Blood pressure pulse wave examination system

Abstract

Provided is a blood pressure pulse wave examination system that can be configured so as to be hoseless. A blood pressure pulse wave examination system comprising: a plurality of wireless cuff devices that are mounted at prescribed sites on a subject; and a blood pressure pulse wave examination device that performs wireless communication with the plurality of wireless cuff devices, controls the plurality of wireless cuff devices, collects pulse wave data from the plurality of wireless cuff devices, and examines the blood vessel state of the subject. Each of the plurality of wireless cuff devices has a cuff that is wound around a prescribed site on the subject, and a wireless unit that is attached to the cuff.

Description

Blood pressure pulse wave inspection system

[0001] The present disclosure relates to a blood pressure pulse wave examination system.

[0002] Conventionally, blood pressure pulse wave testing devices have been used to test blood vessel conditions such as the degree of arteriosclerosis (see, for example, Patent Document 1). The blood pressure pulse wave testing device acquires the blood pressure pulse waves of a subject using multiple cuffs attached to the subject's limbs and toes. The blood pressure pulse wave testing device obtains indices of arteriosclerosis, such as PWV (Pulse Wave Velocity) and ABI (Ankle Brachial Index), based on the blood pressure pulse waves acquired by the multiple cuffs.

[0003] The blood pressure pulse wave inspection device and the multiple cuffs are connected by hoses. The blood pressure pulse wave inspection device is equipped with an air pump and a pressure sensor, and air output from the air pump is supplied to each cuff via the hoses.

[0004] JP 2016-158943 A

[0005] ANALYSIS STUDY OF TIME SYNCHRONIZATION PROTOCOLS IN WIRELESS SENSOR NETWORKS, Salim el khediri Laboratory of Electrical Engineering and Information Technology 2012H. Kopetz and W. Schwabl. Global time in distributed real-time systems. Technical Report 15 / 89, Technische Universit¨at Wien, 1989.

[0006] As mentioned above, conventional blood pressure pulse wave testing devices require hoses to connect multiple cuffs. However, the hoses come into contact with the subject, which is unhygienic. There is also the risk of the subject's foot getting caught in the hose. Furthermore, it takes time to prepare the hoses and to untangle them afterward, which increases the time required to perform the test.

[0007] Therefore, a hose-less system is desirable. If a hose-less system is realized, it will not only solve the above problems, but also simplify the area around the bed where the examination is performed, making the examination easier.

[0008] However, there has not been sufficient consideration given to making blood pressure pulse wave testing hoseless.

[0009] One object of the present disclosure, made in consideration of the above points, is to provide a blood pressure pulse wave inspection system that can be made hoseless, and also to provide various technical ideas for making it hoseless.

[0010] One aspect of the blood pressure pulse wave testing system of the present disclosure comprises: a plurality of wireless cuff devices attached to predetermined parts of a subject; and a blood pressure pulse wave testing device that wirelessly communicates with the plurality of wireless cuff devices, controls the plurality of wireless cuff devices, and collects pulse wave data from the plurality of wireless cuff devices to test the vascular condition of the subject, wherein each of the plurality of wireless cuff devices comprises: a cuff that is wrapped around a predetermined part of the subject; and a wireless unit attached to the cuff.

[0011] According to the present invention, a blood pressure pulse wave inspection system that can be made hoseless can be realized.

[0012] 1 is a perspective view showing the configuration of a wireless cuff device according to the first embodiment; 2 is a perspective view showing a plurality of wireless cuff devices used in a blood pressure pulse wave test according to the first embodiment; 3 is a diagram showing a state in which a wireless cuff device is attached to a subject; 4 is a block diagram showing the configuration of a wireless unit according to the first embodiment; 5 is a block diagram showing the configuration of a blood pressure pulse wave test device according to the first embodiment; 6 is a diagram showing the configuration of a blood pressure pulse wave test device according to another embodiment 1 in the first embodiment; 13A is a perspective view showing a plurality of wireless cuff devices used in the inspection; FIG. 13B is a block diagram showing the configuration of a wireless unit according to a second embodiment; FIG. 13C is a diagram showing an example of the format of a packet transmitted by a wireless unit according to a third embodiment to a blood pressure pulse wave inspection device, in which FIG. 13A is a diagram showing the data structure of the packet, FIG. 13B is a diagram showing the contents of a packet transmitted by a wireless unit to a blood pressure pulse wave inspection device prior to transmitting measurement data, and FIG. 13C is a diagram showing the contents of a packet when transmitting measurement data after transmitting the packet shown in FIG. 13B;FIG. 1 is a block diagram used to explain time synchronization when a ΔΣ (delta sigma) AD converter (hereinafter referred to as ADC) is used. FIG. 2 is a diagram showing a state in which a time synchronization packet is lost. FIG. 3 is a block diagram used to explain a time synchronization method according to embodiment 3. FIG. 4 is a diagram showing the first transmission from a parent device to a child device. FIG. 5 is a diagram showing the first two transmissions from a parent device to a child device. FIG. 6 is a diagram showing the first three transmissions from a parent device to a child device. FIG. 7 is a diagram used to explain setting the start point of a read pointer based on the Td value. FIG. 8 is a diagram showing setting the end point of a read pointer based on the Td value. FIG. 9 is a diagram showing a timing deviation in a child device. 25A block diagram showing an example of the configuration for performing the processing of FIG. 25A is provided for explaining the processing when radio wave loss (packet loss) occurs. FIG. 26A shows an example in which the synchronization method of the third embodiment is applied to a system having a plurality of slave units. FIG. 27A shows an example in which the ADC clock advances slower than the reference clock. FIG. 28A shows an example in which the ADC clock advances faster than the reference clock. FIG. 29A shows an example of the operation of the PRESENTHAM algorithm. FIG. 29A shows an example of the operation of the PRESENTHAM algorithm modified according to the third embodiment. FIG. 30A shows an example of the modification of the PRESENTHAM algorithm. FIG. 31A shows an example in which the time synchronization method and wireless system of the third embodiment are applied to medical equipment.

[0013] <1> Embodiment 1 <1-1> Findings that led to Embodiment 1 Before describing Embodiment 1, the findings of the inventors that led to Embodiment 1 of the present disclosure will be described. The inventors of the present disclosure conceived of realizing a hoseless system by providing a wireless connection between the cuff and the blood pressure pulse wave inspection device.

[0014] In order to realize a hoseless design, the inventors first studied the connection between conventional cuffs and blood pressure pulse wave testing devices. Hoses extend from each of the cuffs attached to the left upper arm, right upper arm, left lower leg, and right lower leg. The blood pressure pulse wave testing device is provided with four connectors for connecting these four hoses. The hose extending from the left upper arm cuff is connected to the left upper arm connector, the hose extending from the right upper arm cuff to the right upper arm connector, the hose extending from the left lower leg cuff to the left lower leg connector, and the hose extending from the right lower leg cuff to the right lower leg connector.

[0015] For example, if a wrong connection is made, such as connecting a hose leading from a cuff for the left upper arm to a connector for the left lower leg, the blood pressure pulse wave monitoring device will produce erroneous test results. Therefore, different colored labels are affixed to each cuff hose and each connector. For example, a yellow label is affixed to the hose leading from the cuff for the left upper arm and the connector for the left upper arm, and a red label is affixed to the hose leading from the cuff for the right upper arm and the connector for the right upper arm. This encourages medical personnel to connect hoses and connectors of the same color, thereby preventing incorrect hose and connector connections.

[0016] However, since wireless communication between multiple cuffs and the blood pressure pulse wave inspection device eliminates the need for hoses, it becomes impossible to associate which cuff corresponds to which part of the body by connecting the hose to the connector. Therefore, some means is needed to enable the blood pressure pulse wave inspection device to recognize which cuff corresponds to which part of the body.

[0017] The inventors of the present disclosure have discovered a configuration suitable for allowing a blood pressure pulse wave inspection device to recognize which cuff belongs to which attachment site even in a hoseless configuration, and have arrived at the present disclosure.

[0018] <1-2> Configuration of First Embodiment Hereinafter, the first embodiment of the present disclosure will be described in detail with reference to the drawings.

[0019] FIG. 1 is a perspective view showing the configuration of a wireless cuff device according to the first embodiment.

[0020] The wireless cuff device 10 includes a cuff 20 and a wireless unit 100 .

[0021] The cuffs 20 each have an internal air bag (not shown) and are wrapped around a predetermined part of the subject. The edge 20 a of each cuff 20 is colored according to the part of the subject on which it is to be worn. For example, the edge 20 a of the cuff 20 for the left upper arm is yellow, the edge 20 a of the cuff 20 for the right upper arm is red, the edge 20 a of the cuff 20 for the left lower limb is green, and the edge 20 a of the cuff 20 for the right lower limb is black. Furthermore, each cuff 20 is also inscribed with letters (not shown) indicating the part of the body on which it is to be worn. A medical professional wears each cuff 20 on a part of the body corresponding to the color and lettering on the cuff 20. Note that the cuffs 20 may be configured in a known manner that has been conventionally used to measure blood pressure pulse waves, and therefore, a description thereof will be omitted here.

[0022] The wireless unit 100 is detachably attached to the cuff 20. The attachment structure of the wireless unit 100 to the cuff 20 can be realized, for example, by forming rails on the surface of the cuff 20 and the back surface of the wireless unit 100 that can engage with each other. In this way, the wireless unit 100 can be easily attached to and detached from the cuff 20 by sliding the wireless unit 100 relative to the cuff 20. Of course, the attachment structure is not limited to this.

[0023] The wireless cuff device 10 is used to perform a blood pressure pulse wave test. In this embodiment, as shown in FIG. 2, four wireless cuff devices 10-1 to 10-4 are used. As shown in FIG. 3, these four wireless cuff devices 10-1 to 10-4 are attached to the left upper arm, right upper arm, left lower leg, and right lower leg of the subject, respectively. In addition to or instead of these attachment sites, for example, when performing an examination on the toes, a wireless cuff device for the toes may be used. The wireless cuff device for the toes may have the same basic configuration as the wireless cuff device 10, but may be a different size. Conversely, when performing a blood pressure pulse wave test using three or fewer wireless cuff devices, three or fewer wireless cuff devices 10 may be used.

[0024] The wireless cuff devices 10 (10-1 to 10-4) communicate wirelessly with the blood pressure pulse wave inspection device 200 via the wireless units 100 (100-1 to 100-4). The wireless cuff devices 10 inflate and depressurize the cuff based on control signals wirelessly transmitted from the blood pressure pulse wave inspection device 200. The wireless cuff devices 10 also wirelessly transmit blood pressure pulse wave measurement results obtained during the inspection to the blood pressure pulse wave inspection device 200.

[0025] FIG. 4 is a block diagram showing the configuration of the wireless unit 100.

[0026] The wireless unit 100 includes a battery 110 , a wireless power supply unit 120 , a user interface unit 130 , a cuff driver 140 , a cuff pressure detector 150 , a wireless communication unit 160 , and a CPU (Central Processing Unit) 170 .

[0027] The battery 110 is, for example, a lithium ion secondary battery, and supplies power to the electrical circuits that make up the wireless unit 100. The wireless power supply unit 120 has a WPT (Wireless Power Transfer) 121 made up of a coil or the like, and a charge control IC (Integrated Circuit) 122 that controls the charging operation of the WPT 121 and the battery 110. With this configuration, the wireless unit 100 is able to wirelessly supply power to the battery 110. The battery 110 and the wireless power supply unit 120 can have various conventionally known configurations.

[0028] The wireless unit 100 does not necessarily have to be configured to supply power wirelessly, but may be configured to supply power wired. However, since many wireless units 100 are used in hospitals and other facilities, configuring the wireless unit 100 to be capable of supplying power wirelessly allows for easy power supply to many wireless units 10 detached from the cuff 20, significantly reducing the workload of medical personnel. Furthermore, while wired power supply can cause contact problems due to aging or other factors, wireless power supply has the advantage of eliminating such problems. Furthermore, since the wireless unit 100 can be detached from the cuff 20 for power supply, it can be charged regardless of whether the cuff 20 is in use. Therefore, if more wireless units 100 than cuffs 20 are prepared, patients will not have to wait for charging, which will prevent delays in examinations.

[0029] The user interface unit 130 has a power button 131, a display unit 132, an LED (Light-Emitting Diode) 133, and a speaker 134. Pressing the power button 131 turns the power of the wireless unit 100 on / off. The display unit 132 displays an image indicating the operating state of the wireless unit 100, a setting image, etc. The LED 133 emits light according to the operating state or alarm state of the wireless unit 100. The speaker 134 outputs alarms and guidance as audio.

[0030] The cuff driver 140 has an air pump 141, a constant exhaust valve 142, and a rapid exhaust valve 143. When the wireless unit 100 is attached to the cuff 20, the air pump 141, the constant exhaust valve 142, and the rapid exhaust valve 143 are connected to an air bag (not shown) of the cuff 20 via a flow path (not shown).

[0031] The air bag of the cuff 20 is inflated by air supplied from an air pump 141, thereby pressurizing the part of the subject where the cuff 20 is attached. When the air bag is inflated, both the constant exhaust valve 142 and the rapid exhaust valve 143 are controlled to a fully closed state, and the constant exhaust valve 142 is opened during pulse wave detection after avascularization until blood pressure determination, and the rapid exhaust valve 143 is further opened after blood pressure determination. In this way, the cuff pressure during blood pressure pulse wave testing is controlled by the cuff driver 140.

[0032] Cuff pressure detection unit 150 has a pressure sensor 151 and an AD converter 152. Pressure sensor 151 is a pressure-electricity conversion sensor formed, for example, of a piezoelectric element, and outputs the pressure inside the air bladder as an electrical signal. AD converter 152 converts the output of pressure sensor 151 into a digital signal and outputs it to CPU 170. In this way, cuff pressure during a blood pressure pulse wave test is detected by cuff pressure detection unit 150, and output to CPU 170. Note that the configuration for detecting cuff pressure is not limited to this, and various configurations capable of detecting cuff pressure can be applied.

[0033] The wireless communication unit 160 has a memory 161 and a UWB (Ultra Wide Band) communication module 162. The memory 161 stores identification information, which is transmitted by the UWB communication module 162 via UWB. The UWB communication module 162 has an antenna and a transmitting / receiving circuit that enable UWB wireless communication. The memory 161 may be built into the CPU 170.

[0034] The UWB communication module 162 performs UWB wireless communication with the blood pressure pulse wave inspection device 200, thereby wirelessly receiving control signals from the blood pressure pulse wave inspection device 200 and wirelessly transmitting blood pressure pulse wave measurement results (blood pressure pulse wave data obtained by the cuff pressure detection unit 150) to the blood pressure pulse wave inspection device 200.

[0035] FIG. 5 is a block diagram showing the configuration of the blood pressure pulse wave inspection device 200.

[0036] The blood pressure pulse wave inspection device 200 includes a UWB communication module 210 , an arithmetic and control unit 220 , and a user interface unit 230 .

[0037] The UWB communication module 210 has an antenna unit 211 consisting of a plurality of antennas, and a transmission / reception processing unit 212. The transmission / reception unit 212 amplifies and demodulates a signal received by the antenna unit 211, and outputs the signal to the calculation / control unit 220. The transmission / reception unit 212 also modulates and amplifies a control signal from the calculation / control unit 220, and outputs the signal to the antenna unit 211.

[0038] The arithmetic control unit 220 includes, as its main components, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU reads a program corresponding to the processing content from the ROM, loads it into the RAM, and works with the loaded program to execute the operations of each element of the arithmetic control unit 220, which will be described below. Note that all or part of the arithmetic control unit 220 may be formed by a hardwired circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0039] The arithmetic and control unit 220 includes a control unit 221 and an arithmetic unit 222 .

[0040] The control unit 221 controls the overall operation of the blood pressure pulse wave inspection device 200. The control unit 221 also generates control signals for controlling the multiple wireless units 100-1 to 100-4. These control signals are transmitted to the multiple wireless units 100-1 to 100-4 via the UWB communication module 210. As a result, for example, the cuff driver 140 of the wireless unit 100 is controlled by the control signal from the control unit 221.

[0041] The calculation unit 222 receives blood pressure pulse wave data from the multiple wireless units 100-1 to 100-4 via the UWB communication module 210 and calculates numerical values ​​serving as indices of the state of the blood vessels, such as PWV and ABI, based on the data. The calculations performed by the calculation unit 222 can be performed using various known processes described in, for example, Cited Document 1, and therefore detailed explanations will be omitted here. The numerical values ​​serving as indices of the state of the blood vessels obtained by the calculation unit 222 are displayed on the display unit 232 of the user interface unit 230.

[0042] In addition to this configuration, the calculation control unit 220 has an arrival direction estimation unit 223 , a distance estimation unit 224 , an attachment part estimation unit 225 , and a determination unit 226 .

[0043] The direction-of-arrival estimation unit 223 estimates the direction of arrival of radio waves from the multiple wireless cuff devices 10-1 to 10-4. The distance estimation unit 224 estimates the distance to the multiple wireless cuff devices 10-1 to 10-4. The estimation of the direction of arrival and distance can be realized by a known positioning function using the UWB communication module 210 having multiple antennas. For example, the direction of arrival can be estimated based on the phase difference between each antenna, and the distance can be estimated based on the reception time difference.

[0044] The attachment part estimation unit 225 estimates the attachment parts of the plurality of wireless cuff devices 10 - 1 to 10 - 4 on the subject based on the arrival direction obtained by the arrival direction estimation unit 223 and the distance obtained by the distance estimation unit 224 .

[0045] Specifically, as can be seen from FIG. 3 , if the positional relationship of the subject with respect to the blood pressure pulse wave inspection device 200 is fixed, it is possible to estimate which wireless cuff device 10-1 to 10-4 is attached to which part of the body the signal comes from, based on the direction and distance of the radio waves from each wireless cuff device 10-1 to 10-4 relative to the blood pressure pulse wave inspection device 200.

[0046] The attachment location estimation unit 225 stores the positional relationship of the subject relative to the blood pressure pulse wave inspection device 200, and estimates the attachment location (left upper arm, right upper arm, left lower leg, or right lower leg) of each wireless cuff device 10-1 to 10-4 based on the stored positional relationship, the arrival direction, and the distance.

[0047] 3 shows an example in which the blood pressure pulse wave inspection device 200 is placed on the right side and head side of the subject, it is preferable to store multiple positional relationships of the blood pressure pulse wave inspection device 200 with respect to the subject in the attachment site estimation unit 225. In this way, the user can select a positional relationship that corresponds to the actual positional relationship from the multiple stored positional relationships, and even if the position of the subject with respect to the blood pressure pulse wave inspection device 200 is changed, the correct attachment site (left upper arm, right upper arm, left lower leg, or right lower leg) can be estimated from the arrival direction and distance.

[0048] In practice, an ID (Identification) is assigned to memory 161 (FIG. 4) of each of wireless cuff devices 10-1 to 10-4, and attachment site estimation unit 225 associates this ID with the attachment site. For example, ID1 = left upper arm, ID2 = right upper arm, ID3 = left lower limb, and ID4 = right lower limb.

[0049] The results of this association are sent to the calculation unit 222 and the determination unit 226. The calculation unit 222 receives the association results (e.g., ID1 = left upper arm, ID2 = right upper arm, ID3 = left lower limb, ID4 = right lower limb) from the attachment site estimation unit 225, and also receives the blood pressure pulse wave data (e.g., ID1 = blood pressure pulse wave data 1, ID2 = blood pressure pulse wave data 2, ID3 = blood pressure pulse wave data 3, ID4 = blood pressure pulse wave data 4) obtained by the wireless cuff devices 10-1 to 10-4 from the UWB communication module 210. The calculation unit 222 associates blood pressure pulse wave data 1 with data for the left upper arm, blood pressure pulse wave data 2 with data for the right upper arm, blood pressure pulse wave data 3 with data for the left lower limb, and blood pressure pulse wave data 4 with data for the right lower limb.

[0050] Then, the calculation unit 222 uses this correspondence to calculate numerical values ​​that serve as indices of the state of blood vessels, such as PWV and ABI. More specifically, the calculation unit 222 can calculate, for example, ABI, PWV, baPWV (Brachial-Ankle Pulse Wave Velocity), CAVI (Cardio-Ankle Vascular Index), etc., based on the blood pressure pulse wave data.

[0051] The determination unit 226 determines the appropriateness of the attachment sites of the multiple wireless cuff devices 10-1 to 10-4 based on the attachment sites estimated by the attachment site estimation unit 225. As described above, each of the wireless cuff devices 10-1 to 10-4 is colored according to the attachment site, and the user is to wear each of the wireless cuff devices 10-1 to 10-4 on the attachment site (left upper arm, right upper arm, left lower leg, and right lower leg) corresponding to the cuff color.

[0052] When the user wears the wireless cuff devices 10-1 to 10-4 on the correct attachment sites, the following should occur: ID1 = left upper arm, ID2 = right upper arm, ID3 = left lower leg, and ID4 = right lower leg. However, if the attachment site estimation unit 225 obtains an estimation result such as ID1 = left lower leg, ID2 = right upper arm, ID3 = left upper arm, and ID4 = right lower leg, it is highly likely that the wireless cuff device 10-1 for the left upper arm and the wireless cuff device 10-3 for the left lower leg have been worn incorrectly.

[0053] The determination unit 226 determines the appropriateness of the attachment sites of the multiple wireless cuff devices 10-1 to 10-4 by comparing the predetermined attachment site relationship with the attachment site relationship obtained by the attachment site estimation unit 225. The determination unit 226 outputs the determination result to the control unit 221. When the control unit 221 receives a determination result indicating that the wireless cuff devices 10-1 to 10-4 are attached to the wrong sites, the control unit 221 outputs an alarm indicating that the attachment sites are wrong from, for example, the display unit 232 and / or speaker 234 of the user interface 230.

[0054] In the configuration of this embodiment, even if the wireless cuff devices 10-1 to 10-4 are attached to the wrong location, the linking by the attachment location estimation unit 225 allows the calculation unit 222 to calculate numerical values ​​that serve as indicators of the state of the blood vessels, such as PWV and ABI, based on the correct correspondence. However, since wireless cuff devices for the upper arm and wireless cuff devices for the lower limbs may differ in size and measurement sensitivity, it is preferable that the wireless cuff devices be attached to predetermined locations. In this embodiment, the provision of the determination unit 226 allows the user to correct any incorrect attachment, thereby preventing a decrease in the accuracy of the blood pressure pulse wave test due to incorrect cuff attachment.

[0055] As described above, according to this embodiment, the blood pressure pulse wave examination system includes a plurality of wireless cuff devices 10-1 to 10-4 attached to predetermined parts of a subject, and a blood pressure pulse wave examination device 200 that wirelessly communicates with the plurality of wireless cuff devices 10-1 to 10-4, controls the plurality of wireless cuff devices 10-1 to 10-4, and collects blood pressure pulse wave data from the plurality of wireless cuff devices 10-1 to 10-4 to examine the state of the blood vessels of the subject. Each of the plurality of wireless cuff devices 10-1 to 10-4 includes a cuff 20 having an air bag and wrapped around a predetermined part of the subject, and a wireless unit 100 attached to the cuff 20. The blood pressure pulse wave inspection device 200 includes an arrival direction estimation unit 223 that estimates the arrival direction of radio waves from the multiple wireless cuff devices 10-1 to 10-4, a distance estimation unit 224 that estimates the distance to the multiple wireless cuff devices 10-1 to 10-4, and an attachment site estimation unit 225 that estimates the attachment sites of the multiple wireless cuff devices 10-1 to 10-4 on the subject based on the estimated arrival direction and distance.

[0056] This makes it possible to realize a blood pressure pulse wave inspection system and a blood pressure pulse wave inspection device 200 that can be made hoseless.

[0057] <1-3> Other Configurations of Embodiment 1 <1-3-1> Alternative Configuration 1 FIG. 6, in which the same reference numerals are used to designate parts corresponding to those in FIG. 5, is a block diagram showing the configuration of a blood pressure pulse wave inspection device 200a of alternative configuration 1 of embodiment 1.

[0058] In addition to the configuration of blood pressure pulse wave inspection device 200 of the above-described embodiment, blood pressure pulse wave inspection device 200a has a blood vessel length estimation unit 301 that estimates the blood vessel length of the subject based on the arrival direction estimated by arrival direction estimation unit 223 and the distance estimated by distance estimation unit 224, and a calculation unit 222 that calculates an index (e.g., PWV, baPWV, CAVI, etc.) that indicates the blood vessel condition of the subject based on the estimated blood vessel length and blood pressure pulse wave data from multiple wireless cuff devices 10-1 to 10-4.

[0059] Here, in order for the calculation unit 222 to calculate PWV, baPWV, CAVI, and the like as indicators of the subject's vascular condition, information on the subject's vascular length is required. Specifically, the vascular length from the heart to each of the wireless cuff devices 10-1 to 10-4 is required. Because it is difficult to actually measure this vascular length, conventionally, a medical professional inputs the subject's height and other information into the blood pressure pulse wave inspection device 200, and the calculation unit 222 virtually calculates the vascular length from the height value.

[0060] In contrast, the blood pressure pulse wave inspection device 200a of this embodiment does not require input of the subject's height because the blood pressure pulse wave inspection device 200a estimates the subject's blood pressure using the blood pressure pulse length estimation unit 301. This makes it possible to realize a blood pressure pulse wave inspection system and a blood pressure pulse wave inspection device that can improve convenience when a hoseless system is used.

[0061] FIG. 7 is a diagram illustrating the estimation of the blood vessel length by the blood vessel length estimation unit 301. In FIG.

[0062] Distances X1, X2, X3, and X4 to the wireless cuff devices 10-1, 10-2, 10-3, and 10-4 are obtained by the distance estimation unit 224. In addition, angles θ1 and θ2 in the figure can be obtained based on the directions of the wireless cuff devices 10-1, 10-2, 10-3, and 10-4 estimated by the direction-of-arrival estimation unit 223.

[0063] The blood vessel length estimation unit 301 calculates the distances Y1 and Y2 in the figure based on the distances X1, X2, X3, and X4 and the angles θ1 and θ2. The distances Y1 and Y2 can be calculated using the cosine law. Because the distances Y1 and Y2 are lengths that depend on the subject's height, the blood vessel length estimation unit 301 can calculate the estimated blood vessel length from the subject's heart to each of the wireless cuff devices 10-1 to 10-4 by substituting the distance Y1 or Y2 into a predetermined model formula.

[0064] One aspect of the blood pressure pulse wave examination system of this embodiment includes a plurality of wireless cuff devices (10-1 to 10-4) attached to predetermined parts of a subject, and a blood pressure pulse wave examination device (200a) that wirelessly communicates with the plurality of wireless cuff devices (10-1 to 10-4), controls the plurality of wireless cuff devices (10-1 to 10-4), and collects blood pressure pulse wave data from the plurality of wireless cuff devices (10-1 to 10-4) to examine the vascular condition of the subject. Each of the plurality of wireless cuff devices (10-1 to 10-4) includes a cuff (20) having an air bag and wrapped around a predetermined part of the subject, and a wireless unit (100) attached to the cuff (20). The blood pressure pulse wave inspection device 200a includes an arrival direction estimation unit 223 that estimates the arrival direction of radio waves from the multiple wireless cuff devices 10-1 to 10-4, a distance estimation unit 224 that estimates the distance to the multiple wireless cuff devices 10-1 to 10-4, a blood vessel length estimation unit 301 that estimates the blood vessel length of the subject based on the estimated arrival direction and distance, and a calculation unit 222 that calculates an index indicating the blood vessel condition of the subject based on the estimated blood vessel length and blood pressure pulse wave data from the multiple wireless cuff devices 10-1 to 10-4.

[0065] <1-3-2> Alternative Form 2 In this alternative form 2, we propose using a wireless heart sound sensor. That is, we use a heart sound sensor that can be wirelessly connected to the blood pressure pulse wave inspection device 200a. Specifically, the heart sound sensor has a wireless transmitter that can wirelessly transmit the detected heart sound signal to the blood pressure pulse wave inspection device 200a. The blood pressure pulse wave inspection device 200a calculates indices that indicate the subject's vascular condition, such as PWV, baPWV, and CAVI, based on the heart sound signal from the heart sound sensor in addition to blood pressure pulse wave data from the multiple wireless cuff devices 10-1 to 10-4.

[0066] The method of calculating indices showing the state of a subject's blood vessels, such as PWV, baPWV, and CAVI, using blood pressure pulse wave data and heart sounds has been widely used for a long time, so a description thereof will be omitted here.

[0067] A feature of this embodiment is that the blood pressure pulse wave inspection device 200a uses a wireless heart sound sensor to estimate the blood vessel length from the heart to each of the wireless cuff devices 10-1 to 10-4. This improves the accuracy of estimating blood vessel length compared to the first embodiment, and makes it possible to more accurately determine indices indicating the blood vessel condition of the subject (PWV, baPWV, CAVI, etc.).

[0068] FIG. 8 is a diagram illustrating the estimation of the blood vessel length by the blood vessel length estimation unit 301. In FIG.

[0069] The distance estimation unit 224 acquires the distances X1, X2, X3, and X4 to each of the wireless cuff devices 10-1, 10-2, 10-3, and 10-4, as well as the distance M1 to the wireless heart sound sensor 400. The direction of arrival estimation unit 223 acquires the direction of the wireless heart sound sensor 400, as well as the direction of each of the wireless cuff devices 10-1, 10-2, 10-3, and 10-4.

[0070] The blood vessel length estimation unit 301 calculates the distance from the wireless heart sound sensor 400 to each of the wireless cuff devices 10-1, 10-2, 10-3, and 10-4 based on the distances X1, X2, X3, X4, and M1 and the directions of each of the wireless cuff devices 10-1, 10-2, 10-3, and 10-4 and the wireless heart sound sensor 400. The distance from the wireless heart sound sensor 400 to each of the wireless cuff devices 10-1, 10-2, 10-3, and 10-4 can be calculated using the cosine law.

[0071] The blood vessel length estimation unit 301 can estimate the blood vessel length from the subject's heart to each of the wireless cuff devices 10-1 to 10-4 by substituting the calculated distance from the wireless heart sound sensor 400 to each of the wireless cuff devices 10-1 to 10-4 into a predetermined model formula. For example, because the blood vessels from the wireless heart sound sensor 400 to each of the wireless cuff devices 10-1, 10-2, 10-3, and 10-4, i.e., the blood vessels from the heart to the blood pressure pulse wave measurement points, extend in an arc from the heart to the blood pressure pulse wave measurement points, the blood vessel length estimation unit 301 calculates the estimated value of the blood vessel length by correcting the straight-line distance to convert it into an arc-shaped curved distance. In this embodiment, the blood vessel length from the heart to each of the wireless cuff devices 10-1 to 10-4 is estimated based on the position of the wireless heart sound sensor 400, which corresponds to the position of the heart. This improves the accuracy of estimating blood vessel length compared to the first embodiment, and makes it possible to more accurately determine indices indicating the blood vessel condition of the subject (PWV, baPWV, CAVI, etc.).

[0072] One aspect of the blood pressure pulse wave examination system of Alternative Form 2 includes a plurality of wireless cuff devices (10-1 to 10-4) attached to predetermined parts of a subject, a blood pressure pulse wave examination device (200a) that wirelessly communicates with the plurality of wireless cuff devices (10-1 to 10-4) to control the plurality of wireless cuff devices (10-1 to 10-4) and collects blood pressure pulse wave data from the plurality of wireless cuff devices (10-1 to 10-4) to examine the state of the blood vessels of the subject, and a wireless heart sound sensor (400).

[0073] The blood pressure pulse wave inspection device 200a includes an arrival direction estimation unit 223 that estimates the arrival direction of radio waves from the multiple wireless cuff devices 10-1 to 10-4 and the wireless heart sound sensor 400, a distance estimation unit 224 that estimates the distance between the multiple wireless cuff devices 10-1 to 10-4 and the wireless heart sound sensor 400, a blood vessel length estimation unit 301 that estimates the blood vessel length based on the distance between the wireless heart sound sensor 400 and the multiple wireless cuff devices 10-1 to 10-4, and a calculation unit 222 that calculates an index showing the blood vessel condition of the subject based on the estimated blood vessel length and blood pressure pulse wave data from the multiple wireless cuff devices 10-1 to 10-4.

[0074] Although the second embodiment has been described with reference to an example using the wireless heart sound sensor 400, other wireless sensors may be used instead of the wireless heart sound sensor 400. Essentially, a wireless sensor may be provided that includes a sensor capable of detecting cardiac behavior, which is the source of a pulse wave from the heart, and a wireless unit that wirelessly transmits the acquired cardiac behavior information to the blood pressure pulse wave inspection device 200a. Specifically, the cardiac behavior information is information used by the blood pressure pulse wave inspection device 200a to determine the timing of blood ejection from the heart. The sensor unit that detects cardiac behavior may be, for example, a vibration sensor that detects chest vibrations in response to the heartbeat. Alternatively, the sensor unit may be a sensor that measures an electrocardiogram.

[0075] Although the second embodiment describes a case in which a total of four wireless cuff devices 10-1 to 10-4 are attached to the upper and lower limbs, the number and positions of the attached wireless cuff devices are not limited to this. When measuring Pulse Wave Velocity using a wireless sensor (e.g., the wireless heart sound sensor 400) attached to the body surface corresponding to the heart, the number of wireless cuff devices may be, for example, one. Note that, as described in Section <1-3-2>, when measuring Pulse Wave Velocity without using a wireless sensor (e.g., the wireless heart sound sensor 400), multiple wireless cuff devices are required. Multiple wireless cuff devices may be attached, for example, to the upper arm and the other upper limb and / or lower limb. Furthermore, as in the case of a segmental pulse wave test, wireless cuff devices may be attached to two different positions on the lower limb, for example. These two wireless cuff devices may be attached at positions corresponding to both ends of the artery that do not sandwich a bifurcation point. The reason for this is common in the field of conventional Pulse Wave Velocity measurement, and therefore will not be explained here.

[0076] When estimating blood vessel length as in other embodiments 1 and 2, the antenna unit 211 is preferably installed under the bed on which the subject is lying. For example, the antenna unit 211 is installed so as to be integrated into the bed or the sheet. In this way, for example, the angles θ1 and θ2 in FIG. 7 do not become too small, and therefore a decrease in the measurement accuracy of the distances Y1 and Y2 can be suppressed.

[0077] <1-3-3> Alternative Form 3 In the above-described alternative forms 1 and 2, the blood pressure pulse wave inspection device 200a estimates the distance and direction to the wireless cuff devices 10-1 to 10-4 and the wireless heart sound sensor 400, and estimates the blood vessel length based on this. However, the wireless cuff devices 10-1 to 10-4 and the wireless heart sound sensor 400 may perform distance measurement wirelessly, and the distance measurement results may be transmitted to the blood pressure pulse wave inspection device 200a.

[0078] 7, for example, wireless cuff devices 10-1 and 10-3 measure distances wirelessly to determine distance Y1, wireless cuff devices 10-2 and 10-4 measure distances wirelessly to determine distance Y2, and wireless cuff devices 10-1 to 10-4 transmit information on distances Y1 and Y2 to blood pressure pulse wave testing device 200a. Blood pressure pulse wave testing device 200a receives the information on distances Y1 and Y2 and estimates the blood vessel lengths between wireless cuff devices 10-1 to 10-4 based on the information.

[0079] 8, for example, the wireless heart sound sensor 400 and each of the wireless cuff devices 10-1 to 10-4 measure distances wirelessly to determine the distance from the wireless heart sound sensor 400 to each of the wireless cuff devices 10-1 to 10-4, and the wireless heart sound sensor 400 or the wireless cuff devices 10-1 to 10-4 transmits this distance information to the blood pressure pulse wave testing device 200a. The blood pressure pulse wave testing device 200a receives this distance information and, based on it, estimates the blood vessel length from the wireless heart sound sensor 400 to each of the wireless cuff devices 10-1 to 10-4.

[0080] In this embodiment, the direction-of-arrival estimation unit 223 and the distance estimation unit 224 of the blood pressure pulse wave inspection device 200a shown in Fig. 6 can be omitted. Also, the antenna unit 211 and the like can be configured without a positioning function.

[0081] <1-3-4> Alternative 4 In addition to the above-described embodiment, the control unit 221 may be configured to pair with a wireless cuff device located within a predetermined distance from among multiple wireless cuff devices, and collect blood pressure pulse wave data from the wireless cuff devices located within the predetermined distance, based on information about the distance to each wireless cuff device estimated by the distance estimation unit 224. In this way, even if multiple blood pressure pulse wave testing systems such as those shown in Fig. 3 are located nearby (for example, within 5 m or in the same testing room), synchronization (interference) with the wireless cuff device of another nearby blood pressure pulse wave testing system can be prevented.

[0082] Based on this concept, a configuration such as that shown in Fig. 9 may be employed. Compared to the blood pressure pulse wave testing device 200 of Fig. 5, the blood pressure pulse wave testing device 200b omits the direction-of-arrival estimation unit 223, the attachment site estimation unit 225, and the determination unit 226. The blood pressure pulse wave testing device 200b includes a distance estimation unit 224 that estimates distances to multiple wireless cuff devices, a selection unit 227 that selects a wireless cuff device located within a predetermined distance range based on the estimated distance, and a calculation unit 222 that calculates an index indicating the vascular condition of the subject based on blood pressure pulse wave data from the wireless cuff device selected by the selection unit 227.

[0083] The control unit 221 controls the transmission / reception processing unit 212 to pair with the wireless cuff device selected by the selection unit 227. In other words, the control unit 221 excludes wireless cuff devices other than the wireless cuff device selected by the selection unit 227 from the pairing targets even if the control unit 221 can receive a wireless signal from the wireless cuff device. For example, even if the received power from a certain wireless cuff device is high, the control unit 221 excludes the wireless cuff device from the pairing targets if the distance to the wireless cuff device is greater than a predetermined distance.

[0084] Unlike the configuration of FIG. 5, the configuration of FIG. 9 does not allow identification of the attachment site, and therefore assumes that the user has attached the wireless cuff to the correct attachment site. However, even if another blood pressure pulse wave examination system is nearby (for example, within 5 m or in the same examination room), it has the advantage of being able to prevent synchronization (interference) with the wireless cuff device of another blood pressure pulse wave examination system.

[0085] Furthermore, even if the wireless cuff devices 10-1 to 10-4 are placed together in one location near the blood pressure pulse wave inspection device 200b before being attached to the subject, all of the wireless cuff devices 10-1 to 10-4 can be paired together based on the distance information.

[0086] Furthermore, the blood pressure pulse wave inspection device 200b of this alternative form 4 only pairs and communicates with wireless cuff devices within a specified distance, which prevents "falsification of blood pressure pulse wave data" through impersonation and unauthorized access to the blood pressure pulse wave inspection device 200b, thereby enhancing cybersecurity.

[0087] As with the above-described alternative form 2, the blood pressure pulse wave testing system and blood pressure pulse wave testing of alternative form 4 is not limited to four wireless cuff devices 10, and can be widely applied to cases where there is one or more wireless cuff devices 10.

[0088] The above-described first embodiment and other embodiments 1 to 4 may also be implemented in combination. Furthermore, in the above-described first embodiment, the blood pressure pulse wave inspection device 200 inspects the state of blood vessels using blood pressure pulse waves detected by the wireless cuff devices 10-1 to 10-4. However, the blood pressure pulse wave inspection device 200 may inspect the state of blood vessels using heart sounds in addition to blood pressure pulse waves. In this case, the blood pressure pulse wave inspection system may be configured to include a heart sound sensor in addition to the configuration shown in FIG. 3 . Here, the blood pressure pulse wave inspection device 200 and the heart sound sensor are connected wirelessly or via a wire. Note that inspection of blood vessels using blood pressure pulse waves and heart sounds is a known technique, as described in, for example, Patent Document 1, and therefore will not be described here.

[0089] In the above-described first embodiment and other embodiments 1 to 3, the case where UWB is used as the wireless system has been described, but the applicable wireless system is not limited to UWB. For example, Bluetooth (registered trademark) may also be used. However, the use of UWB has the advantage that the accuracy of estimating the direction of arrival and distance is increased, thereby enabling more accurate determination of indices indicating the subject's vascular condition (PWV, baPWV, CAVI, etc.).

[0090] In the above-described first embodiment and other embodiments 1 to 3, the term "blood pressure pulse wave data" may be replaced with "pulse wave data." Specifically, the configurations of the above-described embodiments are also applicable to pulse wave testing devices that determine an index of arteriosclerosis based on pulse wave data without using blood pressure data. This also applies to all of the embodiments described below.

[0091] <1-4> Summary of Embodiment 1 and Other Forms 1 to 4 (1) One aspect of the blood pressure pulse wave testing system of the present disclosure is a blood pressure pulse wave testing system comprising: a plurality of wireless cuff devices attached to predetermined parts of a subject; and a blood pressure pulse wave testing device that wirelessly communicates with the plurality of wireless cuff devices, controls the plurality of wireless cuff devices, and collects pulse wave data from the plurality of wireless cuff devices to test the vascular condition of the subject, wherein each of the plurality of wireless cuff devices comprises: a cuff having an air bag and wrapped around a predetermined part of the subject; and a wireless unit attached to the cuff, and the blood pressure pulse wave testing device comprises: an arrival direction estimation unit that estimates the arrival direction of radio waves from the plurality of wireless cuff devices; a distance estimation unit that estimates the distance to the plurality of wireless cuff devices; and an attachment part estimation unit that estimates the attachment parts of the plurality of wireless cuff devices on the subject based on the estimated arrival direction and distance.

[0092] (2) In one aspect of the blood pressure pulse wave inspection system of the present disclosure, in (1), the blood pressure pulse wave inspection device further includes a determination unit that determines the appropriateness of the attachment locations of the plurality of wireless cuff devices based on the estimated attachment locations, and an output unit that outputs the determination result of the determination unit.

[0093] (3) One aspect of the blood pressure pulse wave inspection system of the present disclosure is (1) or (2), wherein the blood pressure pulse wave inspection device and the plurality of wireless cuff devices have UWB communication units, and the arrival direction estimation unit and the distance estimation unit of the blood pressure pulse wave inspection device estimate the arrival direction and the distance based on radio waves in a UWB communication system.

[0094] (4) One aspect of the blood pressure pulse wave inspection device of the present disclosure includes an arrival direction estimation unit that estimates the arrival direction of radio waves from multiple wireless cuff devices; a distance estimation unit that estimates the distance to the multiple wireless cuff devices; and an attachment site estimation unit that estimates the attachment sites of the multiple wireless cuff devices on a subject based on the estimated arrival direction and distance.

[0095] (5) In one aspect of the blood pressure pulse wave inspection device of the present disclosure, in (4), it further includes a determination unit that determines the appropriateness of the attachment locations of the plurality of wireless cuff devices based on the estimated attachment locations, and an output unit that outputs the determination result of the determination unit.

[0096] (6) One aspect of the blood pressure pulse wave inspection device of the present disclosure is the device of (4) above, further comprising a UWB communication unit, wherein the direction of arrival estimation unit and the distance estimation unit estimate the direction of arrival and the distance based on radio waves in a UWB communication system.

[0097] (7) One aspect of the blood pressure pulse wave testing system of the present disclosure is a blood pressure pulse wave testing system comprising: a wireless cuff device attached to a predetermined part of a subject; and a blood pressure pulse wave testing device that wirelessly communicates with the wireless cuff device, controls the wireless cuff device, collects pulse wave data from the wireless cuff device, and tests the vascular condition of the subject, wherein the wireless cuff device comprises: a cuff having an air bag and wrapped around a predetermined part of the subject; and a wireless unit attached to the cuff, and the blood pressure pulse wave testing device comprises: a distance estimation unit that estimates the distance to the wireless cuff device; a selection unit that selects a wireless cuff device located within a predetermined distance range based on the estimated distance; and a calculation unit that calculates an index indicating the vascular condition of the subject based on the pulse wave data from the wireless cuff device selected by the selection unit.

[0098] (8) In one aspect of the blood pressure pulse wave inspection system of the present disclosure, in the above (7), the blood pressure pulse wave inspection device is paired with the wireless cuff device selected by the selection unit.

[0099] (9) One aspect of the blood pressure pulse wave inspection device of the present disclosure is that, in (7), the blood pressure pulse wave inspection device excludes wireless cuff devices other than the wireless cuff device selected by the selection unit from the pairing targets even if it can receive a wireless signal from the wireless cuff device.

[0100] (10) One aspect of the blood pressure pulse wave testing system of the present disclosure includes: a distance estimation unit that estimates distances to multiple wireless cuff devices; a selection unit that selects the wireless cuff devices located within a predetermined distance range based on the estimated distances; and a calculation unit that calculates an index indicating the vascular condition of the subject based on pulse wave data from the wireless cuff device selected by the selection unit.

[0101] (11) In one aspect of the blood pressure pulse wave inspection device of the present disclosure, in the above (10), the device further includes a control unit that controls pairing with the wireless cuff device selected by the selection unit.

[0102] (12) One aspect of the blood pressure pulse wave inspection device of the present disclosure is the device described in (10) above, further including a control unit that controls a wireless cuff device other than the wireless cuff device selected by the selection unit to be excluded from pairing even if a wireless signal can be received from the wireless cuff device.

[0103] (13) One aspect of the blood pressure pulse wave testing system of the present disclosure includes: a wireless cuff device attached to a predetermined part of a subject; and a blood pressure pulse wave testing device that wirelessly communicates with the wireless cuff device, controls the wireless cuff device, collects pulse wave data from the wireless cuff device, and tests the vascular condition of the subject, wherein the wireless cuff device is positioned wirelessly, and the blood pressure pulse wave testing device estimates the vascular length of the subject using the positioning results, and calculates an index indicating the vascular condition of the subject based on the estimated vascular length and the pulse wave data from the wireless cuff device.

[0104] (14) One aspect of the blood pressure pulse wave testing system of the present disclosure is the blood pressure pulse wave testing system of (13), which includes a plurality of the wireless cuff devices, and the blood pressure pulse wave testing device includes: an arrival direction estimation unit that estimates the arrival direction of radio waves from the plurality of wireless cuff devices; a distance estimation unit that estimates the distance to the plurality of wireless cuff devices; a blood vessel length estimation unit that estimates the blood vessel length between the plurality of wireless cuff devices of the subject based on the estimated arrival direction and the distance from the plurality of wireless cuff devices; and a calculation unit that calculates an index indicating the blood vessel condition of the subject based on the estimated blood vessel length and pulse wave data from the plurality of wireless cuff devices.

[0105] (15) One aspect of the blood pressure pulse wave testing system of the present disclosure is the blood pressure pulse wave testing system of (13), further comprising a wireless sensor attached to a position corresponding to the subject's heart, detecting cardiac behavior that is the source of a pulse wave and wirelessly transmitting cardiac behavior information, wherein the blood pressure pulse wave testing device comprises: an arrival direction estimation unit that estimates the arrival direction of radio waves from the wireless cuff device and the wireless sensor; a distance estimation unit that estimates the distance between the wireless cuff device and the wireless sensor; a blood vessel length estimation unit that estimates the blood vessel length of the subject between the wireless cuff device and the wireless sensor based on the estimated arrival direction and distance of the wireless cuff device and the wireless sensor; and a calculation unit that calculates an index indicating the blood vessel condition of the subject based on the estimated blood vessel length, the pulse wave data and the cardiac behavior information.

[0106] (16) One aspect of the blood pressure pulse wave inspection system of the present disclosure is the system of (13) above, which has a plurality of the wireless cuff devices, and the plurality of wireless cuff devices wirelessly determine the distance between each other and wirelessly transmit the distance information to the blood pressure pulse wave inspection device.

[0107] (17) One aspect of the blood pressure pulse wave testing system of the present disclosure is the system (13) further comprising a wireless sensor attached to a position corresponding to the subject's heart, detecting cardiac behavior that is the source of the pulse wave, and wirelessly transmitting cardiac behavior information, wherein the wireless sensor and the wireless cuff device wirelessly determine the distance between each other and wirelessly transmit information about the distance to the blood pressure pulse wave testing device.

[0108] (18) One aspect of the blood pressure pulse wave inspection device of the present disclosure includes: an arrival direction estimation unit that estimates the arrival direction of radio waves from multiple wireless cuff devices attached to predetermined parts of a subject; a distance estimation unit that estimates the distance to the multiple wireless cuff devices; a blood vessel length estimation unit that estimates a blood vessel length between the multiple wireless cuff devices on the subject based on the estimated arrival direction and distance from the multiple wireless cuff devices; and a calculation unit that calculates an index indicating a blood vessel condition of the subject based on the estimated blood vessel length and pulse wave data from the multiple wireless cuff devices.

[0109] (19) One aspect of the blood pressure pulse wave inspection device of the present disclosure includes: a wireless cuff device attached to a predetermined part of a subject; and an arrival direction estimation unit that estimates the arrival direction of radio waves from a wireless sensor attached to a position corresponding to the subject's heart, which detects cardiac behavior that is the source of a pulse wave and wirelessly transmits cardiac behavior information; a distance estimation unit that estimates the distance between the wireless cuff device and the wireless sensor; a blood vessel length estimation unit that estimates the blood vessel length of the subject between the wireless cuff device and the wireless sensor based on the estimated arrival direction and distance of the wireless cuff device and the wireless sensor; and a calculation unit that calculates an index indicating the blood vessel condition of the subject based on the estimated blood vessel length, pulse wave data from the wireless cuff device, and the cardiac behavior information from the wireless sensor.

[0110] <2> Second Embodiment <2-1> Configuration of Second Embodiment FIG. 10, in which the same reference numerals are assigned to parts corresponding to those in FIG. 1, is a perspective view showing the configuration of a wireless cuff device 10' of this embodiment. Compared to the wireless cuff device 10 of the first embodiment, the wireless cuff device 10' of this embodiment includes a wireless tag 30 in a cuff 20'. The wireless tag 30 is located within a communicable distance from the wireless unit 100'. In this embodiment, the wireless tag 30 is an NFC (Near Field Communication) tag. Because the communicable distance of an NFC tag is generally less than 10 cm, the wireless tag 30 is located within a distance of less than 10 cm from the NFC communication module 2161 ( FIG. 12 ) of the wireless unit 100'. Because NFC tags are short-distance and highly directional, interference with nearby wireless devices such as NFC tags is minimized.

[0111] The wireless tag 30 has an NFC communication module that realizes NFC communication with the wireless unit 100', and a memory. The memory stores information about the part of the body where the cuff 20' to which the wireless tag 30 is attached (e.g., the left upper arm, the right upper arm, the left lower leg, or the right lower leg) is to be worn. The memory also stores information indicating the size of the cuff 20' to which the wireless tag 30 is attached (e.g., information indicating whether the size is S, M, or L) and / or information indicating the type of cuff 20' (for adults, children, or newborns).

[0112] The wireless cuff device 10' is used to perform a blood pressure pulse wave test. In this embodiment, as shown in FIG. 11, four wireless cuff devices 10-1' to 10-4' are used. These four wireless cuff devices 10-1' to 10-4' are attached to the left upper arm, right upper arm, left lower leg, and right lower leg of the subject, respectively, as shown in FIG. 3 (10-1 to 10-4 in FIG. 3 can be replaced with 10-1' to 10-4', respectively). In addition to or instead of these attachment sites, for example, when performing an examination on the toes, a wireless cuff device for the toes may be used. This wireless cuff device for the toes may also have the same basic configuration as the wireless cuff device 10', except for its size. Conversely, when performing a blood pressure pulse wave test using three or fewer wireless cuff devices, three or fewer wireless cuff devices 10' may be used.

[0113] The wireless cuff device 10' (10-1' to 10-4') communicates wirelessly with the blood pressure pulse wave inspection device 200 (FIG. 5) via the wireless unit 100' (100-1' to 100-4'). The wireless cuff device 10' inflates and deflates the cuff based on control signals wirelessly transmitted from the blood pressure pulse wave inspection device 200. The wireless cuff device 10' also wirelessly transmits blood pressure pulse wave measurement results obtained during the inspection to the blood pressure pulse wave inspection device 200.

[0114] 12, in which the same reference numerals are assigned to parts corresponding to those in FIG. 4, is a block diagram showing the configuration of a wireless unit 100′ according to embodiment 2. The wireless unit 100′ of this embodiment differs from the wireless unit 100 of embodiment 1 in the configuration of a wireless communication section 160′.

[0115] The wireless communication unit 160′ of this embodiment has an NFC communication module 2161 and a Bluetooth (registered trademark) communication module 2162. In practice, the NFC communication module 2161 and the Bluetooth communication module 2162 each have an antenna and a transmission / reception circuit that enable the respective wireless communication methods.

[0116] The NFC communication module 2161 is capable of wirelessly communicating with the wireless tag 30 provided in the cuff 20' using a wireless communication method that complies with the NFC standard, thereby reading data written in the memory of the wireless tag 30 and writing data to the memory of the wireless tag 30.

[0117] The Bluetooth communication module 2162 wirelessly communicates with the blood pressure pulse wave inspection device 200 (Figure 5) using a wireless communication method compliant with the Bluetooth standard, thereby enabling it to wirelessly receive control signals from the blood pressure pulse wave inspection device 200 and wirelessly transmit blood pressure pulse wave measurement results to the blood pressure pulse wave inspection device 200.

[0118] In the present embodiment, the case where communication with the wireless tag is performed by NFC and communication with the blood pressure pulse wave inspection device is performed by Bluetooth has been described as an example, but this is not limiting. Essentially, the wireless unit 100′ has a first wireless unit that performs wireless communication with the wireless tag 30 provided in the cuff 20′ using a first wireless communication method, and a second wireless unit that performs wireless communication with an external device (the blood pressure pulse wave inspection device 200 in this embodiment) using a second wireless communication method that allows longer-distance communication than the first wireless communication method, and any other configuration is acceptable as long as the first and second wireless units are capable of performing wireless communication with the wireless tag 30 and the external device (the blood pressure pulse wave inspection device 200).

[0119] Next, a blood pressure pulse wave test using the wireless cuff device 10' will be described.

[0120] Before the blood pressure pulse wave test, each cuff 20' is provided with a wireless tag 30. Each wireless tag 30 stores information about the location and size of the attached cuff 20'.

[0121] It is preferable that the wireless tag 30 is built into the cuff 20' so that it is not removed by the user, thereby preventing the correspondence between the wireless tag 30 and the cuff 20' from being artificially disrupted.

[0122] A user such as a medical professional attaches a wireless unit 100' to each cuff 20'. As a result, four wireless cuff devices 10-1' to 10-4' are prepared before the examination, as shown in FIG. 2. Incidentally, the wireless unit 100' is attached to or detached from the cuff 20' in the following situations, for example: When the wireless unit 100' is attached to a newly manufactured cuff 20'. When the cuff 20' is replaced due to deterioration over time. When the size of the cuff 20' is changed at the examination site. When the cuff 20' is cleaned or disinfected.

[0123] The wireless unit 100' attached to the cuff 20' has a common configuration regardless of the location or size of the cuff 20'. This eliminates the need to prepare as many wireless units 100' as there are cuffs 20'. For example, when cleaning or disinfecting a certain cuff 20', the wireless unit 100' can be removed from that cuff 20' and then attached to another cuff 20'.

[0124] Next, the user attaches the four wireless cuff devices 10-1' to 10-4' to predetermined parts of the subject as shown in Fig. 3 (10-1 to 10-4 in Fig. 3 can be replaced with 10-1' to 10-4', respectively). At this time, the user attaches the wireless cuff devices 10-1' to 10-4' to predetermined parts of the subject, using the color and lettering on the edge 20a of each cuff 20-1' to 20-4' as a guide.

[0125] Next, the user turns on the power of the wireless cuff devices 10-1' to 10-4' by operating the power button 131. Note that after turning on the power of the wireless cuff devices 10-1' to 10-4', the wireless cuff devices 10-1' to 10-4' may be placed on the subject.

[0126] When the power of the wireless cuff devices 10-1' to 10-4' is turned on and the user performs a predetermined operation on the blood pressure pulse wave inspection device 200 and / or the wireless cuff devices 10-1' to 10-4', the blood pressure pulse wave inspection device 200 and the wireless cuff devices 10-1' to 10-4' are synchronized and ready for inspection.

[0127] At the start of or before the start of the test, the wireless cuff devices 10-1' to 10-4' read information (such as the attachment location, cuff size, and cuff type) from the wireless tags 30-1 to 30-4 using the NFC communication module 2161, and transmit the read information to the blood pressure pulse wave inspection device 200 using the Bluetooth communication module 2162. This allows the blood pressure pulse wave inspection device 200 to recognize the attachment location, cuff size, and cuff type of each wireless cuff device 10-1' to 10-4'.

[0128] When a user starts a blood pressure pulse wave test, the blood pressure pulse wave test device 200 transmits a control signal to each of the wireless cuff devices 10-1' to 10-4' via Bluetooth communication according to the attachment site, cuff size, and cuff type. In practice, the cuff pressure is controlled according to the cuff size and cuff type.

[0129] Wireless cuff devices 10-1' to 10-4' control cuff driver 140 based on a control signal from blood pressure pulse wave inspection device 200. This allows air to be supplied to and discharged from the air bag of cuff 20', and the cuff pressure is controlled to a value suitable for the inspection.

[0130] The wireless cuff devices 10-1' to 10-4' transmit the cuff pressure detected by the cuff pressure detection unit 150, i.e., blood pressure pulse wave data, via Bluetooth communication to the blood pressure pulse wave inspection device 200. At this time, each wireless cuff device 10-1' to 10-4' (wireless unit 100-1' to 100-4') transmits the blood pressure pulse wave data together with information on the attachment site read from the wireless tag 30-1 to 30-4.

[0131] This allows the blood pressure pulse wave inspection device 200 to recognize which blood pressure pulse wave data received corresponds to which attachment site.

[0132] The blood pressure pulse wave inspection device 200 calculates arteriosclerosis indicators such as pulse wave velocity using the blood pressure pulse wave data from each attachment site. Calculation of pulse wave velocity and other indicators using the blood pressure pulse wave can be performed using known processing, and therefore will not be described here.

[0133] 13A is a diagram showing an example of the format of a packet transmitted from the wireless communication unit 160′ of the wireless unit 100′ to the blood pressure pulse wave inspection device 200. As shown in FIG. 13A, one packet is composed of a preamble (P), an address (A), a payload (PAYLOAD), and a checksum (CRC).

[0134] The preamble (P) is, for example, 1 byte. The address (A) is a unique number assigned to each wireless unit 100' and is, for example, 5 bytes. The payload (PAYLOAD) is, for example, 32 bytes. The checksum (CRC) is, for example, 2 bytes.

[0135] FIG. 13B shows the contents of a packet that the wireless unit 100′ transmits to the blood pressure pulse wave inspection device 200 prior to transmitting measurement data (blood pressure pulse wave data) (e.g., during pairing). The payload (PAYLOAD) contains information about the attachment site, cuff size, actual inflation count information, and other information. The attachment site information indicates the right upper arm, left upper arm, right ankle, left ankle, etc. The cuff size information indicates S, M, L, etc. The cuff type information indicates adult, pediatric, neonatal, etc. The actual inflation count, which will be described in detail below, is the number of times the cuff 20′ has been inflated by the cuff driver 140, e.g., 10 times. The other information includes the software version number of the wireless unit 100′.

[0136] 13C shows the contents of a packet when measurement data (blood pressure pulse wave data) is transmitted after the packet shown in FIG. 13B is transmitted. Status information and measurement data (blood pressure pulse wave data) are placed in the payload (PAYLOAD). The status information is information that indicates the operating status of the wireless unit 100'.

[0137] As described above, the wireless cuff device 10′ of this embodiment includes a cuff 20′ equipped with an NFC tag (wireless tag 30) having attachment site information, and a wireless unit 100′ that is detachably attached to the cuff 20′, wirelessly connected to the NFC tag (wireless tag 30), and wirelessly transmits the attachment site information and data (blood pressure pulse wave data) obtained by driving the cuff 20′ to an examination device (blood pressure pulse wave examination device 200).

[0138] From another perspective, the wireless cuff device 10′ of this embodiment includes a cuff 20′ having an air bag and wrapped around a predetermined part of the subject, a cuff driver 140 that supplies and exhausts air to and from the air bag of the cuff 20′, a cuff pressure detector 150 that detects the cuff pressure of the cuff 20′ during an examination, and a wireless unit 100′ that is detachably attached to the cuff 20′. The wireless unit 100′ includes a first wireless unit (NFC communication module 2161 in this embodiment) that performs wireless communication with the wireless tag 30 provided in the cuff 20′, and a second wireless unit (Bluetooth communication module 2162 in this embodiment) that performs wireless communication with an external wireless unit.

[0139] This makes it possible to realize a hoseless wireless cuff device 10' and a blood pressure pulse wave inspection system.

[0140] According to the configuration of this embodiment, for example, the following effects can be obtained.

[0141] (i) Even if the user does not associate the wireless cuff devices 10-1' to 10-4' with the blood pressure pulse wave inspection device 200, the wireless cuff devices 10-1' to 10-4' automatically associate the wireless cuff devices 10-1' to 10-4' with the blood pressure pulse wave inspection device 200 by sending the information about the wireless cuff devices 10-1' to 10-4' that is stored in the wireless tags 30-1 to 30-4. This reduces the user's workload and prevents incorrect association. In other words, in a conventional blood pressure pulse wave inspection system using an air hose, if the user incorrectly associates the air hose with the connector of the blood pressure pulse wave inspection device (i.e., if the connection is incorrect), the inspection cannot be performed correctly. This can be prevented with the configuration of this embodiment.

[0142] (ii) The wireless unit 100' is configured to be detachable from the cuff 20', and the wireless unit 100' reads information about the type of cuff 20' from the wireless tag 30 fixedly attached to the cuff 20', so the wireless unit 100' can have a common configuration regardless of the location or size of the cuff 20'. This eliminates the need for the user to associate the wireless unit 100' with the cuff 20', further increasing the versatility of the wireless unit 100'.

[0143] Here, unlike the above-described embodiment, if it is assumed that only the wireless unit 100' and the blood pressure pulse wave inspection device 200 are wirelessly connected without using the wireless tag 30, the following inconveniences will arise.

[0144] As a first method that does not use the wireless tag 30, it is conceivable to use dedicated wireless units 100' for each of the left upper arm, right upper arm, left lower leg, and right lower leg, rather than using a common wireless unit 100' for all the attachment sites. Specifically, a wireless unit for the left upper arm is attached to the cuff of the left upper arm, a wireless unit for the right upper arm to the cuff of the right upper arm, a wireless unit for the left lower leg to the cuff of the left lower leg, and a wireless unit for the right lower leg to the cuff of the right lower leg.

[0145] A second method that does not use the wireless tag 30 is one in which the user manually sets the wireless unit 100' to which cuff 20' each wireless unit 100' corresponds.

[0146] However, there is a possibility of incorrect installation in the first method, and incorrect settings in the second method. If such incorrect installation or incorrect settings occur, the blood pressure pulse wave inspection device 200 will incorrectly associate the detection site with the detected blood pressure pulse wave, making it impossible to obtain correct inspection results with the blood pressure pulse wave inspection device 200.

[0147] In this embodiment, since the wireless tag 30 is used, correct test results can be obtained in the blood pressure pulse wave testing device 200 as long as the cuff 20' is attached to the correct location.

[0148] (iii) When the remaining charge of the battery 110 of the wireless unit 100' becomes low, another wireless unit 100' with a charged battery 110 can be attached to the cuff 20'. The newly attached wireless unit 100' reads the information from the wireless tag 30 of the cuff 20' and transmits it to the blood pressure pulse wave inspection device 200. This eliminates the need to manually set the correspondence between the wireless unit 100' and the cuff 20', making it easy to replace the wireless unit 100'.

[0149] (iv) By using a communication method with the wireless tag 30 that has a shorter communication distance than the communication method with the blood pressure pulse wave inspection device 200, the consumption of the battery 110 of the wireless unit 100' is reduced and the charging interval of the battery 110 is extended.

[0150] <2-2> Other forms of embodiment 2 <2-2-1> In the above-mentioned embodiment 2, the case where information on the attachment position and size of the cuff 20′ is stored in the wireless tag 30 has been described, but this is not limiting. In short, any information that allows the blood pressure pulse wave inspection device 200 to identify the attachment position and size of the cuff 20′ is sufficient, and it does not have to be information on the attachment position or size itself.

[0151] <2-2-2> In addition to the configuration of the second embodiment described above, the memory unit of the wireless tag 30 may store a limit number of inflation times, which is the number of inflation times that the cuff 20' is designed to withstand, and the wireless unit 100' may write the actual number of inflation times that the cuff 20' is inflated by the cuff driving unit 140 into the memory unit of the wireless tag 30. If this actual number of inflation times exceeds the previously stored limit number of inflation times, an alarm indicating this may be output.

[0152] A more detailed explanation follows. The limit number of inflations pre-stored in the wireless tag 30 is, for example, 30,000 times. Incidentally, for a toe cuff, it is, for example, about 1,000 times. The wireless tag 30 has a memory area for storing the actual number of inflations. The wireless unit 100' increments the actual number of inflations stored in the wireless tag 30 each time the cuff 20' is inflated. The wireless unit 100' reads the limit number of inflations and the actual number of inflations stored in the wireless tag 30, compares the limit number of inflations with the actual number of inflations, and prompts the user to replace the cuff 20' by displaying a display or outputting an audible alarm. For example, the wireless unit 100' outputs an alarm when the actual number of inflations exceeds the limit number of inflations.

[0153] In the second embodiment, the number of inflations, including the actual number of inflations, is recorded on the wireless tag 30 fixedly attached to the cuff 20', so that it can also accommodate, for example, replacement of the wireless unit 100'. In other words, since the information on the number of inflations is stored in the cuff 20' itself, the number of inflations is carried over regardless of replacement of the wireless unit 100'.

[0154] <2-2-3> In the above-described second embodiment, each wireless cuff device 10-1' to 10-4' (wireless unit 100-1' to 100-4') transmits blood pressure pulse wave data together with information on the attachment site read from the wireless tag 30-1 to 30-4. However, this is not limiting. The point is that it is sufficient if the blood pressure pulse wave inspection device 200 can identify which wireless cuff device 10-1' to 10-4' (wireless unit 100-1' to 100-4') is transmitting blood pressure pulse wave data for which attachment site. Therefore, for example, each wireless cuff device 10-1' to 10-4' (wireless unit 100-1' to 100-4') may transmit information that identifies the attachment site only once to the blood pressure pulse wave inspection device 200, and the blood pressure pulse wave inspection device 200 may then associate the ID (identification information) of each wireless cuff device 10-1' to 10-4' (wireless unit 100-1' to 100-4') with the attachment site. Thereafter, each wireless cuff device 10-1' to 10-4' (wireless unit 100-1' to 100-4') may transmit blood pressure pulse wave data together with its own ID, allowing the blood pressure pulse wave inspection device 200 to recognize the relationship between the blood pressure pulse wave data and the attachment site via the ID.

[0155] <2-2-4> In the second embodiment described above, it is possible that the user may attach the wrong cuff 20'. For example, suppose that the user mistakenly attaches the wireless tag 30-1 for the left upper arm to the cuff 20-2' for the right upper arm. In this case, the blood pressure pulse wave inspection device 200 receives information on the attachment site indicating that the cuff is the left upper arm from the two wireless units 100-1' and 100-2'. In this case, the blood pressure pulse wave inspection device 200 should output an alarm indicating that the wrong wireless tag 30 is attached to the cuff 20'.

[0156] In addition, wireless units 100-1' to 100-4' may be dedicated to the left upper arm, right upper arm, left lower leg, and right lower leg, respectively, and wireless units 100-1' to 100-4' may refer to the information on the attachment site from wireless tags 30-1 to 30-4 and output an error if it is determined that the wrong cuff 20' has been attached.

[0157] <2-2-5> In the second embodiment described above, the blood pressure pulse wave inspection device 200 inspects the state of blood vessels using blood pressure pulse waves detected by the wireless cuff devices 10-1' to 10-4'. However, the blood pressure pulse wave inspection device 200 may inspect the state of blood vessels using heart sounds in addition to blood pressure pulse waves. In this case, the blood pressure pulse wave inspection system may be configured to include a heart sound sensor in addition to the configuration shown in FIG. 3. Here, the blood pressure pulse wave inspection device 200 and the heart sound sensor are wirelessly connected via, for example, Bluetooth communication. Note that inspection of blood vessels using blood pressure pulse waves and heart sounds is a known technique, as described in, for example, Patent Document 1, and therefore will not be described here.

[0158] <2-2-6> In the above-described second embodiment, the wireless cuff device according to the present disclosure is described as being used in a blood pressure pulse wave inspection system, but the wireless cuff device according to the present disclosure is not limited to this and can be applied to systems other than blood pressure pulse wave inspection systems. In other words, in the above-described embodiment, the wireless unit 100' transmits inspection results to the blood pressure pulse wave inspection device 200, but the external device to which the wireless unit 100' cooperates and transmits inspection results is not limited to the blood pressure pulse wave inspection device 200.

[0159] Possible external devices to which the wireless unit 100' cooperates and transmits test results include, for example, a vital sign monitor, a Holter sphygmomanometer, and an exercise stress sphygmomanometer. Control signals and the like are sent from these external devices to the wireless unit 100'. Blood pressure value data, cuff attachment position information, and the like are sent from the wireless unit 100' to the external devices.

[0160] In other words, one aspect of the present disclosure is an examination system that includes a wireless cuff device 10′ and an examination device (e.g., a vital sign monitor, a Holter sphygmomanometer, an exercise stress sphygmomanometer, etc.) that is provided with an external wireless unit and that at least wirelessly transmits a control signal for controlling the cuff driver 140 to the wireless cuff device 10′ and wirelessly receives information on the wireless tag 30 and the cuff pressure from the wireless cuff device 10′.

[0161] <2-2-7> In the above-described second embodiment, the case where the cuff driving unit 140 and the cuff pressure detection unit 150 are provided in the wireless unit 100' has been described. However, the cuff driving unit 140 and the cuff pressure detection unit 150 may be provided in a unit separate from the wireless unit in which the wireless communication unit 160' is provided. In this case, the separate unit may be detachable from the cuff 20', or may be fixed. The wireless unit may be directly attached to the cuff 20', or may be indirectly attached to the cuff 20' via a separate unit. By electrically connecting the wireless unit to the separate unit, the same operation as in the above-described embodiment can be realized.

[0162] <2-8> Summary of embodiment 2 and other forms One aspect of the cuff device of the present disclosure comprises: a cuff having an NFC tag having attachment site information; and a wireless unit that is detachably attached to the cuff, wirelessly connected to the NFC tag, and wirelessly transmits the attachment site information and data obtained by driving the cuff to an inspection device.

[0163] In one aspect of the wireless cuff device of the present disclosure, the wireless unit wirelessly transmits information about the cuff, including the attachment site information, to the testing device prior to transmitting the data.

[0164] In one aspect of the wireless cuff device of the present disclosure, in addition to the attachment site information, at least one of cuff size information and cuff type information is included in one packet that the wireless unit wirelessly transmits to the testing device prior to transmitting the data.

[0165] In one aspect of the wireless cuff device of the present disclosure, the cuff has an air bag and is wrapped around a predetermined part of the subject, and the wireless unit further has a cuff drive unit that supplies and exhausts air to the air bag of the cuff, and a cuff pressure detection unit that detects the cuff pressure of the cuff during testing.

[0166] In one aspect of the wireless cuff device of the present disclosure, the cuff driving section and the cuff pressure detecting section are provided within the wireless unit.

[0167] In one aspect of the wireless cuff device of the present disclosure, the testing device is a blood pressure pulse wave testing device, and the wireless unit at least wirelessly receives a control signal for controlling the cuff driving unit from the blood pressure pulse wave testing device, and wirelessly transmits the attachment site information and cuff pressure data obtained by driving the cuff to the blood pressure pulse wave testing device.

[0168] In one aspect of the wireless cuff device of the present disclosure, the NFC tag has a memory unit, and the memory unit stores information indicating the size and / or type of the cuff in addition to the attachment site information.

[0169] In one aspect of the wireless cuff device of the present disclosure, the NFC tag has a memory unit that stores a maximum number of times the cuff can be inflated, and the wireless unit writes the actual number of times the cuff is inflated by the cuff driver into the memory unit, and when the actual number of times the cuff is inflated exceeds the maximum number of times, outputs an alarm indicating this.

[0170] One aspect of the testing system of the present disclosure includes: the wireless cuff device; and a testing device that wirelessly receives the attachment site information and data obtained by driving the cuff from the wireless cuff device.

[0171] One aspect of the testing system of the present disclosure includes: the wireless cuff device; and a testing device that wirelessly transmits a control signal for controlling the cuff driving unit to the wireless cuff device and wirelessly receives, from the wireless cuff device, the attachment site information and data obtained by driving the cuff.

[0172] <3> Third Embodiment <3-1> Findings that led to the third embodiment Before explaining the third embodiment, the findings of the inventors that led to the third embodiment will be described.

[0173] 2. Description of the Related Art Conventionally, electronic devices such as personal computers synchronize their time with each other using a time synchronization method such as NTP (Network Time Protocol).

[0174] Conventionally, there are various representative time synchronization algorithms for time synchronization in wireless sensor networks, such as TPSN (Timing-sync Protocol for Sensor Network), FTSP (Flooding Synchronisation Time Protocol), Tiny-Sync (check if it is an abbreviation for Tight time Synchronisation), RBS (Reference Broadcast Synchronisation), etc. These time synchronization algorithms are described in, for example, Non-Patent Document 1.

[0175] TPSN is a method of time synchronization by measuring radio wave propagation time. RBS is a method of synchronizing receivers with each other, rather than synchronizing transmitters and receivers. FTSP is a method of synchronizing the transmitter's time with multiple receivers using a single packet. Tiny-Sync is a strict time synchronization method based on measuring radio wave propagation time.

[0176] Incidentally, in NTP, errors of about 100 ms occur due to network delays, OS (basic software), hardware processing delays, and the like.

[0177] Furthermore, in wireless communication between a transmitter and a receiver, as described in Non-Patent Document 2, time synchronization errors occur due to "non-deterministic" delay times that cannot be estimated in advance, making it difficult to suppress time synchronization errors to a very small level. Taking these factors into consideration, the present invention has been developed in accordance with the third embodiment.

[0178] There are the following paired time synchronization methods: In the third embodiment, one of the paired methods shown below is used.

[0179] Master & slave method: One node is the master, and the slave nodes synchronize with the master's reference time (TPSN and FTSP correspond to this). Peer-to-peer method: Nodes on the network communicate directly with all other nodes and exchange time information (RBS corresponds to this). Of these two methods, this third embodiment employs the master & slave method.

[0180] Clock correction method: The clock of each node is corrected for each time synchronization process. Untethered clock method: The clock of each node operates freely, exchanging and storing information for converting local time to each other's time. Of these two methods, this embodiment adopts the untethered clock method.

[0181] Internal synchronization method: The clock error of each node is relatively minimized. External synchronization method: The clock of each node is synchronized with a reference time such as Universal Coordinated Time (UTC) (GPS (Global Positioning System) corresponds to this). Of these two methods, the internal synchronization method is adopted in this third embodiment.

[0182] Sender-to-Receiver method: The node transmitter sends time information, and the receiver synchronizes based on the received information. Receiver-to-Receiver method: This method takes advantage of the characteristic that when two or more receivers receive the same message packet, they receive it almost simultaneously. Of these two methods, this third embodiment employs the Sender-to-Receiver method.

[0183] Furthermore, in this third embodiment, the time synchronization method employs a round trip time method or a TOF (Time of Flight) method, that is, a method of measuring the one-way radio wave propagation time from the time it takes for radio waves to travel back and forth between nodes.

[0184] Next, the time synchronization error will be described.

[0185] To achieve accurate time synchronization, it is necessary to eliminate non-determinism. To understand the cause of errors, a method of analyzing message delay time by breaking it down into factors is proposed, for example, in Non-Patent Document 1. "Non-determinism" refers to delay time that is random (fluctuation) and cannot be estimated in advance. "Determinism" refers to delay time that can be estimated through theoretical calculation.

[0186] 14 is a diagram showing factors that affect the delay time of a message from a wireless transmitter to a wireless receiver, where the left end of the diagram indicates the start of transmission and the right end of the diagram indicates the end of reception.

[0187] The transmission time X1 is the time spent creating a message packet on the sending host computer (hereinafter, the host computer will be simply referred to as the host). The transmission time X1 includes the time it takes to transfer the message packet from the host to the sender. In other words, the transmission time X1 is the waiting time for the operating system to execute a process or task, and is non-deterministic.

[0188] The access time X2 is the delay incurred due to waiting for access to the transmission channel, in other words, the waiting time until another transmitter finishes transmitting on the same channel, and is non-deterministic.

[0189] The transmission time X3 is the time required for the transmitter to transmit the message one bit at a time. The transmission time X3 can be estimated from the length of the message and the wireless communication speed, and is deterministic.

[0190] The radio wave propagation time X4 is the propagation time of radio waves from a transmitter to a receiver. The radio wave propagation time X4 is deterministic because it depends on the fact that radio waves travel 300,000 kilometers in one second and take about 3.3 ns to travel one meter.

[0191] The reception time X5 is the time required for the receiver to receive the message one bit at a time. The reception time X5 can be estimated from the length of the message and the wireless communication speed, and is deterministic.

[0192] The reception time X6 is the time it takes for the message packet to reach the receiving host. The reception time X6 includes the time it takes for the message packet to be transferred from the receiver to the host. In other words, the reception time X6 is the waiting time for the operating system to execute a process task and the waiting time for the receiver driver to be interrupted, and is therefore non-deterministic.

[0193] As can be seen from this, the transmission time X1, access time X2, and reception time X6 are non-deterministic. In the third embodiment, the transmission time X1 and reception time X6 are eliminated from non-determinism by performing real-time processing without an operating system. Furthermore, the access time X2 is eliminated from non-determinism by performing frequency hopping, thereby avoiding carrier sensing required by the Technical Standards Compliance Certification.

[0194] The deterministic transmission time X3 and reception time X5 are estimated from the message length and transmission rate, and the radio wave propagation time X4 is estimated by measuring the round trip time.

[0195] The inventors of the present invention envision applying the time synchronization method according to the third embodiment to a blood pressure pulse wave inspection system and medical equipment that measures pulse waves, detects heart sounds, and measures electrocardiograms. These medical equipment currently use 24-bit ΔΣ AD converters to obtain the necessary resolution and accuracy.

[0196] Delta-sigma AD converters have the advantages of having a high SNR (Signal-to-Noise Ratio), being able to achieve a resolution of 20 bits or more, being easy to correct for linearity errors, and not generating missing codes in principle.However, they have disadvantages such as a relatively low sampling rate and slow start-up time, making them unsuitable for applications that require high-speed switching of the AD converter input.

[0197] There is another AD converter that is different from the ΔΣ AD converter: the successive approximation register (SAR) AD converter. Successive approximation AD converters have the advantage of being able to lower the sampling frequency as much as desired, allowing for one-shot operation with a trigger, and easily increasing the number of input channels when combined with a multiplexer. On the other hand, successive approximation AD converters have disadvantages, such as poor DNL characteristics at resolutions of 18 bits or more, making it difficult to achieve high accuracy, and the occurrence of missing codes when accuracy is poor.

[0198] Currently, it is preferable to use a ΔΣ AD converter to obtain the resolution and accuracy required for medical equipment.

[0199] First, we will consider the time synchronization of a ΔΣ AD converter in comparison with a SAR AD converter.

[0200] FIG. 15 is a diagram illustrating time synchronization when a successive approximation type AD converter (ADC) is used, and FIG. 16 is a diagram illustrating time synchronization when a ΔΣ type AD converter (ADC) is used.

[0201] In these diagrams, the parent unit is the medical device itself equipped with a host computer, and the child unit is a sensor device worn by the subject to measure pulse waves, electrocardiograms, etc. The measurement data measured by the child unit is converted to digital data by an AD converter and sent to the parent unit. The parent unit calculates pulse wave velocity and other parameters based on the received measurement data.

[0202] In these figures, for simplicity, one AD conversion is performed per interval, but it is also possible to perform multiple AD conversions triggered by a time synchronization request. For example, if the interval period is 100 ms and the AD conversion period is 1 ms, 100 samples of measurement data will be returned per interval.

[0203] In the system using the successive approximation type AD converter shown in Figure 15, it is not difficult to build a system that performs AD conversion at a fixed time triggered by a time synchronization packet and sends the measurement data back in a response packet. Although the successive approximation type ADC takes a fixed amount of time for conversion, this conversion time is a "deterministic" time delay, so it does not lead to errors in time synchronization.

[0204] On the other hand, in the system using the ΔΣ AD converter shown in Figure 16, the ΔΣ AD converter performs AD conversion in synchronization with the ADC clock, so there is a non-deterministic time delay between the time synchronization request and the completion of AD conversion, resulting in a decrease in time synchronization performance. Even if AD conversion is started after synchronizing the transmitter reference clock and the ADC clock, the phase will eventually shift. Correcting the ADC clock (skew adjustment) during AD conversion disrupts the cycle and reduces the accuracy of the AD conversion.

[0205] The method of the third embodiment solves this problem of untethered clocks.

[0206] Another issue, as shown in Figure 17, is that if there is wireless interference and the time synchronization packet is lost, the AD conversion trigger cannot be applied, and one interval's worth of measurement data is also lost. This is an issue specific to wireless, and occurs whether a successive approximation AD converter or a ΔΣ AD converter is used. While it is possible for the slave device to automatically perform AD conversion if a time synchronization request does not arrive, an error occurs with the reference clock on the transmitting side during the waiting time while it confirms that the request has not arrived. Additionally, the transmitting side can detect radio interference and resend the time synchronization request, but in this case, the interval interval will be disrupted.

[0207] The method of the third embodiment provides a method that can maintain accurate synchronization and a constant interval even when radio interference occurs.

[0208] <3-2> Detailed Description of the Third Embodiment The third embodiment will now be described in detail with reference to the drawings.

[0209] <3-2-1> Basic Processing FIG. 18 is a block diagram illustrating a time synchronization method according to the third embodiment. Here, the master unit 1000 is, for example, the main unit of a blood pressure pulse wave inspection device, and the slave unit 2000 is, for example, a pulse wave sensor. The pulse wave sensor (slave unit 2000) wirelessly transmits detected blood pressure pulse wave data to the main unit (master unit 1000), which then calculates the pulse wave velocity based on the blood pressure pulse wave data received from the pulse wave sensor (slave unit 2000). In practice, the main unit (master unit 1000) calculates the pulse wave velocity based on the blood pressure pulse wave data received from multiple pulse wave sensors (slave units 2000). Therefore, to accurately calculate the pulse wave velocity, the main unit (master unit 1000) must precisely synchronize its time with the multiple pulse wave sensors (slave units 2000). Note that the master unit 1000 and slave unit 2000 do not necessarily have to be the main unit and pulse wave sensor of a blood pressure pulse wave inspection device. The method of the third embodiment is widely applicable to wireless devices that require highly accurate time synchronization.

[0210] The parent device 1000 has a CPU (Central Processing Unit) 1011, a wireless transmission unit 1012, a wireless reception unit 1013, a reference clock generation unit 1014, a Ta time measurement timer 1015, and a Tb time measurement timer 1016. The CPU 1011, the wireless transmission unit 1012, and the wireless reception unit 1013 are connected via a data bus.

[0211] The slave device 2000 has a CPU 1021, a wireless transmitter 1022, a wireless receiver 1023, an ADC clock generator 1024, a ΔΣ AD converter 1025, a ring buffer 1026, and a FIFO (First In, First Out) memory 1027. Hereinafter, the FIFO memory will be abbreviated as FIFO. The CPU 1021, the wireless receiver 1022, the wireless transmitter 1023, the ΔΣ AD converter 1025, the ring buffer 1026, and the FIFO 1027 are connected via a data bus.

[0212] FIG. 18 shows the flow of event signals, data, and radio waves.

[0213] The operations of the parent device 1000 and the child device 2000 in FIG. 18 will be described with reference to FIGS.

[0214] In parent device 1000, when a reference clock is generated from reference clock generation unit 1014, this reference clock is output to wireless transmission unit 1012 and Ta time measurement timer 1015. Wireless transmission unit 1012 starts transmission at the timing when the reference clock is input, and when transmission is completed, outputs a transmission completion signal to Ta time measurement timer 1015 and Tb time measurement timer 1016. Ta time measurement timer 1015 measures the time Ta from the reference clock to transmission completion. Tb time measurement timer 1016 measures the time Tb from transmission completion to reception completion.

[0215] In the slave device 2000, the ΔΣ type AD converter 1025 performs AD conversion based on the clock from the ADC clock generation unit 1024. In the example of this embodiment, AD conversion is performed at a sampling frequency of 8 kHz (sampling period of 125 μs), as shown in Figures 19 to 23. Note that the number of AD conversion samples is shown roughly to simplify the diagrams.

[0216] The radio wave propagation time Tc from the parent device 1000 to the child device 2000 can be calculated by Tc = Tb / 2. As can be seen from Fig. 19, the time Td from the reference timing of the reference clock until the wireless receiving unit 1022 of the child device 2000 completes reception can be calculated by Td = Ta + Tc. The calculation of this time Td is performed by a calculation unit such as the CPU 1011.

[0217] 19 shows the initial transmission from the parent device 1000 to the child device 2000. In the initial transmission, the parent device 1000 sends a time synchronization request signal to the child device 2000, and upon receiving this (when the reception completion flag is set), the child device 2000 immediately transmits measurement data to the parent device 1000. Furthermore, when the child device 2000 receives the time synchronization request signal, the ADC sample is "6," meaning the write pointer of the ring buffer 1026 is "6," so it enters this value of "6" into the write pointer FIFO.

[0218] 20, when the next reference clock t2 rises in the parent device 1000, the parent device 1000 performs the next transmission. At this time, the parent device 1000 sets the value of Td1 calculated from Ta1, Tb1, and Tc1 from the previous transmission and reception in the transmission data of the wireless transmission unit 1012 and sends it to the child device 2000. The child device 2000 stores the received value of Td1 in the Td value FIFO. Also, since the ADC sample when Td1 was received was "13," meaning the write pointer of the ring buffer 1026 was "13," this value "13" is stored in the write pointer FIFO.

[0219] 21, when the next reference clock t3 rises in the parent device 1000, the parent device 1000 performs the next transmission. At this time, the parent device 1000 sets the value of Td2 calculated from Ta2, Tb2, and Tc2 from the previous transmission and reception in the transmission data of the wireless transmission unit 1012 and sends it to the child device 2000. The child device 2000 stores the received value of Td2 in the Td value FIFO. Also, since the ADC sample when Td2 was received was "21," meaning the write pointer of the ring buffer 1026 was "21," this value "21" is stored in the write pointer FIFO.

[0220] In this way, in the third embodiment, the parent device 1000 transmits the calculated Td value to the child device 2000 at the next reference clock (which may also be called the next transmission cycle). This eliminates the need for special hardware.

[0221] Then, as shown in FIGS. 22 and 23, the child device 2000 sets the start point and end point of the read pointer based on the Td value.

[0222] 22, the slave device 2000 retrieves the write pointer value "6" and Td1 stored in the FIFO 1027, and sets the start point to a position N=Td1 / 125 [units] (in this example, Td is in μs and the sampling frequency of the ΔΣ AD converter 1025 is 8 kHz) before the write pointer value "6." The position of this start point coincides with the rising edge t1 of the reference clock of the master device 1000.

[0223] Next, as shown in FIG. 23 , upon receiving the Td value, the slave device 2000 retrieves the write pointer values ​​"13" and Td2 stored in the FIFO 1027, sets the end point to a position N=Td2 / 125 [units] before the write pointer value "13," and advances the read pointer while retrieving ADC data from the ring buffer 1026 from the current read pointer position to the end point. In this way, the slave device 2000 sets the end point of the read position to the ADC data that is earlier than the write pointer position stored in the FIFO 1027 by the result of dividing the time Td by the sampling period of the ΔΣ type AD converter 1025. Here, the "result of dividing the time Td by the sampling period of the ΔΣ type AD converter 1025" includes a result obtained by rounding or truncating the result of dividing the time Td by the sampling period of the ΔΣ type AD converter 1025.

[0224] The extracted data becomes the ADC data of the previous interval synchronized with the reference clock, and is set in the wireless transmission unit 1022 and transmitted to the parent device 1000 at the response timing for the next reference clock t4.

[0225] In the third embodiment, the same processing is performed with a delay of two clocks from the reference clock of the parent device 1000, and the ADC sample data is sent sequentially.

[0226] As described above, in the third embodiment, the parent device 1000 measures the time Ta from the reference clock until the transmission of a signal to the child device 2000 and the time Tb from the transmission of the signal until the reception of a response signal from the child device 2000, and calculates the time Td from the reference clock until the child device 2000 receives the signal based on the time Ta and the time tb, and transmits this time Td to the child device 2000. The child device 2000 then transmits data within a range corresponding to the time Td.

[0227] Specifically, the slave device 2000 calculates the timing of the reference clock of the master device 1000 from the time Td, and transmits data within a range conforming to the interval of the reference clock.

[0228] This allows the slave device 2000 to wirelessly transmit ADC data synchronized with the reference clock of the master device 1000 without synchronizing the ΔΣ type AD converter 1025 (i.e., in an untethered clock state).

[0229] In the process of setting the starting point at a position N=Td1 / 125 [units] before the start point, if the division of N=Tdx / 125 is not an exact division, the calculation result will be obtained with decimal points. Since N is an integer, in typical software implementations, decimal points are either truncated or rounded. However, depending on the phase difference between the clock of the parent device 1000 and the clock of the child device 2000, a discrepancy of less than one sample may occur regardless of whether truncation or rounding is performed.

[0230] Figure 24 shows this situation. Note that 1 square in Figure 24 = 25 us. Here, let's assume that the ADC sampling rate is 8 kHz (125 us) and Td1 = 325 us is measured by the timer. The calculation results in N = Td1 / 125 = 2.6.

[0231] If the phase difference between the reference clock and the ADC clock is case 1 in the figure, 2.6 is rounded down, and going back two samples from the "5" when Tc1 is received becomes "3", which matches the timing of t1. If it is rounded up and back three samples, it becomes "2", which is one sample off from the timing of t1.

[0232] However, when the phase difference between the reference clock and the ADC clock is case 2 in the figure, 2.6 is rounded down, and going back two samples from the "5" when Tc1 was received becomes "3", which is out of sync with the timing of t1, but when rounded up and back three samples, it becomes "2", which matches the timing of t1.

[0233] In this way, no matter how the fractional part of the division of N = Tdx / 125 is handled, a deviation of less than one sample occurs depending on the phase difference between the clock of the parent device 1000 and the clock of the child device 2000. However, since the ADC data is ultimately oversampled, this deviation is within the allowable range, and the system can be implemented as is.

[0234] However, in the third embodiment, the following process is proposed to achieve more accurate time synchronization. Fig. 25 is a diagram showing an example of this process. Note that 1 square in Fig. 25 = 25 us. Fig. 26 is a block diagram showing an example of a configuration for performing the process of Fig. 25. In the system shown in Fig. 26, compared to the configuration described in Fig. 18, the slave device 2000 has a Te time measurement timer 1028. Incidentally, as with the Ta time measurement timer 1015 and Tb time measurement timer 1016 of the master device 1000, a peripheral built into a general-purpose microcomputer can be used as the Te time measurement timer 1028, so no new parts are required.

[0235] 25, the Te time measurement timer 1028 measures the time Te from the ADC conversion completion interrupt to radio wave reception. The slave device 2000 calculates N using a new calculation formula using the time Te: N=ceil((Td-Te) / 125), where ceil means rounding up.

[0236] In this way, in case 1 of Figure 25, Te1 = 100, so (325 - 100) / 125 = 1.8 is rounded up to 2. "5" - 2 is the position "3", which matches the timing of t1. In case 2, Te1 = 50, so (325 - 50) / 125 = 2.2 is rounded up to 3. "5" - 3 is the position "2", which matches the timing of t1.

[0237] In this way, by introducing the new time Te, this deviation of less than one sample can be reduced to zero, and the child device 2000 can wirelessly transmit ADC data that is synchronized with the parent device 1000's reference clock t1 with high precision.

[0238] 27 shows an example of processing when a packet loss occurs in the radio waves sent from the master device 1000 to the slave device 2000. The master device 1000 can recognize that a packet loss has occurred because there is no response from the slave device 2000. When the master device 1000 recognizes that a packet loss has occurred, it does not resend Td1 at the timing of the next reference clock t3, but instead transmits Td1 Ta2' after reference clock t2. The slave device 2000 stores the received value of Td1 in the Td value FIFO. Furthermore, since the ADC sample when Td1 was received was "16," meaning the write pointer of the ring buffer 26 was "16," it stores this value "16" in the write pointer FIFO.

[0239] When the next reference clock t3 rises in the parent device 1000, the parent device 1000 performs the next transmission. At this time, the parent device 1000 calculates Td2' using Ta2', Tb2, and Tc2 from the previous transmission and reception, sets the calculated value of Td2' in the transmission data of the wireless transmission unit 1012, and sends it to the child device 2000. The child device 2000 stores the received value of Td2' in the Td value FIFO. Also, since the ADC sample when Td2' was received was "21," meaning the write pointer of the ring buffer 1026 was "21," this value "21" is stored in the write pointer FIFO.

[0240] When the slave unit 2000 receives the Td value, it retrieves the write pointer values ​​"16" and Td2' stored in the FIFO 1027, sets the end point to a position N = Td2' / 125 [units] before the write pointer value "16", and reads the read pointer while retrieving the ADC data from the ring buffer 1026 from the current read pointer position to the end point.

[0241] In this way, according to the time synchronization method of the third embodiment, even if a packet is lost due to deterioration of the radio wave, time synchronization is maintained by retransmitting the Td value.

[0242] In other words, if the first radio device (master device 1000) cannot receive a response signal from the second radio device (slave device 2000), it transmits a retransmission signal to the second radio device at time Ta' (Ta2' in the example of FIG. 27) after time Ta. Furthermore, the first radio device obtains time Ta' from the reference clock until it transmits a retransmission signal to the second radio device and time Tb (Tb2 in the example of FIG. 27) from transmitting the retransmission signal until it receives a response signal from the second radio device, and calculates time Td' (Td2' in the example of FIG. 27) from the reference clock until the second radio device receives the retransmission signal based on time Ta' and time Tb. The first radio device transmits time Td' to the second radio device in the next transmission cycle of the retransmission signal, and the second radio device transmits data within a range corresponding to time Td'.

[0243] In addition, the synchronization method of this embodiment 3 may also be applied to a case where there is one parent unit 1000 and multiple child units 2000, and in this case too, synchronization errors between one parent unit 1000 and multiple child units 2000 can be suppressed.

[0244] 28 is a diagram showing an example in which the synchronization method of the third embodiment is applied to a system including a plurality of slave devices. When a plurality of second wireless devices (slave devices 2000a to 2000c) are present, the first wireless device (master device 1000) acquires a plurality of times Ta (Ta, Ta', Ta'' in the example of FIG. 28) from the reference clock to the transmission of a first signal to each of the plurality of second wireless devices (slave devices 2000a to 2000c), and a plurality of times Tb (Tb, Tb', Tb'' in the example of FIG. 28) from the transmission of the first signal to the reception of a response signal from each of the plurality of second wireless devices (slave devices 2000a to 2000c).

[0245] Then, based on the multiple times Ta (Ta, Ta', Ta") and the multiple times Tb (Tb, Tb', Tb"), the first radio device (parent device 1000) calculates multiple times Td (Td, Td', Td") in the example of Figure 28, from the reference clock until each of the multiple second radio devices (child devices 2000a to 2000c) receives the first signal, and transmits the time Td corresponding to each of the multiple times Td (Td, Td', Td") to the multiple second radio devices (child devices 2000a to 2000c) in the next signal cycle of the first signal.

[0246] Each of the multiple second wireless devices (child devices 2000a to 2000c) transmits data within a range corresponding to the time Td (Td, Td', Td'') corresponding to itself among the multiple times Td (Td, Td', Td'').

[0247] This allows the parent device 1000 to acquire data from all of the child devices 2000a to 2000c within a range that conforms to the same reference clock interval, thereby reducing synchronization errors between one parent device 1000 and multiple child devices 2000.

[0248] <3-2-2> Additional Processing Here, as additional processing, a method for synchronizing ADC data with the reference clock of the parent device 1000 with higher accuracy by oversampling the ADC will be described.

[0249] If the sampling rate required for sensor data is 1 KHz, the ADC is normally operated at 1 KHz. In contrast, in the third embodiment, the ΔΣ AD converter 1025 is operated for oversampling at 8 KHz, which is eight times the sampling rate, and downsampling is performed as shown in Fig. 29. Incidentally, as is well known, the ΔΣ AD converter is configured in principle to facilitate oversampling.

[0250] By doing this, the synchronization accuracy can be improved from 1 ms to 125 us.

[0251] Here, the time synchronization interval is generated by the reference clock of the parent device 1000, but the ADC is operated by the clock (ADC clock) of the child device 2000. A discrepancy occurs somewhere depending on the accuracy of the clocks of both devices.

[0252] Fig. 29 is a diagram showing an example in which the ADC clock advances slower than the reference clock, and in this example, 32 samples are normally input during one interval, but occasionally 31 samples are input. Fig. 30 is a diagram showing an example in which the ADC clock advances faster than the reference clock, and in this example, 32 samples are normally input during one interval, but occasionally 33 samples are input.

[0253] By applying, for example, the "Bresenham line drawing algorithm," which data and how many data pieces to average can be calculated automatically to achieve a geometrically equal distribution based on two pieces of information: the ideal number of data pieces in the absence of clock drift in one interval, and the number of actually measured data pieces. In this third embodiment, this processing is called "rubber band processing."

[0254] The rubber band process will now be described in more detail.

[0255] If 32 samples are generated during one interval, as usual, the 32 samples are downsampled to 1 / 8 and a total of four data items are output. In contrast, as shown in Figure 29, if 31 samples are generated during one interval, 24 samples are downsampled to 1 / 8 and three data items are output, and the middle seven samples are downsampled to 1 / 7 and one data item is output, resulting in a total of four data items. As shown in Figure 30, if 33 samples are generated during one interval, the 24 samples are downsampled to 1 / 8 and three data items are output, and the middle nine samples are downsampled to 1 / 9 and one data item is output, resulting in a total of four data items. As another example, if 102 samples are generated during one interval, 50 samples are downsampled to 1 / 25 and two data items are output, and the middle 52 samples are downsampled to 1 / 26 and two data items are output, resulting in a total of four data items.

[0256] The above example is an operation example when the number of output data is set to 4. As long as the number of input samples is equal to or greater than the number of output data (4 in this case), any number of input samples will be downsampled by an appropriate modulus to the number of output data (4 in this case). If the number of input samples is not divisible by the number of output samples, it should be divided so that it is geometrically equal (linear).

[0257] Incidentally, the Bresenham algorithm used in rubber band processing obtains a series of points that approximate a straight line drawn from a given starting point (0,0) to an end point (11,3), as shown in Figure 31. However, since there are 12 pieces of input data and 4 pieces of output data, it should be divided into 12 / 4 = 3 equal parts, but there are 2 samples at both ends and 4 samples in the middle, which is not equal.

[0258] Therefore, in the third embodiment, the Bresenham algorithm is modified. An example of a modification of the Bresenham algorithm according to the third embodiment will be described with reference to FIG. 33 . FIG. 33 shows an example of program code (pseudocode) for implementing the Bresenham algorithm. As shown in FIG. 33 , the calculation formulas for delta and delta in the Bresenham algorithm are each incremented by 1. In addition, the error determination formula is changed from 0.5 to 1.0. With this modification, as shown in FIG. 32 , the number of input data is 12 and the number of output data is 4, and the data is divided equally into four groups of three samples each. Of course, there are multiple variations of the program code for the Bresenham algorithm other than the example shown in FIG. 33 due to optimization and simplification, and variables other than delta, delta, and error may also be used. Even in such cases, it is preferable to modify the Bresenham algorithm using the same concept as described above.

[0259] Incidentally, when considering applying the time synchronization method of the third embodiment to a blood pressure pulse wave inspection device that calculates pulse wave velocity, multiple slave units 2000 correspond to multiple pulse wave sensors, and the master unit 1000 corresponds to the device itself. In such a case, applying the time synchronization method of the third embodiment makes it possible to synchronize low-quality data while maintaining real-time performance even during poor radio signal reception.

[0260] Let me explain in more detail. In the "measurement phase" where pulse wave velocity calculations and blood pressure measurements are performed, it is necessary to transfer 1 ms of data without any omissions, but in the "standby phase" where the waveform is drawn on the screen, even if a few samples are dropped, there is no significant impact. However, if data for a simple one interval period is dropped, the screen will show a baseline (a straight line obtained by interpolation) or a blank display, which is undesirable for a medical device display because it differs in shape from the original waveform. However, if an attempt is made to resend the dropped data, it will not be possible to draw it on the screen until the resend is complete, which will degrade real-time performance.

[0261] Therefore, by using the rubber band processing described above, it is possible to compress (thin out) two intervals of data into one interval of data, so that one interval of data containing two intervals of information can be sent at the next interval without having to resend the data. In this way, real-time performance is maintained.

[0262] In the case of pulse wave, heart sound, and electrocardiogram waveform data, even with common code compression such as ZIP, the data can only be compressed to about 80% of the original data, and the CPU processing load is also large. With the rubber band processing described above, even if the number of input data is two or more intervals, it can always be compressed to the amount of data for one interval, and because it is based on the Bresenham line drawing algorithm mentioned above, the CPU processing load is light and it is fast.

[0263] <3-2-3> Example of Application to Medical Devices Fig. 34 shows an example in which the time synchronization method and wireless system of the third embodiment are applied to medical devices. Fig. 34 shows an example in which the above-described master unit 1000 and slave unit 2000 are used in a blood pressure pulse wave test.

[0264] The blood pressure pulse wave inspection device 3000 has a display unit 3031, a display control unit 3032, a print control unit 3033, a file access unit 3034, a network control unit 3035, and a calculation unit 3036. An external storage device 3041 such as an SD card or USB memory is connected to the file access unit 3034. An external system 3042 such as an in-hospital system or an external printer is connected to the network communication unit 3035 via a LAN or WLAN.

[0265] The parent device 1000 is also wired to the network communication unit 3035. The parent device 1000 has a wireless communication unit 1000X that performs the time synchronization process described with reference to Fig. 18. The wireless communication unit 1000X has a frequency hopping function in addition to the time synchronization function.

[0266] The slave device 2000 has a wireless communication unit 2020X that performs the time synchronization processing described with reference to FIG. 18 . The wireless communication unit 2020X has a frequency hopping function in addition to the time synchronization function. The slave device 2000 also has a blood pressure measurement unit 2020Y and a heart sound measurement unit 2020Z. The slave device 2000 transmits the blood pressure pulse wave measured by the blood pressure measurement unit 2020Y and the heart sound measured by the heart sound measurement unit 2020Z to the master device 1000 via the wireless communication unit 2020X. Here, the slave device 2000 can also transmit the blood pressure pulse wave and the heart sound simultaneously to the master device 1000 by transmitting them at different frequencies using the frequency hopping function.

[0267] The parent unit 1000 receives blood pressure pulse wave data and heart sound data with very small synchronization error sent from the child unit 2000 using the time synchronization method of this embodiment 3, and sends this data to the calculation unit 3036, so that the calculation unit 3036 can obtain highly accurate pulse wave propagation velocity, etc.

[0268] <3-3> Summary of Third Embodiment As described above, according to the third embodiment, in a wireless system having a first wireless device (master device 1000) and a second wireless device (slave device 2000) that performs wireless communication with the first wireless device (master device 1000), a time synchronization method is provided in which transmission data of the second wireless device (slave device 2000) is time-synchronized with a reference clock of the first wireless device (master device 1000), and the first wireless device (master device 1000) transmits a first signal from the reference clock to the second wireless device (slave device 2000). The time Ta from the reference clock until the first signal is received and the time Tb from the transmission of the first signal until the response signal from the second wireless device (sub-device 2000) are received are measured, and the time Td from the reference clock until the second wireless device (sub-device 2000) receives the first signal is calculated based on the time Ta and the time tb. The time Td is transmitted to the second wireless device (sub-device 2000) in the next transmission cycle of the first signal, and the second wireless device (sub-device 2000) transmits data (measurement data) within a range corresponding to the time Td.

[0269] This makes it possible to realize a time synchronization method and a wireless system that can suppress synchronization errors between wireless devices (between the parent device 1000 and the child device 2000) to, for example, 1 ms or less.

[0270] In the third embodiment, the high-resolution, high-precision ΔΣ type AD converter 1025 can be used with an untethered clock (asynchronous).

[0271] Furthermore, according to the third embodiment, the clock drift between the parent device 1000 and the child device 2000 can be reduced by using a rubber band.

[0272] Furthermore, according to the third embodiment, accurate resynchronization is possible even when the radio wave is poor.

[0273] Furthermore, according to the third embodiment, by using a rubber band, it is possible to synchronize low-quality data while maintaining real-time performance even when radio waves are poor.

[0274] Furthermore, according to the third embodiment, no special equipment is required for implementation, and peripherals built into a general-purpose one-chip microcomputer, such as an interval clock, a timer, a register, and a ring buffer, can be used, making it easy to realize.

[0275] In particular, according to the third embodiment, there is no need to use a high-precision oscillator for the ADC clock. The reason for this is explained below. The higher the frequency precision of the clock on the parent device and the ADC clock in the child device, the smaller the deviation. Generally, high-precision clock oscillation sources include temperature-compensated crystal oscillators (TCXOs) and oven-controlled crystal oscillators (OCXOs), but these are specialized components and are expensive. The synchronization method of the third embodiment has a function of reducing clock drift using a rubber band, so that a general-purpose crystal oscillator can be used as the clock oscillation source instead of a high-precision oscillator.

[0276] The above-described third embodiment merely shows one example of the implementation of the present invention, and the technical scope of the present invention should not be construed as being limited by this. In other words, the present invention can be implemented in various forms without departing from the gist or main features thereof.

[0277] In the above-described third embodiment, the case where the ring buffer 1026 is provided as a memory for storing data after AD conversion has been described, but the present disclosure is not limited to this, and a memory other than the ring buffer 1026 may be provided. However, the ring buffer 1026 has the advantage that it requires only a small memory capacity.

[0278] In addition, in the above-mentioned third embodiment, the position of the write pointer of the ring buffer 1026 and the time Td are stored in the FIFO 1027, but the present disclosure is not limited to this, and the function of the FIFO 1027 may be realized by a memory and a program.

[0279] In other words, in one aspect of the present disclosure, the second wireless device (sub-device 2000) has an AD conversion unit (in the example of embodiment 3, a ΔΣ type AD converter 1025) that performs AD conversion of the transmission information, a first memory (in the example of embodiment 3, a ring buffer 1026) that stores the data after AD conversion, and a second memory (in the example of embodiment 3, a FIFO memory 1027), and stores in the second memory the position of the write pointer of the first memory when the first signal is received and the time Td indicated by the received first signal, and controls the range of the data to be transmitted by setting the read position from the first memory based on the position of the write pointer and the time Td stored in the second memory to form the transmission data.

[0280] In the above-mentioned third embodiment, the first radio device (parent device 1000) measures the time Ta from the reference clock to transmitting the first signal to the second radio device (child device 2000), and the time Tb from transmitting the first signal to receiving a response signal from the second radio device. However, since the time Tb is a very small value, depending on the tolerance of the wireless system in which the synchronization method is adopted, the time Tb may be a fixed value rather than being measured directly.

[0281] (1) One aspect of the synchronization method disclosed herein is a synchronization method for synchronizing transmission data of a second radio device with a reference clock of a first radio device, wherein the first radio device obtains a time Ta from the reference clock until a first signal is transmitted to the second radio device and a time Tb from transmitting the first signal until a response signal is received from the second radio device, calculates a time Td from the reference clock until the second radio device receives the first signal based on the time Ta and the time Tb, transmits the time Td to the second radio device in the next transmission cycle of the first signal, and the second radio device transmits data within a range corresponding to the time Td.

[0282] (2) In one aspect of the synchronization method of the present disclosure, in (1), the second radio device calculates the timing of the reference clock of the first radio device from the time Td, and transmits data within a range that conforms to the interval interval of the reference clock.

[0283] (3) One aspect of the synchronization method of the present disclosure is that, in (1), the second radio device has an AD conversion unit that performs AD conversion on transmission information, a first memory that stores the data after AD conversion, and a second memory, and the second memory stores the position of a write pointer of the first memory when the first signal is received and the time Td indicated by the received first signal, and sets a read position from the first memory based on the stored position of the write pointer and the time Td to control the range of data to be transmitted.

[0284] (4) In one aspect of the synchronization method of the present disclosure, in (1), the second radio device sets the end point of the read position to the AD conversion data that is earlier than the position of the write pointer stored in the second memory by the result of dividing the time Td by the sampling period of the AD conversion unit.

[0285] (5) In one aspect of the synchronization method of the present disclosure, in the configuration (3) or (4), the AD conversion unit is a ΔΣ AD converter.

[0286] (6) In one aspect of the synchronization method of the present disclosure, in the above (5), the ΔΣ AD converter oversamples the transmission information, and the second radio device downsamples the oversampled data.

[0287] (7) One aspect of the synchronization method of the present disclosure is the synchronization method according to claim 1, wherein, in (1), when the first radio device is unable to receive the response signal from the second radio device, the first radio device transmits a retransmission signal to the second radio device at a time Ta' that is later than the time Ta; further, the first radio device obtains the time Ta' from the reference clock until the retransmission signal is transmitted to the second radio device and the time Tb from the transmission of the retransmission signal until the response signal from the second radio device is received; calculates a time Td' from the reference clock until the second radio device receives the retransmission signal based on the time Ta' and the time Tb; and transmits the time Td' to the second radio device in a next transmission cycle of the retransmission signal; and the second radio device transmits data within a range corresponding to the time Td'.

[0288] (8) One aspect of the synchronization method of the present disclosure is, in (1), when there are multiple second radio devices, the first radio device obtains multiple times Ta from the reference clock to transmitting the first signal to each of the multiple second radio devices, and multiple times Tb from transmitting the first signal to receiving a response signal from each of the multiple second radio devices, calculates multiple times Td from the reference clock to receiving the first signal by each of the multiple second radio devices based on the multiple times Ta and the multiple times Tb, transmits the time Td corresponding to each of the second radio devices from the multiple times Td to the multiple second radio devices in the next transmission cycle of the first signal, and each of the multiple second radio devices transmits data within a range corresponding to the time Td corresponding to itself from the multiple times Td.

[0289] (9) In one aspect of the synchronization method of the present disclosure, in (3), the first memory is a ring buffer.

[0290] (10) In one aspect of the synchronization method of the present disclosure, in the above (3), the second memory is a FIFO memory.

[0291] (11) One aspect of the synchronization method of the present disclosure is that in (1), the first radio is a parent device of a medical device, the second radio is provided in a biometric information sensor of the medical device, and the data transmitted by the second radio is biometric data obtained by the biometric information sensor.

[0292] (12) One aspect of a wireless system of the present disclosure is a wireless system having a first radio device and a second radio device that performs wireless communication with the first radio device, wherein the first radio device: obtains a time Ta from a reference clock until a first signal is transmitted to the second radio device, and a time Tb from transmitting the first signal until a response signal is received from the second radio device; calculates a time Td from the reference clock until the second radio device receives the first signal based on the time Ta and the time tb; transmits the time Td to the second radio device in the next transmission cycle of the first signal; and the second radio device: transmits transmission data within a range conforming to the time Td.

[0293] (13) In one aspect of the wireless system of the present disclosure, in (12), the second wireless device calculates the timing of the reference clock of the first wireless device from the time Td and transmits data within a range that conforms to the interval interval of the reference clock.

[0294] (14) One aspect of the wireless system of the present disclosure is that, in (12), the second wireless device has an AD conversion unit that performs AD conversion on transmission information, a first memory that stores the data after AD conversion, and a second memory, and the second memory stores the position of a write pointer of the first memory when the first signal is received and the time Td indicated by the received first signal, and sets a read position from the first memory based on the stored position of the write pointer and the time Td to control the range of data to be transmitted.

[0295] (15) In one aspect of the wireless system of the present disclosure, in (14), the second wireless device sets the end point of the read position to the AD conversion data that is earlier than the position of the write pointer stored in the second memory by the result of dividing the time Td by the sampling period of the AD conversion unit.

[0296] (16) One aspect of a first radio device of the present disclosure is a first radio device that performs synchronous communication with a second radio device, the first radio device having: a timer that acquires a time Ta from a reference clock until a first signal is transmitted to the second radio device, and a time Tb from transmitting the first signal until a response signal is received from the second radio device; a calculation unit that calculates a time Td from the reference clock until the second radio device receives the first signal based on the time Ta and the time Tb; and a radio transmission unit that transmits the time Td to the second radio device in the next transmission cycle of the first signal.

[0297] (17) One aspect of a second radio device of the present disclosure is a second radio device that performs synchronous communication with a first radio device, wherein the first radio device acquires a time Ta from a reference clock until transmitting a first signal and a time Tb from transmitting the first signal until receiving a response signal from the second radio device, calculates a time Td from the reference clock until the second radio device receives the first signal based on the time Ta and the time Tb, and transmits the time Td to the second radio device in the next transmission cycle of the first signal, and the second radio device has: an AD conversion unit that performs AD conversion of transmission information; a first memory that stores the AD converted data; a second memory that stores the position of a write pointer in the first memory when the first signal is received from the first radio device and the time Td indicated by the received first signal; and a wireless transmission unit that sets a read position from the first memory based on the stored position of the write pointer and the time Td, and controls a range of data to be transmitted.

[0298] <4> Summary The techniques described in the above embodiments can be combined and implemented. The blood pressure pulse wave inspection system of the present disclosure can take the following forms.

[0299] (1) One aspect of the blood pressure pulse wave testing system of the present disclosure includes: a plurality of wireless cuff devices attached to predetermined parts of a subject; and a blood pressure pulse wave testing device that wirelessly communicates with the plurality of wireless cuff devices, controls the plurality of wireless cuff devices, and collects pulse wave data from the plurality of wireless cuff devices to test the vascular condition of the subject, wherein each of the plurality of wireless cuff devices includes: a cuff that is wrapped around a predetermined part of the subject; and a wireless unit attached to the cuff.

[0300] (2) As described in embodiment 1, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (1) above, wherein the blood pressure pulse wave inspection device includes: an arrival direction estimation unit that estimates the arrival direction of radio waves from the plurality of wireless cuff devices; a distance estimation unit that estimates distances to the plurality of wireless cuff devices; and an attachment site estimation unit that estimates attachment sites of the plurality of wireless cuff devices on the subject based on the estimated arrival direction and distance.

[0301] (3) As described in embodiment 1, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (2), wherein the blood pressure pulse wave inspection device further includes a determination unit that determines the appropriateness of the attachment locations of the plurality of wireless cuff devices based on the estimated attachment locations, and an output unit that outputs the determination result of the determination unit.

[0302] (4) As described in embodiment 1, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (2) or (3), wherein the blood pressure pulse wave inspection device and the plurality of wireless cuff devices have UWB communication units, and the direction-of-arrival estimation unit and the distance estimation unit of the blood pressure pulse wave inspection device estimate the direction-of-arrival and the distance based on radio waves in a UWB communication system.

[0303] (5) As described in the second embodiment, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (1) above, wherein the cuff includes an NFC tag having information about the cuff's attachment site, and the wireless unit is detachably attached to the cuff and wirelessly connected to the NFC tag, and wirelessly transmits the information about the attachment site and data obtained by driving the cuff to the blood pressure pulse wave inspection device.

[0304] (6) As described in embodiment 2, one aspect of the blood pressure pulse wave inspection system of the present disclosure is that in (5), the wireless unit wirelessly transmits information about the cuff, including the attachment site information, to the blood pressure pulse wave inspection device prior to transmitting the data.

[0305] (7) As described in the second embodiment, one aspect of the blood pressure pulse wave inspection system of the present disclosure is that in (6), the packet that the wireless unit wirelessly transmits to the blood pressure pulse wave inspection device prior to transmitting the data includes, in addition to the attachment site information, at least one of the cuff size information and the cuff type information.

[0306] (8) As described in embodiment 2, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (5) above, wherein the cuff has an air bag and is wrapped around a predetermined part of the subject, and the wireless unit further has a cuff drive unit that supplies and exhausts air to and from the air bag of the cuff, and a cuff pressure detection unit that detects the cuff pressure of the cuff during the inspection.

[0307] (9) As described in embodiment 2, one aspect of the blood pressure pulse wave inspection system of the present disclosure is that in (8), the cuff driving unit and the cuff pressure detection unit are provided within the wireless unit.

[0308] (10) As described in embodiment 2, one aspect of the blood pressure pulse wave inspection system of the present disclosure is that in (8), the wireless unit at least wirelessly receives a control signal for controlling the cuff driver from the blood pressure pulse wave inspection device and wirelessly transmits the attachment site information and cuff pressure data obtained by driving the cuff to the blood pressure pulse wave inspection device.

[0309] (11) As described in embodiment 2, one aspect of the blood pressure pulse wave inspection system of the present disclosure is that in (5), the NFC tag has a memory unit, and the memory unit stores the cuff size information and / or cuff type information in addition to the attachment site information.

[0310] (12) As described in the second embodiment, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (8) above, wherein the NFC tag has a memory unit that stores a maximum number of times the cuff can be inflated, and the wireless unit writes the actual number of times the cuff is inflated by the cuff driver into the memory unit, and when the actual number of times the cuff is inflated becomes equal to or exceeds the maximum number of times the cuff can be inflated, outputs an alarm indicating this.

[0311] (13) As described in embodiment 1, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (1), wherein the blood pressure pulse wave inspection device has a distance estimation unit that estimates the distance to the wireless cuff device, and a selection unit that selects the wireless cuff device located within a predetermined distance range based on the estimated distance.

[0312] (14) As described in the first embodiment, in one aspect of the blood pressure pulse wave inspection system of the present disclosure, in (13), the blood pressure pulse wave inspection device excludes wireless cuff devices other than the wireless cuff device selected by the selection unit from the pairing targets even if it can receive a wireless signal from the wireless cuff device.

[0313] (15) As described in embodiment 1, one aspect of the blood pressure pulse wave testing system of the present disclosure is (13) above, wherein the blood pressure pulse wave testing device includes: an arrival direction estimation unit that estimates the arrival direction of radio waves from the plurality of wireless cuff devices; a distance estimation unit that estimates the distance to the plurality of wireless cuff devices; a vascular length estimation unit that estimates the vascular length between the plurality of wireless cuff devices of the subject based on the estimated arrival direction and the distance from the plurality of wireless cuff devices; and a calculation unit that calculates an index indicating the vascular condition of the subject based on the estimated vascular length and pulse wave data from the plurality of wireless cuff devices.

[0314] (16) As described in embodiment 1, one aspect of the blood pressure pulse wave inspection system of the present disclosure is the system of (15) further including: a wireless sensor attached to a position corresponding to the subject's heart, detecting cardiac behavior that is the source of a pulse wave, and wirelessly transmitting cardiac behavior information; the arrival direction estimation unit estimates the arrival direction of radio waves from the wireless cuff device and the wireless sensor; the distance estimation unit estimates the distance between the wireless cuff device and the wireless sensor; the vascular length estimation unit estimates the vascular length of the subject between the wireless cuff device and the wireless sensor based on the estimated arrival direction and distance from the wireless cuff device and the wireless sensor; and the calculation unit calculates an index indicating the vascular condition of the subject based on the estimated vascular length, the pulse wave data, and the cardiac behavior information.

[0315] (17) As described in embodiment 1, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (15) above, wherein the plurality of wireless cuff devices wirelessly determine the distance between each other and wirelessly transmit information about the distance to the blood pressure pulse wave inspection device.

[0316] (18) As described in embodiment 1, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (15) further including a wireless sensor attached to a position corresponding to the subject's heart, detecting cardiac behavior that is the source of the pulse wave, and wirelessly transmitting cardiac behavior information, and the wireless sensor and the wireless cuff device wirelessly determine the distance between them and wirelessly transmit information about the distance to the blood pressure pulse wave inspection device.

[0317] (19) As described in the third embodiment, one aspect of the blood pressure pulse wave inspection system of the present disclosure is a blood pressure pulse wave inspection system in (1), in which the blood pressure pulse wave inspection device described in (1) is a first radio, the wireless cuff device is a second radio, and the transmission data of the second radio is synchronized with a reference clock of the first radio and transmitted, wherein the first radio obtains a time Ta from the reference clock to transmitting a first signal to the second radio, and a time Tb from transmitting the first signal to receiving a response signal from the second radio, calculates a time Td from the reference clock to receiving the first signal by the second radio based on the time Ta and the time Tb, transmits the time Td to the second radio in the next transmission cycle of the first signal, and the second radio transmits data within a range corresponding to the time Td.

[0318] (20) As described in embodiment 3, one aspect of the blood pressure pulse wave inspection system of the present disclosure is that in (19), the second radio device calculates the timing of the reference clock of the first radio device from the time Td and transmits data within a range conforming to the interval interval of the reference clock.

[0319] (21) As described in the third embodiment, one aspect of the blood pressure pulse wave inspection system of the present disclosure is that in (19), the second radio device has an AD conversion unit that performs AD conversion on transmission information, a first memory that stores the AD converted data, and a second memory, and the second memory stores the position of a write pointer of the first memory when the first signal is received and the time Td indicated by the received first signal, and sets a read position from the first memory based on the stored position of the write pointer and the time Td to control the range of data to be transmitted.

[0320] (22) As described in the third embodiment, in one aspect of the blood pressure pulse wave inspection system of the present disclosure, in (21), the second radio device sets the end point of the read position to the AD conversion data that is earlier than the position of the write pointer stored in the second memory by the result of dividing the time Td by the sampling period of the AD conversion unit.

[0321] (23) As described in embodiment 3, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (21) or (22) above, in which the AD conversion unit is a ΔΣ type AD converter.

[0322] (24) As described in embodiment 3, one aspect of the blood pressure pulse wave inspection system of the present disclosure is (23), wherein the ΔΣ type AD converter oversamples the transmitted information, and the second radio device downsamples the oversampled data.

[0323] (25) As described in the third embodiment, in one aspect of the blood pressure pulse wave inspection system of the present disclosure, in (19), if the first radio device cannot receive the response signal from the second radio device, it transmits a retransmission signal to the second radio device at a time Ta' that is later than the time Ta; further, the first radio device obtains the time Ta' from the reference clock until the retransmission signal is transmitted to the second radio device and the time Tb from the transmission of the retransmission signal until the response signal from the second radio device is received; calculates the time Td' from the reference clock until the second radio device receives the retransmission signal based on the time Ta' and the time Tb; and transmits the time Td' to the second radio device in the next transmission cycle of the retransmission signal; and the second radio device transmits data within a range conforming to the time Td'.

[0324] (26) As described in the third embodiment, one aspect of the blood pressure pulse wave inspection system of the present disclosure is, in (19), when there are multiple second radio devices, the first radio device obtains multiple times Ta from the reference clock until the first signal is transmitted to each of the multiple second radio devices, and multiple times Tb from the transmission of the first signal until a response signal is received from each of the multiple second radio devices, calculates multiple times Td from the reference clock until the first signal is transmitted to each of the multiple second radio devices based on the multiple times Ta and the multiple times Tb, transmits the time Td corresponding to each of the second radio devices among the multiple times Td to the multiple second radio devices in the next transmission cycle of the first signal, and each of the multiple second radio devices transmits data within a range corresponding to the time Td corresponding to the first radio device among the multiple times Td.

[0325] (27) In one aspect of the blood pressure pulse wave inspection system of the present disclosure, as described in the third embodiment, in (21), the first memory is a ring buffer.

[0326] (28) In one aspect of the blood pressure pulse wave inspection system of the present disclosure, as described in the third embodiment, in (21), the second memory is a FIFO memory.

[0327] The disclosures of the specifications, drawings and abstracts included in the Japanese applications Nos. 2023-58496, 2023-58512, 2023-58517, 2023-58525 and 2023-58529, filed on March 31, 2023, are incorporated herein by reference.

[0328] The technology of the present disclosure is suitable for blood pressure pulse wave inspection systems and the like.

[0329] 10 (10-1 to 10-4), 10' (10-1' to 10-4') Wireless cuff device 20 (20-1 to 20-4), 20' (20-1' to 20-4') Cuff 20a Edge portion 30 (30-1 to 30-4) Wireless tag 100 Wireless unit 110 Battery 120 Wireless power supply unit 130 User interface unit 140 Cuff driving unit 150 Cuff pressure detection unit 160, 160' Wireless communication unit 161 Memory 162 UWB communication module 170, 1011, 1021 CPU 200, 200a, 200b Blood pressure pulse wave inspection device 210 UWB communication module 220 Arithmetic and control unit 221 Control unit 222 Arithmetic and control unit 223 Direction of arrival estimation unit 224 Distance estimation unit 225 Attachment site estimation unit 226 Determination unit 230 User interface unit 301 Blood vessel length estimation unit 400 Wireless heart sound sensor 1012, 1023 Wireless transmission unit 1013, 1022 Wireless reception unit 1014 Reference clock generation unit 1015 Ta time measurement timer 1016 Tb time measurement timer 1024 ADC clock generation unit 1025 ΔΣ type AD converter 1026 Ring buffer 1027 FIFO memory 1028 Te time measurement timer 2161 NFC communication module 2162 Bluetooth communication module

Claims

1. a plurality of wireless cuff devices attached to predetermined parts of a subject; a blood pressure pulse wave examination device that wirelessly communicates with the plurality of wireless cuff devices, controls the plurality of wireless cuff devices, and collects pulse wave data from the plurality of wireless cuff devices to examine a blood vessel condition of the subject; and Each of the plurality of wireless cuff devices comprises: a cuff that is wrapped around a predetermined part of the subject; a wireless unit attached to the cuff; having Blood pressure pulse wave testing system.

2. The blood pressure pulse wave inspection device an arrival direction estimation unit that estimates arrival directions of radio waves from the plurality of wireless cuff devices; a distance estimation unit that estimates distances to the plurality of wireless cuff devices; an attachment site estimation unit that estimates attachment sites of the plurality of wireless cuff devices on the subject based on the estimated arrival directions and the estimated distances; having 2. The blood pressure pulse wave inspection system according to claim 1.

3. The blood pressure pulse wave inspection device a determination unit that determines the validity of the attachment sites of the plurality of wireless cuff devices based on the estimated attachment sites; an output unit that outputs a determination result of the determination unit; further comprising 3. The blood pressure pulse wave inspection system according to claim 2.

4. the blood pressure pulse wave inspection device and the plurality of wireless cuff devices each have an UWB communication unit; the arrival direction estimation unit and the distance estimation unit of the blood pressure pulse wave inspection device estimate the arrival direction and the distance based on radio waves in an UWB communication system; 4. The blood pressure pulse wave inspection system according to claim 2 or 3.

5. the cuff includes an NFC tag having attachment site information; the wireless unit is detachably attached to the cuff, wirelessly connected to the NFC tag, and wirelessly transmits the attachment site information and data obtained by driving the cuff to the blood pressure pulse wave inspection device.

3. The blood pressure pulse wave inspection system according to claim 2.

6. the wireless unit wirelessly transmits information about the cuff, including the attachment site information, to the blood pressure pulse wave inspection device prior to transmitting the data.

6. The blood pressure pulse wave inspection system according to claim 5.

7. a packet wirelessly transmitted by the wireless unit to the blood pressure pulse wave inspection device prior to transmitting the data, the packet including at least one of the cuff size information and the cuff type information in addition to the attachment site information; 7. The blood pressure pulse wave inspection system according to claim 6.

8. The cuff has an air bag and is wrapped around a predetermined part of the subject, The wireless unit further includes a cuff driving unit that supplies and discharges air to and from the air bag of the cuff, and a cuff pressure detecting unit that detects the cuff pressure of the cuff during testing.

6. The blood pressure pulse wave inspection system according to claim 5.

9. the cuff driving unit and the cuff pressure detecting unit are provided in the wireless unit.

9. The blood pressure pulse wave inspection system according to claim 8.

10. the wireless unit at least wirelessly receives a control signal for controlling the cuff driving unit from the blood pressure pulse wave inspection device, and wirelessly transmits the attachment site information and cuff pressure data obtained by driving the cuff to the blood pressure pulse wave inspection device.

9. The blood pressure pulse wave inspection system according to claim 8.

11. The NFC tag has a storage unit, and the storage unit stores size information and / or type information of the cuff in addition to the attachment site information.

6. The blood pressure pulse wave inspection system according to claim 5.

12. The NFC tag has a storage unit, and the storage unit stores a limit number of times the cuff can be inflated. The wireless unit writes the actual number of inflations of the cuff by the cuff driver into the storage unit, and when the actual number of inflations becomes equal to or greater than the limit number of inflations, outputs an alarm indicating this.

9. The blood pressure pulse wave inspection system according to claim 8.

13. The blood pressure pulse wave inspection device a selection unit that selects the wireless cuff device located within a predetermined distance range based on the estimated distance; Further having 3. The blood pressure pulse wave inspection system according to claim 2.

14. the blood pressure pulse wave examination device excludes wireless cuff devices other than the wireless cuff device selected by the selection unit from the pairing targets even if a wireless signal can be received from the wireless cuff device; The blood pressure pulse wave inspection system according to claim 13.

15. The blood pressure pulse wave inspection device an arrival direction estimation unit that estimates arrival directions of radio waves from the plurality of wireless cuff devices; a distance estimation unit that estimates distances to the plurality of wireless cuff devices; a blood vessel length estimation unit that estimates a blood vessel length between the plurality of wireless cuff devices of the subject based on the estimated directions of arrival and the estimated distances from the plurality of wireless cuff devices; a calculation unit that calculates an index indicating a blood vessel condition of the subject based on the estimated blood vessel length and pulse wave data from the plurality of wireless cuff devices; having 2. The blood pressure pulse wave inspection system according to claim 1.

16. The device further includes a wireless sensor that is attached to a position corresponding to the subject's heart, detects cardiac behavior that is the source of the pulse wave, and wirelessly transmits cardiac behavior information; the arrival direction estimation unit estimates arrival directions of radio waves from the wireless cuff device and the wireless sensor; the distance estimation unit estimates a distance between the wireless cuff device and the wireless sensor; the blood vessel length estimation unit estimates a blood vessel length of the subject between the wireless cuff device and the wireless sensor based on the estimated directions of arrival and distances of the wireless cuff device and the wireless sensor; the calculation unit calculates an index indicating a blood vessel condition of the subject based on the estimated blood vessel length, the pulse wave data, and the cardiac behavior information.

16. The blood pressure pulse wave inspection system according to claim 15.

17. the plurality of wireless cuff devices wirelessly calculate the distances between each other and wirelessly transmit the distance information to the blood pressure pulse wave inspection device; 16. The blood pressure pulse wave inspection system according to claim 15.

18. The device further includes a wireless sensor that is attached to a position corresponding to the subject's heart, detects cardiac behavior that is the source of the pulse wave, and wirelessly transmits cardiac behavior information; The wireless sensor and the wireless cuff device wirelessly determine the distance therebetween and wirelessly transmit the distance information to the blood pressure pulse wave inspection device.

16. The blood pressure pulse wave inspection system according to claim 15.

19. 10. A blood pressure pulse wave examination system in which the blood pressure pulse wave examination device according to claim 1 is a first wireless device, the wireless cuff device is a second wireless device, and transmission data of the second wireless device is transmitted in synchronization with a reference clock of the first wireless device, The first radio device a time Ta from the reference clock until a first signal is transmitted to the second radio device, and a time Tb from the transmission of the first signal until a response signal is received from the second radio device; calculating a time Td from the reference clock until the second radio device receives the first signal based on the time Ta and the time Tb; transmitting the time Td to the second radio device in the next transmission cycle of the first signal; The second radio device Transmitting data within a range conforming to the time Td.

2. The blood pressure pulse wave inspection system according to claim 1.

20. The second radio device calculating the timing of the reference clock of the first radio device from the time Td; Transmitting data within a range conforming to the interval of the reference clock; 20. The blood pressure pulse wave inspection system according to claim 19.

21. The second radio device The device includes an AD converter that performs AD conversion on transmission information, a first memory that stores the AD converted data, and a second memory, the second memory stores a position of a write pointer of the first memory when the first signal is received and the time Td indicated by the received first signal; setting a read position from the first memory based on the stored position of the write pointer and the time Td, and controlling the range of data to be transmitted; 20. The blood pressure pulse wave inspection system according to claim 19.

22. The second radio device the AD conversion data that is earlier than the position of the write pointer stored in the second memory by the result of dividing the time Td by the sampling period of the AD conversion unit is set as the end point of the read position; 22. The blood pressure pulse wave inspection system according to claim 21.

23. The AD conversion unit is a ΔΣ AD converter.

23. The blood pressure pulse wave inspection system according to claim 21 or 22.

24. the ΔΣ AD converter oversamples the transmission information; the second radio device downsamples the oversampled data; 24. The blood pressure pulse wave inspection system according to claim 23.

25. The first radio device If the response signal cannot be received from the second radio device, a retransmission signal is transmitted to the second radio device at a time Ta' that is later than the time Ta; Furthermore, the first radio device The time Ta' from the reference clock until the retransmission signal is transmitted to the second radio device, and the time Tb from the transmission of the retransmission signal until the response signal is received from the second radio device are obtained; calculating a time Td' from the reference clock until the second radio device receives the retransmission signal based on the time Ta' and the time Tb; transmit the time Td' to the second radio device in the next transmission cycle of the retransmission signal; The second radio device Transmitting data within a range conforming to the time Td'.

20. The blood pressure pulse wave inspection system according to claim 19.

26. When there are a plurality of second radio devices, The first radio device acquiring a plurality of times Ta from the reference clock until the first signal is transmitted to each of a plurality of second radio devices, and a plurality of times Tb from the transmission of the first signal until a response signal is received from each of the plurality of second radio devices; calculating a plurality of times Td from the reference clock until each of the plurality of second radio devices receives the first signal based on the plurality of times Ta and the plurality of times Tb; transmitting a time Td corresponding to each of the second radio devices among the plurality of times Td to the plurality of second radio devices in a next transmission cycle of the first signal; Each of the plurality of second radio devices transmit data within a range corresponding to the time Td corresponding to the own device among the plurality of times Td; 20. The blood pressure pulse wave inspection system according to claim 19.

27. the first memory is a ring buffer; 22. The blood pressure pulse wave inspection system according to claim 21.

28. the second memory is a FIFO memory; 22. The blood pressure pulse wave inspection system according to claim 21.