Sleep monitoring system, sleep monitoring method, and control device

Abstract

To provide a sleep monitoring system, a sleep monitoring method, and a control device capable of improving determination accuracy of a breathing state of a sleeper.SOLUTION: The signal transmitter / receiver 3 is, for example, a radar, and repeatedly executes an operation of transmitting a transmission wave to the sleeper and receiving a reflected wave while changing a detection point so as to traverse the body of the sleeper. The calculation unit 10 calculates a body movement displacement amount, which is a time-series change in the distance between the sleeper and the signal transmission / reception unit 3, at each of the plurality of detection points. The body motion displacement amount is a value calculated based on the distance information acquired by the signal transmission / reception unit 3 during a predetermined time, and is a displacement amount of the body according to the respiration of the sleeper. The determination unit 11 determines the respiratory state of the sleeper during sleep based on the amount of body motion displacement calculated by the calculation unit 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sleep monitoring system, a sleep monitoring method, and a control device for monitoring the breathing state of a sleeper while sleeping. [Background technology]

[0002] Conventionally, a physical information detection device is known that detects physical information, including sudden changes in health status and sleep apnea syndrome status, by measuring, for example, breathing and heart rate, as disclosed in Patent Document 1. Patent Document 1 focuses on the phenomenon in which the radar output amplitude increases and decreases in response to changes in respiratory volume when a radar is irradiated onto the chest and abdomen, and the phenomenon in which a time difference occurs between breathing movements in the chest and abdomen. Then, the breathing state during sleep is determined from the time difference between breathing movements in the chest and abdomen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-210137 Summary of the Invention [Problem to be solved by the invention]

[0004] However, sleepers are forced to turn over during sleep. Therefore, because the sleeping person's posture changes as they turn over, it is expected that the radar light emitted to determine the breathing state will be shifted from the chest and abdomen. As a result, there is a possibility that the breathing state during sleep cannot be accurately determined. [Means for solving the problem]

[0005] The sleep monitoring system that solves the above problem includes a signal transmitting / receiving unit that repeatedly transmits a transmission wave to the sleeper and receives a reflected wave while changing the detection point across the sleeper's body, a calculation unit that calculates a body movement displacement amount, which is a time-series change in the distance between the sleeper and the signal transmitting / receiving unit, at each of the multiple detection points, and a determination unit that determines the breathing state of the sleeper while sleeping based on the body movement displacement amount calculated by the calculation unit.

[0006] A sleep monitoring method that solves the above problem includes the steps of causing a signal transmitting / receiving unit to repeatedly transmit a transmission wave to the sleeper and receive a reflected wave while changing the detection point across the sleeper's body; calculating, at each of the plurality of detection points, a body movement displacement amount, which is a time-series change in the distance between the sleeper and the signal transmitting / receiving unit, using a control device that controls the operation of the signal transmitting / receiving unit; and determining, using the control device, the breathing state of the sleeper while sleeping based on the calculated body movement displacement amount.

[0007] The control device that solves the above problem is a device that monitors the breathing state of a sleeper while sleeping in cooperation with a signal transmission / reception unit that repeatedly performs the operation of transmitting transmission waves to the sleeper and receiving reflected waves while changing the detection point so as to cross the sleeper's body, and is equipped with a calculation unit that calculates a body movement displacement amount, which is a time-series change in the distance between the sleeper and the signal transmission / reception unit, at each of the multiple detection points, and a judgment unit that judges the breathing state of the sleeper while sleeping based on the body movement displacement amount calculated by the calculation unit. [Effects of the Invention]

[0008] The present invention can improve the accuracy of determining the respiratory state of a sleeping person. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration of a sleep monitoring system according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of the operation of a signal transmitting / receiving unit. [Figure 3] 10(a) and 10(b) are specific diagrams of detection points acquired by the signal transmitting / receiving unit. [Figure 4] FIG. 10 is an explanatory diagram of the amount of displacement caused by body movement of a sleeping person. [Figure 5] 10A and 10B are graphs showing plotted values ​​of body movement displacement when lying on one's back, where (a) and (b) are graphs during normal breathing, and (c) is a graph during respiratory arrest. [Figure 6] 10A and 10B are graphs showing plotted values ​​of body movement displacement when turning over in bed, where (a) is a graph during normal breathing and (b) is a graph during respiratory arrest. [Figure 7] 10 is a graph showing plot values ​​of body movement displacement when a plurality of sleeping persons are monitored. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described below. (Sleep monitoring system 1) As shown in FIG. 1, the sleep monitoring system 1 includes a control device 2 that controls the operation of the sleep monitoring system 1, and a signal transmitter / receiver 3 that transmits transmission waves to a sleeper and receives reflected waves. The sleep monitoring system 1 monitors the breathing state of the sleeper while sleeping by detecting the body movements of the sleeper using communication signals transmitted and received by the signal transmitter / receiver 3. The number of sleepers targeted for sleep monitoring may be one or more. The sleep state to be monitored is, for example, a state of sleep apnea. The control device 2 monitors the breathing state of the sleeper in cooperation with the signal transmitter / receiver 3.

[0011] (Signal Transmitter / Receiver 3) As shown in FIG. 1, the signal transmitting / receiving unit 3 has a transmitting antenna 4 that transmits a transmission wave to the sleeping person, and a receiving antenna 5 that receives a reflected wave of the transmission wave transmitted from the transmitting antenna 4. In this way, the signal transmitting / receiving unit 3 transmits a transmission wave to the sleeping person and receives a reflected wave reflected from the sleeping person. The signal transmitting / receiving unit 3 is, for example, a radar (millimeter wave radar). The communication signal used by the signal transmitting / receiving unit 3 is preferably, for example, a radio wave. For example, a frequency of 60 GHz is used for the radio wave. The transmitting antenna 4 and the receiving antenna 5 may be separate antennas for transmission and reception, or may be a single antenna shared for transmission and reception.

[0012] As shown in FIG. 2, the signal transmitting / receiving unit 3 is placed near the bed 6. Specifically, the signal transmitting / receiving unit 3 is placed on the side of the bed 6. When placed on the side of the sleeper, the signal transmitting / receiving unit 3 is preferably placed at a height of about 10 to 20 cm from the sleeper's chest. The signal transmitting / receiving unit 3 transmits and receives radio waves to and from the sleeper lying on the bed 6. Note that the signal transmitting / receiving unit 3 may be placed, for example, almost directly above the sleeper or at a relatively low position on the side of the sleeper. In this way, the signal transmitting / receiving unit 3 may be placed in a position where it can widely irradiate signals around the sleeper's chest.

[0013] Even if the sleeper is covered with a duvet 7, the radio waves have a frequency of 60 GHz and therefore pass through the duvet 7. Therefore, even if the signal transmitter / receiver 3 transmits a transmission wave to a sleeper covered with a duvet 7, it is possible to receive the reflected wave.

[0014] The antenna of the signal transmitter / receiver 3 may be, for example, an antenna in which a single horn antenna is mechanically moved using a radio wave rotary joint or the like, or a phased array antenna in which the phase of multiple antennas is switched. That is, the antenna of the signal transmitter / receiver 3 may be movable or fixed. Furthermore, the performance of the antenna, such as its structure and directivity, does not need to be the same for transmission and reception. For example, a fixed horn antenna may be used to increase the directivity of transmission, while a phased array antenna with low directivity may be used for reception. The signal transmitter / receiver 3 outputs a signal of the reflected wave received by the receiving antenna 5 to the control device 2.

[0015] 3(a) and 3(b), the signal transmitting / receiving unit 3 repeatedly transmits a transmitted wave to the sleeping person and receives a reflected wave while changing the detection point K so as to traverse the body of the sleeping person. In this example, it is preferable that the signal transmitting / receiving unit 3 repeats this reciprocating operation while detecting the detection point K on both the outward and return paths. In this way, the signal transmitting / receiving unit 3 acquires the characteristics of the transmitted and received waves at each detection point K by sweeping the detection point K in a predetermined direction at a constant speed.

[0016] (Body movements during sleep) As shown in Figure 4, when a sleeping person is breathing normally, the area around the chest moves up and down by a certain amount. In other words, when a sleeping person is breathing normally, the body movement around the chest, i.e., the body movement displacement Es, is equal to or greater than a certain amount. Therefore, if the body movement displacement Es is equal to or greater than a certain amount, it can be safely determined that breathing is normal. On the other hand, if the body movement displacement Es is less than a certain amount, there is a high possibility that abnormal breathing is occurring.

[0017] 3(a) shows an example in which the body movement displacement Es at each detection point K is acquired by moving the detection point K of the signal transmitting / receiving unit 3 along a line (in this example, along a straight line). In the case of FIG. 3(a), the point cloud of the detection points K detected by the signal transmitting / receiving unit 3 is body movement displacement information for multiple points as acquired data. Note that even if the signal transmitting / receiving unit 3 detects the point cloud of the detection points K linearly, it is not actually a linear point cloud, but rather a point cloud that varies somewhat in the direction intersecting the straight line.

[0018] 3(b), the signal transmitting / receiving unit 3 is not limited to detecting the detection point K on a line, but may also detect the detection point K on a plane. Specifically, the signal transmitting / receiving unit 3 may acquire the detection point K as a set of points on the plane by transmitting and receiving signals to and from a plane including a first line L1 that crosses the body and a second line L2 that intersects with the first line L1. In this example, the first line L1 is a line along the X-axis direction. In this example, the second line L2 is a line along the Y-axis direction that is perpendicular to the X-axis.

[0019] In this case, the detection points K of the signal transmitting / receiving unit 3 are not limited to being acquired in only one linear row, but are acquired in multiple rows. In this case, the signal transmitting / receiving unit 3 may operate in a manner that detects multiple rows at once, or may operate in a manner that performs the process of acquiring transmitted / received waves at each detection point K on the round trip path in multiple rows while changing the row. In the case of Figure 3(b), for example, if the number of detection points K acquired in one row is Nx and the number of rows is Ny, then Nx x Ny detection points K are obtained.

[0020] (Control device 2) As shown in FIG. 1 , the control device 2 is connected to the signal transmitting / receiving unit 3 via a wiring 9. The control device 2 controls the operation of the signal transmitting / receiving unit 3 via the wiring 9. The control device 2 is composed of, for example, a microprocessor and a memory. The microprocessor is composed of, for example, a CPU, an MPU, a GPU, etc. The control device 2 controls the transmission operation of the signal transmitting / receiving unit 3 to transmit a transmission wave, and also acquires data of the reflected wave received by the signal transmitting / receiving unit 3.

[0021] (Configuration for determining sleep apnea) As shown in FIG. 1, the sleep monitoring system 1 includes a calculation unit 10 that calculates a body movement displacement Es, which is a time-series change in the distance between the sleeper and the signal transmission / reception unit 3, at each of a plurality of detection points K. The calculation unit 10 is provided in the control device 2. The calculation unit 10 calculates the body movement displacement Es of the sleeper's body, for example, based on distance information acquired within a predetermined time period (for example, approximately 0.5 to 5 seconds in the past). Specifically, the calculation unit 10 calculates the body movement displacement Es by, for example, finding the difference between the shortest distance and the longest distance among the distance information detected within the predetermined time period. The distance information is, for example, data indicating the distance between the sleeper and the signal transmission / reception unit 3.

[0022] The sleep monitoring system 1 includes a determination unit 11 that determines the breathing state of the sleeper while sleeping based on the body movement displacement Es calculated by the calculation unit 10. The determination unit 11 is provided in the control device 2. The determination unit 11 uses the body movement displacement Es calculated for each detection point K to determine the breathing state of the sleeper while sleeping, for example, from changes in the value of the body movement displacement Es and trends in the points where the body movement displacement Es occurs.

[0023] (Operation of the embodiment) Next, the operation of the sleep monitoring system 1 (control device 2) and the sleep monitoring method of this embodiment will be described.

[0024] (Extraction of monitoring point Kt) 3, the signal transmitting / receiving unit 3 performs a sweep of radio wave transmission and reception along a line that crosses the body of the sleeper, thereby acquiring a large number of detection points K of the body movement displacement Es. The detection points K may be acquired in only one row or in multiple rows. If the detection points K are acquired in multiple rows, the number of detection points K increases in a plane, making it possible to more accurately determine the sleep state of the sleeper.

[0025] In this example, among the multiple detection points K, various fixed objects such as immobile parts of the body, the frame of the bed 6, and the floor are excluded from the monitoring of the body movement displacement Es. That is, the determination unit 11 excludes from the determination any of the multiple detection points K whose body movement displacement Es is equal to or less than a threshold. In this way, the body movement displacement Es is sensed at many detection points K, but any detection point K whose body movement displacement Es is insufficient is excluded from the determination. In this case, any detection point K having a body movement displacement Es with a large amount of reflected wave is excluded from the determination. In this way, a monitoring target point Kt that can be used to determine the sleep state is extracted from the multiple detection points K.

[0026] (Sleep apnea detection) 5(a) to 5(c) are graphs plotting the amount of displacement Es of body movement at a monitoring point Kt when the sleeper is lying on his / her back. Each plot value P shown in this graph is a point on the graph of the amount of displacement Es of body movement at each monitoring point Kt, and is determination data used to determine the respiratory state during sleep. In other words, the plot value P is information on the amount of displacement of body movement at each position where body movement is detected when body movement is measured by sweeping radio wave transmission and reception by the signal transmission and reception unit 3.

[0027] 5 and 6, the horizontal axis corresponds to the width direction of the sleeper (the X-axis direction in FIG. 2, etc.), and the vertical axis corresponds to the height direction of the sleeper (the Y-axis direction in FIG. 2, etc.). The position of the scale "0.00" on the vertical axis is the position in the Y-axis direction where the signal transmitting / receiving unit 3 is located. The plot value P also represents the magnitude of the body movement displacement Es with shades of color; for example, the smaller the body movement displacement Es, the darker the color.

[0028] When breathing during sleep is normal, the plot value P takes one of the following three states (i) to (iii). (i) There is a plot value P where the body movement displacement Es exceeds the specified value. (ii) The plot value P is distributed over a wide range. (iii) The number of plot values ​​P is equal to or greater than the specified number. The determination unit 11 determines the magnitude of the body movement displacement Es of each of the monitoring target points Kt by monitoring whether or not there is a plot value P where the body movement displacement Es exceeds a specified value (condition (i)). The determination unit 11 determines the variation of the monitoring target points Kt by monitoring whether or not the plot values ​​P are distributed over a wide range (condition (ii)). In this example, the determination unit 11 determines that the monitoring target points Kt vary if the plot values ​​P are distributed over a range wider than a predetermined area. The determination unit 11 determines the number of monitoring target points Kt by monitoring whether or not the number of plot values ​​P is equal to or greater than a specified number (condition iii).

[0029] As shown in the flow of Figures 5(a) and 5(b), when a sleeper is breathing normally, at least one of the above-mentioned trends (i) to (iii) will be observed. Therefore, if the determination unit 11 detects at least one of the above-mentioned trends (i) to (iii), it will determine that the sleeper is breathing normally. In other words, when the determination unit 11 detects at least one of the above-mentioned trends (i) to (iii), it will determine that the sleeper is not in a state of respiratory arrest.

[0030] 5(c), when the sleeping person has stopped breathing, plot values ​​P with small body movement displacement Es are detected, and the number of plot values ​​P also decreases. Therefore, when the number of plot values ​​P with body movement displacement Es equal to or less than the specified value is equal to or less than the specified number, the determination unit 11 determines that the sleeping person has stopped breathing.

[0031] In this example, the determination unit 11 monitors the continuation of an apnea state based on whether or not a state in which the plot value P, where the body movement displacement Es is equal to or less than a specified value, continues to be equal to or less than a specified number. When the determination unit 11 detects that this apnea state continues for a specified period of time, it increments the count number of apnea states by one. Then, when the count number of apnea states reaches or exceeds the specified number, the determination unit 11 determines that the sleeper has sleep apnea syndrome (SAS). On the other hand, if the sleeper recovers from the apnea state during the count, the determination unit 11 resets the count number. As a result, it is possible to accurately detect the sleep apnea state of the sleeper.

[0032] Furthermore, experimental results have shown that when a sleeper has stopped breathing, even if breathing has stopped, there is a slight radar signal received. This slight signal received by the radar is a slight movement of the body or a reflected signal from an object that is supposed to be stationary, called clutter, that appears to be a slight movement. Experiments have also shown that this received signal tends to be concentrated in a fairly narrow range. Therefore, the determination unit 11 may determine that the sleeper has stopped breathing when it detects a plot value P where the body movement displacement Es is small, i.e., when it detects that slight body movements are concentrated in a specific area.

[0033] (When rolling over occurs) 6(a) and 6(b) are graphs plotting the body movement displacement Es of the monitoring target point Kt when the sleeper turns over in his / her sleep. As shown in Fig. 6(a), even when the sleeper turns over from a supine position, the plot value P exhibits the trends (i) to (iii) described above. Therefore, even when the sleeper turns over in his / her sleep, the determination unit 11 can determine the breathing state of the sleeper from the plot value P in the same way as when the sleeper turns over in his / her supine position.

[0034] 6(b), when a sleeper who has turned over in his / her sleep falls into a state of respiratory arrest, a plot value P with a small body movement displacement Es is detected, and the number of plot values ​​P also decreases, just as when the sleeper is lying on his / her back. Therefore, just as when the sleeper is lying on his / her back, the determination unit 11 determines that the sleeper has fallen into a state of respiratory arrest when it detects that the body movement displacement Es is equal to or less than a specified value and the number of plot values ​​P is equal to or less than a specified number. This makes it possible to detect sleep apnea in the sleeper even when the sleeper has turned over in his / her sleep, just as when the sleeper is lying on his / her back.

[0035] (Application of Sleep Monitoring System 1) As shown in Fig. 7, the sleeper to be monitored may not be one person, but may be multiple people. When multiple people are monitored, the plot values ​​P are detected so as to be distributed around the position of each sleeper. In Fig. 7, a group of plot values ​​P for a first sleeper, a group of plot values ​​P for a second sleeper, and a group of plot values ​​P for a third sleeper are shown. In this way, when multiple people are monitored, each sleeper can be identified from the collection of distributions of the plot values ​​P.

[0036] Therefore, the determination unit 11 may identify each of the multiple sleepers from the distribution of the monitoring target points Kt and determine the breathing state of each of the multiple sleepers while sleeping. In this case, the sleep monitoring system 1 of this example may be installed in the sleeping space of a daycare center or nursery school, for example. Therefore, simply by installing the sleep monitoring system 1 in the sleeping space, it becomes possible to easily monitor the breathing state of multiple children while sleeping. Note that if an imaging unit such as a camera is used in combination, it is possible to more accurately identify sleepers using the imaging data of the imaging unit.

[0037] (Effects of the embodiment) According to the configuration of the above embodiment, the following effects can be obtained. (1) The sleep monitoring system 1 includes a signal transmitting / receiving unit 3, a calculation unit 10, and a determination unit 11. The signal transmitting / receiving unit 3 repeatedly transmits a transmission wave to the sleeper and receives a reflected wave while changing the detection point K so as to traverse the sleeper's body. The calculation unit 10 calculates a body movement displacement Es, which is a time-series change in the distance between the sleeper and the signal transmitting / receiving unit 3, at each of the multiple detection points K. The determination unit 11 determines the breathing state of the sleeper while sleeping based on the body movement displacement Es calculated by the calculation unit 10.

[0038] This configuration focuses on the fact that body movements of a sleeping person occur not only in the chest, which moves up and down with breathing, but also in other parts of the body. The signal transmitting / receiving unit 3 then performs an operation to detect the body movement displacement Es of each detection point K over a wide area across the sleeping person's body, thereby obtaining a large number of body movement displacement Es including not only the chest but also other parts, and using these body movement displacement Es to determine the sleeping person's respiratory state during sleep. Therefore, the determination of the sleeping person's respiratory state during sleep is less affected by changes in posture, such as turning over in bed. This improves the accuracy of determining the sleeping person's respiratory state.

[0039] (2) The determination unit 11 excludes from the determination any of the multiple detection points K where the change in the body movement displacement Es is equal to or less than a threshold, and determines the breathing state of the sleeping person while sleeping using the body movement displacement Es acquired for each of the remaining monitoring target points Kt. This configuration extracts the body movement displacement Es of the monitoring target points Kt where the value changes due to body movement to determine the breathing state of the sleeping person, which further contributes to improving the accuracy of determining the breathing state of the sleeping person.

[0040] (3) The determination unit 11 determines the respiratory state of the sleeper using at least one of the magnitude of the body movement displacement Es of each of the monitoring target points Kt, the dispersion of the monitoring target points Kt, and the number of the monitoring target points Kt as an index. With this configuration, the respiratory state of the sleeper can be accurately determined using these indexes that are closely related to the sleeper's respiratory state.

[0041] (4) The determination unit 11 determines that the sleeper has stopped breathing when the number of monitoring points Kt where the body movement displacement Es is equal to or less than a specified value is equal to or less than a specified number. With this configuration, if the sleeper stops breathing while sleeping, the monitoring points Kt where the body movement displacement Es is equal to or less than the specified value are detected, and the number of detected monitoring points Kt itself decreases. Therefore, by making a determination based on the phenomenon of respiratory arrest, it is possible to accurately detect whether the sleeper has stopped breathing while sleeping.

[0042] (5) The determination unit 11 identifies each of the multiple sleepers from the distribution of the monitoring target points Kt and determines the breathing state of each sleeper. With this configuration, even when multiple sleepers are targeted, it is possible to monitor the breathing state of each sleeper. Therefore, for example, if the sleep monitoring system 1 is installed in a facility where multiple people sleep, it is possible to monitor the breathing states of multiple sleepers using a single system.

[0043] (6) The signal transmitting / receiving unit 3 transmits and receives signals to and from a plane including a first line L1 that crosses the body and a second line L2 that intersects with the first line L1, thereby acquiring detection points K as a set of points on the plane. As an example, the signal transmitting / receiving unit 3 transmits a transmission wave to the sleeping person and receives a reflected wave, performing this operation both on the outward path crossing the sleeping person's body in one direction and on the return path crossing the sleeping person's body in the other direction, and repeats this reciprocating operation. The calculation unit 10 calculates the body movement displacement Es, and the determination unit 11 determines the respiratory state based on the detection points K on the plane. With this configuration, the signal transmitting / receiving unit 3 acquires detection points K on the plane, making it possible to acquire many detection points K. This shortens the determination time, which in turn contributes to further improving the accuracy of determining the sleeping person's respiratory state.

[0044] (Other embodiments) This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0045] The number of signal transmitter / receiver units 3 is not limited to one, but may be multiple. In this case, it becomes possible to acquire the body movement displacement Es over a wide range of the sleeping person's body, which further contributes to improving the accuracy of determining the sleeping person's respiratory condition.

[0046] The communication signal of the signal transmitter / receiver 3 may be, for example, a sound wave or an ultrasonic wave. The signal transmitting / receiving unit 3 is not limited to radar (millimeter wave radar) and may be any device that can detect the distance to an object from the phase difference between the transmitted wave and the reflected wave.

[0047] The signal transmitting / receiving unit 3 may perform an operation to detect the body movement displacement Es only during, for example, forward movement. The target for determining the respiratory state during sleep is not limited to the monitoring target points Kt, but may be all of the detection points K, for example.

[0048] The signal transmitting / receiving unit 3, the calculation unit 10, and the determination unit 11 may be assembled into a single device. The sleep monitoring system 1 may be installed in an accommodation facility such as a hotel or a guesthouse.

[0049] The phrase "at least one" as used in this disclosure means "one or more" of the desired options. As an example, the phrase "at least one" as used in this disclosure means "only one option" or "both of two options" if the number of options is two. As another example, the phrase "at least one" as used in this disclosure means "only one option" or "any combination of two or more options" if the number of options is three or more.

[0050] The calculation unit 10 and the determination unit 11 may be configured by [1] one or more processors operating according to a computer program (software), or [2] a combination of such a processor and one or more dedicated hardware circuits, such as an application-specific integrated circuit (ASIC), that execute at least some of the various processes (steps). The processor includes a CPU and memory, such as RAM and ROM, that stores program code or instructions configured to cause the CPU to execute the processes. The memory (computer-readable medium) includes any available medium accessible by a general-purpose or dedicated computer. Alternatively, instead of a computer including the processor, a processing circuit configured by one or more dedicated hardware circuits that execute all of the various processes may be used.

[0051] The calculation unit 10 and the determination unit 11 may be configured from independent processors, or may be configured from a processor that shares some of its functions. In this way, the calculation unit 10 and the determination unit 11 are not limited to being independent functional blocks, but may be configured from a single functional block, or may be configured from a functional block that shares some of its functions.

[0052] While the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to those embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure. [Explanation of symbols]

[0053] 1...sleep monitoring system, 2...control device, 3...signal transmitting / receiving unit, 10...calculation unit, 11...determination unit, K...detection point, Es...body movement displacement, Kt...monitoring target point, P...plot value, L1...first line, L2...second line.

Claims

1. a signal transmitting / receiving unit that repeatedly transmits a transmission wave to the sleeper and receives a reflected wave while changing a detection point across the body of the sleeper; a calculation unit that calculates a body movement displacement amount, which is a time series change in the distance between the sleeper and the signal transmitting / receiving unit, at each of the plurality of detection points; a determination unit that determines a breathing state of the sleeper while sleeping based on the amount of body movement displacement calculated by the calculation unit.

2. 2. The sleep monitoring system according to claim 1, wherein the determination unit excludes from the determination any of the plurality of detection points at which the body movement displacement amount is equal to or less than a threshold, and determines the breathing state of the sleeper while sleeping using the body movement displacement amount acquired for each of the remaining monitoring target points.

3. 3. The sleep monitoring system according to claim 2, wherein the determination unit determines the breathing state of the sleeper while sleeping using at least one of the magnitude of the body movement displacement of each of the monitoring target points, the variability of the monitoring target points, and the number of the monitoring target points as an index.

4. 3. The sleep monitoring system according to claim 2, wherein the determination unit determines that the sleeper has stopped breathing when the number of monitoring points at which the body movement displacement amount is equal to or less than a specified value is equal to or less than a specified number.

5. The sleep monitoring system according to claim 2 , wherein the determining unit identifies each of the plurality of sleepers from the distribution of the monitoring target points and determines a breathing state during sleep for each of the sleepers.

6. the signal transmitting and receiving unit transmits and receives signals to and from a plane including a first line that crosses the body and a second line that intersects with the first line, thereby acquiring the detection points as a set of points on the plane; The sleep monitoring system according to claim 1 , wherein the calculation of the body movement displacement by the calculation unit and the determination of the respiratory state by the determination unit are performed based on the detection points on a surface.

7. a step of repeatedly causing the signal transmitting / receiving unit to transmit a transmission wave to the sleeper and receive a reflected wave while changing the detection point so as to traverse the body of the sleeper; a step of calculating, at each of the plurality of detection points, a body movement displacement amount, which is a time series change in the distance between the sleeper and the signal transmitting / receiving unit, by a control device that controls the operation of the signal transmitting / receiving unit; and determining a breathing state of the sleeper while sleeping by the control device based on the calculated body movement displacement.

8. A control device that monitors a breathing state of a sleeper while sleeping in cooperation with a signal transmitting / receiving unit that repeatedly performs an operation of transmitting a transmission wave to the sleeper and receiving a reflected wave while changing a detection point across the body of the sleeper, a calculation unit that calculates a body movement displacement amount, which is a time series change in the distance between the sleeper and the signal transmitting / receiving unit, at each of the plurality of detection points; a determination unit that determines a respiratory state of the sleeper while sleeping based on the body movement displacement calculated by the calculation unit.

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