Electrocardiographic detector

Abstract

To highly accurately obtain an electrocardiogram of an occupant of a mobile body.SOLUTION: In an electrocardiographic detector 10, alternating-current power of a predetermined frequency generated by a signal generator 38 is applied to an occupant who grips a steering wheel 14 and holds sensor electrodes 30L, 30R via a power-supply electrode 32. A detection unit 42 detects the voltages of the sensor electrodes 30L, 30R and also detects a voltage signal indicating an electrocardiographic waveform from the detected voltages. A determination unit 44 determines a gripping state of the occupant on the pair of steering wheels 14 by using the voltage at the frequency of the alternating-current power obtained from the voltages of the sensor electrodes 30L, 30R, and outputs a voltage signal indicating the electrocardiographic waveform of the occupant when the occupant is gripping the steering wheel 14 with both hands. With this, a highly accurate electrocardiogram can be obtained.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a gripping detection device. In this gripping detection device, a first sensor (L) is provided at a left portion in the neutral position of the steering wheel, and a second sensor (R) is provided at a right portion. The first sensor (L) and the second sensor (R) form a capacitance sensor that generates capacitance between the vehicle body and the like. The first sensor (L) and the second sensor (R) are connected to a heartbeat detection unit 14. The heartbeat detection unit 14 outputs a high-frequency signal of a predetermined frequency to the first sensor (L) and the second sensor (R), detects the potentials of the first sensor (L) and the second sensor (R), and determines the contact of the occupant with the steering wheel.

[0003] In addition, a first electrode (L) and a second electrode (R) are connected to the heartbeat detection unit 14. On the steering wheel 22, the first electrode (L) is provided near the first sensor (L), and the second electrode (R) is provided near the second sensor (R). The occupant is arranged to contact the first electrode (L) together with the first sensor (L) and contact the second electrode (R) together with the second sensor (R).

[0004] The heartbeat detection unit 14 determines whether the driver's grip on the steering wheel is a one-handed grip or a two-handed grip from the potential difference (voltage pattern) between the first electrode (L) and the second electrode (R). Further, when it is determined by the heartbeat detection unit 14 that the driver's grip on the steering wheel 22 is a two-handed grip, a signal of the driver's amplitude is output from the potential difference between the first electrode (L) and the second electrode (R).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in the gripping detection device of Patent Document 1, in order to detect the gripping state of the steering wheel by the driver and the electrocardiogram of the driver, in addition to the first sensor (L) and the second sensor (R) on the steering wheel, the first electrode (L) and the second electrode (R) are provided. Further, the gripping detection device detects the capacitance of each of the first sensor (L) and the second sensor (R), and the potentials of the first electrode (L) and the second electrode (R), and there is room for improvement in the detection of the electrocardiogram.

[0007] The present invention has been made in view of the above facts, and an object thereof is to provide an electrocardiogram detection device capable of obtaining a passenger's electrocardiogram with high accuracy.

Means for Solving the Problems

[0008] An electrocardiogram detection device according to a first aspect of the present invention includes a power supply unit that applies AC power of a preset frequency to a passenger as a subject riding in a moving body, and two positions in the moving body that sandwich the passenger's heart. A pair of sensor electrodes arranged opposite to each other and each electrically contactable by the passenger, a detection unit that detects the voltage of each of the pair of sensor electrodes and detects a voltage signal indicating the electrocardiogram waveform of the passenger from the detected voltage, and the pair of Using the voltage of the frequency of the AC power obtained from the voltage of each of the sensor electrodes, a determination unit that determines whether or not the passenger is in contact with each of the pair of sensor electrodes, and when it is determined that the passenger is in contact with each of the pair of sensor electrodes, an output unit that outputs a voltage signal indicating the electrocardiogram waveform of the passenger.

[0009] The electrocardiogram detection device according to the second aspect, in the first aspect, 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 in contact therewith.

[0010] In the third aspect, the electrocardiogram detection device includes, in the second aspect, that one of the pair of sensor electrodes is disposed on the gripping body and the other is disposed on the seat on which the occupant is seated.

[0011] In the fourth aspect, the electrocardiogram detection device includes, in the second aspect, that the pair of sensor electrodes are provided in pairs at the gripping positions of the occupant's right hand and left hand on the gripping body, and the determination unit determines whether the occupant is gripping the gripping body with both hands.

[0012] In the fifth aspect, the electrocardiogram detection device is, in any one of the second to fourth aspects, the gripping body is a steering body for steering the moving body.

[0013] In the sixth aspect, the electrocardiogram detection device includes, in the fourth aspect, that 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.

[0014] In the seventh aspect, the electrocardiogram detection device includes, in any one of the first to sixth aspects, a power supply electrode that comes into contact with the occupant, and a generation unit that is connected to the power supply electrode and generates the AC power of the frequency.

[0015] In the eighth aspect, the electrocardiogram detection device includes, in any one of the first to sixth aspects, a generation unit that is connected to at least one of the pair of sensor electrodes and generates the AC power of the frequency.

[0016] In the ninth aspect, the electrocardiogram detection device includes, in any one of the first to eighth aspects, 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, detecting a peak of the voltage signal, and when a dropout occurs in the peak, using the voltage signal indicating the electrocardiogram waveform of the occupant that has already been output to complement the dropout range of the peak.

Advantages of the Invention

[0017] In the electrocardiogram detection device according to the first aspect, in a moving body in which a subject rides as a passenger, a pair of sensor electrodes are arranged opposite to two positions sandwiching the passenger's heart, and each of them is electrically contactable with the passenger. The detection unit detects the voltage of each of the pair of sensor electrodes and detects a voltage signal indicating the electrocardiogram waveform of the passenger from the detected voltage.

[0018] Here, the power supply unit applies AC power of a preset frequency to the passenger. As a result, when the passenger contacts 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 passenger is in contact with each of the pair of sensor electrodes by using the voltage of the frequency of the AC power obtained from the voltage of each of the pair of sensor electrodes.

[0019] When it is determined that the passenger is in contact with each of the pair of sensor electrodes, the output unit outputs a voltage signal indicating the electrocardiogram waveform of the passenger. Thereby, when the passenger is in contact with each of the pair of sensor electrodes, a highly accurate electrocardiogram waveform (electrocardiogram) can be obtained.

[0020] In the electrocardiogram detection device according to the second aspect, the moving body includes a gripping body gripped by the passenger, and at least one of the pair of sensor electrodes is arranged on the gripping body so that the passenger can contact it. Thereby, when the passenger is in contact with the gripping body, an electrocardiogram waveform can be obtained, and the electrocardiogram waveform can be effectively obtained.

[0021] In the electrocardiogram detection device according to the third aspect, one of the pair of sensor electrodes is arranged on the gripping body and the other is arranged on the seat on which the passenger sits. Thereby, when the passenger sits on the seat and grips the gripping body, an electrocardiogram waveform can be obtained, and the electrocardiogram waveform can be effectively obtained.

[0022] In the electrocardiogram detection device according to the fourth aspect, a pair of sensor electrodes are provided on the gripping body, and the pair of sensor electrodes are provided at the gripping positions of the right hand and the left hand of the occupant. The determination unit determines whether the occupant is gripping the gripping body with both hands. Thereby, when the occupant grips the gripping body with both hands, an electrocardiogram waveform can be obtained, and the electrocardiogram waveform can be obtained more effectively.

[0023] In the electrocardiogram detection device according to the fifth aspect, a steering body for steering a moving body is used as the gripping body. Thereby, when the occupant grips the steering body with both hands and steers the moving body, an electrocardiogram waveform can be obtained, and the electrocardiogram waveform can be obtained more effectively.

[0024] In the electrocardiogram detection device according to the sixth aspect, the determination unit determines the gripping state of the steering body by the occupant, and the output unit outputs the determined gripping state. Therefore, not only the detection of the electrocardiogram waveform, but also the gripping state of whether the occupant is gripping the steering body as the gripping body with both hands, with either the left or right single hand, or not gripping can be determined. Thereby, while suppressing an increase in parts and an increase in cost for detecting the gripping state, the detection of the electrocardiogram waveform and the detection of the occupant's gripping can be performed.

[0025] In the electrocardiogram detection device according to the seventh aspect, the power supply unit includes a power supply electrode that comes into contact with the occupant, and a generation unit that generates AC power of a preset frequency to be applied to the occupant via the power supply electrode. Thereby, AC power of a preset frequency can be effectively applied to the occupant.

[0026] In the electrocardiogram detection device according to the eighth aspect, a generation unit that generates AC power of a preset frequency is connected to at least one of the pair of sensor electrodes. Thereby, when the occupant comes into contact with the sensor electrode, AC power of a preset frequency can be efficiently applied to the occupant.

[0027] In the electrocardiogram detection device according to the ninth aspect, when it is determined that the occupant is in contact with each of the pair of sensor electrodes, a voltage signal indicating the electrocardiogram waveform of the occupant is output. At this time, when the peak of the voltage signal indicating the electrocardiogram waveform of the occupant is detected and there is a missing peak, the output unit uses the peak of the voltage signal indicating the electrocardiogram waveform of the occupant that has already been output to complement the missing peak range. Thereby, it is possible to prevent the occurrence of missing peaks in the electrocardiogram waveform, and an electrocardiogram waveform capable of determining the heart rate can be obtained.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 〔First Embodiment〕 In FIG. 1, a schematic configuration of the main part of the electrocardiogram detection device 10 according to the first embodiment of the present invention is shown in a block diagram. Further, in FIG. 2, a front view of the main part of the vehicle on which the electrocardiogram detection device 10 is mounted is shown as viewed from the occupant side.

[0030] In the drawings, the right side in the vehicle width direction is indicated by the arrow HR, and the upper side is indicated by the arrow UP. Further, in the present embodiment, the grounded state refers to a state in which the vehicle body (not shown) of the vehicle is used as the ground electrode GND and is electrically connected to the ground electrode GND. Furthermore, in the present embodiment, the contact and electrical connection include not only the case where they are directly connected using wiring or the like, but also the case where they are in a contact state via an impedance (capacitor). In the following description, the same reference signs are given to signals having basically the same form regardless of whether they are analog or digital.

[0031] As shown in FIG. 2, a steering device 12 as a steering device 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.

[0032] The electrocardiogram detection device 10 detects whether or not an occupant is gripping the steering wheel 14. Further, when it is detected that the occupant is gripping the steering wheel 14 with both hands, the electrocardiogram detection device 10 detects a signal (voltage signal) indicating the electrocardiogram waveform (electrocardiogram) of the occupant and outputs a signal indicating the electrocardiogram waveform.

[0033] The steering wheel 14 is disposed on the front side of the vehicle of a seat (driver's seat, not shown) on which an occupant (driver) as a subject for driving the vehicle is seated. 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. Further, the steering wheel 14 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. In the steering wheel 14, the boss core portion and the rim core portion are connected by the stay core portion, and the rim portion 16, the boss portion 18, and the stay portion 20 are integrated.

[0034] The steering device 12 includes a steering shaft (not shown), and the steering shaft has an axial direction substantially in the longitudinal direction of the vehicle at the front side of the driver's seat and is rotatably supported by the vehicle body. The steering wheel 14 has a boss core metal part of the boss part 18 fixed to the rear end of the steering shaft on the vehicle side. The steering wheel 14 is integrally rotatable with the steering shaft and is supported by the vehicle body, and the core metal part is grounded to the vehicle body via the steering shaft.

[0035] In the vehicle, when the steering wheel 14 of the steering device 12 is rotationally operated, the steering shaft is rotated and the steered wheels (front wheels) are steered for steering. Note that in FIG. 2, a front view of the steering wheel 14 in a straight-ahead state of the vehicle as seen by the occupant is shown.

[0036] In the rim portion 16 of the steering wheel 14, a resin material such as urethane as an insulating material is used, and a base body (not shown) having a substantially circular cross section (may be substantially elliptical) is disposed. The base body covers the rim core metal part of the rim portion 16, and the rim core metal part is accommodated in the base body by insert molding.

[0037] Also, in the rim portion 16 of the steering wheel 14, a decorative portion 26 as a contact portion (skin) is disposed on the outer side in the radial direction of the base body. The decorative portion 26 is made of leather or resin (a part may be made of wood) and has insulating properties. The rim portion 16 of the steering wheel 14 is covered by the decorative portion 26 over the entire circumference in the radial cross section of the steering wheel 14 of the base body and over the entire circumference (entire area) in the circumferential direction of the steering wheel 14.

[0038] As shown in FIGS. 1 and 2, the electrocardiogram detection device 10 includes sensor electrodes 30L and 30R as a pair of sensor electrodes. 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 the occupant contacts (is close to).

[0039] 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.

[0040] 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 with the decorative portion 26.

[0041] 2, in 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.

[0042] On 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, 32R) are arranged on the inner periphery of the steering wheel 14.

[0043] As a result, in the electrocardiogram detection device 10, when the occupant grips the steering wheel 14 (rim portion 16) with the left hand, the occupant comes into contact (proximity) with 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 the right hand, the occupant comes into contact (proximity) with the sensor electrode 30R and the power supply electrode 32R. When the occupant approaches the sensor electrodes 30L, 30R and the power supply electrodes 32 (32L, 32R), an impedance is generated between the occupant and each of them, and through this impedance, the occupant is in an electrical contact state with the sensor electrodes 30L, 30R and the power supply electrodes 32 (32L, 32R).

[0044] Note that the power supply electrode 32 may be arranged at the position where the occupant contacts when the occupant contacts the sensor electrodes 30L, 30R. For this reason, the power supply electrodes 32 (32L, 32R) may be arranged on the outer peripheral side of the steering wheel 14 and the sensor electrodes 30L, 30R may be arranged on the inner peripheral side of the steering wheel 14 on the rim portion 16.

[0045] As shown in FIG. 1, in the electrocardiogram detection unit 34, a signal generator (oscillator) 38 as a generation unit constituting a power supply unit, a buffer unit 40, a detection unit 42, a determination unit 44, and an output unit 46 are formed. The electrocardiogram detection unit 34 is provided with required functional circuits together with a computer (not shown) including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a non-volatile memory such as a flash memory. As a result, in the electrocardiogram detection unit 34, the CPU reads out a program stored in advance in the memory and expands it in the RAM and executes it, whereby the functions of the signal generator 38, the buffer unit 40, the detection unit 42, the determination unit 44, and the output unit 46 are realized.

[0046] The power supply electrodes 32 (32L, 32R) are connected to the signal generator 38. The signal generator 38 generates a sine wave signal with a preset frequency f and supplies alternating current power P corresponding to the generated sine wave signal to the power supply electrodes 32 (32L, 32R). The occupant is grounded to the vehicle body through a predetermined impedance, such as by sitting on the seat. As a result, when the occupant holds the steering wheel 14 and contacts at least one of the power supply electrodes 32 (32L, 32R), the alternating current power P is applied, and a current change corresponding to the frequency f occurs in the occupant's body (an alternating current flows).

[0047] In the occupant, an ion current change (alternating current) occurs due to the electrical activity in the heartbeat of the heart. This ion current due to the electrical activity in the heartbeat of the heart is generally about 1 mA. The alternating current power P may be power that generates an alternating current of a sufficient magnitude (for example, a current of 10 mA or more) with respect to this ion current when applied to the occupant through the power supply electrode 32.

[0048] In the signal generator 38, a frequency in a band different from the frequency included in the cycle of the heartbeat or the like is applied as the preset frequency f. In the first embodiment, as an example, the frequency f is set to 100 Hz, 150 Hz, or 200 Hz (for example, 100 Hz). Note that the space around the vehicle may include electromagnetic waves or the like caused by a commercial power supply (frequency of 50 Hz or 60 Hz), and it is more preferable to set the frequency to a frequency excluding the frequency of the commercial power supply and the frequencies overlapping with the harmonics of the commercial power supply (for example, 100 Hz or 120 Hz corresponding to the second harmonic).

[0049] At each of the sensor electrodes 30L and 30R, the occupant holds the rim portion 16 of the steering wheel 14 and the occupant's hand makes contact (proximity, electrical contact through a predetermined impedance). As a result, a change in potential corresponding to the ion current change due to the electrical activity in the heartbeat of the occupant's heart occurs in the sensor electrodes 30L and 30R.

[0050] In addition, a current flows through the occupant due to the alternating current power P applied by contacting the power supply electrode 32, and potential changes corresponding to the current of the frequency resulting from the alternating current power P applied to the occupant via the power supply electrode 32 occur in the sensor electrodes 30L and 30R.

[0051] 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) are provided in the buffer section 40 of the electrocardiogram detection section 34. In each of the buffer circuits 50L and 50R, an operational amplifier having an input impedance larger than the output impedance is used, and the sensor electrodes 30L and 30R are connected to the buffer circuits 50L and 50R, respectively.

[0052] As a result, each of the buffer circuits 50L and 50R outputs a signal (voltage signal) S L , S R corresponding to the potential change occurring in the sensor electrodes 30L and 30R. Also, since the occupant is in contact with the power supply electrode 32, the signals S L , S R include a signal S CL , S CR indicating an electrocardiogram waveform, together with signals (voltage signals) S Lf , S Rf of frequency f, and the signals S L , S R are superimposed on the signals S CL , S CR and the signals S Lf , S Rf (S L = S CL + S Lf , S R = S CR + S Rf ).

[0053] The detection unit 42 includes a differential amplifier circuit 52, A / D converters 54A, 54L, and 54R each for converting an analog signal into a digital signal, and filter units 56A, 56L, and 56R each for performing filter processing to extract required frequency components. The differential amplifier circuit 52 has the output sides of buffer circuits 50L and 50R connected to its input side, and the filter unit 56A is connected to its output side via the A / D converter 54A. Note that one of the buffer circuits 50L and 50R (for example, buffer circuit 50L) is connected to the plus side of the differential amplifier circuit 52, and the other (for example, buffer circuit 50R) is connected to the minus side of the differential amplifier circuit 52.

[0054] Also, the output sides of buffer circuits 50L and 50R are connected to the input sides of A / D converters 54L and 54R respectively, and filter units 56L and 56R are connected to the output sides of A / D converters 54L and 54R respectively. Note that the filter units 56A, 56L, and 56R are digital filters that perform filter processing on the signals digital-converted by the A / D converters 54A, 54L, and 54R respectively.

[0055] The filter unit 56A allows signals S CL , S CR of the frequency of the electrocardiogram waveform to pass through (removes signals S Lf , S Rf of frequency f) and performs filter processing using a band-pass filter (BPF) or a low-pass filter (LPF). For example, the filter unit 56A uses an LPF with a cut-off frequency of 40 Hz (it may also be 50 Hz etc.) for heartbeats with a frequency less than 40 Hz to perform filter processing to remove the components of the frequency f of the AC power P (signals S Lf , S Rf ).

[0056] Also, the filter units 56L and 56R perform filter processing that functions as a band-pass filter or a high-pass filter (HPF) that allows the components of the frequency f of the signal generator 38 to pass through. The filter units 56L and 56R extract signals S Lf , S Rf using a BPF with a center frequency of the frequency f.

[0057] As a result, in the detection unit 42, a signal (voltage) detected by the contact of the occupant 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 acquiring the electrocardiogram of the occupant is obtained. LR Also, in the detection unit 42, signals S L detected by each of the filter units 56L and 56R at each of the sensor electrodes 30L and 30R R are signals S that change at a frequency f included in Lf and S Rf are output.

[0058] The determination unit 44 compares the amplitude (which may be the peak value) of each of the signals S Lf and S Rf output from the filter units 56L and 56R with a preset threshold value fth (voltage value) to determine the gripping state of the occupant with respect to the steering wheel 14. The determination unit 44 determines that the occupant is gripping the steering wheel 14 with the left hand when the amplitude of the signal S Lf exceeds the threshold value fth. Also, the determination unit 44 determines that the occupant is gripping the steering wheel 14 with the right hand when the amplitude of the signal S Rf exceeds the threshold value fth. As a result, the determination unit 44 determines which of non-gripping (neither hand is gripping), one-handed gripping with the left hand, one-handed gripping with the right hand, and both-handed gripping is the gripping state of the occupant with respect to the steering wheel 14.

[0059] The output unit 46 outputs the gripping state of the occupant with respect to the steering wheel 14, which is the determination result of the determination unit 44. Also, when the determination unit 44 determines that both hands are gripping (the steering wheel 14 is gripped with both hands), the output unit 46 outputs the signal S LR output from the filter unit 56A to the electrocardiogram waveform generation device 36.

[0060] Next, as the operation of the first embodiment, the operation of the electrocardiogram detection device 10 will be described. Fig. 3 schematically shows the signal flow 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.

[0061] The electrocardiogram detection device 10 starts operating when, for example, the ignition switch of the vehicle is turned on and the vehicle starts running, and stops operating when the ignition switch is turned off and the vehicle stops running.

[0062] When the electrocardiogram detection unit 34 starts operating, the signal generator 38 generates AC power P with a 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. When a passenger touches the power supply electrode 32, an electric current (AC current with a frequency F) corresponding to the AC power P flows through the passenger's body to the vehicle body.

[0063] Also, in the electrocardiogram detection unit 34, the buffer unit 40 of the detection unit 42 detects the potentials generated at the sensor electrodes 30L and 30R at a preset time interval and detects changes in the potentials. As a result, signals S L , S R are output. Further, in the detection unit 42, the differential amplifier circuit 52 generates a differential signal of the signals S L , S R , and performs an A / D conversion process and a filter process using an LPF on this differential signal, thereby outputting a signal S LR excluding the component with the frequency f to the output unit 46.

[0064] At the same time, in the detection unit 42, an A / D conversion process and a filter process using a BPF are performed on each of the signals S L , S R . As a result, in the electrocardiogram detection unit 34, signals S L , S R each containing a signal S Lf , S Rf with the frequency f are output from the detection unit 42 to the determination unit 44.

[0065] In the determination unit 44, the signal SLf , S Rf By using the threshold value fth for S, the gripping state of the occupant on the steering wheel 14 is determined. At this time, the determination unit 44 determines whether the gripping state is non-gripping, one-handed gripping (right one-handed, left one-handed), or both-handed gripping. The electrocardiogram detection unit 34 inputs the determination result of the determination unit 44 to the output unit 46.

[0066] When the occupant is not gripping the steering wheel 14 and neither the left hand nor the right hand of the occupant is in contact with the sensor electrodes 30L and 30R, the signal S L does not include the signal S CL and the signal S Lf , and the signal S R does not include the signal S CR and the signal S Rf . Therefore, the signals S Lf , S Rf input to the determination unit 44 are all at a low level whose amplitude does not exceed the threshold value fth, and the determination unit 44 determines that the steering wheel 14 is not being gripped.

[0067] On the other hand, when the occupant touches the power supply electrode 32, a current corresponding to the alternating current 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 at the sensor electrodes 30L and 30R.

[0068] That is, the power supply electrodes 32 (32L, 32R) are arranged so that the occupant touches them when the occupant grips the steering wheel 14 and contacts the sensor electrodes 30L and 30R. For example, when the occupant grips the steering wheel 14 with the left hand, the occupant's hand (left hand) contacts the sensor electrode 30L and also contacts the power supply electrode 32 (32L). As a result, as shown in FIG. 3, the detection unit 42 detects signals S L , S R corresponding to the heartbeat and the alternating current power P, and signals S L , S R are extracted from these signals S LR and signal S Lf , S Rf .

[0069] In the determination unit 44, when the amplitude of the signal S Lf exceeds the threshold value fth, it is determined that the occupant is gripping the steering wheel 14 with the left hand. When the amplitude of the signal S Rf exceeds the threshold value fth, it is determined that the occupant is gripping the steering wheel 14 with the right hand. At this time, in the detection unit 42, since one of the signals S CL and S CR is not detected, an appropriate signal S LR cannot be obtained.

[0070] On the other hand, when the occupant grips the steering wheel 14 with both hands (left hand and right hand), in the detection unit 42, the signal S CL and the signal S whose amplitude exceeds the threshold value fth Lf The signal S including L , and the signal S CR And the signal S whose amplitude exceeds the threshold value fth Rf The signal S including R is detected.

[0071] Accordingly, the determination unit 44 determines that the occupant is gripping the steering wheel 14 with each of the left hand and the right hand (both hands gripping). Also, in the detection unit 42, the signal S LR output from the filter unit 56A includes the signal S CL and the signal S CR . Therefore, the electrocardiogram detection device 10 (electrocardiogram detection unit 34) can accurately detect an appropriate electrocardiogram waveform.

[0072] Further, in the electrocardiogram detection unit 34, the determination unit 44 can determine the gripping state of the steering wheel 14 by the occupant. Thereby, for example, when the output unit 46 outputs the determination result to a warning system or the like provided in the vehicle, the warning system can give a warning to prompt the occupant to grip the steering wheel 14 when the non-gripping state of the steering wheel 14 has elapsed for a predetermined time.

[0073] In this way, the electrocardiogram detection device 10 applies an alternating current electrode P with a frequency f to the occupant. As a result, when the occupant contacts the sensor electrodes 30L and 30R, the detection unit 42 detects a signal S CL and a signal S Lf included in the signal S L , and a signal S CR and a signal S Rf included in the signal S R can be detected.

[0074] Also, when the determination unit 44 determines from the signals S Lf , S Rf that the gripping state is a two-handed grip, the output unit 46 outputs a signal S CL , S CR corresponding to the signal S LR . As a result, in the electrocardiogram detection device 10, when the occupant is in contact with each of the sensor electrodes 30L and 30R, a highly accurate electrocardiogram waveform (electrocardiogram) can be obtained.

[0075] Also, in the electrocardiogram detection device 10, a pair of sensor electrodes 30L and 30R are arranged on the steering wheel 14. Therefore, when the occupant grips the steering wheel 14 with both hands (pinching the heart) to steer the vehicle, an electrocardiogram waveform can be detected, and the electrocardiogram waveform of the occupant can be obtained more effectively.

[0076] Also, in the electrocardiogram detection device 10, the determination unit 44 can determine the gripping state of the steering wheel 14 by the occupant. Therefore, using the configuration for detecting the electrocardiogram waveform, the gripping state of the steering wheel 14 can be detected. Thus, parts and assembly operations for detecting the gripping state of the steering wheel 14 can be suppressed separately from the configuration for detecting the electrocardiogram waveform, and cost increase can be suppressed.

[0077] In the first embodiment, a power supply electrode 32L is provided corresponding to the sensor electrode 30L, and a power supply electrode 32R is provided corresponding to the sensor electrode 30R. However, the power supply electrode may be arranged at a position where the occupant always contacts, such as the seat section of the seat.

[0078] In the first embodiment, the gripping state of the steering wheel 14 by the occupant can be determined as two-handed gripping, one-handed gripping with either the left or right hand, and non-gripping. However, it may be determined only as two-handed gripping or non-two-handed gripping (one-handed gripping with either the left or right hand and non-gripping) as the gripping state of the steering wheel 14. In this case, the power supply electrode may be installed corresponding to one of the pair of sensor electrodes.

[0079] 〔Second Embodiment〕 Next, a second embodiment of the present invention will be described. The basic configuration of the second embodiment is the same as that of the first embodiment. For functional components and the like that are the same as those in the first embodiment in the second embodiment, the same reference numerals as those in the first embodiment are given and the description thereof is omitted.

[0080] FIG. 4 shows a schematic configuration of the electrocardiogram detection device 60 according to the second embodiment. Further, FIG. 5 shows a front view of the steering wheel 14 according to the second embodiment.

[0081] As shown in FIGS. 4 and 5, the 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 electrodes 32 (32L, 32R). Further, the electrocardiogram detection unit 64 is provided in the electrocardiogram detection device 60 in place of the electrocardiogram detection unit 34, and the electrocardiogram detection unit 64 is different from the electrocardiogram detection unit 34 in that a determination unit 66 is formed in place of the determination unit 44.

[0082] As shown in FIG. 5, on the steering wheel 14, the sensor electrode 62L is arranged in a range of approximately a half circumference on the left side portion, and the sensor electrode 62R is arranged in a range of approximately a half circumference on the right side portion. Each of the sensor electrodes 62L, 62R is arranged over substantially the entire circumference in the circumferential direction of the cross section on the outer periphery of the base body of the rim portion 16.

[0083] As a result, the sensor electrodes 62L and 62R, together with the power supply electrodes 32L and 32R on the rim portion 16, can detect the contact of the occupant with the steering wheel 14 in a wider range than when the sensor electrodes 30L and 30R are arranged.

[0084] Also, as shown in FIG. 4, in the electrocardiogram detection unit 64, the signal generator 38 is connected to each of the sensor electrodes 62L and 62R via a required impedance (for example, capacitor C), and the signal generator 38 supplies an alternating current P with a frequency f to the sensor electrodes 62L and 62R. As a result, in the electrocardiogram detection device 60, the alternating current power with the frequency f can be surely applied to the occupant in contact with the sensor electrodes 62L and 62R.

[0085] Also, the sensor electrodes 62L and 62R are supplied with the alternating current power P from the signal generator 38. For this reason, in the sensor electrodes 62L and 62R, a potential corresponding to the alternating current power P is generated in the non-contact state of the occupant. Further, in the sensor electrodes 62L and 62R, when the occupant comes into contact and the body of the occupant is grounded, the potential decreases compared to the non-contact state.

[0086] Based on the potential in the non-contact state of the occupant with respect to the sensor electrodes 62L and 62R and the potential in the contact state of the occupant with respect to the sensor electrodes 62L and 62R, a threshold value fth is set in the determination unit 66 of the electrocardiogram detection unit 64 so that the contact state and the non-contact state can be discriminated from the amplitudes (which may be peaks) of the signals S Lf 、S Rf .

[0087] In the determination unit 66, when the amplitude of the signal S Lf exceeds the threshold value fth, it is determined that the occupant is not in contact with the sensor electrode 62L, and when the amplitude of the signal S Rf exceeds the threshold value fth, it is determined that the occupant is not in contact with the sensor electrode 62R. As a result, in the determination unit 66, the gripping state (contact state) of the steering wheel 14 by the occupant is determined.

[0088] Next, as the operation of the second embodiment, the operation of the electrocardiogram detection device 10 will be described. Figure 6 schematically shows the signal flow in the electrocardiogram detection unit 64. In Figure 6, (A) shows the contact state of the occupant with the sensor electrodes 62L and 62R, and (B) shows the non-contact state of the occupant with the sensor electrodes 62L and 62R. Also, the "left side" indicates the side of the sensor electrode 30L, and the "right side" indicates the side of the sensor electrode 30R.

[0089] Figure 7 schematically shows the signal output from the output unit 46 in a diagram. In Figure 7, the signal S LR , and the signal Bj as the determination result when held with both hands are shown. In Figure 7, the horizontal axis represents time (sec), the left vertical axis represents the voltage (V) with respect to the signal S LR , and the right side represents the determination result indicated by the signal Bj. High (1) indicates holding with both hands, and Low (0) indicates non-holding.

[0090] In the electrocardiogram detection device 60 (electrocardiogram detection unit 64), when operating, the signal generator 38 supplies AC power P with frequency f to each of the sensor electrodes 62L and 62R. As a result, as shown in Figure 6(B), the signals S L , S R detected by the detection unit 42 of the electrocardiogram detection unit 64 include signals S CL , S CR with small changes and signals S Lf , S Rf with large amplitudes.

[0091] Therefore, when the amplitudes of the signals S Lf , S Rf exceed the threshold value fth, the determination unit 66 determines that the occupant's both hands are in a non-holding state where they are not in contact with the steering wheel 14. As a result, the output unit 46 stops the output of the signal S LR indicating the electrocardiogram waveform.

[0092] On one hand, when the occupant grips the steering wheel 14, the occupant comes into contact with the sensor electrodes 62L and 62R. When the occupant contacts the sensor electrodes 62L and 62R, the sensor electrodes 62L and 62R are grounded through the occupant's body, and a current corresponding to the alternating current P flows. For this reason, a potential drop (mainly, the potential drop due to the alternating current power P) occurs in the sensor electrodes 62L and 62R. As a result, as shown in FIG. 6(A), the signal S L , S R detected by the detection unit 42 includes a signal S CL , S CR with a small change and a signal S Lf , S Rf with a reduced amplitude.

[0093] In the detection unit 42, signals S L , S R detected at the sensor electrodes 62L and 62R are used to extract signals S CL , S CR and output them to the determination unit 66. In the determination unit 66, when the potential drops due to the contact of the occupant and the amplitude of the reduced signal S Lf , S Rf is equal to or less than the threshold value fth, it is determined that the occupant is in contact with the steering wheel 14.

[0094] At this time, in the determination unit 66, if the amplitude of the signal S Lf 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 if the amplitude of the signal S Rf 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. Also, in the determination unit 66, if it is determined that both the occupant's left hand and right hand are gripping the steering wheel 14, it is determined that the steering wheel 14 is gripped with both hands. As a result, as shown in FIG. 7, the signal Bj switches from Low to High.

[0095] Furthermore, since the occupant is gripping the steering wheel 14 with both hands, the signals S L , S R include a signal S CL capable of generating an electrocardiogram waveform., S CR is included. As a result, the output unit 46 outputs the signal S CL , S CR to the electrocardiogram waveform generation device 36 according to the signal S LR . Therefore, the electrocardiogram detection device 60 exhibits the same effects as the electrocardiogram detection device 10 according to the first embodiment.

[0096] Also, in the electrocardiogram detection device 60, AC power P of frequency f is applied to the occupant via the sensor electrodes 62L and 62R, and signals S L , S R are extracted from signals S Lf , S Rf corresponding to the AC power P of frequency f. As a result, compared with the electrocardiogram detection device 10, the number of components and the assembly man-hours can be further suppressed, so that the cost increase can be more effectively suppressed.

[0097] Note that in the first and second embodiments described above, digital filters are applied to the filter units 56A, 56L, and 56R that perform filter processing. However, an analog filter may be used for the filter processing. In this case, the filter unit and the A / D conversion unit may be interchanged so that A / D conversion is performed on the filtered signal.

[0098] Also, 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 electrodes may include noise components, and due to the inclusion of the noise components, it is conceivable that the amplitude of the signal component of frequency f becomes large and exceeds the threshold value fth, resulting in an erroneous determination.

[0099] From here, the power supply unit may apply AC power in which a plurality of frequencies are superimposed to the occupant. In this case, for the plurality of frequencies, it is preferable to select values such that one frequency is not an integer multiple of the other frequency, for example, 100 Hz and 150 Hz. Thereby, it is possible to prevent an erroneous determination caused by noise components.

[0100] Also, in the first and second embodiments, the signal S corresponding to the electrocardiogram waveform was output to the electrocardiogram waveform generation device 36. However, the signal corresponding to the electrocardiogram waveform may be stored in a non-volatile storage medium such as a storage, and the electrocardiogram waveform may be obtained by attaching the storage medium to the electrocardiogram waveform generation device. LR 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

[0101] to the electrocardiogram waveform generation device 36. However, the output unit 46 stores the signal S for a predetermined time while determining the change in the signal S LR and, when it is determined that there is no irregular change in the signal S LR LR LR , if it is for a short period (for example, about several seconds), when it becomes a non-gripping state, the stored signal S LR LR LR LR

[0102] That is, when it is determined that the occupant is in contact with the sensor electrodes 30L, 30R or the sensor electrodes 62L, 62R and the output unit 46 is outputting the signal S LR , the peak of the signal S LR is detected, and when there is a missing peak, the missing peak range may be complemented using the already output signal S LR . Thereby, even if at least one of the occupant's left and right hands is separated from the steering wheel 14 for a short period, the electrocardiogram waveform generation device 36 can continue to measure the occupant's heartbeat and the like.

[0103] Furthermore, in the first embodiment described above, each of the sensor electrodes 30L and 30R is arranged on the steering wheel 14, and in the second embodiment, the sensor electrodes 62L and 62R are arranged on the steering wheel 14. However, one of the pair of sensor electrodes may be arranged on the steering body or the gripping body, and the other may be arranged on the seat section of the seat on which the occupant is seated. Even in this case, it is possible to determine that the occupant is in contact with each of the pair of sensor electrodes and output a detection signal for generating an electrocardiogram waveform, so that it is possible to generate a highly accurate electrocardiogram waveform.

[0104] Also, in the first and second embodiments, the electrocardiogram detection devices 10 and 60 are configured to be able to generate an electrocardiogram of an occupant riding in a vehicle. However, the vehicle may be a two-wheeled vehicle (such as a motorcycle) or a bicycle. In this case, sensor electrodes may be arranged on each of the left and right grips of the handlebar gripped by the occupant, or one of the pair of sensor electrodes may be arranged on the grip of the handlebar and the other may be arranged on the seat (saddle).

[0105] The moving body may also be a wheelchair or the like. When applying a wheelchair as the moving body, one of the pair of sensor electrodes may be arranged on the seat (seat cushion) on which the occupant is seated, and the other may be provided on an arm support attached to a metal frame. The other sensor electrode may be provided on each of the left and right arm supports. Also, alternating current power of frequency f may be applied to the occupant via the pair of sensor electrodes, and since the occupant is always seated on the seat cushion, the power supply electrode may be arranged on the seat cushion together with one of the sensor electrodes.

[0106] As a result, it becomes possible to measure the electrocardiogram of an occupant riding in various moving bodies such as two-wheeled vehicles, bicycles, and wheelchairs, not limited to vehicles (automobiles).

Explanation of Reference Numerals

[0107] 10, 60... Electrocardiogram detection device, 14... Steering wheel (grip body, steering body), 30L, 30R... Sensor electrodes, 32 (32L, 32R)... Power supply electrodes (power supply unit), 34, 64... Electrocardiogram detection unit, 38... Signal generator (power supply unit), 40L, 40R... Buffer unit, 42... Detection unit, 44, 66... Judgment unit, 46... Output unit.

Claims

1. A power supply unit that applies AC power of a preset frequency to a passenger who is a subject riding in a moving body; A pair of sensor electrodes that are arranged to face two positions sandwiching the passenger's heart in the moving body, and each of which allows the passenger to be in electrical contact; A detection unit that detects the voltage of each of the pair of sensor electrodes and detects a voltage signal indicating the electrocardiogram waveform of the passenger from the detected voltage; A determination unit that determines whether or not the passenger is in contact with each of the pair of sensor electrodes by using the voltage of the frequency of the AC power obtained from the voltage of each of the pair of sensor electrodes; 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 including the above.

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

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

4. The pair of sensor electrodes are provided in pairs at the gripping positions of the passenger's right hand and left hand on the gripping body, The determination unit determines whether or not the passenger is gripping the gripping body with both hands. The electrocardiogram detection device according to claim 2 including the above.

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

6. 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 passenger, The electrocardiogram detection device according to claim 4, wherein the output unit outputs the determination result of the determination unit.

7. The power supply unit includes a power supply electrode that comes into contact with the passenger, A generation unit that is connected to the power supply electrode and generates the AC power of the frequency. The electrocardiogram detection device according to claim 1 including the above.

8. The electrocardiogram detection device according to claim 1, wherein the power supply unit includes a generation unit that is connected to at least one of the pair of sensor electrodes and generates 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 peak of the voltage signal is detected, and when a missing portion occurs in the peak, the missing range of the peak is complemented using the voltage signal indicating the electrocardiogram waveform of the occupant that has already been output. The electrocardiogram detection device according to claim 1, which includes this.

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