Electrocardiographic detection device

Abstract

An electrocardiographic detection device according to the present invention includes a power supply unit that applies alternating-current power of a preset frequency to a rider that is a subject that is riding in a moving body, a pair of sensor electrodes that are provided so as to be opposite each other at two positions in the moving body that sandwich the heart of the rider and can each be electrically contacted by the rider, a detection unit that detects the voltage at each of the pair of sensor electrodes and also detects a voltage signal that represents an electrocardiographic waveform for the rider from the detected voltage, a determination unit that uses the voltage at the frequency of the alternating-current power as obtained from the voltage at each of the pair of sensor electrodes to determine whether the rider is contacting each of the pair of sensor electrodes, and an output unit that outputs the voltage signal that represents the electrocardiographic waveform for the rider when it has been determined that the rider is contacting each of the pair of sensor electrodes.

Description

electrocardiogram detector

[0001] The present disclosure relates to an electrocardiogram detection device.

[0002] Japanese Patent Application Laid-Open Publication No. 2016-203660 discloses a grip detection device. In this grip detection device, a first sensor is provided on the left side of the steering wheel when it is in a neutral position, and a second sensor is provided on the right side. The first and second sensors form a capacitance sensor that generates capacitance between the first and second sensors and the vehicle body. The first and second sensors are connected to a heartbeat detection unit, which outputs high-frequency signals of a predetermined frequency to the first and second sensors and detects the potentials of the first and second sensors to determine whether an occupant is touching the steering wheel.

[0003] The heart rate detector is connected to a first electrode and a second electrode. The steering wheel is provided with the first electrode near the first sensor and the second electrode near the second sensor, and the occupant is positioned so that they come into contact with the first electrode together with the first sensor and the second electrode together with the second sensor.

[0004] The heartbeat detection unit determines whether the driver is gripping the steering wheel with one hand or both hands based on the potential difference (voltage pattern) between the first electrode and the second electrode. If the heartbeat detection unit determines that the driver is gripping the steering wheel with both hands, it outputs a signal representing the driver's amplitude based on the potential difference between the first electrode and the second electrode.

[0005] In the grip detection device disclosed in JP 2016-203660 A, in addition to a first sensor and a second sensor, a first electrode and a second electrode are provided on the steering wheel to detect the state of grip of the steering wheel by the driver and the driver's electrocardiogram. Also, the grip detection device detects the capacitance of each of the first sensor and the second sensor and the potential between the first electrode and the second electrode, and there is room for improvement in the detection of the electrocardiogram.

[0006] The present disclosure provides an electrocardiogram detection device that can obtain an electrocardiogram of an occupant with high accuracy.

[0007] An electrocardiogram detection device according to a first aspect of the present disclosure includes a power supply unit that supplies AC power of a predetermined frequency to an occupant as a test subject riding in a mobile body; a pair of sensor electrodes that are arranged in two opposing positions on the mobile body on either side of the occupant's heart, each of which can be electrically contacted by the occupant; a detection unit that detects the voltage of each of the pair of sensor electrodes and detects a voltage signal indicating the occupant's electrocardiogram waveform from the detected voltage; a determination unit that determines whether the occupant is in contact with each of the pair of sensor electrodes using the voltage of the frequency of the AC power obtained from the voltage of each of the pair of sensor electrodes; and an output unit that outputs a voltage signal indicating the occupant's electrocardiogram waveform when it is determined that the occupant is in contact with each of the pair of sensor electrodes.

[0008] In the second aspect of the electrocardiogram detection device, in the first aspect, the moving body includes a gripping body to be gripped by the occupant, and at least one of the pair of sensor electrodes is arranged on the gripping body so that it can be contacted by the occupant gripping the gripping body.

[0009] A third aspect of the electrocardiogram detection device is the second aspect, wherein one of the pair of sensor electrodes is arranged on the grip and the other is arranged on the seat on which the occupant sits.

[0010] A fourth aspect of the electrocardiogram detection device is the second aspect, wherein the pair of sensor electrodes are provided in pairs on the gripping body at positions to be gripped by the occupant's right hand and left hand, and the determination unit determines whether the occupant is gripping the gripping body with both hands.

[0011] The electrocardiogram detecting device of a fifth aspect is the electrocardiogram detecting device of any one of the second to fourth aspects, wherein the gripping body is a steering body for steering the moving body.

[0012] A sixth aspect of the electrocardiogram detection device is the fourth aspect, wherein the gripping body is a steering body for steering the moving body, the determination unit determines the gripping state of the gripping body by the occupant, and the output unit outputs the determination result of the determination unit.

[0013] A seventh aspect of the electrocardiogram detection device is any one of the first to sixth aspects, wherein the power supply unit includes a power supply electrode that comes into contact with the occupant, and a generation unit to which the power supply electrode is connected and that generates the AC power of the frequency.

[0014] An eighth aspect of the electrocardiogram detection device is any one of the first to sixth aspects, wherein the power supply unit is connected to at least one of the pair of sensor electrodes and includes a generating unit that generates the AC power of the frequency.

[0015] A ninth aspect of the electrocardiogram detection device is any one of the first to eighth aspects, wherein when the output unit determines that the occupant is in contact with each of the pair of sensor electrodes and outputs a voltage signal indicating the occupant's electrocardiogram waveform, the output unit detects a peak of the voltage signal, and if there is a gap in the peak, the output unit complements the missing range of the peak using the voltage signal indicating the occupant's electrocardiogram waveform that has already been output.

[0016] In the electrocardiogram detection device of the first aspect, a pair of sensor electrodes are arranged in a vehicle in which a subject is a passenger, facing each other at two positions across the passenger's heart, and each of the sensor electrodes is capable of electrically contacting the passenger. A detection unit detects the voltage of each of the pair of sensor electrodes and detects a voltage signal indicative of the passenger's electrocardiogram waveform from the detected voltage.

[0017] The power supply unit supplies AC power of a predetermined frequency to the occupant. When the occupant touches the sensor electrode, the voltage of the sensor electrode is affected by the AC power, and a voltage corresponding to the frequency of the AC power appears on the sensor electrode. The determination unit determines whether the occupant is touching each of the pair of sensor electrodes using a voltage of the frequency of the AC power obtained from the voltages of each of the pair of sensor electrodes.

[0018] The output unit outputs a voltage signal indicating the electrocardiogram waveform of the occupant when it is determined that the occupant is in contact with each of the pair of sensor electrodes, thereby obtaining a highly accurate electrocardiogram waveform (electrocardiogram) when the occupant is in contact with each of the pair of sensor electrodes.

[0019] In the electrocardiogram detection device of the second aspect, the moving body includes a gripping body to be gripped by an occupant, and at least one of the pair of sensor electrodes is disposed on the gripping body so as to be contactable by the occupant, thereby enabling an electrocardiogram waveform to be obtained when the occupant is in contact with the gripping body, thereby enabling an electrocardiogram waveform to be obtained effectively.

[0020] In the electrocardiogram detection device of the third aspect, one of the pair of sensor electrodes is disposed on the grip and the other is disposed on the seat where the occupant sits, thereby making it possible to obtain an electrocardiogram waveform when the occupant sits on the seat and grips the grip, thereby making it possible to obtain the electrocardiogram waveform effectively.

[0021] In the electrocardiogram detection device of the fourth aspect, a pair of sensor electrodes is provided on the grip, and the pair of sensor electrodes is provided at a position where the occupant holds the grip with their right hand and a position where the occupant holds the grip with their left hand. The determination unit determines whether the occupant is holding the grip with both hands. This makes it possible to obtain an electrocardiogram waveform when the occupant holds the grip with both hands, thereby making it possible to obtain an electrocardiogram waveform more effectively.

[0022] In the electrocardiogram detection device of the fifth aspect, a steering member for steering the vehicle is used as the gripping member, whereby an electrocardiogram waveform can be obtained even when the occupant is steering the vehicle by gripping the steering member with both hands, and thus the electrocardiogram waveform can be obtained more effectively.

[0023] In the electrocardiogram detection device of the sixth aspect, the determination unit determines the grip state of the steering wheel by the occupant, and the output unit outputs the determined grip state. Therefore, in addition to detecting an electrocardiogram waveform, it is possible to determine the grip state of the steering wheel as the grip object, i.e., whether the occupant is gripping the steering wheel as the grip object with both hands, with either the left or right hand, or not at all. This makes it possible to detect an electrocardiogram waveform and detect the occupant's grip while suppressing an increase in parts for detecting the grip state and an increase in costs.

[0024] In the electrocardiogram detection device of the seventh aspect, the power supply unit includes a power supply electrode that is in contact with the occupant, and a generator that generates AC power of a preset frequency to be applied to the occupant via the power supply electrode, thereby making it possible to effectively apply AC power of the preset frequency to the occupant.

[0025] In the electrocardiogram detection device of the eighth aspect, a generator that generates AC power of a preset frequency is connected to at least one of the pair of sensor electrodes, whereby AC power of the preset frequency can be efficiently applied to the occupant when the occupant touches the sensor electrode.

[0026] In the electrocardiogram detection device of the ninth aspect, when it is determined that an occupant is in contact with each of the pair of sensor electrodes, a voltage signal indicating the occupant's electrocardiogram waveform is output. At this time, peaks of the voltage signal indicating the occupant's electrocardiogram waveform are detected, and if there is a missing peak, the output unit complements the missing peak range using peaks of the voltage signal indicating the occupant's electrocardiogram waveform that have already been output. This prevents missing peaks from occurring in the electrocardiogram waveform, and obtains an electrocardiogram waveform from which the heart rate can be determined.

[0027] FIG. 1 is a schematic diagram showing an electrocardiogram detection device according to a first embodiment. FIG. 2 is a front view showing a schematic configuration of a steering wheel according to the first embodiment. FIG. 3 is a schematic diagram showing a signal flow according to the first embodiment. FIG. 4 is a schematic diagram showing an electrocardiogram detection device according to a second embodiment. FIG. 5 is a front view showing a schematic configuration of a steering wheel according to the second embodiment. FIG. 6 is a schematic diagram showing a signal flow according to the second embodiment, showing a state in which an occupant is in contact with a sensor electrode. FIG. 7 is a schematic diagram showing a signal flow according to the second embodiment, showing a state in which an occupant is not in contact with a sensor electrode. FIG. 8 is a line diagram showing an outline of a determination result in a determination unit and a signal output according to the determination result.

[0028]

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. [First Embodiment] Fig. 1 is a block diagram showing a schematic configuration of a main part of an electrocardiogram detection device 10 according to a first embodiment of the present disclosure. Fig. 2 is a front view showing a main part of a vehicle in which the electrocardiogram detection device 10 is mounted, as seen from the passenger side.

[0029] In the drawings, the right side in the vehicle width direction is indicated by an arrow HR, and the up direction is indicated by an arrow UP. In this embodiment, the grounded state refers to a state in which the vehicle body (not shown) is the ground electrode GND and the vehicle is electrically connected to the ground electrode GND. Furthermore, in this embodiment, contact and electrical connection are not limited to direct connection using wiring or the like, but also include contact via an impedance (capacitor). In the following description, the same symbols are used for signals that are fundamentally similar, regardless of whether they are analog or digital.

[0030] As shown in FIG. 2, a steering device 12 is installed in a vehicle (not shown) as a moving body, and the steering device 12 includes a steering wheel 14 as a gripping body and a steering body.

[0031] The electrocardiogram detection device 10 detects whether or not the occupant is gripping the steering wheel 14. When the electrocardiogram detection device 10 detects that the occupant is gripping the steering wheel 14 with both hands, the electrocardiogram detection device 10 detects a signal (voltage signal) indicative of the occupant's electrocardiogram waveform and outputs the signal indicative of the electrocardiogram waveform.

[0032] The steering wheel 14 is disposed in front of a seat (driver's seat, not shown) in which a passenger (driver) who drives the vehicle sits. The steering wheel 14 includes a substantially annular rim portion 16 as a gripping portion, a boss portion 18 provided at the center of the rim portion 16, and a stay portion 20 connecting the rim portion 16 and the boss portion 18. The steering wheel 14 also includes a metal core portion (not shown) as a core portion constituting the skeleton, and the core portion is composed of a substantially annular rim core portion of the rim portion 16, a boss core portion of the boss portion 18, and a stay core portion of the stay portion 20. The boss core portion and the rim core portion are connected by the stay core portion, so that the rim portion 16, the boss portion 18, and the stay portion 20 are integrated into one body in the steering wheel 14.

[0033] The steering device 12 includes a steering shaft (not shown), which is rotatably supported by the vehicle body in front of the driver's seat with its axis aligned approximately in the longitudinal direction of the vehicle. The steering wheel 14 has a boss core portion of a boss portion 18 fixed to the rear end of the steering shaft, and the steering wheel 14 is supported by the vehicle body so as to be rotatable together with the steering shaft, and the core portion is grounded to the vehicle body via the steering shaft.

[0034] In a vehicle, when the steering wheel 14 of the steering device 12 is rotated, the steering shaft is rotated, and the steered wheels (front wheels) are steered to steer the vehicle. Note that Fig. 2 shows a front view of the steering wheel 14 as seen from the driver when the vehicle is traveling straight ahead.

[0035] A base (not shown) made of a resin material such as urethane as an insulating material and having a generally circular cross section (or a generally oval cross section) is disposed in the rim portion 16 of the steering wheel 14. The base covers the rim core metal portion of the rim portion 16, and the rim core metal portion is housed within the base by insert molding.

[0036] Furthermore, a decorative portion 26 is disposed as a contact portion (skin) on the radially outer side of the base body of the rim portion 16 of the steering wheel 14, and the decorative portion 26 is made of leather or resin (part of which may be made of wood) and has insulating properties. The rim portion 16 of the steering wheel 14 is covered with the decorative portion 26 over the entire circumference of the base body in a radial cross section of the steering wheel 14 and over the entire circumference (entire area) of the steering wheel 14.

[0037] 1 and 2 , the electrocardiogram detection device 10 includes a pair of sensor electrodes, namely, a sensor electrode 30L and a sensor electrode 30R. The electrocardiogram detection device 10 also includes a power supply electrode 32 forming a power supply unit, and an electrocardiogram detection unit 34. The sensor electrodes 30L, 30R and the power supply electrode 30 are provided at positions where they come into contact with (close to) an occupant.

[0038] In the electrocardiogram detection device 10, the sensor electrodes 30L, 30R and the power supply electrode 32 are each connected to an electrocardiogram detection unit 34. In the electrocardiogram detection device 10, the electrocardiogram detection unit 34 is also connected to an electrocardiogram waveform generation device 36, which receives a signal indicating the electrocardiogram waveform (electrocardiogram) of the occupant and performs various measurements such as generating an electrocardiogram, measuring the heart rate, and measuring heart rate variability (HRV). Therefore, when the electrocardiogram detection device 10 is connected to the electrocardiogram waveform generation device 36, it functions as an electrocardiogram measurement device.

[0039] The sensor electrodes 30L, 30R and the power supply electrode 32 are each formed in a thin, generally strip-like (sheet-like) shape using a conductive material. The sensor electrodes 30L, 30R and the power supply electrode 32 are disposed on the outer peripheral surface of the base in the rim portion 16 of the steering wheel 14 and are covered by the decorative portion 26.

[0040] 2, on the steering wheel 14, when the vehicle is traveling straight, a sensor electrode 30L is arranged over approximately half the circumference of the left side of the rim portion 16, and a sensor electrode 30R is arranged over approximately half the circumference of the right side of the rim portion 16. The power supply electrode 32 is arranged on the rim portion 16 of the steering wheel 14 so as to be electrically separated (insulated) from each of the sensor electrodes 30L, 30R. The power supply electrode 32 is divided into a power supply electrode 32L corresponding to the sensor electrode 30L and a power supply electrode 32R corresponding to the sensor electrode 30R.

[0041] In the rim portion 16, sensor electrodes 30L and 30R are arranged on the outer periphery of the steering wheel 14, and power supply electrodes 32 (32L and 32R) are arranged on the inner periphery of the steering wheel 14.

[0042] As a result, in the electrocardiogram detection device 10, when the occupant grips the steering wheel 14 (rim portion 16) with his / her left hand, the occupant comes into contact with (close to) the sensor electrode 30L and the power supply electrode 32L. Also, in the electrocardiogram detection device 10, when the occupant grips the steering wheel 14 with his / her right hand, the occupant comes into contact with (close to) the sensor electrode 30R and the power supply electrode 32R. When the occupant approaches the sensor electrodes 30L, 30R and the power supply electrode 32 (32L, 32R), an impedance is generated between the occupant and the sensor electrodes 30L, 30R and the power supply electrode 32 (32L, 32R), and through this impedance, the occupant comes into electrical contact with the sensor electrodes 30L, 30R and the power supply electrode 32 (32L, 32R).

[0043] The power supply electrode 32 may be disposed at a position where the occupant will come into contact with the sensor electrodes 30L, 30R. Therefore, the power supply electrodes 32 (32L, 32R) may be disposed on the outer periphery of the steering wheel 14, and the sensor electrodes 30L, 30R may be disposed on the inner periphery of the steering wheel 14, on the rim portion 16.

[0044] 1 , the electrocardiogram detection unit 34 includes a signal generator (oscillator) 38 serving as a generator constituting a power supply unit, a buffer 40, a detector 42, a determination unit 44, and an output unit 46. The electrocardiogram detection unit 34 includes a computer (not shown) including a central processing unit (CPU) serving as a processor, read-only memory (ROM), random access memory (RAM), and nonvolatile memory such as flash memory, as well as required functional circuits. As a result, the CPU of the electrocardiogram detection unit 34 reads out programs stored in advance in the memory, expands the programs into the RAM, and executes them, thereby realizing the functions of the signal generator 38, the buffer 40, the detector 42, the determination unit 44, and the output unit 46.

[0045] The power supply electrodes 32 (32L, 32R) are connected to a signal generator 38. The signal generator 38 generates a sine wave signal of a preset frequency f and supplies AC power P corresponding to the generated sine wave signal to the power supply electrodes 32 (32L, 32R). An occupant is grounded to the vehicle body via a predetermined impedance by, for example, sitting in a seat. As a result, when the occupant grips the steering wheel 14 and touches at least one of the power supply electrodes 32 (32L, 32R), AC power P is applied, and a current change corresponding to the frequency f occurs in the occupant's body (AC current flows).

[0046] The occupant experiences a change in ionic current (alternating current) due to electrical activity caused by the heartbeat. The ionic current due to electrical activity caused by the heartbeat is generally about 1 mA. The AC power P may be any power that, when applied to the occupant via the power supply electrode 32, generates an AC current (e.g., a current of 10 mA or more) large enough to compensate for the ionic current.

[0047] In the signal generator 38, a frequency in a band different from frequencies included in the cycle of a heartbeat, etc., is applied as the preset frequency f. In the first embodiment, the frequency f is set to 100 Hz, 150 Hz, or 200 Hz (for example, 100 Hz), for example. Note that the space around the vehicle may contain electromagnetic waves, etc., resulting from a commercial power supply (having a frequency of 50 Hz or 60 Hz). Therefore, it is more preferable to set the frequency f to a frequency that excludes the frequency of the commercial power supply and frequencies that overlap with lower harmonics of the commercial power supply (for example, 100 Hz or 120 Hz, which correspond to the second harmonic).

[0048] When an occupant grips the rim portion 16 of the steering wheel 14, their hands come into contact (proximity, electrical contact via a predetermined impedance) with each of the sensor electrodes 30L, 30R, which causes a change in potential in the sensor electrodes 30L, 30R in response to a change in ionic current accompanying electrical activity in the occupant's heartbeat.

[0049] In addition, a current flows through the occupant due to the AC power P that is applied when the occupant comes into contact with the power supply electrode 32, and a change in potential occurs in the sensor electrodes 30L, 30R in accordance with the current frequency that is caused by the AC power P that is applied to the occupant via the power supply electrode 32.

[0050] The buffer section 40 of the electrocardiogram detection section 34 is provided with a buffer circuit 50L for the sensor electrode 30L (for the left hand of the occupant) and a buffer circuit 50R for the sensor electrode 30R (for the left hand of the occupant). Each of the buffer circuits 50L and 50R uses an operational amplifier whose input impedance is larger than its output impedance, and the sensor electrodes 30L and 30R are connected to the buffer circuits 50L and 50R, respectively.

[0051] As a result, each of the buffer circuits 50L and 50R outputs a signal (voltage signal) S corresponding to a change in the potential occurring in the sensor electrodes 30L and 30R. Ｌ , S Ｒ Furthermore, when the occupant is in contact with the power supply electrode 32, the signal S Ｌ , S Ｒ , a signal S indicating an electrocardiogram waveform ＣＬ , S ＣＲ At the same time, a signal (voltage signal) S of frequency f Ｌｆ , S Ｒｆ and signal S Ｌ , S Ｒ is the signal S ＣＬ , S ＣＲ and signal S Ｌｆ , S Ｒｆ and are superimposed (S Ｌ = S ＣＬ +S Ｌｆ , S Ｒ = S ＣＲ +S Ｒｆ ).

[0052] The detection unit 42 includes a differential amplifier circuit 52, A / D converters 54A, 54L, and 54R that convert analog signals into digital signals, and filter units 56A, 56L, and 56R that perform filtering to extract desired frequency components. The input side of the differential amplifier circuit 52 is connected to the output side of each of buffer circuits 50L and 50R, and the output side is connected to the filter unit 56A via the A / D converter 54A. One of the buffer circuits 50L and 50R (e.g., buffer circuit 50L) is connected to the positive side of the differential amplifier circuit 52, and the other (e.g., buffer circuit 50R) is connected to the negative side of the differential amplifier circuit 52.

[0053] The input sides of the A / D converters 54L, 54R are connected to the outputs of the buffer circuits 50L, 50R, and the output sides of the A / D converters 54L, 54R are connected to the filter units 56L, 56R. The filter units 56A, 56L, 56R are digital filters that perform filtering on the signals digitally converted by the A / D converters 54A, 54L, 54R, respectively.

[0054] The filter unit 56A receives the signal S ＣＬ , S ＣＲ (signal S of frequency f) Ｌｆ , S Ｒｆ For example, the filter unit 56A uses an LPF with a cutoff frequency of 40 Hz (or 50 Hz, etc.) for heartbeat frequencies of less than 40 Hz to remove the frequency f component of the AC power P (signal S Ｌｆ , S Ｒｆ ) is filtered to remove them.

[0055] The filter units 56L and 56R perform filtering processing by functioning as a band-pass filter or a high-pass filter (HPF) that passes the component of the frequency f of the signal generator 38. The filter units 56L and 56R filter the signal S using a BPF with a center frequency of the frequency f. Ｌｆ , S Ｒｆ Extract.

[0056] As a result, in the detection unit 42, a signal (voltage) detected when the occupant is in contact with each of the sensor electrodes 30L and 30R is output from the filter unit 56A via the differential amplifier circuit 52 and the A / D converter 54A, and a signal S indicating an electrocardiogram waveform for obtaining an electrocardiogram of the occupant is generated. ＬＲ In the detection unit 42, the filter units 56L and 56R respectively receive the signal S detected at the sensor electrodes 30L and 30R. Ｌ , S Ｒ A signal S that varies at a frequency f included in Ｌｆ , S Ｒｆ Output.

[0057] The determination unit 44 receives the signal S output from the filter units 56L and 56R. Ｌｆ , S Ｒｆ The amplitude (or peak value) of each of the signals S is compared with a preset threshold value fth (voltage value) to determine the grip state of the occupant on the steering wheel 14. Ｌｆ If the amplitude of the signal S exceeds the threshold value fth, the determination unit 44 determines that the occupant is gripping the steering wheel 14 with the left hand. Ｒｆ If the amplitude of exceeds the threshold value fth, it is determined that the occupant is gripping the steering wheel 14 with their right hand. As a result, the determination unit 44 determines whether the occupant is gripping the steering wheel 14 with either one of the following: no grip with both hands, grip with one hand with the left hand, grip with one hand with the right hand, or grip with both hands.

[0058] The output unit 46 outputs the grip state of the occupant on the steering wheel 14, which is the determination result of the determination unit 44. When the determination unit 44 determines that the steering wheel 14 is being gripped with both hands (the steering wheel 14 is being gripped with both hands), the output unit 46 outputs the signal S ＬＲ is output to the electrocardiogram waveform generating device 36.

[0059] Next, as an operation of the first embodiment, the operation of the electrocardiogram detection device 10 will be described. Fig. 3 is a schematic diagram showing the flow of signals in the electrocardiogram detection unit 34. In Fig. 3, the "left side" indicates the sensor electrode 30L side, and the right side indicates the sensor electrode 30R side.

[0060] In the electrocardiogram detection device 10, for example, the electrocardiogram detection unit 34 starts operating when the vehicle's ignition switch is turned on to start the vehicle from traveling, and the electrocardiogram detection unit 34 stops operating when the ignition switch is turned off to stop the vehicle from traveling.

[0061] When the electrocardiogram detection unit 34 starts operating, the signal generator 38 generates AC power P with frequency f. As a result, a voltage corresponding to the AC power P is applied to the power supply electrode 32 of the steering wheel 14, and when the occupant comes into contact with the power supply electrode 32, a current corresponding to the AC power P (AC current with frequency F) flows through the occupant's body to the vehicle body.

[0062] In the electrocardiogram detector 34, the buffer circuit 40 of the detector 42 detects the potentials generated in the sensor electrodes 30L and 30R at preset time intervals, and detects changes in the potentials. As a result, the buffer circuits 50L and 50R output signals S Ｌ , S Ｒ In the detection unit 42, the differential amplifier circuit 52 outputs the signal S Ｌ , S Ｒ A differential signal of is generated, and this differential signal is subjected to A / D conversion processing and filtering processing using an LPF, thereby obtaining a signal S from which the component of frequency f is removed. ＬＲ is output to the output unit 46.

[0063] At the same time, the detection unit 42 detects the signal S Ｌ , S Ｒ The electrocardiogram detection unit 34 performs A / D conversion processing and filtering processing using a BPF on each of the signals S Ｌ , S Ｒ The signal S of frequency f included in each of Ｌｆ , S Ｒｆ is output from the detection unit 42 to the determination unit 44.

[0064] The determination unit 44 determines the signal S Ｌｆ , S ＲｆThe grip state of the occupant on the steering wheel 14 is determined by using a threshold value fth for f. In this case, the determination unit 44 determines whether the grip state is non-grip, one-hand grip (right hand or left hand), or both-hand grip. In the electrocardiogram detection unit 34, the determination result of the determination unit 44 is input to the output unit 46.

[0065] When the occupant is not gripping the steering wheel 14 and neither the left nor right hand of the occupant is in contact with the sensor electrodes 30L, 30R, the signal S Ｌ Signal S ＣＬ and signal S Ｌｆ does not include the signal S Ｒ Signal S ＣＲ and signal S Ｒｆ Therefore, the signal S Ｌｆ , S Ｒｆ In both cases, the amplitude is at a low level that does not exceed the threshold value fth, and the determination unit 44 determines that the steering wheel 14 is not being gripped.

[0066] In contrast, when an occupant touches the power supply electrode 32, a current corresponding to the AC power P of frequency f flows through the occupant's body, and a voltage corresponding to the occupant's heartbeat and a voltage of frequency f appear on the sensor electrodes 30L and 30R.

[0067] That is, the power supply electrodes 32 (32L, 32R) are arranged so that the occupant will come into contact with the sensor electrodes 30L, 30R when gripping the steering wheel 14. For example, when the occupant grips the steering wheel 14 with his / her left hand, the occupant's hand (left hand) comes into contact with the sensor electrode 30L and also with the power supply electrode 32 (32L). As a result, as shown in FIG. 3, the detection unit 42 detects a signal S corresponding to the heart rate and AC power P. Ｌ , S Ｒ is detected, and this signal S Ｌ , S Ｒ From signal S ＬＲ and signal S Ｌｆ , S Ｒｆ is extracted.

[0068] The determination unit 44 determines the signal S ＬｆIf the amplitude of the signal S exceeds the threshold value fth, it is determined that the occupant is gripping the steering wheel 14 with the left hand. Ｒｆ If the amplitude of the signal S exceeds the threshold value fth, it is determined that the occupant is gripping the steering wheel 14 with their right hand. ＣＬ , S ＣＲ Since one of the signals S is not detected, the correct signal S ＬＲ It is currently not possible to obtain this.

[0069] In contrast, when the occupant grips the steering wheel 14 with both hands (left and right hands), the detection unit 42 detects a signal S ＣＬ and a signal S whose amplitude exceeds a threshold value fth Ｌｆ A signal S including Ｌ , and signal S ＣＲ and a signal S whose amplitude exceeds a threshold value fth Ｒｆ A signal S including Ｒ is detected.

[0070] As a result, the determining unit 44 determines that the occupant is gripping the steering wheel 14 with both the left and right hands (two-hand grip). ＬＲ In the ＣＬ and signal S ＣＲ Therefore, the electrocardiogram detection device 10 (electrocardiogram detection unit 34) can accurately detect an appropriate electrocardiogram waveform.

[0071] Furthermore, in the electrocardiogram detection unit 34, the determination unit 44 can determine the state of grip of the steering wheel 14 by the occupant. As a result, for example, the output unit 46 can output the determination result to a warning system or the like provided in the vehicle, and the warning system can issue a warning to encourage the occupant to grip the steering wheel 14 when, for example, a predetermined time has passed since the steering wheel 14 was not gripped.

[0072] In this way, the electrocardiogram detection device 10 applies AC power P of frequency f to the occupant. As a result, when the occupant comes into contact with the sensor electrodes 30L, 30R, the detection unit 42 outputs a signal S ＣＬ and signal S Ｌｆ A signal S including Ｌ, and signal S ＣＲ and signal S Ｒｆ A signal S including Ｒ It is possible to detect

[0073] Furthermore, the determination unit 44 outputs the signal S Ｌｆ , S Ｒｆ By determining that the grip state is a two-handed grip, the output unit 46 outputs a signal S ＣＬ , S ＣＲ A signal S corresponding to ＬＲ As a result, the electrocardiogram detecting device 10 can obtain a highly accurate electrocardiogram waveform (electrocardiogram) when the occupant is in contact with each of the sensor electrodes 30L and 30R.

[0074] Furthermore, in the electrocardiogram detection device 10, a pair of sensor electrodes 30L, 30R are arranged on the steering wheel 14. Therefore, when the occupant steers the vehicle by gripping the steering wheel 14 with both hands (with the heart between them), the electrocardiogram waveform can be detected, and the occupant's electrocardiogram waveform can be obtained more effectively.

[0075] Furthermore, in the electrocardiogram detection device 10, the determination unit 44 can determine the grip state of the occupant on the steering wheel 14. Therefore, the grip state of the steering wheel 14 can be detected using the configuration for detecting an electrocardiogram waveform, and therefore, parts and assembly work for detecting the grip state of the steering wheel 14, separate from the configuration for detecting an electrocardiogram waveform, can be reduced, thereby suppressing an increase in costs.

[0076] In the first embodiment, the power supply electrode 32L is provided corresponding to the sensor electrode 30L, and the power supply electrode 32R is provided corresponding to the sensor electrode 30R. However, the power supply electrodes may be disposed in positions where the occupant always comes into contact, such as the seat cushion of the seat.

[0077] In the first embodiment, the grip state of the steering wheel 14 by the occupant can be determined as being gripped with both hands, gripped with one hand (left or right), or not gripped. However, the grip state of the steering wheel 14 may be determined as being gripped with both hands or not gripped with both hands (gripped with one hand (left or right), or not gripped). In this case, it is sufficient that the power supply electrode is provided corresponding to one of the pair of sensor electrodes.

[0078] Second Embodiment Next, a second embodiment of the present disclosure will be described. The basic configuration of the second embodiment is the same as that of the first embodiment, and functional components and the like in the second embodiment that are the same as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and descriptions thereof will be omitted.

[0079] Fig. 4 shows a schematic configuration of an electrocardiogram detection device 60 according to the second embodiment, and Fig. 5 shows a front view of a steering wheel 14 according to the second embodiment.

[0080] 4 and 5 , an electrocardiogram detection device 60 according to the second embodiment includes a pair of sensor electrodes 62L, 62R, and an electrocardiogram detection unit 64. The pair of sensor electrodes 62L, 62R are provided in the electrocardiogram detection device 60 in place of the pair of sensor electrodes 30L, 30R and the power supply electrode 32 (32L, 32R). The electrocardiogram detection unit 64 is provided in the electrocardiogram detection device 60 in place of the electrocardiogram detection unit 34, and differs from the electrocardiogram detection unit 34 in that a determination unit 66 is provided in place of the determination unit 44.

[0081] As shown in FIG. 5, the steering wheel 14 has a sensor electrode 62L arranged over approximately half the circumference on the left side and a sensor electrode 62R arranged over approximately half the circumference on the right side, and each of the sensor electrodes 62L, 62R is arranged over approximately the entire circumference in the cross-sectional circumferential direction on the outer periphery of the base of the rim portion 16.

[0082] This allows the sensor electrodes 62L, 62R to detect the occupant's contact with the steering wheel 14 over a wider range than when the sensor electrodes 30L, 30R are arranged on the rim portion 16 together with the power supply electrodes 32L, 32R.

[0083] 4, in the electrocardiogram detection unit 64, the signal generator 38 is connected to each of the sensor electrodes 62L, 62R via a required impedance (for example, a capacitor C), and the signal generator 38 supplies AC power P of frequency f to the sensor electrodes 62L, 62R. This allows the electrocardiogram detection device 60 to reliably apply AC power of frequency f to the occupant who is in contact with the sensor electrodes 62L, 62R.

[0084] The sensor electrodes 62L, 62R are supplied with AC power P from the signal generator 38. Therefore, in the sensor electrodes 62L, 62R, a potential corresponding to the AC power P is generated when the sensor electrodes 62L, 62R are not in contact with the occupant. When the sensor electrodes 62L, 62R are in contact with the occupant, they are grounded via the occupant's body, and the potential of the sensor electrodes 62L, 62R decreases compared to when the sensor electrodes are not in contact with the occupant.

[0085] The determination unit 66 of the electrocardiogram detection unit 64 generates a signal S based on the potential when the sensor electrodes 62L and 62R are not in contact with the occupant and the potential when the sensor electrodes 62L and 62R are in contact with the occupant. Ｌｆ , S Ｒｆ The threshold value fth is set so that the contact state and the non-contact state can be distinguished from the amplitude (or peak) of the signal.

[0086] The determination unit 66 receives the signal S Ｌｆ If the amplitude of exceeds the threshold value fth, it is determined that the occupant is not in contact with the sensor electrode 62L, and the signal S Ｒｆ If the amplitude of the signal exceeds the threshold value fth, it is determined that the occupant is not in contact with the sensor electrode 62R. In this way, the determination unit 66 determines the grip state (contact state) of the steering wheel 14 by the occupant.

[0087] Next, the operation of the electrocardiogram detection device 10 will be described as an operation of the second embodiment. Figures 6A and 6B are schematic diagrams showing the flow of signals in the electrocardiogram detection unit 64. Note that Figure 6A shows the state in which the occupant is in contact with the sensor electrodes 62L and 62R, and Figure 6B shows the state in which the occupant is not in contact with the sensor electrodes 62L and 62R. Furthermore, "left side" refers to the sensor electrode 30L side, and "right side" refers to the sensor electrode 30R side.

[0088] 7 is a diagram showing an outline of the signal output from the output unit 46. In FIG. ＬＲ , and the signal Bj as the determination result when the hand is held with both hands. In FIG. 7, the horizontal axis represents time (sec), and the vertical axis on the left represents the signal S ＬＲThe right side is the determination result indicated by the signal Bj, where High (1) indicates a two-handed grip and Low (0) indicates a non-grip.

[0089] In the electrocardiogram detection device 60 (electrocardiogram detection unit 64), when the signal generator 38 is operating, it supplies AC power P of frequency f to each of the sensor electrodes 62L and 62R. As a result, as shown in FIG. 6B , a signal S Ｌ , S Ｒ The signal S ＣＬ , S ＣＲ and a signal S with a large amplitude Ｌｆ , S Ｒｆ Includes:

[0090] Therefore, the signal S Ｌｆ , S Ｒｆ When the amplitude of exceeds the threshold value fth, the determination unit 66 determines that the occupant is in a non-grasping state in which both hands are not in contact with the steering wheel 14. As a result, the output unit 46 outputs a signal S ＬＲ Stops output of

[0091] Meanwhile, when the occupant grips the steering wheel 14, the occupant comes into contact with the sensor electrodes 62L, 62R. When the occupant comes into contact with the sensor electrodes 62L, 62R, the sensor electrodes 62L, 62R are grounded via the occupant's body, and a current corresponding to the AC power P flows. As a result, a drop in potential (mainly a drop in potential due to the AC power P) occurs in the sensor electrodes 62L, 62R. As a result, as shown in FIG. 6A, the signal S detected by the detection unit 42 Ｌ , S Ｒ The signal S ＣＬ , S ＣＲ and the signal S with reduced amplitude Ｌｆ , S Ｒｆ Includes:

[0092] In the detection unit 42, the signal S detected by the sensor electrodes 62L and 62R is Ｌ , S Ｒ From signal S ＣＬ , S ＣＲThe determination unit 66 extracts the signal S Ｌｆ , S Ｒｆ If the amplitude of the signal f is equal to or smaller than the threshold value fth, it is determined that the occupant is in contact with the steering wheel 14.

[0093] At this time, the determination unit 66 determines whether the signal S Ｌｆ If the amplitude of is equal to or less than the threshold value fth, it is determined that the occupant's left hand is gripping the steering wheel 14, and the signal S Ｒｆ If the amplitude of is equal to or less than the threshold value fth, it is determined that the occupant's right hand is gripping the steering wheel 14. Furthermore, if the determination unit 66 determines that the occupant's left and right hands are gripping the steering wheel 14, it determines that the steering wheel 14 is being gripped with both hands. As a result, the signal Bj switches from low to high, as shown in FIG. 7.

[0094] Furthermore, since the occupant is holding the steering wheel 14 with both hands, the signal S Ｌ , S Ｒ A signal S capable of generating an electrocardiogram waveform is included in ＣＬ , S ＣＲ As a result, the output section 46 outputs the signal S ＣＬ , S ＣＲ A signal S corresponding to ＬＲ to the electrocardiogram waveform generating device 36. Therefore, the electrocardiogram detecting device 60 has the same effects as the electrocardiogram detecting device 10 according to the first embodiment.

[0095] In addition, the electrocardiogram detection device 60 applies AC power P of frequency f to the occupant via the sensor electrodes 62L and 62R, and generates a signal S Ｌ , S Ｒ from the signal S corresponding to the AC power P of frequency f Ｌｆ , S Ｒｆ This allows the number of parts and assembly steps to be further reduced compared to the electrocardiogram detection device 10, thereby more effectively suppressing cost increases.

[0096] In the first and second embodiments described above, digital filters are used as the filter units 56A, 56L, and 56R that perform the filtering process. However, analog filters may be used for the filtering process. In this case, the filter units and the A / D converters may be interchanged, and A / D conversion may be performed on the filtered signals.

[0097] In the first and second embodiments, the frequency f generated by the signal generator 38 is a single frequency of 100 Hz. However, the signal detected using the sensor electrode may contain noise components, and the inclusion of noise components may increase the amplitude of the signal component of frequency f, causing it to exceed the threshold value fth and resulting in an erroneous determination.

[0098] The power supply unit may supply AC power with multiple frequencies superimposed on each other to the occupant. In this case, it is preferable to select multiple frequencies such that one frequency is not an integer multiple of the other frequencies, such as 100 Hz and 150 Hz. This can prevent erroneous determinations caused by noise components.

[0099] In the first and second embodiments, the signal S corresponding to the electrocardiogram waveform ＬＲ was output to the electrocardiogram waveform generating device 36. However, the signal corresponding to the electrocardiogram waveform may be stored in a non-volatile storage medium such as a storage device, and the electrocardiogram waveform may be obtained by attaching the storage medium to the electrocardiogram waveform generating device.

[0100] Furthermore, in the first and second embodiments, when it is determined that the occupant is gripping the steering wheel 14 with both hands, the output unit 46 outputs the signal S LR to the electrocardiogram waveform generator 36. However, the output unit 46 outputs the signal S ＬＲ While storing the signal S ＬＲ A change in the signal S ＬＲ If it is determined that there is no irregular change in the signal S, the stored signal S ＬＲ may be output to the electrocardiogram waveform generating device 36.

[0101] That is, the output unit 46 determines that the occupant is in contact with the sensor electrodes 30L, 30R or the sensor electrodes 62L, 62R, and outputs the signal S ＬＲ When the signal S ＬＲ If a peak is missing, the signal S ＬＲ This allows the electrocardiogram waveform generating device 36 to continue measuring the heart rate and the like of the occupant even if at least one of the occupant's left hand and right hand is removed from the steering wheel 14 for a short period of time.

[0102] Furthermore, in the first embodiment described above, the sensor electrodes 30L, 30R are each disposed on the steering wheel 14, and in the second embodiment, the sensor electrodes 62L, 62R are each disposed on the steering wheel 14. However, one of the pair of sensor electrodes may be disposed on the steering body or the grip body, and the other may be disposed on the seat cushion of the seat where the occupant sits. Even in this case, it is possible to determine whether the occupant is in contact with each of the pair of sensor electrodes and output a detection signal for generating an electrocardiographic waveform, thereby enabling the generation of an electrocardiographic waveform with high accuracy.

[0103] In the first and second embodiments, the electrocardiogram detection devices 10 and 60 are configured to generate an electrocardiogram of a vehicle occupant. However, the vehicle may be a two-wheeled vehicle (such as a motorcycle) or a bicycle. In this case, the sensor electrodes may be disposed on the left and right grips of the handlebars held by the occupant, or one of the pair of sensor electrodes may be disposed on the handlebar grips and the other on the seat (saddle).

[0104] The mobile body may also be a wheelchair. When a wheelchair is used as the mobile body, one of the pair of sensor electrodes may be disposed on a seat (seat) on which the occupant sits, and the other may be provided on an arm support attached to a metal frame, or the other sensor electrode may be provided on each of the left and right arm supports. Furthermore, AC power of frequency f may be supplied to the occupant via the pair of sensor electrodes, and since the occupant is always seated in the seat, the power supply electrode may be disposed on the seat together with one of the sensor electrodes.

[0105] This makes it possible to measure the electrocardiograms of passengers not only in vehicles (automobiles), but also in various other moving objects such as motorcycles, bicycles, and wheelchairs.

[0106] In the first and second embodiments, a CPU is used as the processor to realize the functions of the electrocardiogram detection unit 34. However, various processors other than a CPU may also be used. Examples of such processors include programmable logic devices (PLDs) such as field-programmable gate arrays (FPGAs), whose circuit configuration can be changed after manufacture, and dedicated electrical circuits such as application-specific integrated circuits (ASICs), which are processors with circuit configurations specifically designed to execute specific processes. Each process may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (e.g., multiple FPGAs, or a combination of a CPU and an FPGA). The hardware structure of these various processors is, more specifically, an electrical circuit that combines circuit elements such as semiconductor devices.

[0107] The programs described in the first and second embodiments may be provided in a form stored on a non-transitory storage medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a USB (Universal Serial Bus) memory. The programs may also be downloaded from an external device via a network.

[0108] The disclosure of Japanese Patent Application No. 2024-007930, filed on January 23, 2024, is incorporated herein by reference in its entirety.

[0109] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A power supply unit that applies AC power of a preset frequency to a passenger as a subject riding in a moving body, a pair of sensor electrodes disposed to face two positions sandwiching the heart of the passenger in the moving body, and each of the passenger being electrically contactable thereto, a detection unit that detects the voltage of each of the pair of sensor electrodes and detects a voltage signal indicating an electrocardiogram waveform of the passenger from the detected voltage, a determination unit that determines whether the passenger is in contact with each of the pair of sensor electrodes using the voltage of the frequency of the AC power obtained from the voltage of each of the pair of sensor electrodes, and an output unit that outputs a voltage signal indicating the electrocardiogram waveform of the passenger when it is determined that the passenger is in contact with each of the pair of sensor electrodes, an electrocardiogram detection device.

2. The electrocardiogram detection device according to claim 1, wherein the moving body includes a gripping body gripped by the passenger, and at least one of the pair of sensor electrodes is disposed on the gripping body so that the passenger gripping the gripping body can be contacted.

3. The electrocardiogram detection device according to claim 2, wherein one of the pair of sensor electrodes is disposed on the gripping body and the other is disposed on a seat on which the passenger is seated.

4. The electrocardiogram detection device according to claim 2, wherein the pair of sensor electrodes are provided in pairs at a gripping position of the passenger's right hand and a gripping position of the left hand on the gripping body, and the determination unit determines whether the passenger is gripping the gripping body with both hands.

5. The electrocardiogram detection device according to claim 2, wherein the gripping body is a steering body for steering the moving body.

6. The electrocardiogram detection device according to claim 4, wherein the gripping body is a steering body for steering the moving body, the determination unit determines a gripping state of the gripping body by the passenger, and the output unit outputs a determination result of the determination unit.

7. The electrocardiogram detection device according to claim 1, wherein the power supply unit includes a power supply electrode contacted by the passenger and a generation unit connected to the power supply electrode and generating the AC power of the frequency.

8. The electrocardiogram detection device according to claim 1, wherein the power supply unit includes a generation unit connected to at least one of the pair of sensor electrodes and generating the AC power of the frequency.

9. When the output unit determines that the occupant is in contact with each of the pair of sensor electrodes and outputs a voltage signal indicating the electrocardiogram waveform of the occupant, the output unit detects the peak of the voltage signal, and when a missing portion occurs in the peak, the output unit uses the voltage signal indicating the electrocardiogram waveform of the occupant that has already been output to complement the missing range of the peak. The electrocardiogram detection device according to claim 1, comprising:

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