阅读说明：本技术 心电图信号处理装置、个人认证装置以及心电图信号处理方法 (Electrocardiogram signal processing device, personal authentication device, and electrocardiogram signal processing method ) 是由 松本秋宪 于 2018-05-29 设计创作，主要内容包括：心电图信号处理装置(10)具备：信号处理电路(12),其将通过安装于生物体的电极(11)检测到的心电图信号放大后输出；以及同相信号生成电路(13),其使用由信号处理电路(12)放大后的心电图信号,来生成用于使心电图信号所示的心电图波形中的峰的振幅变大的同相信号,并将所生成的同相信号施加于电极(11)。(An electrocardiogram signal processing device (10) is provided with: a signal processing circuit (12) which amplifies and outputs an electrocardiogram signal detected by an electrode (11) attached to a living body; and an in-phase signal generation circuit (13) that generates an in-phase signal for increasing the amplitude of a peak in an electrocardiogram waveform shown by the electrocardiogram signal using the electrocardiogram signal amplified by the signal processing circuit (12), and applies the generated in-phase signal to the electrodes (11).)

1. An electrocardiogram signal processing device is provided with:

a signal processing circuit for amplifying and outputting an electrocardiogram signal detected by an electrode attached to a living body; and

and an in-phase signal generation circuit that generates an in-phase signal for increasing the amplitude of a peak in an electrocardiogram waveform shown by the electrocardiogram signal using the electrocardiogram signal amplified by the signal processing circuit, and applies the generated in-phase signal to the electrodes.

2. The electrocardiogram signal processing apparatus of claim 1,

the in-phase signal generation circuit includes:

a frequency determination unit that determines a frequency corresponding to a time difference between a peak of a P wave and a peak of an R wave in the electrocardiographic waveform; and

and a signal generating unit that generates a signal having the frequency determined by the frequency determining unit as the in-phase signal.

3. The electrocardiogram signal processing apparatus of claim 1,

the in-phase signal generation circuit includes:

a frequency determination unit that determines a frequency corresponding to a time difference between a peak of a Q wave or an S wave and a peak of a T wave in the electrocardiographic waveform; and

and a signal generating unit that generates a signal having the frequency determined by the frequency determining unit as the in-phase signal.

4. The electrocardiogram signal processing apparatus of claim 2 or 3,

the in-phase signal generation circuit further includes an amplitude determination unit that determines an amplitude of the in-phase signal to be generated based on an amplitude of a peak in the electrocardiogram waveform,

the signal generating unit generates a signal having the amplitude determined by the amplitude determining unit as the in-phase signal.

5. The electrocardiogram signal processing apparatus according to any one of claims 2 to 4, wherein,

the in-phase signal generation circuit includes a phase determination unit that generates a control signal for temporarily shifting a phase or temporarily reducing an amplitude of an in-phase signal to be generated,

the signal generating unit generates, as the in-phase signal, a signal including a portion where a phase is temporarily shifted or an amplitude is temporarily decreased, based on the control signal generated by the phase determining unit.

6. The electrocardiogram signal processing apparatus according to any one of claims 1 to 5, wherein,

the electrode to be attached to a living body includes a measurement electrode and a reference electrode,

the signal processing circuit has:

a differential amplifier that amplifies a difference between a signal detected by the measurement electrode and a signal detected by the reference electrode; and

an A/D converter converting a signal output from the differential amplifier into a digital signal,

the in-phase signal generation circuit applies the in-phase signal to the reference electrode using the digital signal output from the a/D converter.

7. A personal authentication device is provided with:

an electrocardiogram signal processing apparatus according to any one of claims 1 to 6;

a storage unit that stores registration information in which a feature amount of an electrocardiogram waveform indicated by an electrocardiogram signal output from the signal processing circuit provided in the electrocardiogram signal processing apparatus is associated with each of a plurality of users; and

an authentication unit that identifies, for a subject, which of the plurality of users the subject is by comparing a feature amount of an electrocardiogram waveform shown in an electrocardiogram signal output by the signal processing circuit provided in the electrocardiogram signal processing apparatus with the registration information held in the storage unit.

8. An electrocardiogram signal processing method comprises the following steps:

a signal acquisition step of acquiring an electrocardiogram signal detected by an electrode attached to a living body; and

an in-phase signal generating step of generating an in-phase signal for increasing an amplitude of a peak in an electrocardiogram waveform shown by the electrocardiogram signal acquired in the signal acquiring step, and applying the generated in-phase signal to the electrodes.

9. A program for causing a computer to execute the steps included in the electrocardiogram signal processing method according to claim 8.

Technical Field

The present invention relates to an electrocardiogram signal processing apparatus, a personal authentication apparatus, and an electrocardiogram signal processing method, and more particularly to a technique for improving accuracy of personal authentication using an electrocardiogram signal.

Background

Electrocardiograph (ecg) signals are electrical signals caused by periodic heart motion, and it is known that waveform patterns of 1 cycle of an electrocardiograph signal (hereinafter referred to as "heartbeat patterns") of each person exhibit different characteristics. In view of this, a personal authentication technique using an electrocardiogram signal has been proposed (for example, see patent document 1).

In patent document 1, the measurement device includes a body impedance measurement unit and an electrocardiogram signal measurement unit that operate simultaneously and in parallel. Thus, a measurement failure or the like is determined using the obtained biological impedance, and then personal authentication is performed using an electrocardiogram signal, thereby realizing highly reliable personal authentication.

Disclosure of Invention

Problems to be solved by the invention

However, in the technique of patent document 1, when the contact resistance between the electrode and the living body is high, for example, when measurement is performed using a so-called dry electrode that does not use conductive paste, there are the following problems: a stable electrocardiogram signal cannot be acquired, and thus personal authentication cannot be performed with high accuracy. This is because, when the contact impedance is high, the electrocardiographic signal is affected by interference noise such as hum noise (hum noise), and the peaks of the P-wave, Q-wave, R-wave, S-wave, T-wave, and U-wave in the heartbeat pattern are unstable.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electrocardiogram signal processing apparatus and the like capable of stably measuring an electrocardiogram signal even when contact impedance between an electrode and a living body is high.

Means for solving the problems

In order to achieve the above object, an electrocardiogram signal processing apparatus according to an aspect of the present invention includes: a signal processing circuit for amplifying and outputting an electrocardiogram signal detected by an electrode attached to a living body; and an in-phase signal generation circuit that generates an in-phase signal for increasing the amplitude of a peak in an electrocardiogram waveform shown by the electrocardiogram signal using the electrocardiogram signal amplified by the signal processing circuit, and applies the generated in-phase signal to the electrodes.

In order to achieve the above object, a personal authentication device according to an aspect of the present invention includes: the electrocardiogram signal processing device; a storage unit that stores registration information in which a feature amount of an electrocardiogram waveform indicated by an electrocardiogram signal output from the signal processing circuit provided in the electrocardiogram signal processing apparatus is associated with each of a plurality of users; and an authentication unit that identifies, for a subject, which of the plurality of users the subject is by comparing a feature amount of an electrocardiogram waveform shown in an electrocardiogram signal output by the signal processing circuit provided in the electrocardiogram signal processing apparatus with the registration information held in the storage unit.

In order to achieve the above object, an electrocardiogram signal processing method according to an aspect of the present invention includes: a signal acquisition step of acquiring an electrocardiogram signal detected by an electrode attached to a living body; and an in-phase signal generating step of generating an in-phase signal for increasing an amplitude of a peak in an electrocardiogram waveform shown by the electrocardiogram signal acquired in the signal acquiring step, and applying the generated in-phase signal to the electrodes.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can realize an electrocardiogram signal processing device and an electrocardiogram signal processing method that can stably measure an electrocardiogram signal even when contact impedance between an electrode and a living body is high, and a personal authentication device provided with the electrocardiogram signal processing device.

Drawings

Fig. 1 is an external view showing a configuration of a personal authentication device according to an embodiment.

Fig. 2A is a diagram showing an example of arrangement of electrodes provided in the electrocardiographic signal processing device shown in fig. 1.

Fig. 2B is a diagram showing a state in which the subject is seated on the electrocardiographic signal processing device shown in fig. 2A.

Fig. 3 is a diagram showing another embodiment of the electrocardiogram signal processing apparatus.

Fig. 4 is a diagram showing still another embodiment of the electrocardiogram signal processing apparatus.

Fig. 5 is a diagram showing an example of the shape of an electrode provided in the electrocardiogram signal processing apparatus.

Fig. 6 is a block diagram showing a configuration of a personal authentication device according to an embodiment.

Fig. 7 is a block diagram showing a detailed configuration of the electrocardiogram signal processing apparatus shown in fig. 6.

Fig. 8 is a diagram showing a heartbeat pattern of an electrocardiogram signal.

Fig. 9 is a flowchart showing a process of the electrocardiographic signal processing device of the personal authentication device according to the embodiment.

Fig. 10 is a flowchart showing a process of the information processing apparatus of the personal authentication apparatus according to the embodiment.

Fig. 11 is a diagram showing an example of display of the display unit when the information processing apparatus performs personal authentication.

Fig. 12 is a diagram showing feature values in a heartbeat pattern of an electrocardiogram waveform.

Fig. 13 is a diagram showing an example of the waveform of an electrocardiographic signal (referred to as registration data a) in the case where an in-phase signal is not superimposed on an electrocardiographic signal processing device.

Fig. 14 is a diagram showing an example of a waveform of an electrocardiogram signal (referred to as registration data B) in a case where an in-phase signal is superimposed on an electrocardiogram signal processing apparatus.

Fig. 15 is a diagram showing an example of a waveform of another electrocardiogram signal (referred to as registration data C) in the case where an in-phase signal is not superimposed on the electrocardiogram signal processing apparatus.

Fig. 16 is a diagram showing the result of personal authentication performed using the electrocardiographic waveforms of the registered data a to C after the feature values of the electrocardiographic waveforms have been registered.

Fig. 17 is a block diagram showing a configuration of an electrocardiographic signal processing device according to a modification of the embodiment.

Fig. 18 is a diagram showing an example of the waveform of an electrocardiogram signal in the case where an in-phase signal is superimposed on the electrocardiogram signal processing apparatus according to the modification.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below are all specific examples of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connection modes of the constituent elements, steps, order of the steps, and the like shown in the following embodiments are examples, and the present invention is not limited thereto. Further, among the components in the following embodiments, components not described in the independent claims representing the uppermost concept of the present invention will be described as arbitrary components. The drawings are not strictly illustrated. In the drawings, substantially the same components are denoted by the same reference numerals, and redundant description is omitted or simplified.

Fig. 1 is an external view showing a configuration of a personal authentication device 100 according to an embodiment. In this figure, the subject 5 to be authenticated is also shown.

The personal authentication device 100 is a device that performs personal authentication on the subject 5, and is configured by an electrocardiographic signal processing device 10, an information processing device 20, and a display unit 25.

The electrocardiographic signal processing device 10 is a measuring device having a structure for a chair in which the subject 5 sits down, measures electrocardiographic signals on the back of the thighs (the posterior femoral muscle group) of the subject 5, and wirelessly transmits the measured electrocardiographic signals to the information processing device 20. The electrocardiogram signal processing apparatus 10 does not necessarily have a chair structure. The electrocardiogram signal processing apparatus 10 may be mounted in a structure that is a chair for different individuals.

The information processing apparatus 20 is an apparatus that: the electrocardiographic signal wirelessly transmitted from the electrocardiographic signal processing device 10 is used to perform personal authentication on the subject 5, and the result thereof is displayed on the display unit 25. The information processing device 20 is implemented by a computer device having a nonvolatile memory such as a hard disk or a ROM that holds programs, a RAM that temporarily holds information, a processor that executes programs, an input/output port for connecting to peripheral devices, and the like. The information processing device 20 is, for example, a personal computer, a portable information terminal such as a smart phone, or the like.

The Display unit 25 is a Display for displaying the result of personal authentication performed by the information processing device 20, and is, for example, an LCD (Liquid Crystal Display). As an output device constituting the personal authentication apparatus 100, an audio output device may be provided instead of the display unit 25 or in addition to the display unit 25.

The personal authentication apparatus 100 may further include an input device (not shown) such as a remote controller or a button for giving instructions to the electrocardiographic signal processing device 10 and the information processing device 20 by the subject 5. The input device may be a separate device connected to the electrocardiographic signal processing device 10 and the information processing device 20 by wire or wirelessly, or may be a device fixed to the electrocardiographic signal processing device 10 or the information processing device 20 by embedding.

Fig. 2A is a diagram showing an example of arrangement of the electrodes 11 provided in the electrocardiographic signal processing device 10 shown in fig. 1. Here, the electrodes 11 are provided at 2 (for the measurement electrodes and the reference electrodes) on the upper surface of the rectangular parallelepiped chair structure so as to be in contact with the back surfaces of the two thighs of the subject 5 when the subject 5 sits on the electrocardiographic signal processing device 10 having the rectangular parallelepiped chair structure. The material of the electrode 11 is, for example, gold, silver, or silver-silver chloride (Ag/AgCl) or the like. The electrode 11 is not necessarily provided in the electrocardiographic signal processing device 10, and an electrode worn in advance by the subject 5 may be used.

Fig. 2B is a diagram showing a state in which the subject 5 is seated on the electrocardiographic signal processing device 10 shown in fig. 2A. The electrode 11 is located on the back of the thigh of the subject 5. The subject 5 may wear clothes such as trousers without exposing the thighs. Electrocardiographic signals of the backs of the thighs of the subject 5 are detected by the electrodes 11 through the clothes. This is because, in the present embodiment, the electrocardiographic signal processing device 10 can stably measure an electrocardiographic signal even when the contact impedance between the electrode and the living body is high.

The form and the installation position of the electrocardiograph signal processing device 10 and the electrodes 11 are not limited to those shown in fig. 1, 2A, and 2B, and may be those shown in fig. 3 and 4, for example.

Fig. 3 is a diagram showing another embodiment of the electrocardiographic signal processing device 10. Here, the electrocardiographic signal processing device 10 is a patch-type electrocardiographic sensor attached to the left chest of the subject 5 via the electrodes 11.

Fig. 4 is a diagram showing another embodiment of the electrocardiographic signal processing device 10. Here, the electrocardiographic signal processing device 10 has a structure like a small-sized portable operation controller, and has an electrode 11 to be contacted by the thumb of the subject 5 at 2 on the front surface of a rectangular parallelepiped case.

Fig. 5 is a diagram showing an example of the shape of the electrode 11 included in the electrocardiographic signal processing device 10. The shape of the electrode 11 may be any of a circle as shown in fig. 5 (a), an ellipse as shown in fig. 5 (b), a square as shown in fig. 5 (c), a rectangle as shown in fig. 5 (d), and a combination thereof (a combination of a plurality of electrodes 11).

Fig. 6 is a block diagram showing the configuration of the personal authentication device 100 according to the present embodiment. The personal authentication apparatus 100 is composed of an electrocardiogram signal processing apparatus 10, an information processing apparatus 20, and a display unit 25.

The electrocardiogram signal processing apparatus 10 includes an electrode 11, a signal processing circuit 12, an in-phase signal generating circuit 13, and a communication unit 14.

As shown in fig. 2A and 2B, the electrode 11 is an electrode (an electrode including a measurement electrode and a reference electrode) attached to a living body, and may be not only a dry electrode but also a wet electrode. The term "attached to a living body" means that the device is provided in a position close to the living body so as to be able to measure an electrocardiogram signal from the living body, and includes not only a case where the device is in direct contact with the skin of the living body but also a case where the device is relatively fixed to the living body via clothing or the like.

The signal processing circuit 12 is a circuit that amplifies and outputs an electrocardiogram signal detected by the electrode 11 attached to the living body.

The in-phase signal generation circuit 13 is a circuit including: using the electrocardiogram signal amplified by the signal processing circuit 12, an in-phase signal for increasing the amplitude of the peak in the electrocardiogram waveform shown by the electrocardiogram signal is generated, and the generated in-phase signal is applied to the electrodes 11.

The communication unit 14 is a communication interface for transmitting information on the electrocardiogram signal output from the signal processing circuit 12 to the information processing device 20, and is, for example, a wireless communication adapter for Bluetooth (registered trademark) or WiFi (registered trademark). Here, the "information on the electrocardiogram signal" is meant to include at least one of the electrocardiogram signal and a feature quantity (information on a peak of an electrocardiogram waveform, etc.) obtained by signal processing for the electrocardiogram signal. The communication unit 14 is not limited to wireless communication, and may be a communication interface for wired communication.

Although not shown, the electrocardiographic signal processing device 10 includes a power supply circuit that supplies dc power to the signal processing circuit 12, the in-phase signal generation circuit 13, and the communication unit 14. The power supply circuit is configured by a battery, a DC/DC converter that converts the voltage of the battery into a desired DC voltage, a regulator circuit that generates a fixed DC voltage based on a commercial power supply, or the like.

The information processing device 20 includes a communication unit 21, an authentication unit 22, and a storage unit 23.

The communication unit 21 is a communication interface that receives information relating to an electrocardiogram signal transmitted from the electrocardiogram signal processing apparatus 10, and is, for example, a wireless communication adapter for Bluetooth (registered trademark) or WiFi (registered trademark). The communication unit 21 is not limited to wireless communication, and may be a communication interface for wired communication.

The storage unit 23 is a device, such as a hard disk, that holds registration information obtained by associating feature quantities of an electrocardiogram waveform shown in an electrocardiogram signal output from the signal processing circuit 12 of the electrocardiogram signal processing device 10 with respective users (user identifiers) among the plurality of users.

The authentication unit 22 is a processing unit that: the feature amount of the electrocardiographic waveform shown in the electrocardiographic signal output from the signal processing circuit 12 of the electrocardiographic signal processing device 10 is compared with the registered information held in the storage unit 23 with respect to the subject 5, thereby identifying which of the plurality of users the subject is. The authentication unit 22 displays the result of the recognition on the display unit 25. As described above, such an authentication section 22 is realized by executing a program by a processor provided in the information processing apparatus 20. The authentication unit 22 performs not only such a process of personal authentication but also a process of acquiring registration information and registering the registration information in the storage unit 23. Specifically, the authentication unit 22 extracts a feature amount necessary for personal authentication from the electrocardiographic signal transmitted from the electrocardiographic signal processing device 10, or acquires the feature amount transmitted from the electrocardiographic signal processing device 10. Then, the extracted or acquired feature amount is stored in the storage unit 23 as registration information in association with the subject 5.

Although not shown, the information processing device 20 includes a power supply circuit that supplies dc power to the communication unit 21, the authentication unit 22, and the storage unit 23. The power supply circuit is configured by a regulator circuit or the like that generates a fixed dc voltage from a commercial power supply.

Fig. 7 is a block diagram showing a detailed configuration of the electrocardiogram signal processing apparatus 10 shown in fig. 6. Here, a detailed circuit diagram of the signal processing circuit 12 and the in-phase signal generating circuit 13 constituting the electrocardiogram signal processing apparatus 10 is shown. In addition, an equivalent circuit of the subject 5 (that is, a signal source 5a of an electrocardiogram signal) is also illustrated in the left part of the figure.

The signal processing circuit 12 includes electrodes 11 (a measurement electrode 11a and a reference electrode 11b), buffer amplifiers (buffers) 30a and 30b, high- pass filters 31a and 31b, a difference amplifier 32, a low-pass filter 33, an a/D converter 34, and a biological potential processing unit 35.

The measurement electrode 11a and the reference electrode 11b are an electrode for measurement and an electrode for measuring a reference potential, respectively.

The buffer amplifiers 30a and 30b are circuits for performing impedance conversion of signals (that is, potentials) detected by the measurement electrode 11a and the reference electrode 11b, and are, for example, voltage followers or the like. That is, the buffer amplifiers 30a and 30b have high input impedance and low output impedance, and do not perform voltage amplification (voltage amplification ratio is 1). In the present specification, the term "amplifier" (or "amplifier") is not limited to an amplifier having a voltage amplification factor larger than 1, and includes an amplifier that performs only impedance conversion (having a voltage amplification factor of 1). The measurement electrode 11a and the buffer amplifier 30a are integrated to form an active electrode. The reference electrode 11b is also similar to the buffer amplifier 30 b. The buffer amplifiers 30a and 30b may have a voltage amplification factor greater than 1.

The high- pass filters 31a and 31b are filters for removing unnecessary low-frequency components from the output signals from the buffer amplifiers 30a and 30b, respectively, and are, for example, CR filters or active filters using operational amplifiers.

The differential amplifier 32 is an amplifier that subtracts the output signal from the high-pass filter 31b from the output signal from the high-pass filter 31a and amplifies the obtained difference, and is configured by, for example, an operational amplifier or the like. The differential amplifier 32 is an example of a circuit that amplifies the difference between the signal detected by the measurement electrode 11a and the signal detected by the reference electrode 11 b. That is, the output signal from the differential amplifier 32 becomes an electrocardiogram signal indicating the potential at the measurement electrode 11a with respect to the potential at the reference electrode 11 b.

The low-pass filter 33 is a filter for removing unnecessary high-frequency components from the output signal from the differential amplifier 32, and is, for example, a CR filter or an active filter using an operational amplifier.

The a/D converter 34 is a converter that samples the output signal from the low-pass filter 33 to convert the output signal into a digital signal, and converts the output signal into a 12-bit digital signal by 1kHz sampling, for example. The a/D converter 34 is an example of an a/D converter that converts the signal output from the differential amplifier 32 into a digital signal.

The biological potential processing unit 35 includes a peak detection unit 35a, and the peak detection unit 35a detects peaks of a P wave, a Q wave, an R wave, an S wave, and a T wave in the heartbeat pattern with respect to an output signal (that is, a digital electrocardiogram signal) from the a/D converter 34. The heartbeat pattern is as shown in fig. 8. Specifically, the peak detecting unit 35a generates information on peaks of P-waves, Q-waves, R-waves, S-waves, and T-waves of the heartbeat pattern (that is, signals indicating the time and amplitude of the peaks) included in the electrocardiographic signal output from the a/D converter 34. The generated information on the peak is then output to the frequency determining unit 40a and the amplitude determining unit 40b of the in-phase signal generating circuit 13.

The biological potential processing unit 35 basically transmits the output signal (that is, a digital electrocardiogram signal) from the a/D converter 34 to the information processing device 20 via the communication unit 14. However, according to a setting in advance (such as an instruction by an input device (not shown)), the biological potential processing unit 35 transmits the electrocardiogram signal to the information processing device 20 via the communication unit 14, and also transmits information on the peak detected by the peak detecting unit 35a to the information processing device 20 via the communication unit 14 as a feature amount.

In the present embodiment, the biopotential processing unit 35 is provided in the electrocardiographic signal processing device 10, but is not limited to this embodiment, and may be provided in the information processing device 20 instead of or in addition to this. In this case, the output signal from the a/D converter 34 is transmitted to the information processing device 20 via the communication unit 14, and information on the peak is generated in the peak detection unit 35a included in the biological potential processing unit 35 provided in the information processing device 20. The generated peak-related information is transmitted to the electrocardiographic signal processing device 10 via the communication unit 21 of the information processing device 20 and the communication unit 14 of the electrocardiographic signal processing device 10, and is used by the frequency determination unit 40a and the amplitude determination unit 40 b.

The in-phase signal generation circuit 13 includes a frequency determination unit 40a, an amplitude determination unit 40b, a signal generation unit 41, and a coupling capacitor 42.

The frequency determination unit 40a determines a frequency corresponding to a time difference between a peak of a P-wave and a peak of an R-wave in the electrocardiographic waveform in the first mode, and determines a frequency corresponding to a time difference between a peak of a Q-wave or an S-wave and a peak of a T-wave in the electrocardiographic waveform in the second mode. Specifically, in the first mode, the frequency determination unit 40a calculates a time difference between a peak of the P-wave and a peak of the R-wave using the information on the peak detected by the peak detection unit 35a, and determines a frequency having the calculated time difference as a cycle. In the second mode, the frequency determination unit 40a calculates a time difference between a peak of the Q-wave or S-wave (for example, a peak having a large amplitude) and a peak of the T-wave using the information about the peak detected by the peak detection unit 35a, and determines a frequency having the calculated time difference as a cycle. The first mode and the second mode are determined by a predetermined setting (instruction by an input device (not shown), for example).

The amplitude determination unit 40b determines the amplitude of the in-phase signal to be generated based on the amplitude of the peak in the electrocardiogram waveform. Specifically, the amplitude determining unit 40b calculates the amplitude of the peak of the R-wave having the largest amplitude among the peaks (for example, the average value of the R-wave height values) using the information about the peaks detected by the peak detecting unit 35 a. Then, the smaller the calculated amplitude of the peak of the R wave, the larger the value as the amplitude of the in-phase signal. For example, the amplitude determination unit 40b previously holds a table in which a plurality of amplitude sections relating to the amplitude of the peak of the R wave are associated with the amplitude of the in-phase signal to be determined. Then, the amplitude determination unit 40b determines the amplitude of the in-phase signal corresponding to the amplitude of the peak of the R wave in the electrocardiographic waveform by referring to the table.

The signal generator 41 generates a signal having the frequency determined by the frequency determining unit 40a and having the amplitude determined by the amplitude determining unit 40b as an in-phase signal. Specifically, the signal generation unit 41 generates a sample data sequence having the frequency determined by the frequency determination unit 40a and the amplitude determined by the amplitude determination unit 40b, converts the sample data sequence into an analog signal by a built-in D/a converter, and passes the analog signal through a built-in low-pass filter. Thus, a sinusoidal signal (for example, a sinusoidal signal of 3Hz and 100 mVpp) having the frequency determined by the frequency determination unit 40a and the amplitude determined by the amplitude determination unit 40b is generated as an in-phase signal for increasing the amplitude of the peak in the electrocardiographic waveform. Furthermore, the in-phase signal need not be synchronized with the electrocardiogram waveform (the peaks of the sine wave of the in-phase signal coincide with the peaks in the electrocardiogram waveform).

The coupling capacitor 42 is a capacitor connected between the output terminal of the signal generating unit 41 and the reference electrode 11b, and applies only the AC component of the output signal from the signal generating unit 41 to the reference electrode 11 b. The coupling capacitor 42 is, for example, a 100pF capacitor.

The digital signal processing in the biological potential processing unit 35, the frequency determining unit 40a, the amplitude determining unit 40b, and the signal generating unit 41 may be implemented by hardware using dedicated logic circuits, or may be implemented by software using programs. In the case of software implementation, the implementation can be realized by a microcomputer having a nonvolatile memory such as a ROM that holds programs, a RAM that temporarily holds information, a processor that executes programs, input/output ports for connection to peripheral circuits, and the like, for example.

Next, the operation of the personal authentication apparatus 100 according to the present embodiment configured as described above will be described.

Fig. 9 is a flowchart showing the processing (electrocardiogram signal processing method) of the electrocardiogram signal processing apparatus 10 of the personal authentication apparatus 100 according to the present embodiment.

The signal processing circuit 12 acquires an electrocardiogram signal detected by the electrodes 11 (the measurement electrode 11a and the reference electrode 11b) attached to the living body (signal acquisition step S10).

Specifically, the signal detected by the measurement electrode 11a is impedance-converted by the buffer amplifier 30a, unnecessary low-frequency components are removed by the high-pass filter 31a, and then the signal is input to the positive input terminal of the differential amplifier 32. On the other hand, the signal detected by the reference electrode 11b is subjected to impedance conversion by the buffer amplifier 30b, and unnecessary low-frequency components are removed by the high-pass filter 31b, and then, the signal is input to the negative input terminal of the differential amplifier 32. In the differential amplifier 32, the difference between the signal input to the positive input terminal and the signal input to the negative input terminal is amplified. The amplified signal is subjected to low-pass filter 33 to remove unnecessary high-frequency components, and then converted into a digital electrocardiogram signal by a/D converter 34, and input to biopotential processing unit 35. The biological potential processing unit 35 generates information on peaks of P-waves, Q-waves, R-waves, S-waves, and T-waves of the heartbeat pattern included in the electrocardiographic signal output from the a/D converter 34 (that is, signals indicating the time and amplitude of the peaks), and outputs the generated information to the in-phase signal generating circuit 13 (the frequency determining unit 40a and the amplitude determining unit 40 b).

Next, an in-phase signal for increasing the amplitude of the peak in the electrocardiogram waveform indicated by the electrocardiogram signal acquired in the signal acquisition step S10 is generated, and the generated in-phase signal is applied to the reference electrode 11b (in-phase signal generation step S20).

More specifically, the frequency determination unit 40a determines a frequency corresponding to a time difference between a peak of a P-wave and a peak of an R-wave in the electrocardiographic waveform in the first mode, and determines a frequency corresponding to a time difference between a peak of a Q-wave or an S-wave and a peak of a T-wave in the electrocardiographic waveform in the second mode (S21). Specifically, in the first mode, the frequency determination unit 40a calculates a time difference between a peak of the P-wave and a peak of the R-wave using the information on the peak detected by the peak detection unit 35a, and determines a frequency having the calculated time difference as a cycle. In the second mode, the frequency determination unit 40a calculates a time difference between a peak of the Q-wave or S-wave (for example, a peak having a large amplitude) and a peak of the T-wave using the information about the peak detected by the peak detection unit 35a, and determines a frequency having the calculated time difference as a cycle.

Next, the amplitude determination unit 40b determines the amplitude of the in-phase signal to be generated based on the amplitude of the peak in the electrocardiogram waveform (S22). Specifically, the amplitude determining unit 40b calculates the amplitude of the peak of the R wave using the information about the peak detected by the peak detecting unit 35a, and determines the larger the calculated amplitude of the peak of the R wave, the larger the value as the amplitude of the in-phase signal.

Finally, the signal generating unit 41 generates a signal having the frequency determined by the frequency determining unit 40a and the amplitude determined by the amplitude determining unit 40b as an in-phase signal, and applies the signal to the reference electrode 11b via the coupling capacitor 42 (S23).

Further, the above-described signal acquisition step S10 and in-phase signal generation step S20 are repeatedly performed at a fixed cycle, and are simultaneously performed in parallel. Therefore, once the in-phase signal is generated in the in-phase signal generating step S20 and applied to the reference electrode 11b, the electrocardiogram signal is acquired in a state in which the in-phase signal is applied to the reference electrode 11b, that is, in a state in which the in-phase signal is superimposed, in the signal acquiring step S10.

Fig. 10 is a flowchart showing the processing (personal authentication method) of the information processing device 20 of the personal authentication device 100 according to the present embodiment. Fig. 11 is a diagram showing an example of display of the display unit 25 when the information processing device 20 performs personal authentication.

When the personal authentication is started, the authentication unit 22 first displays "during measurement of an electrocardiographic waveform" on the measurement information display unit 25a of the display unit 25 (S41), and then displays the electrode display unit 25c indicating the electrode position on the display unit 25 (S42).

Next, the authentication unit 22 instructs the electrocardiographic signal processing device 10 via the communication unit 21 to start measurement of the electrocardiographic signal by the electrocardiographic signal processing device 10, and acquires the electrocardiographic signal via the communication unit 21 of the electrocardiographic signal processing device 10 (S43). Then, the authentication unit 22 extracts a specific frequency component from the acquired electrocardiogram signal, calculates the power spectral density of the extracted frequency component, and extracts information that is significant as an electrocardiogram waveform, thereby adjusting the electrocardiogram waveform (S44).

Next, the authentication unit 22 displays the adjusted electrocardiographic waveform on the display unit 25 as the electrocardiographic waveform display unit 25b (S45), and performs personal authentication in parallel with this (S51 to S57).

In the individual authentication (S51 to S57), the authentication unit 22 first displays the measurement information display unit 25a of the display unit 25 as "being authenticated by electrocardiographic waveform" (S51). Then, the authentication unit 22 detects each peak in the heartbeat pattern by differentiating the adjusted electrocardiographic waveform (S52), and normalizes the amplitude of the electrocardiographic waveform by calculating the relative wave height value of each peak (S53).

Next, the authentication unit 22 generates a feature quantity of the heartbeat pattern shown in fig. 12 as a signature (signature) based on the normalized electrocardiographic waveform (S54). Fig. 12 shows, as characteristic quantities, "P-wave height" indicating the height of a P-wave, "Q-wave height" indicating the height of a Q-wave, "R-wave height" indicating the height of an R-wave, "S-wave height" indicating the height of an S-wave, "T-wave height" indicating the height of a T-wave, "Rq-wave height value" indicating the height difference between an R-wave and a Q-wave, "Pq-wave height value" indicating the height difference between a P-wave and a Q-wave, "Ts-wave height value" indicating the height difference between a T-wave and an S-wave, "Rs-slope" indicating the slope from an R-wave to an S-wave, and "Ss-slope" indicating the slope of the latter half of the peak of an S-wave.

Next, the authentication unit 22 acquires the registration information stored in the storage unit 23 (S55), and authenticates the user corresponding to the signature generated in step S54 with reference to the acquired registration information (S56). That is, a feature quantity most similar to the signature is specified from among the feature quantities registered in the registration information, and the user (user identifier) corresponding to the specified feature quantity is output as a result of personal authentication.

Finally, the authentication unit 22 displays the result of the personal authentication on the display unit 25 as the authentication result display unit 25d (S57). In the example of display of the authentication result display unit 25d shown in fig. 11, the result (probability) of individual authentication for a user identifier of 3 persons is displayed. The user identifier of 3 persons is the user identifier of the first 3 digits from the most similar person to the signature, or a user identifier registered in advance.

Fig. 13 to 16 are diagrams for explaining the features of the personal authentication device 100 according to the present embodiment. More specifically, fig. 13 is a diagram showing a waveform example (that is, an original waveform) of an electrocardiogram signal (referred to as registration data a) in a case where an in-phase signal is not superimposed on the electrocardiogram signal processing apparatus 10. Fig. 14 is a diagram showing a waveform example (that is, a registration/authentication waveform) of an electrocardiogram signal (referred to as registration data B) in a case where an in-phase signal is superimposed on the electrocardiogram signal processing apparatus 10. Fig. 15 is a diagram showing a waveform example (that is, a registration/authentication waveform) of another electrocardiogram signal (referred to as registration data C) in a case where an in-phase signal is not superimposed on the electrocardiogram signal processing apparatus 10. Fig. 16 is a diagram showing the results (accuracy) of the individual authentication performed by the authentication unit 22 using the waveforms after the features of the electrocardiographic waveforms of the registered data a to C are registered as the registered information in the storage unit 23.

As is clear from fig. 16, the highest accuracy (100%) can be obtained when the electrocardiographic waveform is registered using the electrocardiographic signal (registration data B) in the case where the in-phase signal is superimposed on the electrocardiographic signal processing device 10 and personal authentication is performed. This is presumably because, by superimposing the in-phase signal on the electrocardiographic signal, the frequency at which the amplitude of each peak in the electrocardiographic waveform is greatly emphasized increases, and the feature amount of the electrocardiographic waveform is clarified.

As described above, the electrocardiographic signal processing device 10 according to the present embodiment includes: a signal processing circuit 12 for amplifying and outputting an electrocardiogram signal detected by an electrode 11 attached to a living body; and an in-phase signal generation circuit 13 for generating an in-phase signal for increasing the amplitude of a peak in an electrocardiogram waveform shown by the electrocardiogram signal using the electrocardiogram signal amplified by the signal processing circuit 12, and applying the generated in-phase signal to the electrode 11.

Thus, the in-phase signal for increasing the amplitude of the peak in the electrocardiogram waveform shown by the electrocardiogram signal is applied to the electrode 11, and therefore the peak of the heartbeat pattern in the electrocardiogram signal is emphasized, and stable personal authentication can be performed even in the presence of the disturbance noise. That is, an electrocardiogram signal processing apparatus capable of stably measuring an electrocardiogram signal even when the contact impedance between the electrode 11 and the living body is high is provided.

Further, the in-phase signal generation circuit 13 includes: a frequency determination unit 40a that determines a frequency corresponding to a time difference between a peak of a P wave and a peak of an R wave in an electrocardiographic waveform; and a signal generating unit 41 that generates a signal having the frequency determined by the frequency determining unit 40a as an in-phase signal.

Thus, the in-phase signal having a frequency corresponding to the time difference between the peak of the P wave and the peak of the R wave in the electrocardiographic waveform is applied to the electrode 11, and therefore the amplitudes of the peaks of the P wave and the R wave in the heartbeat pattern representing the feature of the subject become large. Therefore, the process of personal authentication using the peaks of the P-wave and the R-wave in the heartbeat pattern becomes stable, and the accuracy is improved.

Alternatively, the in-phase signal generation circuit 13 includes: a frequency determination unit 40a that determines a frequency corresponding to a time difference between a peak of a Q wave or an S wave and a peak of a T wave in an electrocardiographic waveform; and a signal generating unit 41 that generates a signal having the frequency determined by the frequency determining unit 40a as an in-phase signal.

Thus, since the in-phase signal having a frequency corresponding to the time difference between the peak of the Q wave or S wave and the peak of the T wave in the electrocardiographic waveform is applied to the electrode 11, the amplitudes of the peak of the Q wave or S wave and the peak of the T wave in the heartbeat pattern representing the feature of the subject become large. Therefore, the process of personal authentication using the peak of the Q wave or S wave and the peak of the T wave in the heartbeat pattern becomes stable, and the accuracy improves.

The in-phase signal generation circuit 13 further includes an amplitude determination unit 40b, the amplitude determination unit 40b determining the amplitude of the in-phase signal to be generated based on the amplitude of the peak in the electrocardiogram waveform, and the signal generation unit 41 generating a signal having the amplitude determined by the amplitude determination unit 40b as the in-phase signal.

Thus, since the in-phase signal having an amplitude determined based on the amplitude of the peak in the electrocardiographic waveform is applied to the electrode 11, the amplitude can be increased when the amplitude of the peak in the electrocardiographic waveform is insufficient. Therefore, the process of personal authentication using the heartbeat pattern of the electrocardiogram signal becomes stable, and the accuracy is improved.

The electrode 11 attached to the living body includes a measurement electrode 11a and a reference electrode 11b, the signal processing circuit 12 includes a differential amplifier 32 and an a/D converter 34, the differential amplifier 32 amplifies a difference between a signal detected by the measurement electrode 11a and a signal detected by the reference electrode 11b, the a/D converter 34 converts a signal output from the differential amplifier 32 into a digital signal, and the in-phase signal generation circuit 13 applies the in-phase signal to the reference electrode 11b using the digital signal output from the a/D converter 34.

Thus, since the in-phase signal generated based on the signal of the difference between the signal detected by the measurement electrode 11a and the signal detected by the reference electrode 11b is applied to the reference electrode 11b, in-phase noise superimposed on the two signals is removed, and a stable electrocardiogram signal with little influence of disturbance noise can be generated.

The personal authentication device 100 according to the present embodiment includes: the electrocardiogram signal processing apparatus 10; a storage unit 23 that stores registered information in which a feature amount of an electrocardiogram waveform indicated by an electrocardiogram signal output from a signal processing circuit 12 provided in the electrocardiogram signal processing apparatus 10 is associated with each of a plurality of users; and an authentication unit 22 that identifies, for the subject, which of the plurality of users the subject is by comparing the feature quantity of the electrocardiographic waveform indicated by the electrocardiographic signal output from the signal processing circuit 12 included in the electrocardiographic signal processing device 10 with the registered information held in the storage unit 23.

Thus, personal authentication can be performed using an electrocardiogram signal in which the peak of the heartbeat pattern is emphasized, and personal authentication can be performed stably with high accuracy even when the contact impedance between the electrode 11 and the living body is high.

Further, an electrocardiogram signal processing method according to the present embodiment includes the steps of: a signal acquisition step S10 of acquiring an electrocardiogram signal detected by the electrodes 11 (the measurement electrode 11a and the reference electrode 11b) attached to the living body; and an in-phase signal generation step S20 of generating an in-phase signal for increasing the amplitude of the peak in the electrocardiogram waveform indicated by the electrocardiogram signal acquired in the signal acquisition step S10, and applying the generated in-phase signal to the reference electrode 11 b.

Thus, the in-phase signal for increasing the amplitude of the peak in the electrocardiogram waveform is applied to the electrode 11, and therefore the peak of the heartbeat pattern in the electrocardiogram signal is emphasized, and stable personal authentication can be performed even in the presence of the disturbance noise. That is, an electrocardiogram signal processing method capable of stably measuring an electrocardiogram signal even when the contact impedance between the electrode 11 and the living body is high can be realized.

The present invention can also be realized as a program for causing a computer to execute the steps included in the electrocardiogram signal processing method, a program for causing a computer to execute the steps included in the personal authentication method of the information processing apparatus 20, or a computer-readable recording medium such as a CD-ROM on which these programs are recorded.

Next, an electrocardiogram signal processing apparatus according to a modification of the above embodiment will be described.

Fig. 17 is a block diagram showing the configuration of an electrocardiographic signal processing device 10a according to a modification of the above embodiment. The electrocardiogram signal processing apparatus 10a corresponds to: the electrocardiographic signal processing device 10 according to the above-described embodiment is provided with an in-phase signal generating circuit 13a, in which a phase determining unit 40c is added and the signal generating unit 41 is replaced with a new signal generating unit 41a, instead of the in-phase signal generating circuit 13.

The phase determining unit 40c generates a control signal for temporarily shifting the phase or temporarily reducing the amplitude of the in-phase signal to be generated. Specifically, the phase determining unit 40c generates an in-phase signal such as the waveform example shown in fig. 17 using the information about the peak detected by the peak detecting unit 35a, so as to prevent erroneous detection of the T wave. Here, the following waveform is generated as an in-phase signal at 1 Hz: in this waveform, 3 peaks whose central peak amplitude is small among the 3 peaks are repeated at 100 mVpp.

The signal generator 41a generates a signal including a portion where the phase is temporarily shifted or the amplitude is temporarily decreased as an in-phase signal based on the control signal generated by the phase determiner 40 c. Specifically, the signal generator 41a generates an in-phase signal having the frequency determined by the frequency determiner 40a, having the amplitude determined by the amplitude determiner 40b, and including a portion determined by the phase determiner 40c where the phase is temporarily shifted or the amplitude is temporarily decreased. That is, such a sample data sequence is generated, converted into an analog signal by a built-in D/a converter, and then passed through a built-in low-pass filter.

The digital signal processing in the phase determination unit 40c and the signal generation unit 41a may be realized by hardware using a dedicated logic circuit, or may be realized by software using a program. In the case of software implementation, the implementation can be realized by a microcomputer having a nonvolatile memory such as a ROM that holds programs, a RAM that temporarily holds information, a processor that executes programs, input/output ports for connection to peripheral circuits, and the like, for example.

Fig. 18 is a diagram showing an example of a waveform of an electrocardiogram signal (referred to as registration data B') (that is, a registration/authentication waveform) in the case where an in-phase signal is superimposed on the electrocardiogram signal processing apparatus 10a according to the present modification. As is clear from comparison with the waveform example of the registration data B shown in fig. 14 in embodiment 1, the wave height of an unnecessary peak (a dashed line frame in fig. 18) existing between the S-wave and the T-wave is reduced. This improves the accuracy in personal authentication.

As described above, according to the electrocardiographic signal processing device 10a of the present modification, the in-phase signal generating circuit 13a includes the phase determining unit 40c that generates the control signal for temporarily shifting the phase or temporarily reducing the amplitude of the in-phase signal to be generated, and the signal generating unit 41a generates the signal including the portion temporarily shifted in phase or temporarily reduced in amplitude as the in-phase signal based on the control signal generated by the phase determining unit 40 c.

Thus, since the in-phase signal including the portion where the phase is temporarily shifted or the amplitude is temporarily reduced is applied to the electrode 11, the amplitude can be increased only for the peak representing the heartbeat pattern in the electrocardiogram signal. Therefore, the process of personal authentication using the heartbeat pattern of the electrocardiogram signal becomes stable, and the accuracy is improved.

The electrocardiogram signal processing apparatus, the personal authentication apparatus, and the electrocardiogram signal processing method according to the present invention have been described above based on the embodiments and the modifications, but the present invention is not limited to these embodiments and modifications. A mode in which various modifications that occur to those skilled in the art are implemented in the present embodiment and the modifications and other modes in which some of the components in the embodiment and the modifications are combined are also included in the scope of the present invention, as long as the modes do not depart from the gist of the present invention.

For example, in the above-described embodiment and modification, the biological potential processing unit 35 is provided in the electrocardiographic signal processing device 10, but is not limited to this embodiment, and may be provided in the information processing device 20 instead of or in addition to this. When the biological potential processing unit 35 is provided in the information processing device 20, the information on the peak generated by the peak detecting unit 35a of the biological potential processing unit 35 can be used for generation of the signature by the authentication unit 22.

When the biological potential processing unit 35 is provided in the information processing device 20, the frequency determining unit 40a, the amplitude determining unit 40b, and the phase determining unit 40c of the electrocardiographic signal processing device 10 may also be provided in the information processing device 20. In this case, the frequency, amplitude, and control signal determined by the frequency determining unit 40a, the amplitude determining unit 40b, and the phase determining unit 40c are transmitted to the signal generating units 41 and 41a of the electrocardiograph signal processing device 10 via the communication unit 21 of the information processing device 20 and the communication unit 14 of the electrocardiograph signal processing device 10, and are used for generating the in-phase signal.

In the above-described embodiment, the electrocardiogram signal processing apparatus 10 is provided with the frequency determining unit 40a and the amplitude determining unit 40b, but only one of them may be provided. In this case, the signal generator 41 generates an in-phase signal based on information from either the frequency determiner 40a or the amplitude determiner 40 b.

Similarly, in the above-described modification, the electrocardiogram signal processing apparatus 10a is provided with the frequency determining unit 40a, the amplitude determining unit 40b, and the phase determining unit 40c, but at least one of them may be provided. In this case, the signal generator 41a generates an in-phase signal based on information from at least one of the frequency determiner 40a, the amplitude determiner 40b, and the phase determiner 40 c.

The electrocardiographic signal processing device 10a according to the above embodiment may constitute a personal authentication device together with the information processing device 20 and the display unit 25 according to the above embodiment. Thus, since the in-phase signal including the portion where the phase is temporarily shifted or the amplitude is temporarily reduced is applied to the electrode 11, the amplitude can be increased only for the peak representing the heartbeat pattern in the electrocardiogram signal. Therefore, the process of personal authentication using the heartbeat pattern of the electrocardiogram signal becomes stable, and the accuracy is improved.

In the above-described embodiment and modification, the electrocardiographic signal processing devices 10 and 10a process the signals detected by the measurement electrodes with reference to the potential detected by the reference electrode 11b, but the present invention is not limited to this. The signals detected by the plurality of measurement electrodes may be processed based on the potential detected by the reference electrode. When the electrocardiographic signal processing device processes a plurality of signals in this manner, a plurality of electrocardiographic waveforms obtained by these plurality of signals may be averaged or the like and used for personal authentication. In addition, the reference electrode is not necessary. Only the signal of the measurement electrode may be processed with reference to the ground potential. In this case, an in-phase signal is applied to the measurement electrode.

Description of the reference numerals

5: a subject; 10. 10 a: an electrocardiogram signal processing device; 11: an electrode; 11 a: a measuring electrode; 11 b: a reference electrode; 12: a signal processing circuit; 13. 13 a: an in-phase signal generation circuit; 22: an authentication unit; 23: a storage unit; 32: a differential amplifier; 34: an A/D converter; 40 a: a frequency determination unit; 40 b: an amplitude determining section; 40 c: a phase determination unit; 41. 41 a: a signal generation unit; 100: a personal authentication device.