JP4281380B2 - Biological signal measuring device - Google Patents

Biological signal measuring device Download PDF

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Publication number
JP4281380B2
JP4281380B2 JP2003059074A JP2003059074A JP4281380B2 JP 4281380 B2 JP4281380 B2 JP 4281380B2 JP 2003059074 A JP2003059074 A JP 2003059074A JP 2003059074 A JP2003059074 A JP 2003059074A JP 4281380 B2 JP4281380 B2 JP 4281380B2
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electrode
biological signal
frequency
measuring device
signal measuring
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JP2004267298A (en
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慶裕 村岡
茂雄 田辺
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Keio University
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Keio University
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Description

【0001】
【発明の属する技術分野】
本発明は、人間などの生体の筋電、脳波、及び神経活動電位などを測定する生体信号測定装置に関する。
【0002】
【従来の技術】
図6は、従来の生体信号測定装置の構成を示す図である。この従来技術は筋電位測定装置の例を示すもので、筋電位を入力する一対の検出電極51と、検出電極51の電極裏面52に配置され検出電極51から入力された筋電位を増幅する計測増幅器53(詳細は図7に示す)と、計測増幅器53で増幅された筋電位を電池ボックス55へ出力し、逆に電池ボックス55から計測増幅器53へ電力及び基準電圧を供給するシールド線54と、計測増幅器53に電力及び基準電圧を供給し、生体信号測定装置本体(図示せず)のメイン増幅器に計測及び増幅された筋電位を供給する電池ボックス55とを備えるものである。
【0003】
検出電極51は、筋電位を測定するのに適する大きさとして全体として22〜25mmの直径を有し、指向性を考慮することなく筋電位を計測できるように、同心円状に配設されたものであり、この点で空間フィルタとしての機能を有する。
【0004】
図7は、計測増幅器の詳細な構成を示す図である。計測増幅器53は非反転増幅器542及び差動増幅器543によって構成されている。非反転増幅器542は、外付けの抵抗R11及びコンデンサC11、オペアンプ533,534、抵抗535,536によって構成されている。差動増幅器543は、抵抗537,538,540,541及びオペアンプ539によって構成されている。
【0005】
ここで、抵抗535,536の抵抗値をRf=25kΩとすると、計測増幅器53の利得Gは、
G=1+2Rf/R11
=1+50[kΩ]/R11
低域遮断周波数fcは、
fc=1/2πC11R11
となる(特許文献1参照)。
【0006】
【特許文献1】
特開平10−276995号公報
【0007】
【発明が解決しようとする課題】
検出電極51と皮膚との接触による抵抗は大きく不安定であるため、ペースト(導電性の電極ノリ)を付けて皮膚との抵抗を下げて測ることも行われているが、入力インピーダンスが高い計測増幅器53によってインピーダンス変換することによってペーストを付ける必要がなくなる。また、計測増幅器53は筋電位を増幅するので、シールド線54の揺れなどによるノイズが乗ってもSN比が悪くならないという利点もある。しかし、検出電極51と皮膚との接触による分極電圧は、小さいとされる銀−塩化銀製の電極を使ったとしても、約+70mVあるので、これを例えば100倍に増幅すると7Vにもなるため、所定の低域遮断周波数fc以下の周波数領域をカットする必要があるが、筋電位を測定するためには、例えばこの低域遮断周波数fc=5[Hz]としなければならず、利得G=100[倍]として設計した場合、R11=500[Ω],C11=64[μF]となるが、64μFの無極性の電解コンデンサは入手困難な上に、電極裏面に配置する場合、検出電極51が大きく・厚くならざるをえない。したがって、抵抗R11の値を大きくして、利得Gを下げて、コンデンサC11をチップコンデンサのラインナップのある容量まで下げて、低域遮断周波数fcを上げることで対応できるが、その場合には、能動電極としての利点を損なうばかりか、筋電位測定装置として必要とされている帯域まで遮断してしまうことになる。現状では、そのように対応していて、能動電極の利点を生かしきれていない。
【0008】
また、電極の裏面に筋電位測定用としてのフィルタ回路(低域遮断周波数fc=5〜500 [Hz])を組みこんでしまうために、検出電極の大きさ・形状、低域遮断周波数など使用目的が限定されてしまう。すなわち、この大きな同心円電極を用いる筋電位測定装置は、皿電極を用いて低域遮断周波数fc=0.3〜20[Hz](脳波の種類により異なる)とする脳波測定や、小さい同心円電極を用いて低域遮断周波数fc=1〜3 [kHz]とする神経活動電位測定などができない。また、筋電位測定用に限定した場合においても、日本工業規格(JIS規格)によれば、筋電計として備えるべき条件として、同相除去比60dB以上、雑音10μVp−p未満、最低感度10μVという規格に加えて、帯域幅(低域遮断周波数)可変フィルタを内蔵していることが規格の1つとなっているが、従来手法では、その規格を満たしていない。
【0009】
本発明は、上記問題点に鑑み、検出電極を小さくした上で、その裏面に装着する計測増幅器の利得を高くしても、低域遮断周波数を任意に設定することができる生体信号測定装置を提供することを目的とする。
【0010】
また、その計測増幅器の低域遮断周波数を可変として複数の用途に用いることができる生体信号測定装置を提供することを目的とする。
【0011】
【課題を解決するための手段】
本発明の生体信号測定装置は、皮膚表面に配置される第1電極及び第2電極と、第1電極及び第2電極間の信号が入力される計測増幅器と、該計測増幅器の出力を伝送するアクティブシールド線と、該アクティブシールド線の出力を積分して該アクティブシールド線を介して前記計測増幅器の基準電圧として帰還することで前記計測増幅器の所定の低域遮断周波数以下の周波数領域の信号を阻止させる積分回路とを備えることにより前記計測増幅器に低域遮断周波数を決めるためのコンデンサが接続されていないことを特徴とする。
【0012】
また、前記積分回路は、積分のための回路定数を可変として前記低域遮断周波数を可変とすることで、複数の用途の生体電気測定に適用することができる。
【0013】
また、前記積分回路は、前記回路定数の変化を信号によって制御することで前記低域遮断周波数を動的に変化させることで、刺激によるアーチファクトなどを低減することができる。
【0014】
また、第1電極と第2電極とは皮膚に接触する面積が等しいことで、インピーダンスのアンバランスにより同相ノイズが混入することを軽減することができる。
【0015】
また、前記計測増幅器は、その入力に複数種類の電極が切換え可能に接続されることで、複数の用途の電極を用いることができる。
【0016】
また、筋電位を測定する筋電位測定装置であることで、高い増幅利得でありながら、低い低域遮断周波数を設定して、筋電位測定に必要とされる周波数領域を欠かすことなく増幅することができる。
【0017】
また、脳波を測定する脳波測定装置であることで、安静な姿勢を保つ必要がなくなり、日常生活をおくりながら脳波をSN比良く測定することができる。
【0018】
また、神経活動電位を測定する神経活動電位測定装置であることで、伝導速度が速い上に手指などに配置する場合もあり、小さな検出電極を必要とする神経活動電位測定であっても検出電極の裏面に計測増幅器を装着する能動電極を実現できる。
【0019】
【発明の実施の形態】
以下、添付図面を参照しながら本発明の好適な実施の形態について詳細に説明する。
【0020】
図1は、本発明の第1実施の形態による生体信号測定装置の構成を示す図である。検出電極11、電極裏面12、計測増幅器13、アクティブシールド線14、電池ボックス15は、それぞれ、図6に示す従来の生体信号測定装置の検出電極51、電極裏面52、計測増幅器53、シールド線54、電池ボックス55に対応し、本実施の形態の生体信号測定装置は、計測増幅器53外付けのコンデンサC11を割愛して、計測及び増幅された筋電位を電池ボックス15において積分して計測増幅器13の基準電圧として帰還する回路を設けたものである。具体的には、アクティブシールド線14から出力される筋電位を抵抗R3、コンデンサC1、オペアンプ16で積分してアクティブシールド線14を介して計測増幅器13の基準電圧とするものである。これによって電極裏面12からコンデンサをなくしたので軽量化されると共に検出電極11を小さくすることができる。アクティブシールド線14はステレオイヤホンコード(1芯シールドの平行線)などの柔軟なコードが適する。
【0021】
ここで、利得G及び低域遮断周波数fcについて説明する。図6のC11はなくなり、抵抗535,536はそれぞれ25kΩであるので、非反転増幅器の利得は1+50k/R1、差動増幅器の利得は1、図1の積分器は−1/(jωC1R3)を差動増幅器の入力に負帰還するものであるので、全体の利得Gは、
G=(1+50k/R1)×1/{1−1/(jωC1R3)}
となる。このとき、
ω→∞で、G=1+50k/R1
ω→0で、G=0(従来例ではG=1)
となる。低域遮断周波数fc(=ω/2π)は、
ωC1R3=1
となるときで、
fc=1/2πC1R3
となる。したがって、計測増幅器13の利得Gは抵抗R1によって、低域遮断周波数fcはコンデンサC1及び抵抗R3によって、それぞれ独立に調節できる。コンデンサC1及び抵抗R3は、その値を設計する上で物理的な大きさや利得Gの制約を受けないため、低域遮断周波数fcの値を自由に選択することができる。抵抗R3を可変抵抗にしておけば、筋電位(5〜500Hz)、脳波(0.3〜20Hz:脳波の種類により異なる)、及び神経活動電位(1k〜3kHz)などの測定対象に応じて、計測増幅器13の低域遮断周波数fcを自由に設定できる。また、抵抗R3をフォトモスリレー17などで抵抗R2に切換えることにより低域遮断周波数fcを動的に切換えることができ、神経伝導速度検査の場合などに、刺激を加える際に信号により抵抗R3と抵抗R2とを動的に切換えることによって、刺激によるアーチファクトの混入時のみに選択的に低域遮断周波数fcを高く設定し、早く基線にも戻るようにすることによって全体として刺激によるアーチファクトを低減することができる。また、電源が両極性ではなく片電源である場合には、オペアンプ16の非反転入力をアースではなく、電源電位V+を抵抗R4,R5で分圧した中間電位に接続すれば良い。
【0022】
図2は、汎用の検出電極の構成例を示す図である。図2(a)は、直径15mm程度の神経活動電位測定用の同心円の検出電極11と同じ形状の電極21を貼り合わせその電極21からリード線を介して他の形状の電極22a,22b(皿電極又はディスポ電極など)につなげて使用する例示す。また、予め検出電極11にリード線を付けておいて、他の形状の電極を接続する構成にしても良い。図2(b)は、貼り合わせる電極21とこれにリード線を介して皿電極又はディスポ電極22a,22bを接続する例を示す。図2(c)は、貼り合わせる電極23とこれにリード線を介してスナップ(凹凸一対の留め金具)24a,24bに接続して、更にスナップの相手側からリード線を介して別の電極(図示せず)に接続する例を示す。図2(d)は、フレキシブルな電極25であって、表面には直径15mmの同心円電極を、裏面には例えば直径25mm程度の筋電位測定用の同心円電極を描いておくなど、違う大きさの同心円電極に変換する例を示す。フレキシブルな電極にすることで電極面全体が皮膚に密着するので電極が同心円で接触し、空間フィルタとしての特性を生かすことができる。なお、同心円電極の両電極は等面積とすることで、インピーダンスのアンバランスにより同相ノイズが混入することを軽減することができる。
【0023】
図3は、汎用の検出電極の他の構成例を示す図である。図3(a)は、検出電極11にコネクタ31を介してメススナップ32a,32bを接続し、オススナップ33c,33dを有する皿電極33a,33bをスナップ留めする例を示す。コネクタ31は検出電極11の同心円の各電極とメススナップ32a,32bとをそれぞれエナメル線で接続し、計測増幅器13及びエナメル線をエポキシで固めることで構成することができる。図3(b)は、図3(a)に示すメススナップ32a,32bに、オススナップ37a,37bが固設されるコネクタ38をスナップ留めし、そのコネクタ38からさらにリード線39を介して大きな直径の同心円の検出電極40を接続する例を示す。図3(c)は、検出電極11にステレオイヤホンソケット34を接続し、ステレオイヤホンジャック35を差し込み、更にリード線36を介して検出電極(図示せず)を接続する例を示す。
【0024】
図4は、専用の検出電極を設けない構成例を示す図である。図2及び図3は、ある検出電極があって、他の検出電極を用いることができるように汎用性を持たせたものであるが、特に所定の検出電極を接続しておかずに、複数種類の検出電極を接続するコネクタを設ける構成とすることもできる。すなわち、両面基板41の下面にメススナップ42をはめ込み固定して、上面に計測増幅器13のIC43を装着し、それぞれを銅箔44で接続する例である。これによれば専用の検出電極の存在を気にしたりすることなく複数の検出電極を用いることができる。
【0025】
図5は、脳波を測定する場合の検出電極の接続例を示す図である。検出電極11a,11b間、検出電極11b,11c間、検出電極11c,11d間、及び検出電極11d,11e間にそれぞれ計測増幅器13a,13b,13c,13dを接続して、各検出電極11a,11b,11c,11d,11e間の脳波を測定することができる。
【0026】
なお、本発明は上記実施の形態に限定されるものではない。
【0027】
本発明は、筋電位測定専用の筋電位測定装置であっても良いし、脳波測定専用の脳波測定装置であっても良いし、神経活動電位測定専用の神経活動電位測定装置であっても良い。
【0028】
【発明の効果】
以上のように、本発明によれば、高い利得かつ任意の低域遮断周波数の能動電極を実現することができる。また、低域遮断周波数を可変として、筋電位測定、神経活動電位測定及び脳波測定などの複数の用途に用いることができる。
【図面の簡単な説明】
【図1】本発明の第1実施の形態による生体信号測定装置の構成を示す図である。
【図2】汎用の検出電極の構成例を示す図である。
【図3】汎用の検出電極の他の構成例を示す図である。
【図4】専用の検出電極を設けない構成例を示す図である。
【図5】脳波を測定する場合の検出電極の接続例を示す図である。
【図6】従来の生体信号測定装置の構成を示す図である。
【図7】計測増幅器の詳細な構成を示す図である。
【符号の説明】
11,51 検出電極
13,53 計測増幅器
14 アクティブシールド線
16 オペアンプ
17 フォトモスリレー
22a,22b ディスポ電極
24a,24b スナップ
31 コネクタ
32a,32b メススナップ
33c,33d オススナップ
33a,33b 皿電極
34 ステレオイヤホンソケット
35 ステレオイヤホンジャック
36 リード線
37a,37b オススナップ
38 コネクタ
39 リード線
40 検出電極
41 両面基板
42 メススナップ
43 IC
44 銅箔
54 シールド線
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biological signal measuring apparatus that measures myoelectricity, brain waves, nerve action potentials, and the like of a living body such as a human being.
[0002]
[Prior art]
FIG. 6 is a diagram showing a configuration of a conventional biological signal measuring apparatus. This prior art shows an example of a myoelectric potential measuring device, and a pair of detection electrodes 51 for inputting myoelectric potential and a measurement for amplifying myoelectric potential input from the detection electrode 51 disposed on the electrode back surface 52 of the detection electrode 51. An amplifier 53 (shown in detail in FIG. 7), and a shield line 54 that outputs the myoelectric potential amplified by the measurement amplifier 53 to the battery box 55 and conversely supplies power and a reference voltage from the battery box 55 to the measurement amplifier 53. And a battery box 55 for supplying electric power and a reference voltage to the measurement amplifier 53 and supplying a measured and amplified myoelectric potential to a main amplifier of a biological signal measuring device main body (not shown).
[0003]
The detection electrode 51 has a diameter of 22 to 25 mm as a whole suitable for measuring myoelectric potential, and is arranged concentrically so that myoelectric potential can be measured without considering directivity. In this respect, it has a function as a spatial filter.
[0004]
FIG. 7 is a diagram showing a detailed configuration of the measurement amplifier. The measurement amplifier 53 includes a non-inverting amplifier 542 and a differential amplifier 543. The non-inverting amplifier 542 includes an external resistor R11 and a capacitor C11, operational amplifiers 533 and 534, and resistors 535 and 536. The differential amplifier 543 includes resistors 537, 538, 540, 541 and an operational amplifier 539.
[0005]
Here, when the resistance value of the resistors 535 and 536 is Rf = 25 kΩ, the gain G of the measurement amplifier 53 is
G = 1 + 2Rf / R11
= 1 + 50 [kΩ] / R11
The low cut-off frequency fc is
fc = 1 / 2πC11R11
(See Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 10-276995
[Problems to be solved by the invention]
Since the resistance due to the contact between the detection electrode 51 and the skin is large and unstable, measurement is also performed by applying a paste (conductive electrode glue) and reducing the resistance with the skin, but the input impedance is high. By performing impedance conversion by the amplifier 53, it is not necessary to apply paste. In addition, since the measurement amplifier 53 amplifies the myoelectric potential, there is an advantage that the SN ratio does not deteriorate even if noise due to shaking of the shield wire 54 is applied. However, the polarization voltage due to the contact between the detection electrode 51 and the skin is about +70 mV even if a silver-silver chloride electrode, which is supposed to be small, is used. Although it is necessary to cut a frequency region below a predetermined low-frequency cutoff frequency fc, in order to measure myoelectric potential, for example, this low-frequency cutoff frequency fc = 5 [Hz] must be set, and a gain G = 100 When designed as [double], R11 = 500 [Ω] and C11 = 64 [μF], but it is difficult to obtain a nonpolar electrolytic capacitor of 64 μF, and when it is arranged on the back surface of the electrode, the detection electrode 51 is It must be large and thick. Therefore, it can be dealt with by increasing the value of the resistor R11, lowering the gain G, lowering the capacitor C11 to a certain capacity of the chip capacitor lineup, and raising the low cut-off frequency fc. This not only impairs the advantage as an electrode, but also cuts off the band required as a myoelectric potential measuring device. At present, this is the case, and the advantages of the active electrode are not fully utilized.
[0008]
Also, since the filter circuit for measuring myoelectric potential (low cut-off frequency fc = 5 to 500 [Hz]) is incorporated on the back surface of the electrode, the size and shape of the detection electrode, the low cut-off frequency, etc. are used. The purpose is limited. That is, this myoelectric potential measuring apparatus using a large concentric electrode uses a dish electrode to measure an electroencephalogram with a low cut-off frequency fc = 0.3 to 20 [Hz] (depending on the type of electroencephalogram) or a small concentric electrode. Nerve action potential measurement using a low cut-off frequency fc = 1 to 3 [kHz] cannot be performed. In addition, even when limited to the measurement of myoelectric potential, according to the Japanese Industrial Standard (JIS standard), as conditions to be provided as an electromyograph, a standard that a common mode rejection ratio is 60 dB or more, noise is less than 10 μVp-p, and minimum sensitivity is 10 μV. In addition to the above, it is one of the standards to have a built-in bandwidth (low cut-off frequency) variable filter, but the conventional method does not satisfy the standard.
[0009]
In view of the above problems, the present invention provides a biological signal measuring apparatus capable of arbitrarily setting a low cut-off frequency even if the detection electrode is made small and the gain of a measurement amplifier mounted on the back surface is increased. The purpose is to provide.
[0010]
It is another object of the present invention to provide a biological signal measuring apparatus that can be used for a plurality of applications by changing the low cut-off frequency of the measurement amplifier.
[0011]
[Means for Solving the Problems]
The biological signal measuring apparatus of the present invention transmits a first amplifier and a second electrode arranged on the skin surface, a measurement amplifier to which a signal between the first electrode and the second electrode is input, and an output of the measurement amplifier. An active shield line and an output of the active shield line are integrated and fed back as a reference voltage of the measurement amplifier via the active shield line to obtain a signal in a frequency region below a predetermined low-frequency cutoff frequency of the measurement amplifier. And a capacitor for determining a low cut-off frequency is not connected to the measurement amplifier .
[0012]
Further, the integration circuit can be applied to bioelectric measurements for a plurality of uses by making the circuit constant for integration variable and making the low-frequency cutoff frequency variable.
[0013]
Further, the integration circuit can reduce artifacts due to stimulation by dynamically changing the low cut-off frequency by controlling the change of the circuit constant by a signal.
[0014]
In addition, since the first electrode and the second electrode have the same area in contact with the skin, it is possible to reduce in-phase noise due to impedance imbalance.
[0015]
In addition, the measurement amplifier can use electrodes for a plurality of applications by connecting a plurality of types of electrodes to its input in a switchable manner.
[0016]
In addition, by being a myoelectric potential measuring device that measures myoelectric potential, it is possible to amplify without missing the frequency region required for myoelectric potential measurement by setting a low low-frequency cutoff frequency while having a high amplification gain. Can do.
[0017]
Moreover, since it is an electroencephalogram measurement apparatus that measures electroencephalograms, it is not necessary to maintain a resting posture, and electroencephalograms can be measured with good S / N ratio while living daily.
[0018]
In addition, since it is a nerve action potential measuring device that measures the nerve action potential, it may be placed on a finger or the like with a fast conduction speed, and even if it is a nerve action potential measurement that requires a small detection electrode, the detection electrode It is possible to realize an active electrode in which a measurement amplifier is mounted on the back surface of the substrate.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0020]
FIG. 1 is a diagram showing the configuration of the biological signal measuring apparatus according to the first embodiment of the present invention. The detection electrode 11, the electrode back surface 12, the measurement amplifier 13, the active shield line 14, and the battery box 15 are respectively the detection electrode 51, the electrode back surface 52, the measurement amplifier 53, and the shield line 54 of the conventional biological signal measurement device shown in FIG. Corresponding to the battery box 55, the biological signal measuring apparatus of the present embodiment omits the capacitor C11 external to the measurement amplifier 53, integrates the measured and amplified myoelectric potential in the battery box 15, and measures the measurement amplifier 13. A circuit that feeds back as a reference voltage is provided. Specifically, the myoelectric potential output from the active shield line 14 is integrated by the resistor R3, the capacitor C1, and the operational amplifier 16 and used as the reference voltage of the measurement amplifier 13 via the active shield line 14. As a result, the capacitor is eliminated from the electrode back surface 12, so that the weight can be reduced and the detection electrode 11 can be made small. The active shield line 14 is preferably a flexible cord such as a stereo earphone cord (parallel wire of a single core shield).
[0021]
Here, the gain G and the low-frequency cutoff frequency fc will be described. Since C11 in FIG. 6 is eliminated and the resistors 535 and 536 are each 25 kΩ, the gain of the non-inverting amplifier is 1 + 50 k / R1, the gain of the differential amplifier is 1, and the integrator of FIG. 1 is −1 / (jωC1R3). Since the feedback is negatively fed to the input of the dynamic amplifier, the overall gain G is
G = (1 + 50k / R1) × 1 / {1-1 / (jωC1R3)}
It becomes. At this time,
At ω → ∞, G = 1 + 50k / R1
ω → 0, G = 0 (G = 1 in the conventional example)
It becomes. The low cut-off frequency fc (= ω / 2π) is
ωC1R3 = 1
When
fc = 1 / 2πC1R3
It becomes. Therefore, the gain G of the measurement amplifier 13 can be adjusted independently by the resistor R1, and the low-frequency cutoff frequency fc can be adjusted independently by the capacitor C1 and the resistor R3. Since the capacitor C1 and the resistor R3 are not restricted by physical size or gain G in designing their values, the value of the low-frequency cutoff frequency fc can be freely selected. If the resistance R3 is a variable resistance, depending on the measurement object such as myoelectric potential (5 to 500 Hz), brain wave (0.3 to 20 Hz: depending on the type of brain wave), and nerve action potential (1 k to 3 kHz), The low cut-off frequency fc of the measurement amplifier 13 can be set freely. Further, the low-frequency cutoff frequency fc can be dynamically switched by switching the resistor R3 to the resistor R2 by the photo moss relay 17 or the like. By dynamically switching the resistor R2, the low cut-off frequency fc is selectively set high only when the artifact due to the stimulus is mixed, and the artifact by the stimulus is reduced as a whole by quickly returning to the base line. be able to. Further, when the power source is not a bipolar power source but a single power source, the non-inverting input of the operational amplifier 16 may be connected to an intermediate potential obtained by dividing the power source potential V + by the resistors R4 and R5 instead of the ground.
[0022]
FIG. 2 is a diagram illustrating a configuration example of a general-purpose detection electrode. FIG. 2 (a) shows an electrode 21a, 22b (dish) having a diameter of about 15 mm, which is bonded to an electrode 21 having the same shape as that of a concentric detection electrode 11 for measuring a nerve action potential. An example of connecting to an electrode or a disposable electrode is shown. Alternatively, a lead wire may be attached to the detection electrode 11 in advance, and an electrode having another shape may be connected. FIG. 2 (b) shows an example in which the electrode 21 to be bonded and the dish electrode or disposable electrode 22a, 22b are connected to the electrode 21 via a lead wire. FIG. 2 (c) shows an electrode 23 to be bonded and a snap (a pair of concave and convex fasteners) 24a and 24b connected to this via a lead wire, and another electrode (from the other side of the snap via a lead wire). An example of connection is shown. FIG. 2 (d) shows a flexible electrode 25 having a concentric electrode having a diameter of 15 mm on the surface and a concentric electrode for measuring myoelectric potential having a diameter of about 25 mm on the back surface. An example of conversion to concentric electrodes is shown. By making the electrode flexible, the entire electrode surface is in close contact with the skin, so that the electrodes are concentrically contacted, and the characteristics as a spatial filter can be utilized. Note that, by setting both electrodes of the concentric electrodes to have the same area, it is possible to reduce the occurrence of common-mode noise due to impedance imbalance.
[0023]
FIG. 3 is a diagram illustrating another configuration example of the general-purpose detection electrode. FIG. 3A shows an example in which female snaps 32a and 32b are connected to the detection electrode 11 via a connector 31, and the plate electrodes 33a and 33b having male snaps 33c and 33d are snapped. The connector 31 can be configured by connecting the concentric electrodes of the detection electrode 11 and the female snaps 32a and 32b with enamel wires, and fixing the measurement amplifier 13 and the enamel wires with epoxy. In FIG. 3 (b), a connector 38 to which male snaps 37a and 37b are fixed is snapped to the female snaps 32a and 32b shown in FIG. 3 (a), and the connector 38 is further extended via a lead wire 39. The example which connects the detection electrode 40 of the concentric circle of a diameter is shown. FIG. 3 (c) shows an example in which a stereo earphone socket 34 is connected to the detection electrode 11, a stereo earphone jack 35 is inserted, and a detection electrode (not shown) is connected via a lead wire 36.
[0024]
FIG. 4 is a diagram illustrating a configuration example in which a dedicated detection electrode is not provided. 2 and 3 are provided with versatility so that a certain detection electrode can be used and another detection electrode can be used. In particular, a plurality of types can be used without connecting a predetermined detection electrode. A connector for connecting the detection electrodes may be provided. That is, in this example, the female snap 42 is fitted and fixed to the lower surface of the double-sided substrate 41, the IC 43 of the measurement amplifier 13 is mounted on the upper surface, and each is connected by the copper foil 44. According to this, a plurality of detection electrodes can be used without worrying about the existence of the dedicated detection electrodes.
[0025]
FIG. 5 is a diagram illustrating a connection example of detection electrodes when measuring an electroencephalogram. Measuring amplifiers 13a, 13b, 13c, 13d are connected between the detection electrodes 11a, 11b, between the detection electrodes 11b, 11c, between the detection electrodes 11c, 11d, and between the detection electrodes 11d, 11e, respectively. , 11c, 11d, and 11e can be measured.
[0026]
The present invention is not limited to the above embodiment.
[0027]
The present invention may be a myoelectric potential measurement device dedicated to myoelectric potential measurement, an electroencephalogram measurement device dedicated to electroencephalogram measurement, or a neural action potential measurement device dedicated to nerve action potential measurement. .
[0028]
【The invention's effect】
As described above, according to the present invention, an active electrode having a high gain and an arbitrary low cutoff frequency can be realized. In addition, the low cut-off frequency can be made variable and used for a plurality of uses such as myoelectric potential measurement, nerve action potential measurement, and electroencephalogram measurement.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a biological signal measuring apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration example of a general-purpose detection electrode.
FIG. 3 is a diagram showing another configuration example of a general-purpose detection electrode.
FIG. 4 is a diagram illustrating a configuration example in which a dedicated detection electrode is not provided.
FIG. 5 is a diagram showing a connection example of detection electrodes when measuring an electroencephalogram.
FIG. 6 is a diagram showing a configuration of a conventional biological signal measuring apparatus.
FIG. 7 is a diagram showing a detailed configuration of a measurement amplifier.
[Explanation of symbols]
11, 51 Detection electrodes 13, 53 Measuring amplifier 14 Active shield line 16 Operational amplifier 17 Photo MOS relays 22a, 22b Disposable electrodes 24a, 24b Snap 31 Connectors 32a, 32b Female snaps 33c, 33d Male snaps 33a, 33b Dish electrodes 34 Stereo earphone socket 35 Stereo earphone jack 36 Lead wire 37a, 37b Male snap 38 Connector 39 Lead wire 40 Detection electrode 41 Double-sided substrate 42 Female snap 43 IC
44 Copper foil 54 Shielded wire

Claims (8)

皮膚表面に配置される第1電極及び第2電極と、
第1電極及び第2電極間の信号が入力される計測増幅器と、
該計測増幅器の出力を伝送するアクティブシールド線と、
該アクティブシールド線の出力を積分して該アクティブシールド線を介して前記計測増幅器の基準電圧として帰還することで前記計測増幅器の所定の低域遮断周波数以下の周波数領域の信号を阻止させる積分回路と
を備えることにより前記計測増幅器に低域遮断周波数を決めるためのコンデンサが接続されていないことを特徴とする生体信号測定装置。
A first electrode and a second electrode disposed on the skin surface;
A measurement amplifier to which a signal between the first electrode and the second electrode is input;
An active shield line for transmitting the output of the measurement amplifier;
An integrating circuit for blocking a signal in a frequency region below a predetermined low cut-off frequency of the measurement amplifier by integrating an output of the active shield line and feeding back as a reference voltage of the measurement amplifier via the active shield line; And a capacitor for determining a low cut-off frequency is not connected to the measurement amplifier .
前記積分回路は、積分のための回路定数を可変として前記低域遮断周波数を可変とすることを特徴とする請求項1記載の生体信号測定装置。The biological signal measuring apparatus according to claim 1, wherein the integrating circuit makes the low-frequency cutoff frequency variable by making a circuit constant for integration variable. 前記積分回路は、前記回路定数の変化を信号によって制御することで前記低域遮断周波数を動的に変化させることを特徴とする請求項2記載の生体信号測定装置。The biological signal measuring apparatus according to claim 2, wherein the integration circuit dynamically changes the low-frequency cutoff frequency by controlling a change in the circuit constant with a signal. 第1電極と第2電極とは皮膚に接触する面積が等しいことを特徴とする請求項1乃至3いずれかに記載の生体信号測定装置。The biological signal measuring device according to claim 1, wherein the first electrode and the second electrode have the same area in contact with the skin. 前記計測増幅器は、その入力に複数種類の電極が切換え可能に接続されることを特徴とする請求項1乃至4いずれかに記載の生体信号測定装置。The biological signal measuring device according to claim 1, wherein a plurality of types of electrodes are switchably connected to the input of the measurement amplifier. 筋電位を測定する筋電位測定装置であることを特徴とする請求項1乃至4いずれかに記載の生体信号測定装置。The biosignal measuring device according to claim 1, wherein the biosignal measuring device measures myoelectric potential. 脳波を測定する脳波測定装置であることを特徴とする請求項1乃至4いずれかに記載の生体信号測定装置。The biological signal measuring apparatus according to claim 1, wherein the biological signal measuring apparatus is an electroencephalogram measuring apparatus that measures an electroencephalogram. 神経活動電位を測定する神経活動電位測定装置であることを特徴とする請求項1乃至4いずれかに記載の生体信号測定装置。5. The biological signal measuring device according to claim 1, wherein the biological signal measuring device is a nerve action potential measuring device for measuring a nerve action potential.
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