Biological information measuring device

Abstract

The biological information measuring device of the present invention comprises: a first electrode; a second electrode; a third electrode; an electrode contact sensing unit, which senses and outputs a state in which all the electrodes are in contact with the surface of the measurement object; and a control unit, which performs measurement processing of the biological information, wherein the electrode contact sensing unit comprises: a bias power supply, which applies voltage to the first electrode and the second electrode respectively; a first comparator and a second comparator; and a contact state determination unit, which determines whether all the electrodes are in contact with the surface of the measurement object based on the output of the first comparator and the output of the second comparator, and wherein the control unit performs processing to disconnect the bias power supply and perform measurement processing only when all the electrodes are in contact with the surface of the measurement object.

Description

Technical Field

[0001] The present invention belongs to the technical field related to health care, and in particular relates to a biological information measuring device. Background Art

[0002] In recent years, it has become common to manage health by measuring information related to an individual's body / health (hereinafter also referred to as biological information) such as blood pressure values ​​and electrocardiogram waveforms using measuring equipment and recording and analyzing the measurement results using information terminals.

[0003] As an example of the measuring device described above, a portable ECG measuring device has been proposed that immediately measures the ECG waveform when abnormalities such as chest pain and palpitations occur in daily life, with the expectation that it will contribute to the early detection and appropriate treatment of heart disease (e.g., Patent Document 1, etc.).

[0004] Patent document 1 discloses a portable electrocardiograph having three electrodes for measurement on the main body, and proposes a technique for obtaining a correct electrocardiograph by preventing the baseline swing of the electrocardiograph caused by the pressure change of the hand holding the main body. Specifically, the following technique is described: a third measuring electrode is provided with a part of the hand holding the electrocardiograph as a reference potential, and the difference between the potential difference between the third measuring electrode and the first measuring electrode in contact with the chest and the potential difference between the third measuring electrode and the second measuring electrode in contact with the holding hand is amplified as an electrocardiograph signal.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 9-56686 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, even according to the technology described in Patent Document 1, there is a problem that when measurement is performed without the three electrodes properly contacting the measurement object, the contact resistance between the electrodes and the measurement object (skin) is not small enough, resulting in inability to accurately measure biological information.

[0010] In view of the above-mentioned prior art, an object of the present invention is to provide a technology that can perform measurement only when all of the three electrodes are properly in contact with the measurement object in a biological information measuring device using three or more electrodes, thereby enabling measurement of biological information with high accuracy.

[0011] Technical Solution

[0012] In order to solve the above-mentioned problems, the biological information measuring device of the present invention is a biological information measuring device which is provided with a first electrode, a second electrode and a third electrode and measures the biological information of the measuring object based on the potential difference between the first electrode and the second electrode, and is characterized in that it comprises: an electrode contact sensing unit which senses and outputs the state in which the first electrode, the second electrode and the third electrode are all in contact with the surface of the measuring object; and a control unit which performs measurement processing for measuring the biological information, and the electrode contact sensing unit comprises: a bias power supply which applies a bias to the first electrode and the second electrode respectively in such a way that the first electrode and the second electrode become contact sensing potentials which are higher than the potential of the third electrode. applying voltage; a first comparator and a second comparator, connected to the first electrode and the second electrode, respectively, for comparing the contact sensing potential with the respective potentials of the first electrode and the second electrode; and a contact state determination unit, for determining whether all of the first electrode, the second electrode, and the third electrode are in contact with the surface of the measurement object based on the output of the first comparator and the output of the second comparator, wherein the control unit disconnects the first electrode and the second electrode from the bias power supply and performs the measurement process when the electrode contact sensing unit outputs that all of the first electrode, the second electrode, and the third electrode are in contact with the surface of the measurement object.

[0013] Here, the bias power supply may be a power supply common to the first electrode and the second electrode, or may be a separate power supply for each electrode.

[0014] According to the above configuration, measurement will not start unless all three electrodes are properly in contact with the surface of the object to be measured, so that biological information can be measured more accurately by using a signal with a high S (Signal: signal) / N (Noise: noise) ratio (signal-to-noise ratio). In addition, the control unit performs a process of disconnecting (OFF) the bias power supply from the circuit before executing the measurement process, so that noise generated by connecting the power supply can be eliminated.

[0015] In addition, the biological information measuring device of the present invention can also be the following device: the third electrode is a ground electrode, the biological information measuring device has a first differential amplifier, the first differential amplifier is connected to the first electrode and the second electrode, amplifies and outputs the potential difference between the first electrode and the second electrode, and the control unit measures the biological information of the measurement object based on the output of the first differential amplifier.

[0016] With such a configuration, an AD (Analog to Digital) converter of a signal can be made to share a ground line (GND), making it easy to remove common mode noise of the signal during AD conversion.

[0017] In addition, the biological information measuring device of the present invention can also be the following device: it comprises: a second differential amplifier, which is connected to the first electrode and the third electrode, and amplifies and outputs the potential difference between the first electrode and the third electrode; a third differential amplifier, which is connected to the second electrode and the third electrode, and amplifies and outputs the potential difference between the second electrode and the third electrode; and a fourth differential amplifier, which is connected to the output side of the second differential amplifier and the output side of the third differential amplifier, and amplifies and outputs the potential difference between the output voltage of the second differential amplifier and the output voltage of the third differential amplifier, and the control unit measures the biological information of the measurement object based on the output of the fourth differential amplifier.

[0018] With such a configuration, when the analog signal output from the fourth differential amplifier is amplified, common mode noise of the signal can be easily removed.

[0019] In addition, the biological information may be an electrocardiogram waveform, that is, the biological information measuring device may be an electrocardiograph. In measuring the electrocardiogram waveform, it is necessary to measure the change of a smaller signal, and therefore, it is preferable to apply the present invention which can obtain a signal with less noise and high precision.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to provide a technique in which, in a living body information measuring device using three or more electrodes, measurement can be performed only when all of the three electrodes are properly in contact with a measurement object, thereby enabling measurement of living body information with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 These are six views showing the structure of the portable electrocardiogram measuring device according to the embodiment. Figure 1 (A) is a front view showing the structure of the portable electrocardiogram measuring device according to the embodiment. Figure 1 (B) is a rear view showing the structure of the portable electrocardiogram measuring device according to the embodiment. Figure 1 (C) is a left side view showing the structure of the portable electrocardiogram measuring device according to the embodiment. Figure 1 (D) is a right side view showing the structure of the portable electrocardiogram measuring device according to the embodiment. Figure 1 (E) is a plan view showing the structure of the portable electrocardiogram measurement device according to the embodiment. Figure 1(F) is a bottom view showing the structure of the portable electrocardiogram measuring device according to the embodiment.

[0023] Figure 2 This is a block diagram illustrating the functional configuration of the portable electrocardiogram measurement device according to the embodiment.

[0024] Figure 3 This is a circuit diagram showing a part of the electrical circuit configuration of the portable electrocardiogram measuring device according to the first embodiment.

[0025] Figure 4 This is a flowchart showing the flow of electrocardiographic waveform measurement processing in the portable electrocardiographic measurement device according to the embodiment.

[0026] Figure 5 This is a flowchart showing a subroutine of processing for electrode contact sensing in the portable electrocardiogram measurement device according to the embodiment.

[0027] Figure 6 This is a circuit diagram showing a part of the electrical circuit configuration of a portable electrocardiogram measuring device according to a modified example. DETAILED DESCRIPTION

[0028] <Implementation Method 1>

[0029] Hereinafter, specific embodiments of the present invention will be described based on the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the present embodiments do not limit the scope of the present invention to these.

[0030] (Electrocardiogram measuring device)

[0031] Figure 1 1 is a diagram showing the configuration of the portable electrocardiograph 10 in this embodiment. Figure 1 (A) is a front view showing the front of the main body. Similarly, Figure 1 (B) is the rear view. Figure 1 (C) is the left view, Figure 1 (D) is the right view, Figure 1 (E) is a top view, Figure 1 (F) is a bottom view.

[0032] A left electrode 12a is provided on the bottom surface of the portable electrocardiograph 10 for contacting the left side of the body during electrocardiogram measurement, and a first right electrode 12b for contacting the middle segment of the right index finger and a second right electrode 12c for contacting the base segment of the right index finger are similarly provided on the upper surface of the opposite side.

[0033] During electrocardiographic measurement, the portable electrocardiograph 10 is held with the right hand, and the right index finger is placed on the upper surface of the portable electrocardiograph 10 in a manner that the first right electrode 12b and the second right electrode 12c are correctly contacted. On this basis, the left electrode is brought into contact with the skin at a position corresponding to the desired measurement method. For example, when measuring by the so-called I lead, the left electrode is brought into close contact with the palm of the left hand, and when measuring by the so-called V4 lead, the left electrode is brought into contact with the skin slightly to the left of the pit of the stomach / below the nipple of the left chest.

[0034] Various operation parts and indicators are arranged on the left side of the portable electrocardiograph 10. Specifically, there are a power switch 16, a power LED 16a, a BLE (Bluetooth (registered trademark) Low Energy) communication button 17, a BLE communication LED 17a, a memory remaining display LED 18, and a battery replacement LED 19.

[0035] Furthermore, a measurement status notification LED 13 and an analysis result notification LED 14 are provided on the front surface of the portable electrocardiograph 10 , and a battery storage port and a battery cover 15 are provided on the rear surface of the portable electrocardiograph 10 .

[0036] In addition, Figure 2 A block diagram showing the functional structure of the portable electrocardiograph 10 is recorded in FIG. Figure 2 As shown, the portable electrocardiograph 10 is configured as follows: it has functional units including a control unit 101, an electrode unit 12, an amplifier 102, an AD (Analog to Digital) conversion unit 103, a timing unit 104, a storage unit 105, a display unit 106, an operation unit 107, a power supply unit 108, a communication unit 109, an analysis unit 110, and a contact sensing unit 111.

[0037] The control unit 101 is a unit responsible for controlling the portable electrocardiograph 10, and is configured to include, for example, a CPU (Central Processing Unit) etc. When accepting a user's operation via the operation unit 107, the control unit 101 controls each component of the portable electrocardiograph 10 in a manner that performs various processes such as electrocardiographic measurement and information communication according to a prescribed program. It should be noted that the prescribed program is stored in and read from the storage unit 105 described later.

[0038] The control unit 101 also includes an analysis unit 110 for analyzing an electrocardiographic waveform as a functional block. The analysis unit 110 analyzes the measured electrocardiographic waveform to determine whether the waveform is disordered or not, and outputs at least a result of whether the electrocardiographic waveform at the time of measurement is normal.

[0039] The electrode unit 12 is composed of a left electrode 12a, a first right electrode 12b, and a second right electrode 12c, and functions as a sensor for detecting an electrocardiogram waveform. The amplifier 102 has a function of amplifying a signal representing an electrocardiogram waveform output from the electrode unit 12 as described later. The AD converter 103 has a function of converting the analog signal amplified by the amplifier 102 into a digital signal and transmitting it to the control unit 101.

[0040] The timing unit 104 has a function of measuring time with reference to the RTC (Real Time Clock). For example, as described later, when performing electrode contact sensing, the time that all electrodes of the left electrode 12a, the first right electrode 12b, and the second right electrode 12c are in contact with the body is counted. In addition, when measuring electrocardiogram, the time until the measurement is completed can be counted and output.

[0041] The storage unit 105 includes a main storage device such as a RAM (Random Access Memory) and stores various information such as application programs, measured electrocardiogram waveforms, analysis results, etc. In addition to the RAM, a long-term storage medium such as a flash memory may be provided.

[0042] The display unit 106 includes the aforementioned power LED 16a, BLE communication LED 17a, memory remaining display LED 18, and battery replacement LED 19, and communicates the status of the device to the user by lighting or flashing the LEDs. In addition, the operation unit 107 includes the power switch 16, the communication button 17, etc., receives input operations from the user, and has a function for causing the control unit 101 to execute processing corresponding to the operation.

[0043] The power supply unit 108 is configured to include a battery that supplies power required for the operation of the device. The battery may be a secondary battery such as a lithium ion battery, or a primary battery.

[0044] The communication unit 109 includes an antenna for wireless communication and has at least a function of communicating with other devices such as an information processing terminal by BLE communication. Alternatively, a terminal for wired communication may be provided.

[0045] The contact sensing unit 111 is configured to include an electrical circuit connected to the left electrode 12a and the first right electrode 12b, and has the function of sensing and outputting the state in which all electrodes of the left electrode 12a, the first right electrode 12b, and the second right electrode 12c are in correct contact with various parts of the body. Figure 3 , the contact sensing unit 111 is described in detail. Figure 3 11 is a circuit diagram for explaining an electric circuit constituting the touch sensor unit 111 .

[0046] The contact sensing unit 111 is roughly configured as follows: a left sensing unit 91 connected to the left electrode 12a, a right sensing unit 92 connected to the first right electrode 12b, and a contact state determination unit 93 that determines whether all electrodes are in contact based on the output of the left sensing unit 91 and the output of the right sensing unit 92.

[0047] The left sensing unit 91 is configured to include a left comparator 910, a left bias power supply 911, a left switch element 912, a left pull-up resistor 913, a left RC (Resistance-Capacitance) filter 914, a left reference voltage power supply 915, left reference voltage resistors 916a, 916b and left hysteresis resistors 917a, 917b.

[0048] The left bias power supply 911 applies a bias voltage (e.g., about 3V) to the left electrode 12a in such a manner that the left electrode 12a has a bias potential higher than that of the second right electrode 12c. The left switch element 912 is composed of, for example, a field effect transistor (FET) and the like, and switches the left bias power supply 911 and the circuit on / off under the control of the control unit 101. The left pull-up resistor 913 maintains the potential of the connected circuit at a high potential, and the left RC filter 914 removes high-frequency components and inputs the voltage from the left bias power supply 911 to the -input terminal of the left comparator 910. Hereinafter, the potential input to the -input terminal of the left comparator 910 is referred to as the left bias potential.

[0049] A predetermined contact sensing reference voltage (e.g., about 1.5 V) supplied from the left reference voltage power supply 915 and adjusted by the left reference voltage resistors 916a and 916b is input to the + input terminal of the left comparator 910. Hereinafter, the potential input to the + input terminal of the left comparator 910 is referred to as the left sensing reference potential.

[0050] The left comparator 910 is composed of, for example, an operational amplifier, and when the left bias potential is lower than the left sensing reference potential by a predetermined hysteresis amount, the left comparator 910 outputs a high (High). On the other hand, when the left bias potential is equal to or higher than the left sensing reference potential, the left comparator 910 outputs a low (Low).

[0051] When both the left electrode 12a and the second right electrode 12c are in correct contact with the skin of the body, the current flows to the second right electrode 12c, which has a lower potential than the left electrode 12a, via the impedance of the human body, and a voltage drop is generated in the left pull-up resistor 913, and the left bias potential decreases. As a result, the output of the left comparator 910 changes from low to high. It should be noted that the circuit of the dotted line portion in the figure shows the path of the current via the impedance of the human body.

[0052] Similar to the left sensing unit 91, the right sensing unit 92 is also constructed to include a right comparator 920, a right bias power supply 921, a right switching element 922, a right pull-up resistor 923, a right RC filter 924, a right reference voltage power supply 925, right reference voltage resistors 926a, 926b and right hysteresis resistors 927a, 927b.

[0053] The right bias power supply 921 applies a bias voltage to the first right electrode 12b in such a manner that the first right electrode 12b has a bias potential higher than that of the second right electrode 12c. In addition, the configuration and function of each element of the right sensing unit 92 are the same as those of the left sensing unit 91 with respect to the left electrode 12a, and therefore, detailed description thereof is omitted.

[0054] The contact state determination unit 93 is composed of, for example, an AND circuit, and when both the left comparator 910 and the right comparator 920 output high, it is determined that all the electrodes of the left electrode 12a, the first right electrode 12b, and the second right electrode 12c are in correct contact, and this meaning is output to the control unit 101.

[0055] It should be noted that if Figure 3 As shown, the left electrode 12a is connected to the + input terminal of the differential amplifier 94, the first right electrode 12b is connected to the - input terminal of the differential amplifier 94, and the second right electrode 12c is connected to GND. The differential amplifier 94 amplifies and outputs the potential difference between the left electrode 12a and the first right electrode 12b, and the output is transmitted to the amplifier 102 and the AD converter 103 via a filter circuit (not shown), thereby performing electrocardiographic measurement.

[0056] (ECG measurement processing using a portable electrocardiograph)

[0057] Next, based on Figures 1 to 5 The operation of the portable electrocardiograph 10 when performing electrocardiographic measurement will be described. Figure 4 is a flowchart showing the sequence of processing when the portable electrocardiograph 10 is used to perform electrocardiographic measurement. Figure 5 1 is a flowchart showing a subroutine of processing for electrode contact sensing in the portable electrocardiograph 10 .

[0058] Reference Figure 4 First, before measurement, the user operates the power switch 16 to turn on the power of the portable electrocardiograph 10. Then, the power LED 16a lights up to indicate that the power is on. Then, the user holds the portable electrocardiograph 10 with the right hand, and makes the right index finger contact the first right electrode 12b and the second right electrode 12c, and makes the left electrode 12a contact the skin at the position where the measurement is to be performed. Then, the control unit 101 detects the contact state of each electrode via the electrode unit 12 and the contact state sensing unit 111 (S101).

[0059] Here, based on Figure 5 First, when the power switch 16 is turned on, the control unit 101 turns on the left switch element 912 and the right switch element 922 to apply a bias voltage to the left electrode 12a and the first right electrode 12b (S201).

[0060] As described above, if the left electrode 12a, the first right electrode 12b, and the second right electrode 12c are all in contact with the body, the left comparator 910 and the right comparator 920 both output high, and the contact state determination unit 93 outputs this to the control unit 101. Then, if the high signal is continuously output for a specified time (for example, three seconds), it is set that each electrode is in a state of correct contact with the measurement object. Here, it is sufficient to refer to the timing unit 104 to determine whether the specified time has passed. In step S202, the control unit 101 resets (sets to 0) the timer count value (hereinafter referred to as the contact time count value) for measuring the time when all electrodes are in contact.

[0061] Next, in step S203, when the control unit 101 determines that the left electrode 12a, the first right electrode 12b, and the second right electrode 12c are in contact with the body, the control unit 101 proceeds to step S204 to determine whether a predetermined time has passed in this state. On the other hand, in step S203, when it is determined that all electrodes are not in contact correctly, the control unit 101 returns to step S202, resets the contact time count value, and repeats the subsequent processing.

[0062] In step S204, if it is determined that the specified time has not passed, the process returns to step S203 and the subsequent processing is repeated. On the other hand, in step S204, if it is determined that the specified time has passed, the left switch element 912 and the right switch element 922 are disconnected, the pull-up resistor is disabled (step S205), and the subroutine ends.

[0063] If you return to Figure 4After the subroutine of step S101 is finished, the control unit 101 performs the actual electrocardiogram measurement process (step S102). During the electrocardiogram measurement, the control unit 101 stores the measured value in the storage unit 105 at any time, and flashes the measurement status notification LED 13 on the front of the main body at a predetermined rhythm, thereby indicating that the electrocardiogram measurement is in progress (S103).

[0064] Next, the control unit 101 performs the following processing: it is determined whether the time of electrocardiographic measurement has passed the prescribed measurement time (for example, thirty seconds) (step S104). Here, if it is determined that the prescribed time has not passed, the process returns to step S102 and the subsequent processing is repeated. On the other hand, if it is determined that the prescribed measurement time has passed, the measurement is terminated, and the process of flashing the measurement status notification LED 13 is terminated (step S105).

[0065] Next, the analysis unit 110 of the control unit 101 analyzes the measurement data (ECG waveform) stored in the storage unit 105 (S106), and the analysis result is stored in the long-term storage device together with the ECG waveform (S107). Then, the control unit 101 displays the analysis result through the analysis result notification LED 14 (S108), and a series of processing is terminated. It should be noted that the display of the analysis result can be, for example, lighting the LED only when an abnormality occurs in the ECG waveform, or can be set to light the LED by a lighting / flashing method corresponding to the analysis result.

[0066] According to the portable electrocardiograph 10 of this embodiment constructed as described above, the user can start measurement after operating the power switch 16 without performing any operation other than bringing the electrodes into contact with the measurement site, and measurement will not start if all the electrodes are not properly in contact, thereby obtaining highly accurate measurement results.

[0067] Furthermore, the first right electrode 12 b is connected to GND to function as a GND electrode, so that the AD converter of the signal can be shared with GND, making it easy to remove common mode noise of the signal during AD conversion.

[0068] <Modification>

[0069] It should be noted that, in the above-mentioned embodiment, the first right electrode 12b functions as a GND electrode, but it is not necessarily necessary to adopt such a structure. Figure 6 Another configuration example of the portable electrocardiograph is shown in . It should be noted that the same reference numerals are given to the same configurations as those in the first embodiment, and detailed descriptions thereof are omitted.

[0070] like Figure 6As shown, the portable electrocardiograph of this modification includes three differential amplifiers, namely, a left differential amplifier 95a, a right differential amplifier 95b, and a left-right differential amplifier 95c, and is configured to measure an electrocardiographic waveform using the outputs of these differential amplifiers.

[0071] Specifically, in the left differential amplifier 95a, the potential input for the left electrode 12a is input on the + side, and the potential input for the second right electrode 12c is input on the - side, and the potential difference between them is output. In addition, in the right differential amplifier 95b, the potential input for the first right electrode 12b is input on the + side, and the potential input for the second right electrode 12c is input on the - side, and the potential difference between them is output.

[0072] In addition, in the left and right differential amplifiers 95c, the output potential of the left differential amplifier 95a is inputted to the + side, and the output potential of the right differential amplifier 95b is inputted to the - side, and the potential difference between them is outputted. Then, the signals outputted from the left and right differential amplifiers 95c are transmitted to the amplifier 102 and the AD converter 103 via a filter circuit (not shown), thereby performing electrocardiographic measurement.

[0073] With such a configuration, the second right electrode 12c is used as a reference electrode, and a potential difference between the left electrode 12a and the first right electrode 12b is amplified to obtain a signal. Therefore, when the signal is amplified, its common mode noise can be easily removed.

[0074] <Others>

[0075] The above-mentioned embodiments are merely exemplary of the present invention, and the present invention is not limited to the above-mentioned specific embodiments. The present invention can be variously modified and combined within the scope of its technical concept.

[0076] For example, the switch element in the above embodiment is not limited to FET, and the comparator and differential amplifier are not necessarily implemented by an operational amplifier. In addition, although not described in detail in the above embodiment, the electrocardiograph can also be effectively utilized by cooperating with other information terminal devices through the BLE communication function based on the communication unit 109. Conversely, it can also be set as an electrocardiograph without a communication function and an LED display unit.

[0077] It should be noted that, in the above description, the present invention is applied to a portable electrocardiograph, but the present invention may be applied to a non-portable electrocardiograph or other biological measuring devices such as a body composition analyzer.

[0078] Description of Reference Numerals

[0079] 10: Portable electrocardiograph

[0080] 13: Measurement status notification LED

[0081] 12a: Left electrode

[0082] 12b: First right electrode

[0083] 12c: Second right electrode

[0084] 14: Analysis result notification LED

[0085] 15: Battery cover

[0086] 16: Power switch

[0087] 16a: Power LED

[0088] 17: Communication button

[0089] 17a: BLE communication LED

[0090] 18: Memory remaining display LED

[0091] 19: Battery replacement LED

[0092] 91: Left sensor

[0093] 910: left comparator

[0094] 911: Left bias power supply

[0095] 912: Left switch element

[0096] 913: Pull-up resistor on the left

[0097] 914: Left RC filter

[0098] 915: Left reference voltage supply

[0099] 916a, 916b: Left reference voltage resistor

[0100] 917a, 917b: left hysteresis resistor

[0101] 92: Right sensor

[0102] 93: Contact status determination unit

[0103] 94: Differential Amplifier

[0104] 95a: Left differential amplifier

[0105] 95b: Right differential amplifier

[0106] 95c: Left and right differential amplifier

Claims

1. A biological information measuring device, comprising a first electrode, a second electrode and a third electrode, and measuring biological information of a measurement object based on a potential difference between the first electrode and the second electrode, characterized in that: have: an electrode contact sensing unit, sensing and outputting a state in which the first electrode, the second electrode, and the third electrode are all in contact with the surface of the measurement object; as well as a control unit that performs a measurement process for measuring the biological information, The electrode contact sensing unit comprises: a bias power supply for applying voltage to the first electrode and the second electrode respectively in such a manner that the first electrode and the second electrode have a contact sensing potential higher than that of the third electrode; A first comparator and a second comparator are connected to the first electrode and the second electrode, respectively, and compare the contact sensing potential with the potentials of the first electrode and the second electrode; as well as A contact state determination unit determines whether all of the first electrode, the second electrode, and the third electrode are in contact with the surface of the measurement object based on the output of the first comparator and the output of the second comparator. When the electrode contact sensing unit outputs that all of the first electrode, the second electrode, and the third electrode are in contact with the surface of the measurement object, the control unit disconnects the first electrode and the second electrode from the bias power supply and performs the measurement process.

2. The biological information measuring device according to claim 1, characterized in that: The third electrode is a ground electrode, The biological information measuring device includes a first differential amplifier connected to the first electrode and the second electrode, and amplifies and outputs a potential difference between the first electrode and the second electrode. The control unit measures biological information of the measurement object based on the output of the first differential amplifier.

3. The biological information measuring device according to claim 1, characterized in that: have: a second differential amplifier connected to the first electrode and the third electrode, amplifying and outputting a potential difference between the first electrode and the third electrode; a third differential amplifier connected to the second electrode and the third electrode, amplifying and outputting a potential difference between the second electrode and the third electrode; as well as a fourth differential amplifier connected to the output side of the second differential amplifier and the output side of the third differential amplifier, amplifying and outputting a potential difference between an output voltage of the second differential amplifier and an output voltage of the third differential amplifier, The control unit measures biological information of the measurement object based on the output of the fourth differential amplifier.

4. The biological information measuring device according to any one of claims 1 to 3, characterized in that: The biological information is an electrocardiogram waveform.

5. The biological information measuring device according to any one of claims 1 to 3, characterized in that: The biological information measuring device is a portable device.

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