Electrocardiographic data detection device

Abstract

To provide an electrocardiographic data detection device capable of detecting electrocardiographic data of a person seated on a seat even when installed in a seat of a moving body.SOLUTION: An electrocardiographic data detection device comprises: a plurality of electrodes (110) which are provided on a seat back portion (12) of a seat (10) of a moving body and arranged to face a human body; a difference signal generation unit (131A) which generates a difference signal between signals of two electrodes among the plurality of electrodes, and generates a plurality of difference signals from the signals of plural sets of two electrodes; and an electrocardiographic data detection unit (133A) which obtains electrocardiographic data on the basis of the plurality of difference signals. The plurality of electrodes comprise three or more first electrodes (110A) which are arranged along a lateral width direction of the seat back portion in a first region (12A) located on a side close to a seat portion of the seat back portion, and at least one second electrode (110B) which is arranged in a second region (12B) located above the first region in the seat back portion. The plurality of difference signals include at least six or more difference signals obtained from signals of the three or more first electrodes and signals of the at least one second electrode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, there has been an electrocardiogram measurement device that includes a pair of insulated measurement electrodes that should be placed facing each other on the human body in an electrically insulated state, and a measurement circuit that detects a change in voltage that occurs due to electrostatic capacitive coupling between each insulated measurement electrode and the human body, amplifies the difference between the two voltages detected by both insulated measurement electrodes, and outputs the amplified difference as an electrocardiogram waveform signal (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-082938 Summary of the Invention [Problem to be solved by the invention]

[0004] When a conventional electrocardiogram measuring device is installed on a seat of a moving object such as a vehicle, if the human body moves due to vibrations caused by the movement of the moving object, the distance between the measuring insulated electrodes and the human body changes significantly, which could make it impossible to measure electrocardiogram data.

[0005] Therefore, an object of the present invention is to provide an electrocardiogram data detection device that can detect the electrocardiogram data of a person seated in a seat even when the device is installed in the seat of a moving body. [Means for solving the problem]

[0006] An electrocardiogram data detection device according to an embodiment of the present disclosure includes a plurality of electrodes provided in the backrest of a seat mounted on a vehicle having a seat portion and a backrest, the electrodes arranged to face the body of a person seated on the seat; a differential signal generation unit that generates differential signals between signals from two of the plurality of electrodes, the differential signal generation unit generating a plurality of differential signals from signals from multiple pairs of the two electrodes; and an electrocardiogram data detection unit that obtains electrocardiogram data based on the plurality of differential signals, wherein the plurality of electrodes include three or more first electrodes arranged along the width direction of the backrest in a first region closer to the seat portion, and at least one second electrode arranged in a second region of the backrest that is higher than the first region, and the plurality of differential signals are at least six or more differential signals obtained from signals from three or more first electrodes and a signal from at least one second electrode. [Effects of the Invention]

[0007] It is possible to provide an electrocardiogram data detection device that can detect electrocardiogram data of a person seated in a seat of a moving body even when the device is installed in the seat. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of the configuration of an electrocardiogram data detection device 100 according to an embodiment. [Figure 2] 10 is a diagram showing the arrangement of four electrodes 110 in the backrest portion 12. FIG. [Figure 3] FIG. 2 is a diagram showing an example of the arrangement of four electrodes 110 in a front view. [Figure 4] FIG. 12 shows 12 positions where electrodes 110 can be placed in an experiment. [Figure 5A] FIG. 10 is a diagram showing an example of measurement results of electrocardiogram data. [Figure 5B] FIG. 10 is a diagram showing an example of the arrangement of a plurality of electrodes 110 in five selections. [Figure 6A] FIG. 10 is a diagram showing an example of measurement results of electrocardiogram data. [Figure 6B]10 is a diagram showing an example of the arrangement of a plurality of electrodes 110 in the embodiment and comparative examples 1-4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment to which the electrocardiogram data detection device of the present disclosure is applied will be described.

[0010] <Embodiment> <Electrocardiogram Data Detection Device 100> 1 is a diagram showing an example of the configuration of an electrocardiogram data detection device 100 according to an embodiment. The electrocardiogram data detection device 100 includes electrodes 110, a buffer circuit 115, an ADC (Analog to Digital Converter) 120, an MCU (Micro Controller Unit) 130, and an I / F (Interface) driver 140. The ADC 120, the MCU 130, and the I / F driver 140 constitute an ECU (Electronic Control Unit) 150. The ECU 150 is mounted on a vehicle, for example, and is connected to a higher-level device via an in-vehicle network, for example.

[0011] The electrocardiogram data detected by the electrocardiogram data detection device 100 is data indicating the electrical activity of the heart, and includes data including an electrocardiogram waveform, etc., or heartbeat data indicating heartbeats (heartbeat intervals, or heart rate obtained from the heartbeat intervals) obtained based on the electrocardiogram data. In this embodiment, an example in which the heartbeat intervals are obtained will be described.

[0012] As an example, the electrocardiogram data detection device 100 is a device that detects electrocardiogram data of a driver seated in the driver's seat 10 of a vehicle. A vehicle is an example of a moving body. The seat 10 has a seat portion 11 and a backrest portion 12. FIG. 1 shows the driver's seat 10 of a vehicle. However, the electrocardiogram data detection device 100 may also be a device that detects electrocardiogram data of a passenger other than the driver who is seated in a seat 10 other than the driver's seat of the vehicle. Furthermore, the moving body is not limited to a vehicle, and may be a train, steam locomotive, airplane, etc.

[0013] In the following, the relationship between front and rear, up and down, and left and right in the vehicle in which the seat 10 is installed will be used for explanation. The side on which the vehicle moves forward is the front, and the side on which the vehicle moves backward is the rear. Left is the left in the forward direction of the vehicle, and right is the right in the forward direction of the vehicle. Up and down are up and down in the vertical direction. The seat 10 is installed in the interior of the vehicle facing forward of the vehicle. Therefore, the relationship between front and rear, up and down, and left and right with respect to the body of the person seated in the seat 10 corresponds to the relationship between front and rear, up and down, and left and right in the vehicle described above.

[0014] <Electrode 110> A plurality of electrodes 110 are provided inside the backrest 12 of the driver's seat 10 of a vehicle. More specifically, the plurality of electrodes 110 are provided on the reverse side of the skin of the backrest 12, and face the waist or back of the driver seated in the seat 10. The skin of the backrest 12 is the skin of the outer surface of the backrest 12 that comes into contact with the waist or back of the seated driver.

[0015] In the following, as an example, a configuration will be described in which four electrodes 110 are arranged in two rows in the vertical direction, with three electrodes 110 arranged in the lower row and one electrode 110 arranged in the upper row. As an example, the four electrodes 110 are equal in size. Details of the arrangement of the four electrodes 110 will be described later using FIG. 2. However, the number of electrodes 110 is not limited to four. It is preferable that the number of electrodes 110 is at least four, and it is sufficient that at least three electrodes 110 are arranged in the lower row and at least one electrode 110 is arranged in the upper row. Details of this will be described later.

[0016] The electrodes 110 are capacitively coupled to the driver's body, which faces them, via the seat cover or clothing, and measure electrical signals generated in the human body during cardiac activity (beating) as induced signals generated at the electrodes 110. Therefore, by detecting the voltage difference between two of the four electrodes 110, the potential difference between two points on the body can be detected and electrocardiogram data can be measured. The electrodes 110 are connected to the ECU 150 via a buffer circuit 115 such as a voltage follower circuit. The voltage signal input from the buffer circuit 115 to the ECU 150 represents the voltage of each electrode 110.

[0017] <adc120> The ADC 120 is provided between the buffer circuit 115 and the MCU 130. The ADC 120 samples the voltage signal input from the buffer circuit 115 at sufficiently short time intervals, such as several msec, to convert it into a digital signal and output it to the MCU 130.

[0018] In this embodiment, the ADC 120 operates constantly and outputs data to the electrocardiogram data detection device 100, but it may be configured to perform conversion for 60 seconds or more intermittently.

[0019] <mcu130> The MCU 130 includes a calculation unit 130A, a control unit 130B, and a communication I / F 130C. The MCU 130 is realized by a computer including a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an input / output interface, an internal bus, and the like.

[0020] The calculation unit 130A has a differential signal generation unit 131A, a signal determination unit 132A, and a heartbeat detection unit 133A. The signal determination unit 132A and the heartbeat detection unit 133A have memories 132A1 and 133A1, respectively. The heartbeat detection unit 133A is an example of an electrocardiogram data detection unit.

[0021] The calculation unit 130A, control unit 130B, and communication I / F 130C, as well as the differential signal generation unit 131A, signal determination unit 132A, and heartbeat detection unit 133A inside the calculation unit 130A, are shown as functional blocks of the functions of the program executed by the MCU 130. Also, memories 132A1 and 133A1 are functional representations of the memory of the MCU 130. Note that the MCU 130 may have memories other than those shown here, but these are omitted from FIG. 1.

[0022] <Arithmetic section 130A> The calculation unit 130A generates heartbeat data such as heartbeat intervals based on the voltage value output from the ADC 120, and outputs the data to the communication I / F 130C.

[0023] <Differential signal generation unit 131A> The differential signal generator 131A selects two different voltage values ​​from the four voltage values ​​output from the ADC 120 and constantly calculates differential signals. Because there are four voltage values ​​on the subtractor side and four voltage values ​​on the subtracted side, simply calculating all differential signals results in 4 × 4 = 16 differential signals. However, the differential value of the same electrode is zero, so there is no point in calculating differential signals. Furthermore, if the subtractor and subtracted sides are swapped, the calculated differential value simply has the opposite sign to the value before the swap, and can be considered equivalent electrocardiographic data. Therefore, there is no point in calculating differential signals both before and after the swap. For this reason, in this embodiment, differential signals are generated by selecting two different voltages from the four voltage values, generating 4C2 = (4 * 3) / 2 = 6 differential signals. Each differential signal is identified by the combination of the four electrodes 110. The differential signals are evaluated by the signal evaluation unit 132A using the ratio of the signal level to the noise level (SN ratio). The differential signal generating section 131A outputs the differential signal associated with the measurement electrode to the signal determining section 132A and the heartbeat detecting section 133A.

[0024] <Signal determination unit 132A> The signal determination unit 132A calculates the S / N ratios of the six differential signals input from the differential signal generation unit 131A, and determines whether the S / N ratios are suitable for detecting electrocardiogram data, for example, by determining whether they are equal to or greater than a predetermined S / N ratio, and outputs the determination result to the heartbeat detection unit 133A.

[0025] The S / N ratio calculated by the signal determination unit 132A is the average value of values ​​over a predetermined time period, for example, 60 seconds. When continuously calculating the S / N ratio, the differential signal data for 60 seconds output from the ADC 120 and the differential signal data for the next 60 seconds used to calculate the S / N ratio may be data that is continuous or separated by a predetermined time interval. Furthermore, the data may partially overlap, such as calculating the first S / N ratio by calculating the differential signal output from the ADC 120 between 0 and 60 seconds, and calculating the second S / N ratio by calculating the differential signal output from the ADC 120 between 30 and 90 seconds.

[0026] The determination result of the signal determination unit 132A, for example, indicates data among the six differential signals that have a predetermined S / N ratio or higher, arranged in descending order of S / N ratio, and the electrode number corresponding to the S / N ratio. Another example of the determination result indicates that there is no data with a predetermined S / N ratio or higher. The calculation logic used by the signal determination unit 132A to calculate the S / N ratio is stored in memory 132A1, and the determination result of the signal determination unit 132A is also stored in memory 132A1.

[0027] <Heartbeat detection unit 133A> The heartbeat detection unit 133A stores the differential signals input from the differential signal generation unit 131A in the memory 133A1. For the differential signals determined by the signal determination unit 132A to be suitable for detecting electrocardiogram data, the heartbeat detection unit 133A records the time at which a heartbeat (heart beat) occurs based on each differential signal input from the differential signal generation unit 131A, and if the time at which the previous heartbeat occurred is recorded, records the time interval between that time and the previous heartbeat.

[0028] Incidentally, electrocardiogram data is generated by electrical signals that occur in conjunction with the contractions of the atria and ventricles of the heart, and is composed of P waves, QRS waves, T waves, etc., and the time at which a heartbeat occurs in each differential signal is primarily determined by the peak position of the QRS wave, which is the largest signal. However, in reality, the waveform of the electrocardiogram data measured varies depending on the attachment positions of the electrodes relative to the heart, so the time at which a heartbeat occurs is determined based on a predetermined calculation logic stored in memory 133A1.

[0029] The heartbeat detector 133A outputs heartbeat data corresponding to a differential signal indicating the time at which a heartbeat occurs or a time interval to the communication I / F 130C. Note that the heartbeat data corresponding to one differential signal is made up of multiple pieces of data corresponding to the number of heartbeats in 60 seconds.

[0030] The communication I / F 130C transmits the heartbeat data input from the heartbeat detection unit 133A to a higher-level device of the ECU 150 via an in-vehicle network driven by an I / F driver 140.

[0031] The heart rate data is used to evaluate, for example, the driver's level of tension or stress, or sleepiness.

[0032] <Arrangement of Electrodes 110> 2 is a diagram showing the arrangement of four electrodes 110 in the backrest 12. The backrest 12 is provided with a first region 12A and a second region 12B. The first region 12A is located on the lower side, and the second region 12B is located above the first region 12A.

[0033] The four electrodes 110 are divided into three first electrodes 110A provided in the first region 12A and one second electrode 110B provided in the second region 12B. The three first electrodes 110A are arranged parallel to each other in the horizontal direction within the first region 12A. The second electrode 110B is located above the three first electrodes 110A and, for example, is located at the same position in the left-right direction as the rightmost first electrode 110A among the three first electrodes 110A. The second region 12B in which the one second electrode 110B is located is smaller than the first region 12A in which the three first electrodes 110A are located, and its center is located to the right of the center of the first region 12A in the left-right direction. Note that, hereinafter, when there is no need to distinguish between the first electrode 110A and the second electrode 110B, they will simply be referred to as electrodes 110.

[0034] Vibrations caused by the vehicle traveling cause roll and pitch vibrations in the seat 10. When such vibrations occur, the driver's upper body is shaken, which makes it easier for the upper body to slip off the backrest 12.

[0035] Here, the arrangement of the four electrodes 110 will be described using Fig. 3 in addition to Fig. 2. Fig. 3 is a diagram showing an example of the arrangement of the four electrodes 110 when viewed from the front. Fig. 3 transparently shows the arrangement of the four electrodes 110 when the backrest portion 12 is viewed from the front. Fig. 3 also shows the first region 12A and the second region 12B. Note that the front view means looking from the front side toward the rear side to see the front surface (front).

[0036] The second region 12B is smaller than the first region 12A, is located above the first region 12A, and has a center to the right of the first region 12A in the left-right direction. Therefore, the center of the second region 12B is located to the upper right of the center of the first region 12A.

[0037] 3 is set as the reference position for the height positions of the first electrode 110A and the second electrode 110B. The height position of the lower end of the backrest 12 is set to coincide with the height position of the rear end of the seat surface of the seat 11.

[0038] The backrest portion 12 is usually set at an angle that is slightly tilted rearward from the angle perpendicular to the horizontal plane, but Figure 3 shows an example of the configuration of the backrest portion 12 as viewed from the front in an upright position.

[0039] 3 indicate the height from a reference position. The height positions (270 mm, 350 mm) of the first electrode 110A and the second electrode 110B indicate the vertical distance from the reference position when the backrest 12 is upright. Therefore, when the backrest 12 is tilted rearward from an angle perpendicular to the horizontal plane, the first electrode 110A and the second electrode 110B are located at the distance indicated by the height positions from the rear end of the seat surface of the seat 11 along the tilt angle direction.

[0040] The three first electrodes 110A and one second electrode 110B have the same size in front view, and for example, a horizontal (left-right) length of 40 mm and a vertical (up-down) length of 30 mm. For example, the three first electrodes 110A and one second electrode 110B are rectangular.

[0041] The three first electrodes 110A are positioned at the same height, and the horizontal pitch between the three first electrodes 110A is 50 mm. As an example, the second electrode 110B is positioned at the same horizontal (left-right) position as the rightmost first electrode 110A among the three first electrodes 110A.

[0042] The reason why the second electrode 110B arranged in the second region 12B is positioned to the right of the center in the left-right direction of the human body is to obtain a differential signal with a larger S / N ratio when measuring electrocardiographic data. This is because, in a typical person, the vector of the electromotive force generated when the heart beats is directed roughly from the right shoulder to the left leg. Therefore, by providing electrodes along this electromotive force vector, specifically by positioning the second electrode 110B arranged in the upper second region 12B to the right of the center in the left-right direction of the human body, a larger differential signal can be obtained.

[0043] It is sufficient that the electrocardiogram data detection device 100 includes three or more first electrodes 110A. Therefore, four or more first electrodes 110A may be arranged in parallel in the horizontal direction within the first region 12A.

[0044] Furthermore, the electrocardiogram data detection device 100 may include at least one second electrode 110B. Therefore, two or more second electrodes 110B may be arranged in parallel in the horizontal direction within the second region 12B. Furthermore, the number of second electrodes 110B may be smaller than the number of first electrodes 110A. When there are multiple second electrodes 110B, the pitch of the multiple second electrodes 110B in the left-right direction may be equal to the pitch of the multiple first electrodes 110A.

[0045] The one or more second electrodes 110B, the number of which is less than the number of first electrodes 110A, are arranged to the right of the first electrodes 110A in the left-right direction. Therefore, even when there are multiple second electrodes 110B, the center of the second region 12B in a front view is located to the upper right of the center of the first region 12A.

[0046] Furthermore, the multiple first electrodes 110A may be arranged not parallel to one another in the horizontal direction within the first region 12A. In such a case, it is sufficient that all of the multiple first electrodes 110A have overlapping sections in the vertical direction. In other words, it is sufficient that the multiple first electrodes 110A are arranged along the horizontal direction within the first region 12A.

[0047] Similarly, when there are multiple second electrodes 110B, the multiple second electrodes 110B may be arranged not parallel to one another in the horizontal direction within the second region 12B. In such a case, it is sufficient that all of the multiple second electrodes 110B have overlapping sections in the vertical direction. In other words, it is sufficient that the multiple second electrodes 110B are arranged along the horizontal direction within the second region 12B.

[0048] Furthermore, the first electrode 110A and the second electrode 110B are rectangular, for example, but may be other shapes. The first electrodes 110A may have different shapes from one another. Similarly, if there are multiple second electrodes 110B, the second electrodes 110B may have different shapes from one another.

[0049] <Height positions of the three first electrodes 110A> As an example, the three first electrodes 110A are disposed such that their lower ends are 255 mm above the reference position. The three first electrodes 110A may be disposed above the height corresponding to the height of the iliac crest of a driver seated in the seat 10. According to "Kawachi Makiko and Mochimaru Masaaki, 2005 AIST Human Body Dimension Database, National Institute of Advanced Industrial Science and Technology H16PRO 287," the iliac crest of approximately 95% of people is 248 mm above the reference position. In other words, the three first electrodes 110A may be disposed such that their lower ends are 248 mm or above the reference position. However, since the second electrode 110B is located above the three first electrodes 110A and there are restrictions on the height position of the second electrode 110B, the three first electrodes 110A only need to be positioned so that the height position of their lower ends is 248 mm or more from the reference position, provided that the relationship with the restriction on the height position of the second electrode 110B is satisfied.

[0050] <Height position of second electrode 110B> As an example, the second electrode 110B is disposed such that the upper end is positioned at a height of 365 mm from the reference position. The second electrode 110B may be disposed below a height corresponding to the height of the lower corners of the shoulder blades of a driver seated in the seat 10. According to "Kawachi Makiko and Mochimaru Masaaki, 2005 AIST Human Body Dimension Database, National Institute of Advanced Industrial Science and Technology H16PRO 287," the lower corners of the shoulder blades of approximately 95% or more people are positioned at a height of 384 mm from the reference position. In other words, the second electrode 110B may be disposed such that the upper end is positioned at a height of 384 mm or less from the reference position. However, three first electrodes 110A are located below the second electrode 110B, and each first electrode 110A has the condition regarding the lower limit of its lower end as described above, so the second electrode 110B only needs to be positioned so that its upper end is at a height position of 384 mm or less, provided that it satisfies the relationship with the restriction on the height position of the first electrode 110A.

[0051] <Experiment> Fig. 4 is a diagram showing 12 positions where electrodes 110 can be arranged in an experiment. Fig. 4 shows positions S1 to S12 where electrodes 110 can be arranged, 12 positions arranged in four rows (four columns) in the vertical direction and three columns (one column) in the horizontal direction. The size of each of positions S1 to S12 is equal to the size of electrode 110, and as an example, the horizontal (left-right) length is 40 mm and the vertical (up-down) length is 30 mm. Fig. 4 also shows a first region 12A that is the same as the first region 12A shown in Fig. 3, and omits the second region 12B.

[0052] The allocation of positions S1 to S12 is as shown in FIG. 4, with the top first row being S7, S8, and S9 from left to right. The second row being S1, S2, and S3 from left to right. The third row being S4, S5, and S6 from left to right. The bottom fourth row being S10, S11, and S12 from left to right. Positions S1 to S12 are all positions where electrodes 110 can be placed on the backrest 12.

[0053] In addition, the height of the center of the top row (S7, S8, S9) is 430 mm, and the height of the bottom end is 415 mm, so the first row is higher than the height of the lower corner of the scapula (384 mm).

[0054] The height position of the center of the second stage (S1, S2, S3) is 350 mm, and the height position of the top end is 365 mm, so the second stage is lower than the height position of the lower corners of the scapula. The height position of this second stage is equal to the height position of second electrode 110B shown in Figure 3. The position of second electrode 110B shown in Figure 3 is position S3.

[0055] The height position of the center of the third stage (S4, S5, S6) is 270 mm, and the height position of the bottom end is 255 mm, so the third stage is higher than the height position of the iliac crest (248 mm). The height position of this third stage is equal to the height positions of the three first electrodes 110A shown in Figure 3. The positions of the three first electrodes 110A shown in Figure 3 are S4, S5, and S6.

[0056] The height position of the center of the bottom four rows (S10, S11, S12) is 190 mm, and the height position of the top end is 205 mm, so the fourth row is lower than the height position of the iliac crest (248 mm).

[0057] <Electrocardiogram data measurement results> 5A is a diagram showing an example of the measurement results of electrocardiogram data. The seat 10 was placed on a vibration table, and five positions S1 to S12 shown in FIG. 4 were selected to arrange the electrodes 110, and six types of vibration patterns (A1, RS, RL, PS, PL, A2) were generated to measure the electrocardiogram data of the seated occupant.

[0058] 5A, the horizontal axis represents time, and indicates that the vibration pattern changes over time from A1 to RS, RL, PS, PL, and A2. The vertical axis represents the number of differential signals with an SN (Signal to Noise) ratio of 2.5 or more out of 50 differential signals calculated by the differential signal generating unit 131A after 50 measurements.

[0059] The 50 measurements were obtained by seating 25 adults (18 men and 7 women) in the seat 10, with each person receiving two measurements. Each measurement measured the differential signal for 60 seconds for each vibration pattern. Note that a signal-to-noise ratio of the differential signal of 2.5 or higher indicates a good differential signal that can be used to calculate electrocardiogram data.

[0060] The S / N ratio was determined by taking the maximum value of the differential signals obtained from the electrodes in each measurement. This is because electrocardiogram data can be acquired if even one good differential signal with an S / N ratio of 2.5 or higher is obtained. For example, if the maximum S / N ratio of six differential signals obtained from four electrodes 110 is 5.5, the number of differential signals with an S / N ratio of 2.5 or higher was measured, based on the rule that the S / N ratio for that measurement should be 5.5.

[0061] FIG. 5B is a diagram showing an example of the arrangement of a plurality of electrodes 110 in five selections. The five selections include cases 1 to 4 and an embodiment. In case 1, three electrodes 110 were arranged at three positions (S7, S8, S9) in the first row. In case 2, three electrodes 110 were arranged at three positions (S1, S2, S3) in the second row. In case 3, three electrodes 110 were arranged at three positions (S4, S5, S6) in the third row. In case 4, three electrodes 110 were arranged at three positions (S10, S11, S12) in the fourth row. In the embodiment, four electrodes 110 were arranged at position S3 in the second row and three positions (S4, S5, S6) in the third row, similar to the four electrodes 110 shown in FIG. 3. Electrocardiogram data was measured by selecting the positions in these five ways.

[0062] Furthermore, vibration pattern A1 is a stationary state before vibration is applied by the vibration table, and the seat 10 is not vibrating. Vibration pattern RS is a vibration pattern in which the vibration table generates small vibrations in the roll direction in the seat 10. Vibration pattern RL is a vibration pattern in which the vibration table generates large vibrations in the roll direction in the seat 10. Vibration pattern PS is a vibration pattern in which the vibration table generates small vibrations in the pitch direction in the seat 10. Vibration pattern PL is a vibration pattern in which the vibration table generates large vibrations in the pitch direction in the seat 10. Vibration pattern A2 is a state in which the vibration table is stationary after vibration pattern PL, and the seat 10 is not vibrating.

[0063] 5A, the number of differential signals with an S / N ratio of 2.5 or more was significantly smaller in Case 1 (first row) and Case 4 (fourth row) than in Case 2 (second row) and Case 3 (third row). Even in vibration patterns A1 and A2, in which the seat 10 was not vibrating, the number of differential signals with an S / N ratio of 2.5 or more in Case 1 (first row) was around 30, and the number of differential signals with an S / N ratio of 2.5 or more in Case 4 (fourth row) was 41 to 42.

[0064] Furthermore, the embodiment had a greater number of differential signals with an S / N ratio of 2.5 or greater in all vibration patterns than cases 1 to 4. Case 3 (third row) generally had results similar to those of the embodiment, but case 2 (second row) had a smaller number of differential signals with an S / N ratio of 2.5 or greater than case 3 (third row).

[0065] From the above results, it was determined that placing the electrodes 110 on the first and fourth tiers would not lead to the acquisition of good electrocardiographic data, and therefore measurements were performed on the second and third tiers below.

[0066] Fig. 6A is a diagram showing an example of the measurement results of electrocardiogram data. The seat 10 was placed on a vibration table, and five positions S1 to S6 shown in Fig. 4 were selected to arrange a plurality of electrodes 110, and six vibration patterns (A1, RS, RL, PS, PL, A2) were generated to measure the electrocardiogram data of the seated occupant. The six vibration patterns are the same as the six vibration patterns described above.

[0067] In Figure 6A, as in Figure 5A, the horizontal axis represents time, and the vibration pattern changes over time from A1 to RS, RL, PS, PL, and A2. The vertical axis represents the number of differential signals with an S / N ratio of 2.5 or higher among the 50 electrocardiogram data obtained by performing 50 measurements. The 50 measurements were performed in the same manner as described above.

[0068] In the embodiment and comparative examples 1-4, the positions S1 to S12 were selected from the following five patterns: Fig. 6B is a diagram showing an example of the arrangement of a plurality of electrodes 110 in the embodiment and comparative examples 1-4.

[0069] In the embodiment, positions S3, S4, S5, and S6 were selected, similar to the four electrodes 110 shown in FIG. 3. In Comparative Example 1, three positions S4, S5, and S6 were selected. In Comparative Example 2, five positions S1, S2, S3, S4, and S5 were selected. In Comparative Example 3, five positions S1, S2, S3, S4, and S6 were selected. In Comparative Example 4, five positions S1, S2, S3, S5, and S6 were selected.

[0070] In the vibration patterns A1 and A2 in which the seat 10 does not vibrate, the number of differential signals with an S / N ratio of 2.5 or more was approximately 50 in all of the embodiment and comparative examples 1-4.

[0071] The measurement results of the embodiment were particularly improved for the vibration patterns RS and RL compared to the measurement results of Comparative Example 1. By adding the electrode 110 (first electrode 110A) to position S3, the signal-to-noise ratio of the electrocardiogram data for vibrations in the roll direction was improved. On the other hand, for the vibration patterns PS and PL in the pitch direction, the measurement results of the embodiment were equivalent to the measurement results of Comparative Example 1, and it was found that adding the electrode 110 (first electrode 110A) to position S3 had little effect on vibrations in the pitch direction.

[0072] In Comparative Example 2-4, the positions at which electrodes 110 are not placed are different from each other among the three positions on the third row. However, in Comparative Example 2-4, the signal-to-noise ratio deteriorated due to vibration in the pitch direction, and even when three electrodes 110 were placed at three positions on the second row, the results were not good.

[0073] From the above, it was found that for vibrations in the pitch direction, the embodiment in which three electrodes 110 are arranged in the third tier and Comparative Example 1 have a better S / N ratio than Comparative Examples 2 to 4. In other words, it was found that it is preferable to have three or more electrodes 110 in the third tier. Furthermore, for vibrations in the roll direction, the S / N ratio of the embodiment in which an electrode 110 is added at position S3 in the second tier was better than that of Comparative Example 1. In other words, it was found that it is preferable to arrange three electrodes 110 in the third tier and then have at least one electrode 110 in the second tier.

[0074] In addition to the embodiment, the results of Comparative Example 1 were relatively good, while the results of Comparative Examples 2 to 4 were poor. In Comparative Example 1, there are three electrodes 110 in the third stage, so three differential signals are obtained from the third stage, but in Comparative Examples 2 to 4, there are only two electrodes 110 in the third stage, so only one differential signal is obtained from the third stage.

[0075] Thus, it is believed that the difference between Comparative Example 1 and Comparative Examples 2-4 was caused by whether or not there were three electrodes 110 in the third row. Note that, in the arrangement of the electrodes 110 in Comparative Examples 2-4, when one more electrode 110 was removed from the second row, the number of differential signals with an S / N ratio of 2.5 or greater was further reduced. More specifically, when the electrode 110 at position S3 was omitted in Comparative Example 2, when the electrode 110 at position S2 was omitted in Comparative Example 3, and when the electrode 110 at position S1 was omitted in Comparative Example 4, the number of differential signals with an S / N ratio of 2.5 or greater was the same or less.

[0076] In this embodiment, the number of good differential signals with an S / N ratio of 2.5 or more is considered to have increased due to a total of six differential signals: three differential signals obtained from positions S4 and S5, positions S4 and S6, and positions S5 and S6 in the third stage, and three differential signals obtained from position S3 in the second stage and positions S4, S5, and S6 in the third stage.

[0077] While the above describes the measurement results for the electrocardiogram data detection device 100 of an embodiment having a configuration including three first electrodes 110A and one second electrode 110B, it was confirmed that the measurement results for an electrocardiogram data detection device 100 having a configuration including four or more first electrodes 110A or two or more second electrodes 110B showed similar trends. Furthermore, even when the number of first electrodes 110A was increased to five or more, there was no change in the rate of obtaining differential signals with an S / N ratio of 2.5 or higher. Therefore, the upper limit of the number of first electrodes 110A may be set to five.

[0078] <Effects> The electrocardiogram data detection device 100 includes a seat 11 and a backrest 12, a plurality of electrodes 110 that are provided on the backrest 12 of a seat 10 mounted on a vehicle and that is arranged to face the body of a person seated on the seat 10, a differential signal generation unit 131A that generates differential signals between signals of two of the plurality of electrodes 110, the differential signal generation unit 131A generating a plurality of differential signals from signals of a plurality of pairs of two electrodes 110, and a heartbeat detection unit 133A (electrocardiogram data detection unit) that obtains electrocardiogram data based on the plurality of differential signals. The backrest 12 includes a sensor (detector) and a sensor detection unit, and the plurality of electrodes 110 include three or more first electrodes 110A arranged along the width direction of the backrest 12 in a first region 12A of the backrest 12 that is closer to the seat 11, and at least one second electrode 110B arranged in a second region 12B of the backrest 12 that is located above the first region 12A, and the plurality of differential signals are at least six or more differential signals obtained from signals of the three or more first electrodes 110A and a signal of the at least one second electrode 110B.

[0079] When the seat vibrates as the moving object moves, the lower part of the upper body, such as the waist, moves little, but the upper part, such as the shoulders, moves more and is more likely to separate from the backrest 12. Therefore, even when the seat vibrates as the moving object moves, the three or more first electrodes 110A in the lower first region 12A can acquire three or more signals from the waist, which moves relatively little. Because the human body does not easily separate from the three or more first electrodes 110A, it becomes easier to obtain at least one or more differential signals with a high S / N ratio from the three or more signals obtained from the three or more first electrodes 110A. Furthermore, even when the seat vibrates, at least one second electrode 110B in the upper second region 12B acquires a signal, so at least one or more differential signals with a high S / N ratio can be obtained from six differential signals obtained from at least one signal obtained from at least one second electrode 110B and three or more signals obtained from the three or more first electrodes 110A.

[0080] Therefore, it is possible to provide an electrocardiogram data detection device 100 that can detect electrocardiogram data of a person seated in a seat even when the electrocardiogram data detection device 100 is installed in a seat of a moving body.

[0081] Furthermore, the number of second electrodes 110B may be less than the number of first electrodes 110A. By increasing the number of first electrodes 110A in first region 12A from which signals can be acquired more stably, differential signals can be acquired stably, and electrocardiogram data can be detected stably.

[0082] Furthermore, the center of second region 12B may be located to the upper right of the center of first region 12A in the up-down and left-right relationship based on the body of the person sitting in seat 10. Since at least one second electrode 110B is located to the upper right of three or more first electrodes 110A, a differential signal with a high S / N ratio can be obtained using second electrode 110B, making it possible to acquire electrocardiogram data with high accuracy.

[0083] Alternatively, three or more first electrodes 110A may be positioned above a height position corresponding to the iliac crest of a person seated in the seat 10, and at least one second electrode 110B may be positioned below a height position corresponding to the lower corner of the scapula of the person seated in the seat 10. By positioning three or more first electrodes 110A above the iliac crest, signals can be stably acquired from an area above the pelvis where there are few large bones. By positioning one second electrode 110B below the lower corner of the scapula, signals can be stably acquired from an area below the scapula where there are few large bones. Therefore, it is possible to provide an electrocardiogram data detection device 100 that can stably detect electrocardiogram data of a person seated in a seat of a vehicle, even when the device is installed in the seat of the vehicle.

[0084] The above describes an electrocardiogram data detection device according to an exemplary embodiment of the present disclosure. However, the present disclosure is not limited to the specifically disclosed embodiment, and various modifications and variations are possible without departing from the scope of the claims.

[0085] The following additional notes are provided regarding the above-described embodiments. (Appendix 1) a plurality of electrodes provided in the backrest of a seat having a seat portion and a backrest and mounted on a moving body, the electrodes being arranged to face the body of a person sitting in the seat; a differential signal generating unit that generates a differential signal of signals of two electrodes among the plurality of electrodes, the differential signal generating unit generating a plurality of the differential signals from signals of a plurality of pairs of the two electrodes; an electrocardiogram data detection unit that obtains electrocardiogram data based on the plurality of differential signals; Including, The plurality of electrodes Three or more first electrodes are arranged along a width direction of the backrest in a first region of the backrest that is closer to the seat portion; at least one second electrode disposed in a second region of the backrest portion located above the first region; and An electrocardiogram data detection device, wherein the plurality of differential signals are at least six differential signals obtained from signals from the three or more first electrodes and a signal from the at least one second electrode. (Appendix 2) 2. The electrocardiogram data detection device according to claim 1, wherein the number of the second electrodes is smaller than the number of the first electrodes. (Appendix 3) An electrocardiogram data detection device as described in Appendix 1 or 2, wherein the center of the second area is located to the upper right and to the right of the center of the first area in a vertical and horizontal relationship based on the body of a person sitting in the seat. (Appendix 4) the three or more first electrodes are arranged above a height position corresponding to a height position of the iliac crest of a person sitting in the seat, An electrocardiogram data detection device as described in any one of Appendices 1 to 3, wherein the at least one second electrode is positioned below a height position corresponding to the height position of the lower corners of the shoulder blades of a person sitting in the seat. [Explanation of symbols]

[0086] 100 Electrocardiogram data detection device 110 electrodes 110A 1st electrode 110B 2nd electrode 115 Buffer Circuit 120 ADC 130 MCU 140 I / F driver 150 ECU 130A calculation section 130B Control section 130C Communication I / F 131A Differential signal generation section 132A Signal judgment section 133A Heartbeat detector (an example of an electrocardiogram data detector)

Claims

1. a plurality of electrodes provided in the backrest of a seat having a seat portion and a backrest and mounted on a moving body, the electrodes being arranged to face the body of a person sitting in the seat; a differential signal generating unit that generates a differential signal of signals of two electrodes among the plurality of electrodes, the differential signal generating unit generating a plurality of the differential signals from signals of a plurality of pairs of the two electrodes; an electrocardiogram data detection unit that obtains electrocardiogram data based on the plurality of differential signals; Including, The plurality of electrodes Three or more first electrodes are arranged along a width direction of the backrest in a first region of the backrest that is closer to the seat portion; at least one second electrode disposed in a second region of the backrest portion located above the first region; and An electrocardiogram data detection device, wherein the plurality of differential signals are at least six differential signals obtained from signals from the three or more first electrodes and a signal from the at least one second electrode.

2. The electrocardiogram data detection device according to claim 1 , wherein the number of the second electrodes is smaller than the number of the first electrodes.

3. The electrocardiogram data detection device according to claim 1 , wherein the center of the second region is located to the upper right and to the right of the center of the first region in a vertical and horizontal relationship based on the body of the person sitting in the seat.

4. the three or more first electrodes are arranged above a height position corresponding to a height position of the iliac crest of a person sitting in the seat, 4. The electrocardiogram data detection device according to claim 1, wherein the at least one second electrode is positioned below a height position corresponding to the height position of the lower corners of the shoulder blades of a person sitting in the seat.

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