JPH11332839A - Electrode abnormality detection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure of an electrode abnormality (accidental separation of electrode) detection circuit in an electrocardiogram measuring apparatus or the like. SOLUTION: This electrode abnormality detection circuit detects accidental separation of a measuring electrode in a medical apparatus or the like for measuring bio-medical signals inputted through two measuring electrodes mounted on a living being. There are arranged a differential input amplification circuit 1 wherein when the measuring electrode is normally mounted, no DC potential difference is generated between the bio-medical signals S1 and S2 inputted and when the measuring electrode is accidentally separated, the DC potential difference is generated and amplified between the bio-medical signals S1 and S2 inputted to be outputted and a transistor circuit 2 equipped with a transistor Q1 which operates by an output voltage of the differential input amplification circuit 1 as generated when the measuring electrode is accidentally separated to output an electrode abnormality detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode abnormality detection circuit in living body measurement, and more particularly to an electrode abnormality detection circuit in electrocardiogram measurement of medical equipment and the like.

[0002]

2. Description of the Related Art Conventionally, an electrode abnormality detection circuit has been used in an electrocardiogram measurement by a medical device for the purpose of detecting that an electrode attached to a living body has come off the living body. FIG.
FIG. 2 is a circuit diagram showing an example of a conventional electrode abnormality detection circuit. The differential input amplifier circuit 4 differentially inputs two biological signals from the electrodes. The constant current output circuit 5 is connected to one biological signal input. A band-pass filter 6 is connected to the output of the differential input amplifier circuit 4, and a transistor circuit 7 is connected to the output of the band-pass filter 6, and switches an electrode abnormality (electrode detachment) detection signal output.

Next, the operation will be described. First, a measurement electrode is attached to the surface of a living body for the purpose of measuring an electrocardiogram. The constant current output circuit 5 is connected to one of the biological signal inputs, and supplies a small AC constant current to the living body through one of the inputs of the differential input amplifier circuit 4 and the measurement electrode.

If the measuring electrode is normally mounted on the surface of the living body, the minute AC constant current is input to the other input of the differential input amplifier circuit 4 together with the biological signal through the other measuring electrode. You. Then, the minute AC constant current is input to the differential input amplifier circuit 4 with the same phase and the same amplitude, and the differential input amplifier circuit 4 outputs only the biological signal. As a result, only the biological signal is input to the band-pass filter 6 and the signal of the band to be passed (frequency band of minute AC constant current) is not input, so the output of the band-pass filter 6 is the output signal of the transistor circuit 7. Cannot be switched. Therefore, the electrode detachment detection signal remains normal.

However, when one or both of the measurement electrodes on the surface of the living body comes off, the minute AC constant current becomes a differential input to the differential input amplifier circuit 4, and the differential input amplifier circuit 4 Outputs a signal obtained by amplifying the constant current. as a result,
Since an AC signal of a band to be passed is input to the band-pass filter 6, an output signal of the transistor circuit 7 is switched by an output of the band-pass filter 6. Therefore, the electrode detachment detection signal becomes abnormal and detects that the electrode has come off.

In addition to the conventional technology described above, for example,
Japanese Unexamined Patent Publication No. Hei 4-97732 also discloses that an electrode detachment detection circuit detects an electrode detachment during measurement of an electrocardiogram using a constant current circuit or a hysteresis comparator.

[0007]

In the above-mentioned prior art, in the electrode abnormality detection circuit using two electrodes, the separation of the electrodes is detected by using an AC constant current output circuit, a filter circuit, a comparator, and the like. Therefore, there is a problem that the circuit configuration of the detection circuit becomes complicated.

An object of the present invention is to provide an electrode abnormality detecting circuit having a simplified circuit configuration.

[0009]

A first electrode abnormality detection circuit according to the present invention detects a detachment of the measurement electrode in a medical device or the like which measures a biological signal input through a measurement electrode attached to a living body. An electrode abnormality detection circuit that does not generate a DC potential difference between the input biological signals when the measurement electrode is normally mounted, and detects the input biological signal when the measurement electrode comes off. It is characterized in that a DC potential difference is generated between signals.

A second electrode abnormality detection circuit according to the present invention is an electrode abnormality detection circuit for detecting a detachment of the measurement electrode in a medical device or the like for measuring a biological signal input through a measurement electrode attached to a living body. When the measurement electrode is properly mounted, no DC potential difference is generated between the input biological signals, and when the measurement electrode comes off, the DC potential difference between the input biological signals is not generated. A differential input amplifier circuit that generates, amplifies, and outputs a signal, and a transistor circuit that includes a transistor that operates by an output voltage of the differential input amplifier circuit when the measurement electrode is disconnected and outputs an electrode abnormality detection signal. It is characterized by having.

A third electrode abnormality detection circuit according to the present invention is an electrode abnormality detection circuit for detecting detachment of the measurement electrode in a medical device or the like for measuring a biological signal input via a measurement electrode attached to a living body. Therefore, when the measurement electrode is normally mounted, no DC potential difference is generated between the input biological signals, and when the measurement electrode is removed, the DC potential difference between the input biological signals is not generated. A differential input amplifier circuit that generates, amplifies, and outputs the output signal, and compares an output voltage of the differential input amplifier circuit with a reference voltage for determination to output an electrode abnormality detection signal when the measurement electrode comes off. And a comparator circuit having a comparator.

A fourth electrode abnormality detection circuit according to the present invention is an electrode abnormality detection circuit for detecting a detachment of the measurement electrode in a medical device or the like for measuring a biological signal input via a measurement electrode attached to a living body. A first DC voltage is connected to one biological signal input terminal, and a second DC voltage having a potential difference from the first DC voltage is connected to the other biological signal input terminal.

A fifth electrode abnormality detection circuit according to the present invention includes a differential input amplifier circuit to which a biological signal is input, and a transistor circuit to which an output of the differential input amplifier circuit is input. The circuit is configured such that a reference DC voltage for measurement via a first resistor and one biological signal input terminal via a second resistor are connected to a positive input terminal, and the reference for measurement via a third resistor is connected to the circuit. A first differential amplifier in which a DC voltage and its own output terminal via a fourth resistor are connected to a negative input terminal, and a DC voltage via a fifth resistor and the other via a sixth resistor; Of the first differential amplifier via a seventh resistor and its own output terminal via an eighth resistor are connected to the negative side input terminal. And a second differential amplifier connected to the Connected resistor to said second differential-based output terminal of the amplifier via a said base through a resistor earthed and the 10 is connected to the emitter, 11
The power supply voltage for circuit operation via the resistor and the electrode abnormality detection signal terminal include a transistor connected to the collector.

A sixth electrode abnormality detection circuit according to the present invention includes a differential input amplifier circuit to which a biological signal is input, and a comparator circuit to which an output of the differential input amplifier circuit is input. The circuit is configured such that a reference DC voltage for measurement via a first resistor and one biological signal input terminal via a second resistor are connected to a positive input terminal, and the reference for measurement via a third resistor is connected to the circuit. A first differential amplifier in which a DC voltage and its own output terminal via a fourth resistor are connected to a negative input terminal, and a DC voltage via a fifth resistor and the other via a sixth resistor; Of the first differential amplifier via a seventh resistor and its own output terminal via an eighth resistor are connected to the negative side input terminal. And a second differential amplifier connected to the An output terminal of the second differential amplifier is connected to a negative input terminal, and a power supply voltage for circuit operation via a twelfth resistor and the reference DC voltage for measurement via a thirteenth resistor are connected to a positive input terminal. And a comparator in which the power supply voltage for circuit operation via a fourteenth resistor and an electrode abnormality detection signal terminal are connected to an output terminal.

[0015]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, in which a differential input amplifier circuit 1 biased with a DC voltage and a transistor circuit operated by an output voltage of the differential input amplifier circuit 1 are shown. And 2.

In the differential input amplifier circuit 1, the biological signal S
1 is connected to the measurement reference DC voltage V1 via the resistor R1 and is input to the differential amplifier IC1. Biological signal S
2 is connected to a DC voltage V2 having a value different from the measurement reference DC voltage V1 via a resistor R5, and is input to the differential amplifier IC2. R2 and R6 are biological protection resistors.
The differential amplifiers IC1 and IC2 amplify the differential components of the biological signals S1 and S2, and output the biological signals to the electrocardiogram waveform terminal and the transistor circuit 2.

The transistor Q1 of the transistor circuit 2
Is connected to the output of the differential amplifier IC2 via the resistor R9. The collector of the transistor Q1 is connected to a power supply voltage Vcc for circuit operation via a resistor R11 and an electrode abnormality detection signal terminal. The transistor Q1 is turned on or off by the output voltage of the differential amplifier IC2, and outputs the signal.

Next, the operation of the first embodiment of the present invention will be described with reference to FIG.

First, a measurement electrode is attached to a living body in order to perform an electrocardiogram measurement, and biological signals S1 and S2 are input to a differential input amplifier circuit 1. The biological signal S1 is connected to a measurement reference DC voltage V1 via a resistor R1 and a differential amplifier IC
1 has been entered. The biological signal S2 is connected to the DC voltage V2 via the resistor R5, and is input to the differential amplifier IC2.

Normally, when the measuring electrode is normally attached to the living body, there is no DC potential difference between the biological signal S1 and the biological signal S2, and the output of the differential amplifier IC2 is
It becomes an electrocardiogram waveform centering on the measurement reference DC voltage V1. Therefore, the base voltage of the transistor Q1 is V1 ×
{R10 / (R9 + R10)} (where the AC signal of the electrocardiogram waveform is very small compared to the measurement reference DC voltage V1 and can be almost ignored), and does not reach the base saturation voltage, so the transistor Q1 remains OFF Becomes As a result, a "normal" signal, that is, a high level (Vcc) signal is output as an electrode abnormality (electrode detachment) detection signal.

However, when the measuring electrode is removed from the living body, or when the electrode cord connected to the measuring electrode is removed from the differential input amplifier circuit 1, the signal between the biological signal S1 and the biological signal S2 is lost. , A DC potential difference (V2-V1) occurs. The output of the differential amplifier IC2 is the output of the amplified potential difference ｛(V2−V1) × (1 + R8 / R7) + V
1｝. Accordingly, the base voltage of the transistor Q1 is [{(V2−V1) × (1 + R8 / R7) + V1}.
× {R10 / (R9 + R10)}], and reaches the base saturation voltage, so that the transistor Q1 is turned on. As a result, an "abnormal", that is, a low level (GND) signal is output as an electrode abnormality (electrode detachment) detection signal.

In the above-described first embodiment, a potential difference is provided between the biological signals S1 and S2, and when the electrode is detached, the potential difference is amplified and output to detect the electrode detachment. Therefore, there is no need to add a complicated circuit such as a constant current output circuit, a filter circuit, and a comparator as in the related art. For this reason, there is an effect that the circuit configuration is simplified and the present invention can be applied to a small electrocardiogram measuring device.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram showing a second embodiment of the present invention, and is different in that the transistor circuit 2 in the first embodiment shown in FIG. Therefore, the output of the differential input amplifier circuit 1 is input to the comparator circuit 3. And
When the electrode comes off the living body during the measurement of the electrocardiogram, the output of the differential input amplifier circuit 1 changes as described in the first embodiment, and the comparator IC3 of the comparator circuit 3 compares the level and detects the electrode coming off. Is detected.

At this time, the voltage divided by the resistors R12 and R13 connected to the positive input terminal of the comparator IC3 is equal to the output of the differential input amplifier circuit 1 when the electrode is disconnected. The electrode abnormality detection signal is at a low level (GND) when input to the input terminal, and the electrode abnormality detection signal when the output of the differential input amplifier circuit 1 when the electrode is normal is input to the negative input terminal of the comparator IC3. May be set to a high level (Vcc).

The above-described second embodiment has an effect that the electrode detachment detection level can be set more precisely, in addition to the effect of the first embodiment.

[0027]

As described above, according to the present invention, a potential difference is provided between the biological signals of the two electrodes, and the potential difference is amplified to detect the detachment of the electrodes. As a result, there is an effect that the circuit configuration is simplified and the electrocardiogram measuring device can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional electrode abnormality detection circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Differential input amplifier circuit 2 Transistor circuit 3 Comparator circuit IC1 Differential amplifier IC2 Differential amplifier IC3 Comparator Q1 Transistor R1-R14 Resistance S1, S2 Biosignal V1 Measurement reference DC voltage V2 DC voltage Vcc Circuit operation power supply voltage

Claims (6)

[Claims] 1. An electrode abnormality detection circuit for detecting detachment of a measurement electrode in a medical device or the like for measuring a biological signal input via a measurement electrode mounted on a living body, wherein the measurement electrode is normally mounted. In this case, a DC potential difference is not generated between the input biological signals, and a DC potential difference is generated between the input biological signals when the measurement electrode comes off. Detection circuit. 2. An electrode abnormality detection circuit for detecting detachment of the measurement electrode in a medical device or the like for measuring a biological signal input via a measurement electrode mounted on a living body, wherein the measurement electrode is normally mounted. When the measurement electrode is disconnected, a DC potential difference is generated between the input biological signals, and the DC potential difference is generated between the input biological signals, amplified, and output. An electrode abnormality detection circuit comprising: an input amplification circuit; and a transistor circuit including a transistor that operates by an output voltage of the differential input amplification circuit when the measurement electrode is disconnected and outputs an electrode abnormality detection signal. . 3. An electrode abnormality detection circuit for detecting detachment of the measurement electrode in a medical device or the like for measuring a biological signal input via a measurement electrode mounted on a living body, wherein the measurement electrode is normally mounted. When the measurement electrode is disconnected, a DC potential difference is generated between the input biological signals, and the DC potential difference is generated between the input biological signals, amplified, and output. An input amplifier circuit, comprising: a comparator circuit including a comparator that outputs an electrode abnormality detection signal when the measurement electrode comes off by comparing an output voltage of the differential input amplifier circuit with a reference voltage for determination. An electrode abnormality detection circuit, characterized in that: 4. An electrode abnormality detection circuit for detecting a detachment of the measurement electrode in a medical device or the like for measuring a biological signal input through a measurement electrode attached to a living body, wherein one of the biological signal input terminals is An electrode abnormality detection circuit, wherein a first DC voltage is connected, and a second DC voltage having a potential difference from the first DC voltage is connected to the other biological signal input terminal. 5. A differential input amplifying circuit to which a biological signal is input, and a transistor circuit to which an output of the differential input amplifying circuit is input, wherein the differential input amplifying circuit is connected via a first resistor. The measurement reference DC voltage and one biological signal input terminal via the second resistor are connected to the positive input terminal, and the measurement reference DC voltage via the third resistor and the fourth resistance are connected via the fourth resistor. A first differential amplifier having its own output terminal connected to the negative input terminal; a DC voltage via the fifth resistor and the other biological signal input terminal via the sixth resistor connected to the positive input terminal; A second differential amplifier connected to a negative terminal, the output terminal of the first differential amplifier being connected via a seventh resistor, and the output terminal of the first differential amplifier being connected via an eighth resistor. And wherein the transistor circuit comprises: a second differential via a ninth resistor The output terminal of the band is connected to the base, the ground and the base via the tenth resistor are connected to the emitter, and the power supply voltage for circuit operation via the eleventh resistor and the electrode abnormality detection signal terminal are connected. An electrode abnormality detection circuit having a transistor connected to a collector. 6. A differential input amplifier circuit to which a biological signal is input, and a comparator circuit to which an output of the differential input amplifier circuit is input, wherein the differential input amplifier circuit is connected via a first resistor. The measurement reference DC voltage and one biological signal input terminal via the second resistor are connected to the positive input terminal, and the measurement reference DC voltage via the third resistor and the fourth resistance are connected via the fourth resistor. A first differential amplifier having its own output terminal connected to the negative input terminal; a DC voltage via the fifth resistor and the other biological signal input terminal via the sixth resistor connected to the positive input terminal; A second differential amplifier connected to a negative terminal, the output terminal of the first differential amplifier being connected via a seventh resistor, and the output terminal of the first differential amplifier being connected via an eighth resistor. Wherein the comparator circuit has an output terminal of the second differential amplifier. A power supply voltage for circuit operation via a twelfth resistor and the reference DC voltage for measurement via a thirteenth resistor are connected to a positive input terminal, and connected via a fourteenth resistor. An electrode abnormality detection circuit comprising a comparator having the circuit operation power supply voltage and an electrode abnormality detection signal terminal connected to an output terminal.