Biological information measuring device

Abstract

To provide an electrocardiographic device that allows an electrocardiographic waveform excellent in precision to be acquired and is capable of detecting the state of contact of each electrode.SOLUTION: A biological information measuring device having a first electrode, a second electrode, and a third electrode for measuring biological information on a measurement target on the basis of a potential difference between the first electrode and the second electrode with an electric potential of the third electrode as a reference electric potential includes: a first non-inverting amplifier circuit; a first pull-up resistor; first contact signal output means; a second non-inverting amplifier circuit; a second pull-up resistor; second contact signal output means; a differential amplifier circuit for amplifying the difference between a first amplified electric potential amplified by the first non-inverting amplifier circuit and output, and a second amplified electric potential amplified by the second non-inverting amplifier circuit and output, and outputting the biological information; and control means for executing processing for measuring the biological information.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a healthcare-related technical field, and in particular to a bioinformation measuring device. [Background technology]

[0002] In recent years, it has become common to use measuring devices to measure information related to an individual's physical and health, such as blood pressure and electrocardiogram waveforms (hereinafter referred to as biometric information), and to record and analyze the measurement results on an information terminal to manage health.

[0003] As an example of such a measuring instrument, a portable electrocardiogram measuring device has been proposed that immediately measures electrocardiogram waveforms when abnormalities such as chest pain or palpitations occur in daily life, and is expected to contribute to the early detection of heart disease and appropriate treatment (for example, Patent Document 1).

[0004] Patent Document 1 discloses a configuration of a portable biosignal telemeter device that acquires an electrocardiogram using three electrodes attached to a subject, the configuration having an electrode abnormality detection circuit that detects the attachment state of the electrodes to the subject and outputs an electrode detachment signal in the event of an electrode attachment abnormality. With this configuration, if there is an abnormality in the attachment state of the electrodes, the user can recognize this and can take measures such as reattaching the electrodes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-269417 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the technology described in Patent Document 1, when there is an electrode attachment abnormality, this is notified and the power supply to the circuit for electrocardiogram waveform measurement (and transmission of the waveform data to the outside) is cut off. However, in reality, even during electrocardiogram measurement, the potential of the electrodes may fluctuate due to body movement, etc., and the electrodes may be determined to be attached incorrectly. In addition, especially in winter when the skin is prone to dryness, the electrodes may be determined to be not attached correctly even if they are in contact with the skin. This may cause problems such as electrocardiogram measurement being interrupted many times midway or not being able to start at all.

[0007] In view of the above problems, an object of the present invention is to provide a technique capable of obtaining an accurate electrocardiogram waveform and detecting the contact state of each electrode. [Means for solving the problem]

[0008] In order to solve the above problems, the biological information measuring device according to the present invention employs the following configuration. A biological information measuring device comprising a first electrode, a second electrode, and a third electrode, the biological information measuring device measuring biological information of a measurement target based on a potential difference between the first electrode and the second electrode, the potential of the third electrode being set as a reference potential, a first non-inverting amplifier circuit including a first amplifier having a non-inverting input terminal to which the potential of the first electrode is input; a first pull-up resistor connected between the first electrode and the first non-inverting amplifier circuit; a first contact signal output means including the first non-inverting amplifier circuit and configured to output a signal related to a contact state of the first electrode with the measurement target using an output signal from the first non-inverting amplifier circuit; a second non-inverting amplifier circuit including a second amplifier having a non-inverting input terminal to which the potential of the second electrode is input; a second pull-up resistor connected between the second electrode and the second non-inverting amplifier circuit; a second contact signal output means including the second non-inverting amplifier circuit, and outputting a signal related to a contact state of the second electrode with the measurement target using an output signal from the second non-inverting amplifier circuit; a differential amplifier circuit that amplifies a difference between a first amplified potential that is amplified and output by the first non-inverting amplifier circuit and a second amplified potential that is amplified and output by the second non-inverting amplifier circuit, and outputs the biological information; A control means for executing a process of measuring the biological information; The biological information measuring device has the following features.

[0009] The resistance value of the pull-up resistor can be, for example, 200 MΩ or more, more preferably 300 MΩ or more. With the above-mentioned configuration, the signal indicating the potential of the first electrode and the second electrode is amplified in a stage before the input of the differential amplifier that amplifies and outputs the potential difference between the first electrode and the second electrode, so that it is possible to accurately measure biological information using a signal with a high S (Signal) / N (Noise) ratio. In addition, since the pull-up resistor is disposed between the first electrode and the second electrode and the non-inverting amplifier circuit to which each electrode is connected, it is possible to reduce noise in the signal indicating the potential of each electrode. And, since the configuration is such that the output signal from the non-inverting amplifier circuit to which such a signal is input is used to output a signal related to the contact state of each electrode with the measurement target, there is no risk of the circuit for contact detection affecting the electrocardiogram waveform, and it is possible to perform accurate measurement of the electrocardiogram waveform and detection of the contact state of the electrodes in parallel.

[0010] Furthermore, the first contact signal output means may output a signal relating to the contact state of the first electrode with respect to the measurement target using the first amplified potential, and the second contact signal output means may output a signal relating to the contact state of the second electrode with respect to the measurement target using the second amplified potential. Conversely, each contact signal output means may output a signal relating to the contact state of each electrode with respect to the measurement target using a signal having an amplification factor of 1.

[0011] The bioinformation measuring device may further include a storage means for storing a signal related to a contact state of the first electrode with respect to the measurement target and a signal related to a contact state of the second electrode with respect to the measurement target during at least the measurement process of the bioinformation, thereby making it possible to check the contact state of the electrodes during electrocardiogram measurement later.

[0012] The first contact signal output means and the second contact signal output means may each include an A (Analog) / D (Digital) converter, and the bioinformation measuring device may further include a contact state classifying means for classifying the contact state of the first electrode and the second electrode with respect to the measurement target into at least three stages using the digital signal output from the A / D converter. Also, the classified information on the contact state may be stored in the storage means at least during the measurement process of the bioinformation.

[0013] The threshold value for classifying the digitized signal can be appropriately set by the user based on the contact resistance, the quality of the electrocardiogram recording, etc. With this configuration, the user can check the contact state classified into stages according to the contact level, rather than as an analog value, and can easily grasp the contact state of the electrodes. Effect of the Invention

[0014] According to the present invention, it is possible to provide a biological information measuring device that can obtain an accurate electrocardiogram waveform and detect the contact state of each electrode. [Brief description of the drawings]

[0015] [Figure 1]FIG. 1A is a front view showing the configuration of a portable electrocardiogram measuring device according to an embodiment. FIG. 1B is a rear view showing the configuration of a portable electrocardiogram measuring device according to an embodiment. FIG. 1C is a left side view showing the configuration of a portable electrocardiogram measuring device according to an embodiment. FIG. 1D is a right side view showing the configuration of a portable electrocardiogram measuring device according to an embodiment. FIG. 1E is a plan view showing the configuration of a portable electrocardiogram measuring device according to an embodiment. FIG. 1F is a bottom view showing the configuration of a portable electrocardiogram measuring device according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating the functional configuration of the portable electrocardiogram measuring device according to the embodiment. [Diagram 3] Fig. 3 is a circuit diagram showing a part of the electric circuit configuration of the portable electrocardiogram measuring device according to the embodiment. Fig. 4A shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 100 MΩ, Fig. 4B shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 200 MΩ, Fig. 4C shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 300 MΩ, and Fig. 4D shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 400 MΩ. Fig. 5 is a graph showing the number of electrocardiogram waveforms measured at resistance values ​​of 100 MΩ, 200 MΩ, 300 MΩ, and 400 MΩ that meet the pass / fail criteria for baseline stability. [Figure 4] Fig. 4A is a first diagram showing the relationship between the pull-up resistance value and the electrocardiographic waveform of the portable electrocardiograph according to the embodiment. Fig. 4B is a second diagram showing the relationship between the pull-up resistance value and the electrocardiographic waveform of the portable electrocardiograph according to the embodiment. Fig. 4C is a third diagram showing the relationship between the pull-up resistance value and the electrocardiographic waveform of the portable electrocardiograph according to the embodiment. Fig. 4D is a fourth diagram showing the relationship between the pull-up resistance value and the electrocardiographic waveform of the portable electrocardiograph according to the embodiment. [Diagram 5] FIG. 5 is an explanatory diagram for explaining an experimental example of the portable electrocardiogram measuring device according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of a process flow related to electrocardiogram measurement performed by the portable electrocardiogram measuring device according to the embodiment. [Figure 7]FIG. 7 is a circuit diagram showing a part of the electric circuit configuration of a portable electrocardiogram measuring device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Embodiment 1> Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, and the like of the components described in the embodiments are not intended to limit the scope of the present invention.

[0017] (Electrocardiogram measuring device) Fig. 1 is a diagram showing the configuration of a portable electrocardiograph 10 in this embodiment. Fig. 1A is a front view showing the front of the main body, and similarly Fig. 1B is a rear view, Fig. 1C is a left side view, Fig. 1D is a right side view, Fig. 1E is a plan view, and Fig. 1F is a bottom view.

[0018] A left side electrode 12a is provided on the bottom surface of the portable electrocardiograph 10, which is brought into contact with the left side of the body during electrocardiogram measurement, and a first right side electrode 12b is provided on the upper surface of the opposite side, which is brought into contact with the middle joint of the index finger of the right hand, and a second right side electrode 12c is provided on the upper surface of the opposite side, which is brought into contact with the proximal joint of the index finger of the right hand.

[0019] When measuring electrocardiograms, the portable electrocardiograph 10 is held in the right hand, and the index finger of the right hand is placed on the top surface of the portable electrocardiograph 10 so as to properly contact the first right-side electrode 12b and the second right-side electrode 12c. Then, the left electrode 12a is brought into contact with the skin at a position corresponding to the desired measurement method. For example, when measuring with a so-called I lead, the left electrode 12a is placed on the palm of the left hand and brought into contact, and when measuring with a so-called V4 lead, the left electrode 12a is brought into contact with the skin slightly to the left of the epigastric region of the left chest and below the nipple. Let them touch it.

[0020] Various operation units and indicators are arranged on the left side surface of the portable electrocardiograph 10. Specifically, a power switch 16, a power LED 16a, a BLE (Bluetooth (registered trademark) Low Energy) communication button 17, a BLE communication LED 17a, a remaining memory display LED 18, a battery replacement LED 19, and the like are provided.

[0021] Furthermore, a measurement state notification LED 13 and an analysis result notification LED 14 are provided on the front side of portable electrocardiograph 10, and a battery storage port and a battery cover 15 are disposed on the rear side of portable electrocardiograph 10.

[0022] Fig. 2 is a block diagram showing the functional configuration of the portable electrocardiograph 10. As shown in Fig. 2, the portable electrocardiograph 10 includes the following functional units: a control unit 101, an electrode unit 12, an amplifier unit 102, an A / D conversion unit 103, a timer unit 104, a memory unit 105, a display unit 106, an operation unit 107, a power supply unit 108, a communication unit 109, a contact detection unit 111, and an A / D conversion unit 112.

[0023] The control unit 101 is a means for controlling the portable electrocardiograph 10, and is configured to include, for example, a CPU (Central Processing Unit) and the like. When the control unit 101 accepts a user's operation via the operation unit 107, the control unit 101 controls each component of the portable electrocardiograph 10 to execute various processes such as electrocardiogram measurement and information communication according to a predetermined program. The predetermined program is stored in the storage unit 105 described below and is read out from there.

[0024] The control unit 101 also includes, as functional modules, an analysis unit 110 that analyzes an electrocardiogram waveform, and a contact condition classification unit 113. The analysis unit 110 analyzes the measured electrocardiogram waveform for the presence or absence of waveform disturbance, and outputs a result as to whether or not the electrocardiogram waveform at least at the time of measurement is normal. The contact condition classification unit 113 classifies the level of the contact condition of the left electrode 12a and the first right electrode 12b detected by the contact detection unit 111 into four stages. The detection of the contact condition and the level classification will be described later.

[0025] 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. Specifically, the second right electrode 12c is used as a ground (GND) electrode, and the potential difference between the potential of the left electrode 12a and the potential of the first right electrode 12b with respect to the reference potential is continuously measured to obtain an electrocardiogram waveform. A specific circuit configuration for detecting an electrocardiogram waveform will be described later.

[0026] As described below, the amplifier unit 102 has a function of amplifying a signal indicating an electrocardiogram waveform output from the electrode unit 12. The A / D converter 103 has a function of converting the analog signal amplified by the amplifier unit 102 into a digital signal and transmitting the digital signal to the control unit 101.

[0027] The timer unit 104 has a function of measuring time by referring to an RTC (Real Time Clock). For example, as described later, when performing electrode contact detection processing, the timer unit 104 counts the time that all of the left electrode 12a, the first right electrode 12b, and the second right electrode 12c are in contact with the body. In addition, the timer unit 104 may count the time until the end of electrocardiogram measurement and output the count.

[0028] The storage unit 105 includes a main storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores various information such as application programs, measured electrocardiogram waveforms, analysis results, etc. In addition to the RAM and ROM, the storage unit 105 includes a long-term storage medium such as a flash memory.

[0029] The display unit 106 includes a measurement status notification LED 13, an analysis result notification LED 14, a power LED 16a, a BLE communication LED 17a, a remaining memory display LED 18, a battery replacement LED 19, etc., and notifies the user of the device status by turning on or off the LEDs. The operation unit 107 includes a power switch 16, a communication button 17, etc., and has a function of accepting input operations from the user and causing the control unit 101 to execute processing according to the operation.

[0030] The power supply unit 108 includes a battery that supplies the power necessary to operate the device. The battery may be a secondary battery such as a lithium ion battery, or a primary battery.

[0031] The communication unit 109 includes an antenna for wireless communication, and has a function of communicating with other devices such as an information processing terminal by at least BLE communication. It may also include a terminal for wired communication.

[0032] The contact detection unit 111 includes an electric circuit connected to the left electrode 12a and the first right electrode 12b, detects the contact state between the left electrode 12a and the first right electrode 12b and the skin surface of the measurement target, and outputs a signal according to the level of the contact state. The A / D conversion unit 112 converts the analog signal output by the contact detection unit 111 into a digital signal and transmits it to the control unit 101.

[0033] (Electrical circuit configuration) Contact state detection and electrocardiogram waveform measurement in the portable electrocardiograph 10 according to this embodiment will be described below with reference to Fig. 3. Fig. 3 is a circuit diagram showing an outline of an electric circuit including each electrode of the portable electrocardiograph 10.

[0034] 3, the second right electrode 12c is connected to a reference potential GND and functions as a ground electrode. The first right electrode 12b is connected to a power supply potential V1 via a right pull-up resistor 911. The left electrode 12a is connected to a power supply potential V1 via a left pull-up resistor 921. The power supply potential V1 is set to a potential (e.g., 4 V) higher than the reference potential GND and capable of securing a sufficient bias.

[0035] Therefore, when the power supply is ON and both the first right-side electrode 12b and the second right-side electrode 12c are properly in contact with the skin of the body, a current flows through the impedance of the human body to the second right-side electrode 12c, which has a lower potential than the first right-side electrode 12b, and the potential of the first right-side electrode 12b fluctuates. Such a fluctuation in potential corresponds to the state of contact between the first right-side electrode 12b (and the second right-side electrode 12c) and the skin surface.

[0036] That is, the more firmly the first right electrode 12b is in contact with the skin, the lower the potential becomes, and the contact state between the first right electrode 12b and the skin can be determined based on the potential. The same is true for the left electrode 12a. Note that the circuit shown by the dashed line in Fig. 3 indicates the path of the current via the impedance of the human body.

[0037] In order to ensure the accuracy of the electrocardiogram waveform to be detected, the right pull-up resistor 911 and the left pull-up resistor 921 are set to a sufficiently high resistance value (e.g., 200 MΩ, preferably 300 MΩ or more). The relationship between the electrocardiogram waveform and the pull-up resistor value will be described in detail later.

[0038] In addition, five amplifiers are arranged in the circuit shown in FIG. 3: a right non-inverting amplifier 912, a right buffer amplifier 913, a left non-inverting amplifier 922, a left buffer amplifier 923, and a differential amplifier 94.

[0039] 3, the potential of the first right electrode 12b is input to the + input terminal of the right non-inverting amplifier 912. Then, a right amplified signal amplified by an amplification factor defined by a first amplification factor determining resistor 931 and a third amplification factor determining resistor 933 is output from the output terminal of the right non-inverting amplifier 912 and input to the - terminal of the differential amplifier 94. Meanwhile, a signal of the same potential as that input to the + input terminal of the right non-inverting amplifier 912 is input to the + input terminal of the right buffer amplifier 913 via the right non-inverting amplifier 912. That is, the right non-inverting amplifier 912 functions not only as a normal amplifier (signal amplifier) ​​but also as a buffer (voltage follower).

[0040] The right buffer amplifier 913 functions as a buffer, and a signal having the same potential as the potential input to the + input terminal is output from the output terminal. The output signal is input to the A / D conversion unit 112 as a right contact state signal 915, converted into a digital signal, and transmitted to the control unit 101. That is, the right buffer amplifier 913 in this embodiment is configured to be included in the first contact signal output means according to the present invention.

[0041] The potential of the left electrode 12a is input to the positive input terminal of the left non-inverting amplifier 922. A left amplified signal amplified by an amplification factor defined by the second amplification factor determining resistor 932 and the third amplification factor determining resistor 933 is output from the output terminal of the left non-inverting amplifier 922 and input to the positive terminal of the differential amplifier 94. Meanwhile, a signal of the same potential as that input to the positive input terminal of the left non-inverting amplifier 922 is input to the positive input terminal of the left buffer amplifier 923 via the left non-inverting amplifier 922. That is, like the right non-inverting amplifier 912, the left non-inverting amplifier 922 also functions as a normal amplifier and also as a buffer. The resistance values ​​of the first amplification factor determining resistor 931 and the second amplification factor determining resistor 932 are set to the same value.

[0042] The left buffer amplifier 923 functions as a buffer, and a signal having the same potential as the potential input to the + input terminal is output from the output terminal. The output signal is input to the A / D conversion unit 112 as a left contact state signal 925, converted into a digital signal, and transmitted to the control unit 101. That is, the left buffer amplifier 923 in this embodiment is configured to be included in the second contact signal output means according to the present invention.

[0043] The differential amplifier 94 is a differential amplifier that amplifies and outputs the difference between the potential of the first right electrode 12b, which is input to the - input terminal and amplified and output by the right non-inverting amplifier 912, and the potential of the left electrode 12a, which is input to the + input terminal and amplified and output by the left non-inverting amplifier 922. That is, the differential amplifier 94 is included in the amplifier unit 102, and the signal output from the differential amplifier 94 is the electrocardiographic signal to be measured. The electrocardiographic signal is further input to the A / D conversion unit 103, and the digitally converted signal is transmitted to the control unit 101, and is recorded in the storage unit 105 by the control unit 101 as an electrocardiographic waveform.

[0044] As described above, the signal input to the differential amplifier 94 is a signal that has already been amplified by the right non-inverting amplifier 912 and the left non-inverting amplifier 922 before the input stage, so that a signal with a high S / N ratio can be used for electrocardiogram measurement, thereby improving resistance to electromagnetic noise, etc.

[0045] (Experimental example regarding pull-up resistor value) If body movement occurs during electrocardiogram measurement, the human body resistance and the contact resistance between the electrodes and the skin will change, causing the potential of each electrode to fluctuate (this phenomenon is particularly noticeable during electrocardiogram measurement in winter when the skin is prone to drying). For this reason, it is desirable to set the pull-up resistance value high, at several hundred megaohms, so that it is not affected by body movement. Below, we will explain the results of an experiment regarding the pull-up resistance value.

[0046] In the experiment according to this experimental example, electrocardiogram measurements (recordings) were performed with pull-up resistance values ​​of 100MΩ, 200MΩ, 300MΩ, and 400MΩ. The results are shown in Figures 4A to 4D and 5. Figure 4A shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 100MΩ, Figure 4B shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 200MΩ, Figure 4C shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 300MΩ, and Figure 4D shows an example of an electrocardiogram waveform measured when the pull-up resistance value is 400MΩ. Figure 5 is a graph showing the number of electrocardiogram waveforms measured at resistance values ​​of 100MΩ, 200MΩ, 300MΩ, and 400MΩ that met the pass / fail criteria for baseline stability.

[0047] 4A to 4D, the higher the pull-up resistance, the more accurately the electrocardiogram waveform is measured. In particular, when the resistance is 100 MΩ, it can be seen that the baseline of the electrocardiogram fluctuates significantly. On the other hand, when the resistance is 400 MΩ, no such baseline fluctuation is observed and the waveform appears stable.

[0048] The graph in FIG. 5 shows how many of the 26 ECG waveforms pass the test, with the pass / fail criteria being whether they fall within a range of ±500 LSB from the AD value of 1024 LSB (Least Significant Bit), which is the center of the ECG baseline. At 100 MΩ, only 9 ECG waveforms, less than half, pass the test, whereas at a pull-up resistance value of 200 MΩ or more, 20 or more ECG waveforms meet the pass criteria. From this, it is considered desirable to set the pull-up resistance value to 200 MΩ or more. Furthermore, in view of the number of passes at 200 MΩ, 300 MΩ, and 400 MΩ, a pull-up resistance value of 300 MΩ or more is more desirable.

[0049] (Information stored in the memory unit) The contact state classification unit 113, which is a functional module of the control unit 101, classifies the level of the contact state with the skin of each of the first right electrode 12b and the left electrode 12a into four levels, namely, "good contact," "slightly poor contact," "poor contact," and "no contact," using the right contact state signal 915 and the left contact state signal 925 digitally converted by the A / D conversion unit 112. When the right contact state signal 915 and the left contact state signal 925 fluctuate over time, the level indicating the contact state fluctuates to reflect the fluctuation. For this reason, information indicating the classified level of the contact state is recorded in the storage unit 105 as time-series data.

[0050] The measured electrocardiogram waveform and the classified contact state levels are linked to information on the time when each piece of information was acquired and stored in the storage unit 105. For this reason, the electrocardiogram waveform and the contact state level can be used in synchronization, and for example, when the stored electrocardiogram waveform is later checked by displaying it on a display, the contact state levels of the first right electrode 12b and the left electrode 12a at the time when the waveform was detected can be checked together with the electrocardiogram waveform.

[0051] Furthermore, the analysis unit 110 analyzes the measured electrocardiogram waveform for the presence or absence of waveform disturbances, and outputs a result as to whether or not the electrocardiogram waveform at least at the time of measurement is normal. The analysis result is notified to the user by lighting or blinking the analysis result notification LED 14, and is also recorded in the storage unit 105. By using the information stored in this manner, it is possible to display information on the electrocardiogram waveform and contact level in association with information on the analysis result by the analysis unit 110 and information on the measurement time, thereby further improving user convenience.

[0052] (Electrocardiogram measurement processing using a portable electrocardiogram) Next, the operation of the portable electrocardiograph 10 when performing electrocardiogram measurement will be described. Fig. 6 is a flowchart showing the procedure of processing when performing electrocardiogram measurement using the portable electrocardiograph 10.

[0053] 6, the user first operates the power switch 16 to turn on the portable electrocardiograph 10 prior to measurement. Then, the power LED 16a lights up to indicate that the power is on. Then, the user holds the portable electrocardiograph 10 in the right hand, touches the first right electrode 12b and the second right electrode 12c with the right index finger, and touches the left electrode 12a to the skin at the location where measurement is to be performed. Then, the control unit 101 starts detecting the contact state of each electrode and classifying the contact level via the electrode unit 12 and the contact detection unit 111 (S101).

[0054] Next, the control unit 101 executes electrocardiogram measurement processing (S102). While electrocardiogram measurement is being performed, the control unit 101 stores the measured values ​​in the storage unit 105 at any time, and indicates that electrocardiogram measurement is being performed by causing the measurement status notification LED 13 on the front side of the main unit to flash at a predetermined rhythm (S103).

[0055] Next, the control unit 101 performs a process to determine whether the electrocardiogram measurement time has passed a predetermined measurement time (e.g., 30 seconds) (S104). If it is determined that the predetermined time has not yet passed, the process returns to step S102 and repeats the subsequent processes. On the other hand, if it is determined that the predetermined measurement time has passed, the control unit 101 ends the measurement and performs a process to end the blinking of the measurement state notification LED 13 (S105).

[0056] Next, the analysis unit 110 of the control unit 101 analyzes the measurement data (electrocardiogram waveform) stored in the storage unit 105 (S106), and the analysis result is stored in a long-term storage medium together with the electrocardiogram waveform and the classified contact state level (S107). Then, the control unit 101 displays the analysis result using the analysis result notification LED 14 (S108), and ends the series of processes. Note that the analysis result may be displayed, for example, by lighting the LED only when an abnormality is found in the electrocardiogram waveform, or by lighting the LED in a lighting / blinking manner according to the analysis result.

[0057] According to the portable electrocardiograph 10 of the present embodiment configured as described above, the user can start measurement after operating the power switch 16 without performing any other operation than contacting the electrodes with the measurement site. In addition, since pull-up resistors (connected to bias potential) are arranged between each of the first right electrode 12b and the left electrode 12a and the amplifier for buffering and amplifying, noise in the signal indicating the potential of each electrode can be reduced. As a result, even if detection of the electrode contact state and electrocardiogram measurement are performed simultaneously, an accurate electrocardiogram waveform can be obtained with a signal having a high S / N ratio.

[0058] In addition, the contact levels of the first right electrode 12b and the left electrode 12a with respect to the measurement target can be classified into stages and recorded in synchronization with the electrocardiogram waveform. Therefore, when the electrocardiogram waveform is later output to a display or the like for confirmation, the contact levels of each electrode at the time the electrocardiogram waveform was detected can be confirmed together with the electrocardiogram waveform.

[0059] <Modification> The above-described embodiment is merely an illustrative example of the present invention, and the present invention is not limited to the above-described specific embodiment. Various modifications and combinations of the present invention are possible within the scope of the technical concept thereof.

[0060] For example, in the electrical circuit according to the above embodiment, in order to detect the contact state, a signal indicating the potential of the first right-side electrode 12b is input to the right-side buffer amplifier 913 via the right-side non-inverting amplifier 912 and then output to the A / D conversion unit 112. However, it is not necessarily necessary to provide the right-side buffer amplifier 913 in order to detect the contact state.

[0061] An electric circuit diagram relating to such a modified example is shown in Fig. 7. As shown in Fig. 7, a signal indicating the potential of the first right-side electrode 12b is amplified and output by a right-side non-inverting amplifier 912, and the amplified signal is input to an input terminal of a differential amplifier 94 and is also output as is as a right-side contact state signal 915. The same applies to the circuit relating to detection of the contact state of the left-side electrode 12a.

[0062] Although not shown here, a modified example is also possible in which the right buffer amplifier 913 is omitted and a signal having the same potential as the negative input terminal of the right non-inverting amplifier 912 (similar to the circuit diagram of the embodiment shown in FIG. 3) is output as it is as the right contact state signal 915. The same applies to the circuit related to detection of the contact state of the left electrode 12a.

[0063] <Other> In addition, in the above embodiment, the right contact state signal 915 and the left contact state signal 925 are configured to be output to the A / D conversion unit 112, but this is not necessarily limited thereto, and may be configured to be output to a comparator for determining the contact state in two stages, for example. Although not described in detail in the above embodiment, the BLE communication function of the communication unit 109 allows the electrocardiograph to be used in cooperation with other information terminal devices. Conversely, it is also possible to provide an electrocardiograph that does not have a communication function or an LED display unit.

[0064] Although the present invention has been applied to a portable electrocardiograph in the above, the present invention can also be applied to a non-portable electrocardiograph, and can also be applied to biological information measuring devices other than an electrocardiograph. [Explanation of symbols]

[0065] 10. Portable electrocardiograph 12a...Left electrode 12b...First right electrode 12c...Second right electrode 13 Measurement status notification LED 14...Analysis result notification LED 15 Battery cover 16 Power switch 16a...Power LED 17 Communication button 17a...BLE communication LED 18. Remaining memory indicator LED 19 Battery replacement LED 911 Right pull-up resistor 912 Right non-inverting amplifier 913 Right side buffer amplifier 915...Right side contact status signal 921 Left pull-up resistor 922 Left non-inverting amplifier 923 Left side buffer amplifier 925: Left contact status signal 931: First gain determining resistor 932: Second gain determining resistor 933 Third amplification factor determining resistor 94 Differential Amplifier 941: ECG signal GND: Reference potential V1...Power supply potential

Claims

1. A biological information measuring device comprising a first electrode, a second electrode, and a third electrode, the biological information measuring device measuring biological information of a measurement target based on a potential difference between the first electrode and the second electrode, with a potential of the third electrode being set as a reference potential, a first non-inverting amplifier circuit including a first amplifier having a non-inverting input terminal to which the potential of the first electrode is input; a first pull-up resistor connected between the first electrode and the first non-inverting amplifier circuit; a first contact signal output means including the first non-inverting amplifier circuit and a first A / D converter, and outputting a signal relating to a contact state of the first electrode with the measurement object using an output signal from the first non-inverting amplifier circuit; a second non-inverting amplifier circuit including a second amplifier having a non-inverting input terminal to which the potential of the second electrode is input; a second pull-up resistor connected between the second electrode and the second non-inverting amplifier circuit; a second contact signal output means including the second non-inverting amplifier circuit and a second A / D converter, and outputting a signal relating to a contact state of the second electrode with the measurement object using an output signal from the second non-inverting amplifier circuit; a differential amplifier circuit that amplifies a difference between a first amplified potential amplified and output by the first non-inverting amplifier circuit and a second amplified potential amplified and output by the second non-inverting amplifier circuit, and outputs the biological information; a contact state classification means for classifying the contact states of the first electrode and the second electrode with respect to the measurement object into at least three levels using the digital signals output from the first A / D converter and the second A / D converter; a control means for executing a process for measuring the biological information; A biological information measuring device having the same.

2. the first contact signal output means outputs a signal relating to a contact state of the first electrode with the measurement object using the first amplified potential; the second contact signal output means outputs a signal relating to a contact state of the second electrode with the measurement object using the second amplified potential.

2. The biological information measuring device according to claim 1, wherein:

3. The device further includes a storage means for storing a signal relating to a contact state of the first electrode with respect to the measurement object and a signal relating to a contact state of the second electrode with respect to the measurement object during at least the measurement process of the biological information.

2. The biological information measuring device according to claim 1, wherein:

4. The method further includes a storage means for storing the classified information on the contact state during at least the measurement process of the biological information.

2. The biological information measuring device according to claim 1, wherein:

5. the first pull-up resistor and the second pull-up resistor have a resistance value of 200 MΩ or more; 2. The biological information measuring device according to claim 1, wherein:

6. the first pull-up resistor and the second pull-up resistor have a resistance value of 300 MΩ or more; 6. The biological information measuring device according to claim 5.

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