JP2019080643A - Biological signal measurement device, contact state determination system, and contact state determination method - Google Patents

Abstract

To determine presence/no presence of imperfect contact and a location of the imperfect contact.SOLUTION: A biological signal measurement device 10 comprises: a differential amplifier circuit 20; a plurality of detection electrodes 31, 32; a reference electrode 30; a plurality of resistance elements 41, 42; a plurality of switch elements 51-56; and a power supply 60. By changing over connection forms of the plurality of switch elements 51-56, output voltage Voutp of the differential amplifier circuit 20 in the case of using the reference electrode 30 and the detection electrode 31, output voltage Voutn of the differential amplifier circuit 20 in the case of using the reference electrode 30 and the detection electrode 32, and output voltage Voutd of the differential amplifier circuit 20 in the case of using the reference electrode 30, the detection electrode 31 and the detection electrode 32, are measured. By using the output voltages Voutp, Voutn, and Voutd of the plurality of forms, determination of imperfect contact or measurement of contact resistance is performed for each electrode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a biological signal measuring device capable of detecting a contact state of a detection electrode with a living body.

  Patent Document 1 describes an apparatus for measuring a biological signal using a differential amplifier circuit. The device described in Patent Document 1 includes a differential amplification circuit, a first measurement electrode, a second measurement electrode, and a reference electrode.

  The first measurement electrode, the second measurement electrode, and the reference electrode are mounted on the surface of the living body. One of the first measurement electrode and the second measurement electrode is connected to the inverting input terminal of the differential amplifier circuit, and the other is connected to the non-inverting input terminal of the differential amplifier circuit. The reference electrode is connected to the reference potential terminal of the differential amplifier circuit, and the reference electrode and the reference potential terminal are grounded.

Japanese Patent Application Publication No. 2003-339656

  However, in the configuration described in Patent Document 1, even if any of the first measurement electrode, the second measurement electrode, and the reference electrode causes a contact failure with the living body, the electrodes having the contact failure are individually determined. Can not do it.

  Therefore, an object of the present invention is to provide a biological signal measuring device capable of determining the presence or absence of contact failure and the location of the contact failure, a contact condition determination system, and a contact condition determination method.

  The biological signal measurement device according to the present invention includes a first detection electrode, a second detection electrode, a reference electrode, a differential amplifier circuit, a first resistance element, a second resistance element, a power supply, a first switch element, a second switch element, a second A third switch element, a fourth switch element, a fifth switch element, and a sixth switch element are provided.

  The first detection electrode, the second detection electrode, and the reference electrode are respectively attached to the living body. The differential amplifier circuit has a first input terminal to which the first detection electrode is connected, and a second input terminal to which the second detection electrode is connected. The first resistance element is connected between the first input terminal and the reference potential. The second resistance element is connected between the second input terminal and the reference potential. The power supply is connected to the reference electrode and outputs a contact state detection voltage.

  The first switch element selects conduction and opening between the first detection electrode and the first input terminal. The second switch element selects conduction and opening between the second detection electrode and the second input terminal. The third switch element selects conduction and release between the first input terminal and the reference potential. The fourth switch element selects conduction and release between the second input terminal and the reference potential. The fifth switch element selects conduction and opening between the reference electrode and the power supply. The sixth switch element selects conduction and release between the reference electrode and the reference potential.

  In this configuration, a mode in which the reference electrode and the first detection electrode are connected between the power supply and the differential amplification circuit by selection of conduction and opening of the plurality of switch elements, between the power supply and the differential amplification circuit In addition, select the mode in which the reference electrode and the second detection electrode are connected, and the mode in which the reference electrode and the first detection electrode and the second detection electrode in parallel are connected between the power supply and the differential amplifier circuit. Be done. In these aspects, the connection states of the reference electrode, the first detection electrode, and the second detection electrode are different. Therefore, the contact state of each of the reference electrode, the first detection electrode, and the second detection electrode can be detected by measuring the output voltage of the differential amplifier circuit in each aspect. In addition, the opening of the fifth switch element and the conduction of the sixth switch make it possible to measure a normal biological signal.

  The contact state determination system of the present invention includes each configuration of the above-described biological signal measurement device, and a contact state determination unit. The contact state determination unit is connected to the output terminal of the differential amplifier circuit, and detects the contact state using the output voltage.

  In this configuration, at least one of the determination of the contact failure and the measurement of the contact resistance is realized.

  Moreover, in the contact state determination system of this invention, it is preferable to provide the following structure. The contact state determination system includes a biological signal processor. The biological signal processing unit is connected to the output terminal of the differential amplifier circuit, and measures the biological signal using the output voltage.

  In this configuration, measurement of the biological signal is further realized.

  Further, in the contact state determination system of the present invention, the contact state determination unit detects the presence or absence of the contact failure using the output voltage.

  In this configuration, the determination of the contact failure is realized.

  Further, in the contact state determination system of the present invention, the contact state determination unit measures the contact resistance using the output voltage when there is no contact failure.

  In this configuration, the contact resistance is measured. Furthermore, in this configuration, the contact resistance can not be measured when there is a contact failure, and unnecessary measurement of the contact resistance is suppressed.

  Further, the contact state determination method of the present invention includes the following steps. The contact state determination method is a differential amplification circuit in which a contact state detection voltage is applied from the reference electrode side and connected to the first detection electrode in a state where the first detection electrode and the reference electrode are respectively mounted on a living body Measuring a first output voltage of The contact state determination method is a differential amplification circuit in which a contact state detection voltage is applied from the reference electrode side and connected to the second detection electrode in a state where the second detection electrode and the reference electrode are respectively attached to the living body Measuring a second output voltage of The contact state determination method applies a contact state detection voltage from the reference electrode side in a state where the first detection electrode, the second detection electrode, and the reference electrode are respectively attached to the living body, and And measuring the third output voltage. The contact state determination method detects the contact state of the first detection electrode, the second detection electrode, and the reference electrode with the living body using the first output voltage, the second output voltage, and the third output voltage. Process.

  In this method, a mode in which the reference electrode and the first detection electrode are connected between the power supply and the differential amplification circuit by selection of conduction and opening of the plurality of switch elements, between the power supply and the differential amplification circuit In addition, select the mode in which the reference electrode and the second detection electrode are connected, and the mode in which the reference electrode and the first detection electrode and the second detection electrode in parallel are connected between the power supply and the differential amplifier circuit. Be done. In these aspects, the connection states of the reference electrode, the first detection electrode, and the second detection electrode are different. Therefore, by measuring the first output voltage, the second output voltage, and the third output voltage, the contact states of the reference electrode, the first detection electrode, and the second detection electrode can be detected.

  Moreover, the contact state determination method of this invention may perform the following process. In the contact state determination method, after performing the step of measuring the first output voltage and the step of measuring the second output voltage, the contact state of each of the first detection electrode and the second detection electrode with the living body is determined. Perform a primary detection step to detect. The contact state determination method performs the step of measuring the third output voltage after the primary detection step, and measures the contact resistance using the first output voltage, the second output voltage, and the third output voltage. Perform the measurement process.

  In this method, the contact resistance is measured after determining the presence or absence of the contact failure. Therefore, when it is not necessary to measure the contact resistance, such as when there is a contact failure, the contact resistance is not measured.

  According to the present invention, it is possible to determine the presence or absence of contact failure and the location of the contact failure.

It is a circuit diagram of a living body signal measuring device concerning a 1st embodiment of the present invention. It is a block diagram of the contact state determination system which concerns on the 1st Embodiment of this invention. It is a flowchart which shows an example of the determination processing of the contact state which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows a 1st connection aspect. It is a circuit diagram which shows a 2nd connection aspect. It is a circuit diagram showing the 3rd connection mode. It is a flowchart of processing including determination of contact failure. It is a table showing the relation between each output voltage and contact failure. It is a circuit diagram showing the 4th connection mode. It is a circuit diagram showing the 5th connection mode. It is a flowchart which shows the process in the case of performing the determination of contact failure in multiple times. It is a circuit diagram of a biological signal measuring device concerning a 2nd embodiment of the present invention.

  A biological signal measurement device and a biological signal measurement method according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a biological signal measuring apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, the biological signal measurement device 10 includes a differential amplifier circuit 20, a reference electrode 30, a detection electrode 31, a detection electrode 32, a resistance element 41, a resistance element 42, a switch element 51, a switch element 52, a switch element. 53, the switch element 54, the switch element 55, the switch element 56, and the power supply 60 are provided. The detection electrode 31 corresponds to the "first detection electrode" of the present invention, and the detection electrode 32 corresponds to the "second detection electrode" of the present invention. The resistive element 41 corresponds to the "first resistive element" of the present invention, and the resistive element 42 corresponds to the "second resistive element" of the present invention. The switch element 51 corresponds to the "first switch element" of the present invention, and the switch element 52 corresponds to the "second switch element" of the present invention. The switch element 53 corresponds to the "third switch element" of the present invention, and the switch element 54 corresponds to the "fourth switch element" of the present invention. The switch element 55 corresponds to the "fifth switch element" of the present invention, and the switch element 56 corresponds to the "sixth switch element" of the present invention.

  The differential amplifier circuit 20 includes an inverting input terminal, a non-inverting input terminal, and an output terminal. The non-inverting input terminal corresponds to the "first input terminal" of the present invention, and the inverting input terminal corresponds to the "second input terminal" of the present invention.

  The differential amplifier circuit 20 amplifies a differential signal of the signal input to the inverting input terminal and the signal input to the non-inverting input terminal by the set gain G, and outputs the amplified signal from the output terminal. The output signal (output voltage Vout) corresponds to the biological signal to be output as the biological signal measuring device 10.

  The detection electrode 31, the detection electrode 32, and the reference electrode 30 are mounted at different positions on the living body 90.

  The detection electrode 31 is connected to the non-inversion input terminal via the switch element 51. The switch element 51 selects conduction and opening between the detection electrode 31 and the non-inversion input terminal. The detection electrode 32 is connected to the inverting input terminal via the switch element 52. The switch element 52 selects conduction and opening between the detection electrode 32 and the inverting input terminal.

  The reference electrode 30 is connected to the power supply 60 via the switch element 55. The switch element 55 selects conduction and opening between the reference electrode 30 and the power supply 60. The reference electrode 30 is connected to a reference potential (for example, a ground potential) via the switch element 56. Switch element 56 selects conduction and release between reference electrode 30 and the reference potential.

  The resistance element 41 is connected between the non-inversion input terminal and a reference potential (for example, the ground potential). The resistive element 41 determines the input resistance on the non-inverting input terminal side of the differential amplifier circuit 20. The switch element 53 is connected between the resistance element 41 and the reference potential. Switch element 53 selects conduction and opening between resistance element 41 and the reference potential.

  The resistance element 42 is connected between the inverting input terminal and a reference potential (for example, the ground potential). Resistance element 42 determines the input resistance on the inverting input terminal side of differential amplifier circuit 20. The switch element 54 is connected between the resistive element 42 and the reference potential. Switch element 54 selects conduction and opening between resistance element 42 and the reference potential.

  The reference potential to which the resistance element 41 is connected, the reference potential to which the resistance element 42 is connected, and the reference potential to which the reference electrode 30 is connected are the same potential.

  The power supply 60 generates a detection signal. The detection signal is an alternating current signal.

  The biological signal measurement device 10 having such a configuration determines the contact state of the detection electrode 31, the contact state of the detection electrode 32, and the contact state of the reference electrode 30, as described below. The determination of the contact state of the detection electrode 31 includes at least one of the determination of a contact failure between the detection electrode 31 and the living body 90 and the measurement of the resistance value Rcp of the contact resistance 911 between the detection electrode 31 and the living body 90. The determination of the contact state of the detection electrode 32 includes at least one of the determination of a contact failure between the detection electrode 32 and the living body 90, and the measurement of the resistance value Rcn of the contact resistance 912 between the detection electrode 32 and the living body 90. The determination of the contact state of the reference electrode 30 includes at least one of the determination of a contact failure between the reference electrode 30 and the living body 90 and the measurement of the resistance value Rcr of the contact resistance 910 between the reference electrode 30 and the living body 90.

  By providing the above configuration, the biological signal measurement device 10 determines the contact state of the detection electrode 31 to the living body 90, the contact state of the detection electrode 32 to the living body 90, and the contact state of the reference electrode 30 to the living body 90. it can.

  FIG. 2 is a block diagram of the contact state determination system according to the first embodiment of the present invention. As shown in FIG. 2, the contact state determination system 11 includes a control unit 70, a contact state determination unit 71, and a biological signal processing unit 72 in addition to the configuration of the biological signal measurement device 10 described above. If only the determination of the contact state is performed, the biological signal processing unit 72 can be omitted.

  The control unit 70 is connected to the contact state determination unit 71, the biological signal processing unit 72, and each switch element. The contact state determination unit 71 and the biological signal processing unit 72 are connected to the output terminal of the differential amplifier circuit 20.

  The control unit 70 controls the contact state determination unit 71, the biological signal processing unit 72, and each switch element. The control unit 70 controls each switch element so as to realize each connection mode described later.

  The contact state determination unit 71 measures the contact resistance value and determines the contact state using the output signal in each connection mode.

  The biological signal processing unit 72 performs predetermined processing (for example, filter processing etc.) on the output signal and outputs it. At this time, the biological signal processing unit 72 may perform this processing when the contact state determination unit 71 detects that there is no contact failure.

  FIG. 3 is a flowchart showing an example of the determination processing of the touch state according to the first embodiment of the present invention. FIG. 4 is a circuit diagram showing a first connection mode. FIG. 5 is a circuit diagram showing a second connection mode. FIG. 6 is a circuit diagram showing a third connection mode.

The contact state determination unit 71 of the contact state determination system 11 measures the output voltage v _outp in the first connection mode (S11). ^Here , v _outp = Vp · e ^jωt , Vp (≧ 0) is the amplitude of v _outp , ω is the angular frequency (angular velocity) of v _p , and t is time. This angular velocity coincides with the angular velocity of the detection signal.

  In the first connection mode, as shown in FIG. 4, the switch element 51, the switch element 53, the switch element 54, and the switch element 55 are conductive to each other. The switch element 52 and the switch element 56 are open.

  In the first connection mode, the detection signal output from the power supply 60 is input to the non-inverting input terminal of the differential amplification circuit 20 through the reference electrode 30, the contact resistance 910, the contact resistance 911, and the detection electrode 31. Be done. Further, the non-inversion input terminal of the differential amplifier circuit 20 is connected to the reference potential via the resistance element 41, and the inversion input terminal is connected to the reference potential via the resistance element 42.

Therefore, this output voltage v _outp is expressed by the following equation. The resistance values of the resistance element 41 and the resistance element 42 are the same and are Rs. Also, let the voltage of the detection signal be v _s . v _s = a ^Vs · ^e jωt, is the amplitude of Vs (≧ 0) is _{v s, ω} is a _{v s} of the angular frequency (angular velocity), t is the time. Also, G is the gain of the differential amplifier circuit 20.

接触状態判定システム１１の接触状態判定部７１は、第２接続態様にて出力電圧Ｖｏｕｔｎを測定する（Ｓ１２）。なお、ｖ_ｏｕｔｎ＝−Ｖｎ・ｅ^ｊωｔであり、Ｖｎ（≧０）はｖ_ｏｕｔｎの振幅であり、ωはｖ_ｏｕｔｎの角周波数（角速度）であり、ｔは時刻である。この角速度は、検出用信号の角速度と一致する。

The contact state determination unit 71 of the contact state determination system 11 measures the output voltage Voutn in the second connection mode (S12). In _addition, v is a ^{outn = -Vn · e jωt, Vn} (≧ 0) is _v is the amplitude of the _{outn, ω} is the _{v outn} of the angular frequency (angular velocity), t is the time. This angular velocity coincides with the angular velocity of the detection signal.

  In the second connection mode, as shown in FIG. 5, the switch element 52, the switch element 53, the switch element 54, and the switch element 55 are conductive to each other. The switch element 51 and the switch element 56 are open.

  In the second connection mode, the detection signal output from the power source 60 is input to the inverting input terminal of the differential amplifier circuit 20 via the reference electrode 30, the contact resistance 910, the contact resistance 912, and the detection electrode 32. Ru. Further, the non-inversion input terminal of the differential amplifier circuit 20 is connected to the reference potential via the resistance element 41, and the inversion input terminal is connected to the reference potential via the resistance element 42.

Therefore, this output voltage v _outn is expressed by the following equation. The resistance values of the resistance element 41 and the resistance element 42 are the same and are Rs. Also, let the voltage of the detection signal be v _s .

接触状態判定システム１１の接触状態判定部７１は、第３接続態様にて出力電圧ｖ_ｏｕｔｄを測定する（Ｓ１３）。なお、Ｖｐ＞Ｖｎならば、ｖ_ｏｕｔｄ＝Ｖｄ・ｅ^ｊωｔであり、Ｖｄ（≧０）はｖ_ｏｕｔｄの振幅であり、ωはｖ_ｏｕｔｄの角周波数（角速度）であり、ｔは時刻である。この角速度は、検出用信号の角速度と一致する。一方、Ｖｐ＜Ｖｎならば、ｖ_ｏｕｔｄ＝−Ｖｄ・ｅ^ｊωｔであり、Ｖｄ（≧０）はｖ_ｏｕｔｄの振幅であり、ωはｖ_ｏｕｔｄの角周波数（角速度）であり、ｔは時刻である。この角速度は、検出用信号の角速度と一致する。

The contact state determination unit 71 of the contact state determination system 11 measures the output voltage v _outd in the third connection mode (S13). It should be noted that, if Vp> _Vn, is a ^{v outd = Vd · e jωt,} Vd (≧ 0) is _v is the amplitude of the _{outd, ω} is the _{v outd} of the angular frequency (angular velocity), t is the time. This angular velocity coincides with the angular velocity of the detection signal. On the other hand, if Vp _<Vn, is a ^{v outd = -Vd · e jωt,} Vd (≧ 0) is _v is the amplitude of the _{outd, ω} is the _{v outd} of the angular frequency (angular velocity), t is the time . This angular velocity coincides with the angular velocity of the detection signal.

  In the third connection mode, as shown in FIG. 6, the switch element 51, the switch element 52, the switch element 53, the switch element 54, and the switch element 55 are conductive. The switch element 56 is open.

  In the third connection mode, the detection signal output from the power source 60 is distributed to the detection electrode 31 side and the detection electrode 32 side via the reference electrode 30 and the contact resistance 910. The detection signal distributed to the detection electrode 31 side is input to the non-inversion input terminal of the differential amplifier circuit 20 via the contact resistance 911 and the detection electrode 31. The detection signal distributed to the detection electrode 32 side is input to the inverting input terminal of the differential amplifier circuit 20 via the contact resistance 912 and the detection electrode 32. Further, the non-inversion input terminal of the differential amplifier circuit 20 is connected to the reference potential via the resistance element 41, and the inversion input terminal is connected to the reference potential via the resistance element 42.

Therefore, this output voltage v _outd is expressed by the following equation. The resistance values of the resistance element 41 and the resistance element 42 are the same and are Rs. Also, let the voltage of the detection signal be v _s .

なお、Ａｐ、Ａｎは次式で表される。

Here, Ap and An are expressed by the following equations.

接触状態判定システム１１の接触状態判定部７１は、上述の出力電圧ｖ_ｏｕｔｐ、ｖ_ｏｕｔｎ、ｖ_ｏｕｔｄを用いて（式１から式５を用いて）、基準電極３０と生体９０との接触抵抗９１０の抵抗値Ｒｃｒを算出する（Ｓ１４）。

The contact state determination unit 71 of the contact state determination system 11 uses the above-described output voltages v _outp , v _outn and v _outd (using formulas 1 to 5) to make the contact resistance 910 between the reference electrode 30 and the living body 90. The resistance value Rcr of is calculated (S14).

  The resistance value (contact resistance value of the reference electrode 30) Rcr of the contact resistance 910 of the reference electrode 30 is expressed by the following equation.

接触状態判定システム１１の接触状態判定部７１は、算出された接触抵抗９１０の抵抗値Ｒｃｒと上述のｖ_ｏｕｔｐ、ｖ_ｏｕｔｎとを用いて（式１、式２、式６を用いて）、検出電極３１と生体９０との接触抵抗９１１の抵抗値Ｒｃｐ、および、検出電極３２と生体９０との接触抵抗９１２の抵抗値Ｒｃｎを算出する（Ｓ１５）。

Contact state determination unit 71 of the contact determination system 11, the resistance value Rcr the above _v outp of the calculated contact resistance _910, by using the _{v outn} (Formula 1, Formula 2, using equation 6), the detection The resistance value Rcp of the contact resistance 911 between the electrode 31 and the living body 90 and the resistance value Rcn of the contact resistance 912 between the detection electrode 32 and the living body 90 are calculated (S15).

  The resistance value (contact resistance value of the detection electrode 31) Rcp of the contact resistance 911 of the detection electrode 31 is expressed by the following equation.

検出電極３２の接触抵抗値（検出電極３２の接触抵抗値）Ｒｃｎは、次の式で表される。

The contact resistance value (contact resistance value of the detection electrode 32) Rcn of the detection electrode 32 is expressed by the following equation.

このように、本実施形態の構成を備えることによって、生体信号測定装置１０は、検出電極３１、検出電極３２、および、基準電極３０の接触抵抗値を個別に算出できる。これにより、生体信号測定装置１０は、検出電極３１、検出電極３２、および、基準電極３０の生体９０への接触状態を判定できる。

As described above, by providing the configuration of the present embodiment, the biological signal measurement device 10 can individually calculate the contact resistance values of the detection electrode 31, the detection electrode 32, and the reference electrode 30. Thus, the biological signal measurement device 10 can determine the contact state of the detection electrode 31, the detection electrode 32, and the reference electrode 30 with the living body 90.

  In the above description, the voltage source is represented by a sine wave to simplify the operation description. However, it is also possible to use an alternating current signal (for example, a square wave etc.) having a certain amplitude, and the signal from the voltage source is not limited to a sine wave.

Although the case where calculation of contact resistance was performed was shown in the flow shown in the above-mentioned FIG. 3, it is also possible to perform determination of a contact failure using the process shown in this flow. FIG. 7 is a flowchart of processing including determination of contact failure. FIG. 8 is a table showing the relationship between each output voltage and contact failure. FIG. 8 shows the relationship between the combination of whether the resistance values Rcp, Rcn, Rcr of each contact resistance are normal or abnormal (contact failure), and the voltage values of the output voltages v _outp , v _outn , v _outd. ing.

The contact state determination unit 71 measures the output voltage v _outp in the first connection mode (S11). The contact state determination unit 71 measures the output voltage _voutn in the second connection mode (S12). The contact state determination unit 71 determines that the absolute value Vp of the amplitude of the output voltage v _outp in the first connection mode is not less than or equal to the determination threshold Vth p for contact failure (S21: NO), and the amplitude of the output voltage v _{outn in} the second connection mode If the absolute value Vn of is not equal to or less than the determination threshold Vthn for contact failure (S22: NO), it is determined that there is no contact failure (S23). Note that the determination threshold Vthp for the detection electrode 31 and the determination threshold Vthn for the detection electrode 32 are, for example, experimentally determined in advance, or the minimum of the output voltage necessary for measuring the biological signal in the biological signal measuring device 10 Is set by the amplitude level of

If the absolute value Vn of the amplitude of the output voltage _Voutn in the second connection mode is larger than the threshold Vthn for the determination of contact failure (S22: YES), the contact state determination unit 71 determines that there is a contact failure on the detection electrode 31 side. It determines (S24).

In the contact state determination unit 71, the absolute value Vp of the amplitude of the output voltage _voutp in the first connection mode is larger than the threshold Vthp for determination of contact failure (S21: YES), and the amplitude of the output voltage _{voutn in} the second connection mode If the absolute value Vn of is not equal to or less than the determination threshold Vthn for contact failure (S25: NO), it is determined that there is a contact failure on the detection electrode 31 side (S26).

The contact state determination unit 71 determines that the amplitude Vp of the output voltage v _outp in the first connection mode is larger than the determination threshold Vthp for contact failure (S21: YES), and the absolute value of the amplitude of the output voltage v out _{n in} the second connection mode If the value Vn is larger than the determination threshold Vthn for contact failure (S25: YES), it is determined that there is a contact failure in any part (S27).

When the contact state determination unit 71 determines that there is no contact failure, the absolute value Vp of the amplitude of the output voltage _voutp of the first connection mode is compared with the absolute value Vn of the amplitude of the output voltage _voutn of the second connection mode. . The contact state determination unit 71 determines that the absolute value Vp of the amplitude of the output voltage _voutp in the first connection mode and the absolute value Vn of the amplitude of the output voltage _{voutn in} the second connection mode are not substantially the same (S28: NO). The output voltage v _outd in the third connection mode is measured (S13), and the contact resistance to each electrode is calculated (S30). The process of step S30 corresponds to the process of steps S14 and S15 shown in FIG. 3 described above.

The contact state determination unit 71 determines that the absolute value Vp of the amplitude of the output voltage _voutp in the first connection mode and the absolute value Vn of the amplitude of the output voltage _{voutn in} the second connection mode are substantially the same (S28: YES) The process ends without measuring the contact resistance.

  By performing such processing, the contact state determination system 11 can reliably determine the contact failure with respect to each electrode, and can calculate the contact resistance in a state in which the contact failure does not occur.

  In addition, when the biological signal measurement apparatus 10 which consists of the above-mentioned structure is used, a measurement of a biological signal can be performed by the following connection aspect. FIG. 9 is a circuit diagram showing a fourth connection mode. FIG. 10 is a circuit diagram showing a fifth connection mode.

  As shown in FIG. 9, in the fourth connection mode, the switch element 51, the switch element 52, the switch element 53, the switch element 54, and the switch element 56 are conductive to each other. The switch element 55 is open.

  As shown in FIG. 10, in the fifth connection mode, the switch element 51, the switch element 52, and the switch element 56 are conductive to each other. The switch element 53, the switch element 54, and the switch element 55 are open.

  By using these connection modes, the power supply 60 is separated from the biological signal measurement system, and the reference electrode 30 is connected to the reference potential. Thereby, the biological signal measurement device 10 can measure a biological signal. Under the present circumstances, in the 4th connection mode shown in FIG. 9, the input resistance of the differential amplifier circuit 20 is determined by the resistance element 41 and the resistance element 42, and in the 5th connection mode shown in FIG. The input resistance of is determined by the input impedance of the differential amplifier circuit 20. In any case, the biological signal measurement device 10 can reliably measure a biological signal.

  Moreover, in the above-mentioned description, although the contact state determination system 11 showed the aspect which performs determination of contact failure and measurement of contact resistance once, you may perform determination and measurement in multiple times temporally at the time of measurement. FIG. 11 is a flowchart showing processing in the case where the determination of the contact failure is performed a plurality of times.

  As shown in FIG. 11, the contact state determination system 11 determines a contact failure at the initial stage of measurement of a biological signal (S41). If there is a contact failure (S42: YES), the contact state determination system 11 notifies the contact failure (S47).

  If there is no contact failure (S42: NO), the contact state determination system 11 measures a biological signal (S43). If the re-determination condition is not satisfied (S44: NO), the contact state determination system 11 continues the measurement of the biological signal (S43). If the re-determination condition is satisfied (S44: YES), the contact state determination system 11 determines the contact state (S45).

  The redetermining condition can be set, for example, by the number of measurements of the biological signal, the elapsed time from the start of the measurement of the biological signal, and the like. In the case of the number of measurements, the contact state determination system 11 determines that the re-determination condition is satisfied when the number of measurements exceeds the threshold. In the case of the elapsed time, the contact state determination system 11 determines that the re-determination condition is satisfied when the elapsed time exceeds the threshold.

  Furthermore, the re-determination condition may be based on the amount of change in the resistance value of the contact resistance. That is, the contact state determination system 11 sequentially stores the resistance value of the contact resistance for each measurement, and calculates the fluctuation amount. When the fluctuation amount exceeds the threshold value, the contact state determination system 11 determines that the re-determination condition is satisfied.

  If there is no contact failure (S46: NO), the contact state determination system 11 continues the measurement of the biological signal (S43). If there is a contact failure (S46: YES), the contact state determination system 11 notifies the contact failure (S47).

  Thereby, the contact state determination system 11 can also reliably determine a contact failure that occurs later.

  Next, a biological signal measurement apparatus according to a second embodiment will be described with reference to the drawings. FIG. 12 is a circuit diagram of a biological signal measuring apparatus according to a second embodiment of the present invention.

  As shown in FIG. 12, the biological signal measurement device 10A according to the second embodiment is the same as the biological signal measurement device 10 according to the first embodiment in that the detection electrode 33, the detection electrode 34, the switch element 570, and the switch It differs in that the element 571 and the switch element 572 are provided. Furthermore, the biological signal measurement device 10A differs from the biological signal measurement device 10 in that the reference electrode 30 is replaced with a reference electrode 301 and a reference electrode 302. The other configuration of the biological signal measurement device 10A is the same as that of the biological signal measurement device 10, and the description of the same parts will be omitted.

  Roughly speaking, the biological signal measurement device 10A has a plurality of measurement points of the biological signal as compared with the biological signal measurement device 10.

  The detection electrode 33 and the detection electrode 34 are mounted at different positions on the living body 90. Furthermore, the detection electrode 33 and the detection electrode 34 are mounted at different positions of the living body 90 with respect to the detection electrode 31 and the detection electrode 32.

  The switch element 570 selectively connects the reference electrode 301 and the reference electrode 302 to the switch element 55 or the switch element 56.

  The switch element 571 selectively connects the detection electrode 31 and the detection electrode 33 to the switch element 51. The switch element 572 selectively connects the detection electrode 32 and the detection electrode 34 to the switch element 52.

  When the switch element 570 connects the reference electrode 301 to the switch element 55 or the switch element 56, the switch element 571 connects the detection electrode 31 to the switch element 51, and the switch element 572 connects the detection electrode 32 to the switch element. Connect with 52.

  When the switch element 570 connects the reference electrode 302 to the switch element 55 or the switch element 56, the switch element 571 connects the detection electrode 33 to the switch element 51, and the switch element 572 connects the detection electrode 34 to the switch element. Connect with 52.

  In each of these connection modes, each of the connection modes for the contact state determination described above is adopted by switch element 51, switch element 52, switch element 53, switch element 54, switch element 55, and switch element 56, thereby making contact. The state determination system can separately determine each contact failure of the detection electrode 31, the detection electrode 32, the detection electrode 33, the detection electrode 34, the reference electrode 301, and the reference electrode 302. Further, the contact state determination system adopts each connection mode for the above-mentioned contact state determination, thereby making the contact resistance value Rcp1 of the contact resistance 911 between the detection electrode 31 and the living body 90, the contact between the detection electrode 32 and the living body 90 Contact resistance value Rcn1 of resistance 912, contact resistance value Rcp3 of contact resistance 913 between detection electrode 33 and living body 90, contact resistance value Rcn2 of contact resistance 914 between detection electrode 34 and living body 90, reference electrode 301 and living body 90 The measurement of the contact resistance value Rcr1 of the contact resistance 9101 and the contact resistance value Rcr2 of the contact resistance 9102 between the reference electrode 302 and the living body 90 can be separately performed.

  In addition, although the measurement location of a biosignal showed the aspect of two locations in FIG. 12, three or more locations may be sufficient. In this case, SPnT switch elements may be used as the switch elements 570, 571 and 572, where n is the number of measurement points.

10, 10A: biological signal measurement device 11: contact state determination system 20: differential amplifier circuit 30, 301, 302: reference electrode 31, 32, 33, 34: detection electrode 41, 42: resistance element 51, 52, 53, 54, 55, 56, 570, 571 572: switch element 60: power source 70: control unit 71: contact state determination unit 72: biological signal processing unit 90: living body 910, 911, 912, 913, 914, 9101, 9102: Contact resistance

Claims (7)

A first detection electrode, a second detection electrode, and a reference electrode each attached to a living body;
A differential amplifier circuit having a first input terminal to which the first detection electrode is connected, and a second input terminal to which the second detection electrode is connected;
A first resistance element connected between the first input terminal and a reference potential;
A second resistive element connected between the second input terminal and the reference potential;
A power supply connected to the reference electrode and outputting a contact state detection voltage;
A first switch element for selecting conduction and opening between the first detection electrode and the first input terminal;
A second switch element for selecting conduction and opening between the second detection electrode and the second input terminal;
A third switch element for selecting conduction and opening between the first input terminal and the reference potential;
A fourth switch element for selecting conduction and opening between the second input terminal and the reference potential;
A fifth switch element for selecting conduction and opening between the reference electrode and the power supply;
A sixth switch element for selecting conduction and opening between the reference electrode and the reference potential;
And a biosignal measuring device. Each configuration of the biological signal measurement device according to claim 1;
A contact state determination unit connected to an output terminal of the differential amplification circuit and detecting a contact state using an output voltage;
A contact state determination system comprising:   The touch condition determination system according to claim 2, further comprising a biological signal processing unit connected to the output terminal of the differential amplifier circuit and configured to measure a biological signal using the output voltage. The contact state determination unit
The presence or absence of contact failure is detected using the output voltage,
The contact state determination system according to claim 2 or claim 3. The contact state determination unit
When there is no contact failure, the contact resistance is measured using the output voltage,
The contact state determination system according to claim 4. A first output of a differential amplifier circuit connected to the first detection electrode by applying a contact state detection voltage from the reference electrode side in a state where the first detection electrode and the reference electrode are respectively mounted on a living body Measuring the voltage;
In a differential amplifier circuit in which the contact state detection voltage is applied from the reference electrode side in a state in which the second detection electrode and the reference electrode are respectively attached to the living body, and connected to the second detection electrode Measuring a second output voltage;
In the differential amplifier circuit, the contact state detection voltage is applied from the reference electrode side in a state where the first detection electrode, the second detection electrode, and the reference electrode are respectively attached to a living body. Measuring a third output voltage;
By using the first output voltage, the second output voltage, and the third output voltage, the contact state of each of the first detection electrode, the second detection electrode, and the reference electrode with the living body is obtained. A process of detecting
And a contact state determination method. After performing the step of measuring the first output voltage and the step of measuring the second output voltage,
Performing a primary detection step of detecting a contact state between each of the first detection electrode and the second detection electrode and the living body,
Performing a step of measuring the third output voltage after the first detection step;
Performing a contact resistance measurement step of measuring contact resistance using the first output voltage, the second output voltage, and the third output voltage;
The contact state determination method according to claim 6.

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