, it is possible to evaluate the contact pressure of the electrode part with respect to the body without requiring a detector such as a pressure sensor dedicated to the detection of the contact pressure of the electrode part.

  The measurement apparatus according to a preferred aspect of the present invention includes a current generation means (for example, a current generation unit 32) that causes a current (for example, a measurement current I) to flow between the electrodes of the first electrode pair via the body of the subject, and the first electrode. Electrode selection means (for example, electrode selection unit 36) for selecting one of the pair and the second electrode pair, and voltage detection means (for example, measurement voltage V) for detecting the voltage between the electrodes of the electrode pair selected by the electrode selection means (for example, measurement voltage V) Voltage detector 34), and the first calculating means includes a first calculating means according to a current generated by the current generating means and a voltage detected by the voltage detecting means in a state where the electrode selecting means selects the first electrode pair. The impedance is calculated, and the second calculation means calculates the second impedance according to the current generated by the current generation means and the voltage detected by the voltage detection means in a state where the electrode selection means selects the second electrode pair. In the above aspect, it is possible to easily switch between the two-electrode method and the four-electrode method according to the selection target of the electrode selection means.

  A measuring apparatus according to a preferred aspect of the present invention includes a contact state determination unit (for example, the control unit 22) that determines whether or not a contact state between the body of the subject and the electrode unit is appropriate according to a contact pressure index, and the body and electrode of the subject. And an information generation unit (for example, control unit 22) that calculates biological information corresponding to the second impedance when the contact state determination unit determines that the contact state with the unit is appropriate. In the above aspect, since the biological information is generated when the contact state (for example, contact pressure) between the body of the subject and the electrode portion is appropriate, the biological information that depends on the contact state between the body of the subject and the electrode portion ( For example, there is an advantage that (subcutaneous fat thickness) can be measured with high accuracy.

  In a preferred aspect of the present invention, the measurement process including the calculation of the first impedance by the first calculation means, the calculation of the second impedance by the second calculation means, and the calculation of the contact pressure index by the index calculation means is performed a plurality of times. The contact state determination means determines the suitability of the contact state between the body of the subject and the electrode unit for each measurement process by comparing the contact pressure index measured in each measurement process with a reference value (for example, the reference value CREF). To do. In the above aspect, it is possible to detect a change in the contact state (contact pressure) between the body of the subject and the electrode unit by comparing the contact pressure index calculated in each measurement process with a reference value. Although the reference value of the contact pressure index is arbitrary, for example, the contact pressure index measured in one measurement process (for example, the first measurement process) is compared with the contact pressure index in each subsequent measurement process. A configuration using a reference value is preferable.

  In a preferred aspect of the present invention, the information generating means generates biological information when the determination that the contact state is appropriate continues for a predetermined number of times (for example, threshold value MTH). In the above aspect, since the biological information is generated when the determination that the contact state is appropriate continues for a predetermined number of measurement processes (that is, when the contact state is stable), the contact state changes in an unstable manner. Compared to a configuration in which biological information is generated in a state, there is an advantage that biological information that depends on the contact state can be measured with high accuracy.

  In a preferred aspect of the present invention, the first electrode pair includes a first electrode (for example, the electrode E1) and a second electrode (for example, the electrode E2), and the second electrode pair includes the first electrode and the second electrode. A third electrode (for example, electrode E3) and a fourth electrode (for example, electrode E4) disposed between the first electrode, the second electrode, the third electrode, and the fourth electrode are arranged in a first direction (for example, It is formed in a long shape in the (X direction), and is arranged with a space between each other in a second direction (for example, the Y direction) orthogonal to the first direction. According to the above aspect, each electrode can be reliably brought into contact with the body of the subject.

  The measurement device according to each of the above aspects is realized by, for example, cooperation between an arithmetic processing device and a program (software). The program according to the present invention calculates a first impedance by a two-electrode method using a first electrode pair to a computer to which an electrode unit including a first electrode pair and a second electrode pair in contact with the body of a subject is connected. 1 calculation process (for example, process S3), a second calculation process (for example, process S6) for calculating the second impedance by the four-electrode method using the first electrode pair and the second electrode pair, and an electrode section for the subject's body An index calculation process (for example, process S8) for calculating a contact pressure index corresponding to the contact pressure based on the difference between the first impedance and the second impedance is executed. According to the above program, the same operation and effect as the measuring apparatus of the present invention are realized. The program of the present invention is provided to a user in a form stored in a computer-readable recording medium and installed in the computer, or provided from a server device in a form of distribution via a communication network and installed in the computer. Is done.

1 is an external view of a measuring apparatus according to a first embodiment of the present invention. It is a block diagram of the electric constitution of a measuring device. It is a flowchart of a measurement process. It is explanatory drawing of the current path of a measurement current, and the detection position of a measurement voltage. It is a graph which shows the relationship between a contact pressure and the impedance of a measurement site | part. It is a flowchart of the measurement process in 2nd Embodiment.

<A: First Embodiment>
FIG. 1 is a configuration diagram of a measuring apparatus 100 according to the first embodiment. The measuring apparatus 100 is a biometric instrument that measures biological information (for example, an index related to body composition) related to the body of a subject. In the first embodiment, the subcutaneous fat thickness Lf of an arbitrary part to be measured (hereinafter referred to as “measurement part”) in the body of the subject is exemplified as the biological information. As shown in FIG. 1, the measuring apparatus 100 includes a main body portion 12 and an electrode portion (probe) 14. The main body portion 12 and the electrode portion 14 are electrically connected via a cable 16. In addition, it is also possible to comprise the main-body part 12 and the electrode part 14 integrally.

  The electrode unit 14 includes a housing 142 that can be held by a user (subject himself / herself or a measurer), and an electrode pair PA and an electrode pair PB formed on the surface 144 of the housing 142. The electrode pair PA is a pair of the electrode E1 and the electrode E2, and the electrode pair PB is a pair of the electrode E3 and the electrode E4. Each of the four electrodes E1 to E4 is formed in an elongated shape (substantially rectangular shape) in the X direction, and is arranged at intervals in the Y direction perpendicular to the X direction. As shown in FIG. 1, the electrode E3 and the electrode E4 are located between the electrode E1 and the electrode E2. FIG. 1 illustrates the case where the electrodes E1 to E4 are arranged at equal intervals. The user can move the electrode unit 14 so that the four electrodes E1 to E4 are in contact with the measurement site of the subject's body.

  FIG. 2 is a block diagram of the electrical configuration of the measuring apparatus 100. As shown in FIG. 2, the main body unit 12 includes a control unit 22, a storage unit 24, an operation unit 26, and a display unit 28. The control unit 22 (CPU) controls each element of the measurement apparatus 100 by executing a program stored in the storage unit 24. The storage unit 24 is a storage circuit (for example, ROM or RAM) that stores programs executed by the control unit 22 and various data used by the control unit 22.

  The operation unit 26 is an input device that accepts an instruction from a user, and includes a plurality of operators as shown in FIG. For example, the start of measurement of the subcutaneous fat thickness Lf is instructed by an operation on the operation unit 26. The display unit 28 (for example, a liquid crystal display device) displays various images under the control of the control unit 22. For example, the display unit 28 displays measurement procedure guidance using the measurement apparatus 100 and measurement results (subcutaneous fat thickness Lf) of the measurement apparatus 100.

  As shown in FIG. 2, the electrode unit 14 includes a current generation unit 32, a voltage detection unit 34, and an electrode selection unit 36 housed in the casing 142, in addition to the electrode pair PA and the electrode pair PB described above. Note that the current generation unit 32, the voltage detection unit 34, and the electrode selection unit 36 can be installed in the main body unit 12.

  The current generator 32 in FIG. 2 supplies the measurement current I between the electrode E1 and the electrode E2. The measurement current I is an alternating current having a predetermined frequency (for example, 500 kHz or 6.25 kHz) that flows between the electrode E1 and the electrode E2 via the body of the subject. The voltage detector 34 detects a voltage V (hereinafter referred to as “measurement voltage”) V between the pair of electrodes E. The measurement voltage V detected by the voltage detector 34 is converted into a digital signal by an A / D converter (not shown) and then supplied to the controller 22.

  The electrode selection unit 36 selects either the electrode pair PA or the electrode pair PB as the connection destination of the voltage detection unit 34. As shown in FIG. 2, the electrode selection unit 36 of the first embodiment includes a switch SW1 and a switch SW2. The switch SW1 connects the terminal TV1 of the voltage detector 34 to one of the electrode E1 (contact a) and the electrode E3 (contact b), and the switch SW2 connects the terminal TV2 of the voltage detector 34 to the electrode E2 (contact a) and Connect to one of the electrodes E4 (contact b).

  FIG. 3 is a flowchart of the measurement process executed by the control unit 22. When an instruction to start measurement is given to the operation unit 26 in a state where the four electrodes E1 to E4 of the electrode unit 14 are in contact with the measurement site 60 of the subject, for example, at a predetermined interval defined by an interrupt signal, FIG. The measurement process is repeated. The variable n means the number of measurement processes (n is a natural number). FIG. 4 is a schematic diagram of the current path of the measurement current I and the detection position of the measurement voltage V during execution of the measurement process.

  When the n-th measurement process is started, the control unit 22 controls the electrode selection unit 36 so that the electrode pair PA is selected as a connection destination of the voltage detection unit 34 (S1). Specifically, the control unit 22 controls each of the switch SW1 and the switch SW2 to the contact a side, so that the terminal TV1 of the voltage detection unit 34 is connected to the electrode E1 as shown in part (A) of FIG. In addition, the terminal TV2 is connected to the electrode E2. Electrode E3 and electrode E4 are electrically insulated from voltage detector 34. The controller 22 operates the current generator 32 and the voltage detector 34 in the above state (S2). Therefore, the voltage detection unit 34 detects the measurement voltage V between the electrode E1 and the electrode E2 in a state where the measurement current I generated by the current generation unit 32 flows from the electrode E1 to the electrode E2 via the measurement site 60. To do.

  The controller 22 calculates the impedance ZA [n] according to the measured current I and the measured voltage V in the process S2 (S3). A known technique is arbitrarily employed for calculating the impedance ZA [n]. As can be understood from the above description, the control unit 22 calculates the impedance ZA [n] by the two-electrode method using the electrode pair PA (the electrode pair PB is not used) by executing the processes S1 to S3. Means (first calculation means) to perform is realized.

As shown in part (A) of FIG. 4, on the path of the measurement current I, in addition to the bioimpedance RB of the measurement site 60 (subcutaneous fat), the contact impedance RC1 between the electrode E1 and the measurement site 60 and A contact impedance RC2 between the electrode E2 and the measurement site 60 is attached. Accordingly, the impedance ZA [n] calculated in the process S3 is approximately expressed by the following formula (1).
ZA [n] = RB + RC1 + RC2 (1)

  When the impedance ZA [n] is calculated by the above procedure, the control unit 22 controls the electrode selection unit 36 so that the electrode pair PB is selected as the connection destination of the voltage detection unit 34 (S4). Specifically, the control unit 22 controls each of the switch SW1 and the switch SW2 to the contact b side so that the terminal TV1 of the voltage detection unit 34 is connected to the electrode E3 as shown in part (B) of FIG. At the same time, the terminal TV2 is connected to the electrode E4. The controller 22 operates the current generator 32 and the voltage detector 34 in the above state (S5). Therefore, in a state where the measurement current I flows from the electrode E1 to the electrode E2 via the measurement site 60, the voltage detection unit 34 detects the measurement voltage V between the electrode E3 and the electrode E4.

  The controller 22 calculates the impedance ZB [n] according to the measurement current I and the measurement voltage V in the process S5 (S6). A known technique is arbitrarily employed for calculating the impedance ZB [n]. As will be understood from the above description, the control unit 22 executes the process S4 to the process S6, thereby calculating the impedance ZB [n] by the four-electrode method using the electrode pair PA and the electrode pair PB (first step). 2 calculation means) is realized. Further, the control unit 22 determines the resistance R (the real part of the impedance ZB [n]) and the reactance X (the imaginary part of the impedance ZB [n]) from the phase difference θ between the measurement current I and the measurement voltage V and the impedance ZB [n]. ) And the ratio R / X between them is calculated (S7).

In the process S5, since the measurement voltage V is measured using the electrode pair PB located inside the electrode pair PA, the contact impedance RC1 of the electrode E1 and the contact impedance RC2 of the electrode E2 do not affect the measurement voltage V. Further, since almost no current flows through the terminal TV1 and the terminal TV2 of the voltage detector 34, the contact impedance RC3 of the electrode E3 and the contact impedance RC4 of the electrode E4 do not affect the measurement voltage V. As described above, since the contact impedance RC (RC1 to RC4) of each electrode E can be ignored in the four-electrode method, the impedance ZB [n] calculated in the process S6 is expressed by the following formula (2). It substantially matches the bioimpedance RB of the measurement site 60.
ZB [n] = RB (2)

The controller 22 calculates a contact pressure index C [n] corresponding to the difference between the impedance ZA [n] calculated in the process S3 and the impedance ZB [n] calculated in the process S6 (S8). Specifically, the control unit 22 calculates the difference between the impedance ZA [n] and the impedance ZB [n] as the contact pressure index C [n] as shown in the following formula (3).
C [n] = ZA [n] −ZB [n] (3)

By substituting Equation (1) and Equation (2) into Equation (3), the following Equation (4) is derived.
C [n] = RC1 + RC2 (4)
As expressed by Equation (4), the contact pressure index C [n] corresponds to the added value of the contact impedance RC1 of the electrode E1 and the contact impedance RC2 of the electrode E2. The contact impedance RC (RC1, RC2) changes according to the contact pressure (pressing force) acting on the measurement site 60 from the electrode portion 14. Therefore, it is possible to use the contact pressure index C [n] of Equation (3) as an index of the contact pressure of the electrode unit 14 with respect to the measurement site 60.

  FIG. 5 is a chart showing the relationship between the contact pressure acting on the measurement site 60 from the electrode section 14 and each impedance. Each of the cases where the numerical values of the impedance ZA [n] measured by the two-electrode method, the impedance ZA [n] measured by the four-electrode method, and the contact pressure index C [n] change the contact pressure. Is shown. Part (A) of FIG. 5 is a measurement result when the subject's abdomen is the measurement site 60, and part (B) of FIG. 5 is a measurement result when the subject's upper arm (second arm) is the measurement site 60. .

  As shown in FIG. 5, the impedance ZA [n] of the two-electrode method decreases as the contact pressure of the electrode portion 14 with respect to the measurement site 60 increases, whereas the impedance ZB [n] of the four-electrode method hardly changes. . Therefore, the contact pressure index C [n] changes according to the contact pressure with respect to the measurement site 60. Specifically, the correlation that the contact pressure index C [n] decreases as the contact pressure increases is understood from FIG. In consideration of the above tendency, in the first embodiment, the contact pressure index C [n] calculated in the process S8 is used for evaluating the suitability of the contact state (contact pressure) between the measurement site 60 and the electrode unit 14. .

  When the contact pressure index C [n] is calculated in the process S8 of FIG. 3, the control unit 22 determines whether or not the measurement process being executed at the current stage is the first (n = 1) (S9). ). When the result of the process S9 is positive, the control unit 22 stores the contact pressure index C [n] (C [1]) calculated in the process S8 of the current measurement process in the storage unit 24 as the reference value CREF. Thus, the first measurement process is terminated (S10). The reference value CREF is a numerical value that serves as a reference for the contact pressure index C [n] calculated in each measurement process after the second time.

  When the result of the process S9 is negative (that is, when the second and subsequent measurement processes are being executed), the control unit 22 determines the contact calculated in the process S8 in the current stage (n-th) measurement process. A fluctuation amount δC [n] is calculated when the pressure index C [n] is compared with the reference value CREF in the storage unit 24 (S11). Specifically, the fluctuation amount δC [n] is an absolute value of the difference between the contact pressure index C [n] and the reference value CREF (δC [n] = | C [n] −CREF |). Then, the control unit 22 determines whether or not the fluctuation amount δC [n] is below a predetermined threshold value δTH (S12). The threshold value δTH is set to a numerical value of about 50Ω, for example.

  When the contact pressure with respect to the measurement site 60 has increased significantly immediately after the start of measurement (the first measurement process), there is a high possibility that the subcutaneous fat at the measurement site 60 has been greatly deformed by the pressure applied by the electrode portion 14. As described above, the subcutaneous fat thickness Lf cannot be accurately estimated in a state where the measurement site 60 is deformed. Therefore, when it is determined in the process S12 that the fluctuation amount δC [n] exceeds the threshold value δTH (that is, when the contact pressure changes significantly compared to when the first measurement process is performed), the control unit 22 Then, after notifying the user of a warning (measurement error) that the contact pressure with respect to the measurement site 60 is inappropriate, the n-th measurement process is terminated (S13). The method for warning the user is arbitrary, but for example, display of an image on the display unit 28 or output by sound is preferable. As understood from the above description, the control unit 22 executes the process S12 to determine whether or not the connection state between the measurement site 60 and the electrode unit 14 (each electrode E) is appropriate according to the contact pressure index C [n]. Means (contact state determination means) are determined.

  On the other hand, when the contact pressure with respect to the measurement site 60 is maintained within an appropriate range (that is, when the measurement site 60 has not been deformed excessively since the execution of the first measurement process), the contact pressure index C [n ] Is a numerical value within a predetermined range (for example, a range of (CREF ± δTH)) including the reference value CREF. Therefore, when it is determined in the process S12 that the fluctuation amount δC [n] is less than the threshold value δTH, the control unit 22 determines the impedance ZB [n] (bioimpedance RB) calculated in the process (S6) of the current (n-th) measurement process. ) To calculate the subcutaneous fat thickness Lf (S14). That is, the element (information generating means) that calculates biological information when it is determined that the contact state between the measurement site 60 and the electrode unit 14 is appropriate (S12: YES) by executing the process S14 by the control unit 22. ) Is realized.

Since the subcutaneous fat is less likely to generate the phase difference θ between the measurement current I and the measurement voltage V as compared to the muscle, the phase difference θ decreases as the subcutaneous fat thickness Lf at the measurement site 60 increases. Therefore, the ratio R / X calculated in the process S7 tends to increase as the subcutaneous fat thickness Lf increases. Considering the above tendency, the subcutaneous fat thickness Lf (the depth of the subcutaneous fat with the surface of the measurement site 60 as a reference (zero)) is expressed by the following formula (5) including the constant a and the constant b. The constant a and the constant b are statistically selected according to the correlation between the ratio R / X and the measured value of the subcutaneous fat thickness Lf. The relationship between the subcutaneous fat thickness Lf and the ratio R / X is also described in detail in Patent Document 1.
Lf = −a−b × (R / X) (5)

  In the process S14 of FIG. 3, the control unit 22 calculates the formula (5) for the ratio R / X calculated in the process S7 according to the impedance ZB [n] (the biological impedance RB of the measurement site 60) of the four-electrode method. By executing, the subcutaneous fat thickness Lf is calculated as biometric information. And the control part 22 displays on the display part 28 the subcutaneous fat thickness Lf calculated by process S14 as a measurement result (S15). As understood from the above description, the numerical value of the subcutaneous fat thickness Lf displayed on the display unit 28 changes every time the measurement process is performed, and the contact pressure of the electrode unit 14 with respect to the measurement site 60 is compared with that at the start of measurement. If the measurement site 60 has changed significantly (that is, when the measurement site 60 is greatly deformed compared to when the first measurement process is executed), a warning is notified to the user.

  In the first embodiment exemplified above, the impedance ZA [n] measured by the two-electrode method using the electrode pair PA and the impedance ZB [n] measured by the four-electrode method using the electrode pair PA and the electrode pair PB are used. ] Is calculated as an index of the contact pressure of the electrode part 14 with respect to the measurement site 60. That is, each electrode E used for measuring the subcutaneous fat thickness Lf is used for calculating the contact pressure index C [n]. Therefore, it is possible to evaluate the contact state between the measurement site 60 and each electrode E with a simple configuration without requiring a detector such as a pressure sensor dedicated to the detection of the contact pressure of the electrode portion 14.

  In the first embodiment, the suitability of the contact pressure of the electrode part 14 (each electrode E) with respect to the measurement site 60 is determined according to the contact pressure index C [n], and when it is determined that the contact pressure is appropriate, it is subcutaneous. Measurement of the fat thickness Lf (S14) is performed. Therefore, it is possible to suppress a measurement error caused by an abnormality in the contact pressure of the electrode unit 14 (for example, excessive pressing on the measurement site 60). Further, since the user is notified when the contact pressure of the electrode portion 14 is inappropriate, the user can adjust the electrode portion 14 so that the contact pressure is in an appropriate state (therefore, a highly accurate measurement can be performed). Is also realized).

  By the way, the contact pressure index C [n] (contact impedance RC1, RC2) depends not only on the contact pressure of the electrode part 14, but also on the skin state (for example, wet and dry state) of the measurement site 60. Therefore, in the configuration in which the reference value CREF is fixed to a predetermined value, the contact pressure index C [n] is attributed to the skin state of the measurement site 60 even when the contact pressure of the electrode portion 14 does not change (subcutaneous fat does not deform). The variation amount δC [n] between the reference value CREF and the reference value CREF may exceed the threshold value δTH, and it may be determined in step S12 that the contact pressure of the electrode unit 14 is inappropriate. On the other hand, in the first embodiment, the contact pressure index C [n] calculated in the past (first) measurement process is used as the reference value CREF to determine the suitability of the contact pressure in the second and subsequent measurement processes. When compared with the configuration in which the reference value CREF is fixed to a predetermined value, the influence of the skin condition of the measurement site 60 is reduced for the determination in the process S12. Therefore, there is an advantage that a change in contact pressure of the electrode part 14 (presence or absence of deformation of the measurement site 60) can be evaluated with high accuracy.

<B: Second Embodiment>
A second embodiment of the present invention will be described below. In addition, about the element which an effect | action and a function are equivalent to 1st Embodiment in each form illustrated below, each reference detailed in the above description is diverted and each detailed description is abbreviate | omitted suitably.

  FIG. 6 is a flowchart of the measurement process executed by the control unit 22 of the second embodiment. As shown in FIG. 6, the measurement process of the second embodiment is the content obtained by adding processes S20 to S23 to the measurement process of the first embodiment (FIG. 3).

  When the contact pressure index C [1] is set to the reference value CREF in the first measurement process (S10), the control unit 22 initializes the variable M stored in the storage unit 24 to zero (S20). The variable M means the number of times that the determination (S12: YES) that the contact pressure of the electrode portion 14 with the measurement site 60 is appropriate is continued.

  If it is determined that the variation δC [n] is lower than the threshold δTH (ie, the contact pressure of the electrode unit 14 is appropriate) in the process S12 of each measurement process after the second time, the control unit 22 stores it in the storage unit 24. 1 is added to the variable M (S21), and it is determined whether or not the variable M after the addition is below a predetermined threshold value MTH (S22). When the result of the process S22 is negative (that is, when the contact pressure is determined to be appropriate continuously over the MTH measurement processes), the control unit 22 uses the four-electrode method as in the first embodiment. The calculation (S14) of the subcutaneous fat thickness Lf according to the impedance ZB [n] measured in (S4 to S6) and the display (S15) are executed. On the other hand, when the result of the process S22 is affirmative (when the number M of times that the contact pressure is continuously determined to be appropriate is still less than the threshold value MTH), the control unit 22 executes the process S14 and the process S15. The n-th measurement process is terminated.

  If it is determined that the variation amount δC [n] exceeds the threshold value δTH (that is, the contact pressure of the electrode unit 14 is inappropriate) in the process S12 of each measurement process after the second time, the control unit 22 gives an error to the user. While performing notification (S13), the variable M memorize | stored in the memory | storage part 24 is initialized to zero (S23). As will be understood from the above description, until the number M of times that the contact pressure of the electrode portion 14 is continuously determined (S12: YES) reaches the threshold value MTH (that is, the contact pressure of the electrode portion 14). The calculation (S14) and output (S15) of the subcutaneous fat thickness Lf are not executed until the value is stabilized. Therefore, there is an advantage that the subcutaneous fat thickness Lf can be calculated with high accuracy as compared with the configuration in which the calculation of the subcutaneous fat thickness Lf is started before the contact pressure of the electrode portion 14 is stabilized.

<C: Modification>
Each of the above-described embodiments can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined.

(1) Modification 1
The biological information generated by the measuring apparatus 100 is not limited to the subcutaneous fat thickness Lf. For example, the muscle thickness Lm of the measurement site 60 can be calculated as biological information. The fat percentage F of the measurement site 60 is approximated as the ratio of the subcutaneous fat thickness Lf to the sum of the subcutaneous fat thickness Lf and the muscle thickness Lm (F = Lf / (Lf + Lm). It is expressed by (6).
Lm = (Lf / F) -Lf (6)
The control unit 22 calculates the fat percentage F from the impedance ZB [n] calculated in the process S6 (that is, the biological impedance RB of the measurement site 60) and calculates the subcutaneous fat thickness Lf by the calculation of the above formula (5). The muscle thickness Lm is calculated by executing the calculation of Equation (6) for the fat percentage F and the subcutaneous fat thickness Lf.

(2) Modification 2
In each of the above embodiments, the contact pressure index C [n] is applied to determine the suitability of the contact pressure of the electrode unit 14 with respect to the measurement site 60. However, the contact pressure index C [n] is directly applied to the generation of biological information. It is also possible. For example, as the contact pressure of the electrode part 14 with respect to the measurement site 60 is larger (the contact pressure index C [n] is smaller), the subcutaneous fat is pressed and the subcutaneous fat thickness Lf tends to decrease. Therefore, a configuration is adopted in which the contact pressure index C [n] is included in the calculation formula of the subcutaneous fat thickness Lf as a correction term so that the error (decrease) in the subcutaneous fat thickness Lf caused by the pressing by the electrode portion 14 is compensated. Is done. Specifically, an arithmetic expression is selected so that the subcutaneous fat thickness Lf increases as the contact pressure index C [n] is smaller (the contact pressure is large and the deformation of the measurement site 60 is large). As can be understood from the above examples, the method of using the contact pressure index C [n] is arbitrary, and according to the contact pressure index C [n] as in the process S12 of the first embodiment or the second embodiment. The element (contact state determination means) for determining the suitability of the contact pressure of the electrode unit 14 can be omitted.

(3) Modification 3
The order of the calculation of the impedance ZA [n] by the two-electrode method and the calculation of the impedance ZB [n] by the four-electrode method is arbitrary. Further, the specific method for calculating the impedance ZA [n] and the impedance ZB [n] is appropriately changed. For example, a configuration in which the representative value (for example, average value or median value) of each impedance when measurement by the two-electrode method is repeated a predetermined number of times is determined as the impedance ZA [n] in the processing S3, or measurement by the four-electrode method Can be adopted in which the representative value (for example, average value or median value) of each impedance when it is repeated for a predetermined number of times is determined as impedance ZB [n] in step S6.

(4) Modification 4
In each of the above embodiments, the contact pressure index C [n] calculated in the first measurement process is set as the reference value CREF, but the method for selecting the reference value CREF is arbitrary. For example, a configuration in which a predetermined value selected in advance is used as the reference value CREF, or a measurement process after the contact pressure of the electrode unit 14 is determined to be stable (for example, measurement in which the result of process S22 in FIG. 6 is negative). A configuration in which the contact pressure index C [n] calculated in the processing) is used as the reference value CREF can also be adopted.

(5) Modification 5
The relationship between the difference between the impedance ZA [n] and the impedance ZB [n] (contact impedance RC and contact pressure) and the contact pressure index C [n] (method for calculating the contact pressure index C [n]) is changed as appropriate. . For example, in each of the above-described embodiments, the case where the contact pressure index C [n] decreases as the contact pressure of the electrode portion 14 with respect to the measurement site 60 increases (the contact impedance RC decreases) is exemplified, but the contact pressure increases. The contact pressure index C [n] is calculated so that the contact pressure index C [n] increases as the contact pressure index C [n] increases (for example, the reciprocal of the difference between the impedance ZA [n] and the impedance ZB [n] is calculated as the contact pressure index C [n]. ] Can also be employed. As understood from the above description, the process S8 in which the control unit 22 calculates the contact pressure index C [n] is performed by using the contact pressure index C [n] corresponding to the contact pressure of the electrode unit 14 with respect to the measurement site 60 as the impedance. It is included as a process for calculating according to a difference (typically a difference) between ZA [n] and impedance ZB [n].

100: Measuring device, 12: Main body, 14: Electrode, 142: Case, PA, PB ... Electrode pair, E (E1 to E4) ... Electrode, 16 ... Cable, 22 ... Control unit, 24... Storage unit, 26... Operation unit, 28... Display unit, 32... Current generation unit, 34 ... voltage detection unit, 36 ... electrode selection unit, SW1, SW2. ...... Measurement site.

Claims (6)

An electrode portion including a first electrode pair and a second electrode pair in contact with the subject's body;
First calculating means for calculating a first impedance by a two-electrode method using the first electrode pair;
A second calculating means for calculating a second impedance by a four-electrode method using the first electrode pair and the second electrode pair;
A measuring apparatus comprising: an index calculating unit that calculates a contact pressure index corresponding to a contact pressure of the electrode part with respect to the body of the subject based on a difference between the first impedance and the second impedance. Current generating means for passing a current through the body of the subject between the electrodes of the first electrode pair;
Electrode selection means for selecting one of the first electrode pair and the second electrode pair;
Voltage detecting means for detecting the voltage between the electrodes of the electrode pair selected by the electrode selecting means,
The first calculating unit calculates the first impedance according to a current generated by the current generating unit and a voltage detected by the voltage detecting unit in a state where the electrode selecting unit selects the first electrode pair. ,
The second calculating unit calculates the second impedance according to a current generated by the current generating unit and a voltage detected by the voltage detecting unit in a state where the electrode selecting unit selects the second electrode pair. The measuring apparatus according to claim 1. Contact state determination means for determining the suitability of the contact state between the body of the subject and the electrode part according to the contact pressure index;
The information generation means which produces | generates the biometric information according to a said 2nd impedance when the said contact state determination means determines that the contact state of a test subject's body and the said electrode part is appropriate. Item 2. The measuring device according to item 2. The measurement apparatus according to claim 3, wherein the information generation unit calculates a subcutaneous fat thickness as the biological information. A measurement process including the calculation of the first impedance by the first calculation means, the calculation of the second impedance by the second calculation means, and the calculation of the contact pressure index by the index calculation means is performed a plurality of times,
The contact state determination means uses the contact pressure index measured in one measurement process as a reference value, and compares the contact pressure index measured in each subsequent measurement process with the reference value to determine the body of the subject. The measurement apparatus according to claim 3 or 4, wherein the suitability of the contact state with the electrode unit is determined for each measurement process. The measurement apparatus according to claim 5, wherein the information generation unit generates the biological information when the determination that the contact state is appropriate continues over a predetermined number of measurement processes.

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