JP2004239729A - Movement sensitive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a movement sensing device which can determine validity of a detected value showing distance to an object, so that the influence of noise can be removed, and, e.g., comparatively small movement of the object can be accurately detected. <P>SOLUTION: The movement sensing device 1 is equipped with a distance sensor 11 which detects a distance to the object and outputs a plurality of detected values showing the distance during a first period, an arithmetic unit 22 which obtains an average value of a first value showing dispersion in the first period of the plurality of output detected values and a second value showing dispersion in a second period which is a small period formed by sub-dividing the first period, in the first period, and a determination device 23 which determines validity of the plurality of output detected values, based on the first value and the average value of the second values in the first period. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motion detection device using a distance sensor, and more particularly to a motion detection device that can remove the influence of noise by being able to judge the validity of a detection value indicating a distance to an object.
[0002]
[Prior art]
Conventionally, as a motion detection device, a plurality of distance sensors are used to detect a distance to a target region, and based on the detected distance, monitor the movement of a person existing between the target region and the distance sensor. There has been a motion detection device (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2002-329262 A (Page 3-8, FIG. 1-5)
[0004]
[Problems to be solved by the invention]
However, according to the conventional apparatus as described above, for example, when it is desired to detect a small movement (for example, respiration) of a person, a change in the detected distance is very small. Due to the influence, the motion detection may be inaccurate. Further, for example, when an element that obtains a detection value by a calculation using the amount of received light as a denominator, such as a semiconductor position detection element (PSD (Position Sensitive Detector)), is used as the distance sensor, for example, the distance or reflection of the object is used. Depending on the rate or the like, when the amount of received light decreases, noise included in the detection signal sometimes appears remarkably.
[0005]
Therefore, the present invention provides a motion detection device that can remove the influence of noise by being able to determine the validity of a detection value representing the distance to an object, and can accurately detect, for example, even a relatively small motion of the object. It is aimed at.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a motion detecting apparatus according to the first aspect of the present invention detects a distance to a target object 2 as shown in FIGS. A distance sensor 11 that outputs a plurality of detected values during the period; a first value representing a variation in the output plurality of detected values within the first period; and a small period obtained by subdividing the first period. An arithmetic unit 22 for calculating an average value of a second value representing a variation within a second period during the first period, and an arithmetic unit 22; and the first value and the first period of the second value. And a judging device 23 for judging the validity of the plurality of output detection values based on the average value of the detection values.
[0007]
With this configuration, the first value representing the variation in the first period of the plurality of detection values output by the distance sensor 11 during the first period, and a small value obtained by subdividing the first period. An arithmetic unit 22 calculates an average value of a second value representing a variation in a second period, which is a period, within the first period, and calculates the first value and the first value of the second value. Since the validity of the plurality of output detection values is determined by the determination device 23 based on the average value within the period, the validity of the detection value indicating the distance to the target object can be determined, so that noise can be reduced. It is possible to provide a motion detection device that can remove the influence and can accurately detect, for example, even a relatively small motion of the object.
[0008]
Furthermore, as described in claim 2, in the motion detection device 1 according to claim 1, the first value sets a predetermined threshold value more than an average value of the second value in the first period. It may be configured so that if it is larger than the threshold, it is determined to be valid, and if it is equal to or smaller than the threshold value, it is determined to be invalid.
[0009]
In order to achieve the above object, a motion detecting apparatus according to a third aspect of the present invention detects a distance to a target object 2 as shown in FIGS. A distance sensor 11 that outputs a plurality of detected values during the period; a first value representing a variation in the output plurality of detected values within the first period; and a small period obtained by subdividing the first period. An arithmetic unit 22 that obtains a third value indicating a variation of each of the small periods of the average value of the detection values in the second period, which is: based on the first value and the third value, A judgment device 23 for judging the validity of the plurality of output detection values.
[0010]
With this configuration, the first value representing the variation in the first period of the plurality of detection values output by the distance sensor 11 during the first period, and a small value obtained by subdividing the first period. The arithmetic unit 22 obtains a third value indicating a variation in each small period of the average value of the detection values in the second period, which is a period, based on the first value and the third value. Since the validity of the plurality of output detection values is determined by the determination device 23, it is possible to determine the validity of the detection value indicating the distance to the target object, thereby eliminating the influence of noise. A motion detection device capable of accurately detecting even a relatively small motion of an object can be provided.
[0011]
Further, as described in claim 4, the motion detection device 1 according to claim 3 determines that the first value is invalid when the first value is larger than the third value by more than a predetermined threshold value, It may be configured to determine that it is valid when it is equal to or smaller than the threshold value.
[0012]
In addition, as described in claim 5, in the motion detection device 1 according to any one of claims 1 to 4, for example, as shown in FIG. A light irradiating means 31 for irradiating light; a position detecting element 36 for receiving a reflected light beam of the light beam reflected by the object 2 and outputting differently according to the light receiving position; an output from the position detecting element 36 A distance calculation device 39 for obtaining a detection value indicating the distance to the object 2 based on the principle of trigonometry based on the triangulation method; the distance calculated by the distance calculation device 39 may be used as the plurality of outputs.
[0013]
In order to achieve the above object, a motion detection device according to the invention according to claim 6 is a distance sensor that detects a distance to an object 2 as shown in FIGS. 5, 6, and 7, for example. A distance sensor 11 having a detection element 36 that outputs two values whose difference changes according to the distance; and a determination for determining the validity of the output detection value based on the sum of the two output values. Device 23.
[0014]
With this configuration, the distance sensor 11 having the detection element 36 that outputs two values whose difference changes according to the distance, and the output detection value based on the sum of the two output values. And a judgment device 23 for judging the validity of the object, it is possible to judge the validity of the detection value indicating the distance to the target object, so that the influence of noise can be removed. A motion detection device that can detect the motion can be provided.
[0015]
According to a seventh aspect of the present invention, in the motion detection device 1 according to any one of the first to sixth aspects, the fourth value representing the variation within the first period is a predetermined threshold value. May be regarded as an important matter for determining that the plurality of output detection values in the first period are invalid.
[0016]
Further, in the above-described motion detection device 1, the distance sensor 11 is plural, and the output of the distance sensor 11 determined to be invalid among the plurality of distance sensors 11 by the validity determination by the determination device 23 is not adopted. Is configured.
[0017]
Further, in the above-described motion detecting device 1, the distance sensor 11 is plural; out of the distance sensors 11 determined to be valid by the validity determination by the determining device 23, the output of the distance sensor 11 in the past fixed period. It is preferable that the output of the distance sensor 11 having the largest fluctuation is adopted.
[0018]
Further, in the above-described motion detecting device 1, the distance sensor 11 is plural; of the distance sensors 11 determined to be valid by the validity determination by the determining device 23, the peak of the output spectrum in a past fixed period in the past. May be adopted so as to employ the output of the distance sensor 11, which is the clearest.
[0019]
Further, the spectrum is evaluated by determining the outputs of a predetermined number of the distance sensors 11 in the descending order of the output fluctuation during a certain period in the past, among the distance sensors 11 determined to be valid by the validity determination by the determination device 23. May be selected, and the output of each of the selected distance sensors 11 may be compared for evaluation.
[0020]
The spectrum is evaluated by selecting, from among the distance sensors determined to be valid by the determination of the validity by the determination device 23, the output of the distance sensor whose output fluctuation during a past fixed period exceeds a predetermined threshold. The output may be evaluated by comparing the outputs of the selected distance sensors.
[0021]
Further, in the motion detection device 1 described above, the motion of the object 2 may be detected based on at least the output of the distance sensor 11 determined to be valid, based on the validity determination by the determination device 23.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding members are denoted by the same or similar reference numerals, and overlapping description will be omitted.
[0023]
FIG. 1 is a schematic perspective view of a motion detection device 1 according to an embodiment of the present invention. The motion detection device 1 detects a distance to an object and outputs a plurality of detection values representing the distance during a first period. And a control device 20 for inputting a detection value indicating the distance obtained. The target object exists in the target space. In the present embodiment, a plurality of distance sensors 11 are provided. The distance to the target is a distance from the distance sensor 11 to the target. If the target object does not exist, the distance sensor 11 detects the distance to the object existing in the target space. Here, the distance to the upper surface of the bed 3 is detected. Note that a specific description of the first period will be described later. The details of each of the above components will be described later. The motion detection device 1 detects the motion of an object existing in an object space. Further, the target object is to breathe. That is, the target object is a person or an animal. In the present embodiment, the target object is the person 2. The target space is on the bed 3. The drawing shows a case where the person 2 is lying on the bed 3 (existing in a sleeping state). Further, the motion detection device 1 can detect the respiration of the person 2 existing on the bed 3. In the present embodiment, the detection value representing the distance is a distance value that is the distance itself, or an output value corresponding to the distance value. Hereinafter, these are simply called distances. Hereinafter, embodiments will be described in terms of distance.
[0024]
Here, bedding 4 is further laid on person 2, and covers a part of person 2 and a part of bed 3. In this case, the distance sensor 11 detects the distance to the bedding 4. When the bedding 4 is not used, the distance sensor 11 detects a distance to the person 2 itself (for example, a body part).
[0025]
It is preferable that the plurality of distance sensors 11 be installed via the housing 10 on which the plurality of distance sensors 11 can be installed. This makes installation easier than installing a plurality of distance sensors 11 alone. Here, the housing 10 is disposed approximately above the head of the person 2. Further, here, the housing 10 is attached to a movable stand 7. The housing 10 is arranged approximately above the head of the person 2 by arranging the stand 7 at the end of the bed 3 on the head side of the person 2. Further, since the stand 7 is movable, installation of the housing 10 is facilitated. That is, installation of the motion detection device 1 is facilitated. Furthermore, since installation is easy, it can be installed at a necessary place at a hospital or the like when needed, which is simple. In the present embodiment, the housing 10 (distance sensor 11) is installed on the stand 7, but if a wall or ceiling is present, the housing 10 (distance sensor 11) may be on the wall or ceiling. It may be appropriately determined according to the above. Further, a plurality of distance sensors 11 are installed on the housing 10 in correspondence with a plurality of distance measurement target points (hereinafter, referred to as target points 5 (see FIG. 3)), which are target points for detecting distances. Have been. Note that the distance sensors 11 are preferably arranged in two or more rows in the housing 10.
[0026]
FIG. 2 is a schematic perspective view showing an example in which the housing 10 is installed on a ceiling (not shown). In this case, it is preferable to install the device approximately above the chest of the person 2 on the bed 3. In other words, it may be arranged above a position where the chest of the person 2 will be located, for example, a position slightly shifted from the center of the bed 3. This arrangement makes it easier to detect the breathing of the person 2 on the bed 3. This is because the movement of the person 2 on the bed 3 due to respiration tends to be large from the chest to the periphery of the abdomen, and the displacement direction is substantially parallel to the distance measurement direction of the distance sensor 11. Hereinafter, a case where the housing 10 (the distance sensor 11) is installed via the stand 7 will be described.
[0027]
An example of the arrangement of target points will be described with reference to the schematic plan view of FIG. A plurality of target points are arranged as shown. Thereby, the plurality of target points form the detection area 50 in a predetermined range. In the present embodiment, it is preferable that the predetermined range is set to a range that covers the positions that the abdomen, chest, back, and shoulders of the person 2 can take while sleeping. The target points 5 are preferably arranged in two or more rows, for example, as shown in the figure.
[0028]
FIG. 3A illustrates a case where a plurality of target points 51a to 54c corresponding to each of the plurality of distance sensors 11 are arranged so as not to overlap with adjacent target points 51a to 54c, respectively. In this case, for example, as shown in the figure, the plurality of target points 5 are located in the detection area 50 near the outer peripheral portion of the bed 3 and the target points 51a, 51b, 51c, 54a, 54b, 54c are located at the center of the bed 3. The target points 52a, 52b, 52c, 53a, 53b, and 53c (hereinafter, simply referred to as target points 5 when not distinguishing them) are arranged near the portion so as not to overlap with each other. As shown in the figure, the target points 5 are preferably arranged in a grid pattern. The plurality of target points 5 are to be arranged within a range that covers the positions that the abdomen, chest, back, and shoulders of the person 2 on the bed 3 (below the bedding 4 (see FIG. 1)) can take while sleeping. Is preferred. In the present embodiment, the number of arrangements is 4 rows and 3 columns (hereinafter referred to as 4 × 3) in the figure, but may be determined as appropriate depending on the location where motion is detected, the condition of the person 2, etc. It may be 3, 4 × 4 or 2 × 2.
[0029]
With this arrangement, even with a relatively small number of distance sensors, the detection area 50 can be widened, so that efficiency is high. That is, a relatively small number of distance sensors 11 can detect the distance in the detection area 50 in a required range, so that a small and highly efficient motion detection device 1 (see FIG. 1) can be provided. Further, even when an irradiation type sensor that detects a distance by irradiating the distance sensor 11 with a light beam as described later is used, the distance sensors 11 corresponding to the adjacent target points 5 do not simultaneously irradiate as described later. Such a control is not required, and the motion detection device 1 can have a simpler configuration. Even in the case where the target points 5 do not overlap in this way, as described later, the light beam that should be received is mixed with the light beam emitted from the other distance sensor 11, and the accurate distance If the detection is difficult, it is necessary to control the distance sensor 11 so that it does not simultaneously emit a light beam.
[0030]
As shown in the arrangement example of FIG. 3B, adjacent target points 5 may overlap. In this way, the blind spot in the detection area 50 can be reduced, which is effective for detecting a distance with higher accuracy. At this time, when an irradiation type sensor that detects a distance by irradiating the distance sensor 11 with light, for example, is used, it is necessary to control so that the distance sensors 11 corresponding to the overlapping target points 5 do not simultaneously emit a light beam. . This is because, for example, when a plurality of distance sensors 11 simultaneously irradiate a light beam, for example, a light beam that should be received is mixed with a light beam irradiated from another distance sensor 11 and is influenced by each other, thereby causing a distance difference. This is because it becomes difficult to detect. FIG. 3B shows a case where the area of the target point is increased to explain a state where the target points overlap.
[0031]
In addition, the distance sensor 11 is configured so that the wavelength of the light beam to be projected is different for each sensor as described later, and the transmission wavelength band corresponding to the light beam to be irradiated on the light receiving lens 37a described later by means such as coating. Is passed, it is not necessary to control not to irradiate a light beam at the same time even when adjacent target points 5 overlap. Further, when the distance sensor 11 causes the light source of the illuminating light beam to blink at a constant frequency different for each distance sensor 11, and furthermore, a signal of only that frequency is provided with an electric bandpass filter described later. In this case, there is no need to perform control so that irradiation is not performed at the same time even when adjacent target points 5 overlap.
[0032]
Here, as shown in FIG. 3B, an example of control of the operation when the irradiation type sensor is used as the distance sensor 11 and the target points 5 corresponding to the plurality of distance sensors 11 overlap will be described. Such control may be performed by the control unit 21 of the control device 20 described later. In the case of the irradiation type sensor, control is performed such that after the distance of one distance sensor 11 is detected, the distance of the next distance sensor 11 is detected. That is, control is performed so that the plurality of distance sensors 11 do not detect distances at the same time. Such an operation is repeated until the distances of all the provided distance sensors 11 are detected. Note that this series of operations is one cycle, and the time of one cycle is T.
[0033]
In addition, instead of performing the distance detection by the distance sensor 11 one by one as described above, control is performed so that the distances of the adjacent target points 5 are not simultaneously detected (for example, the target points 5 for which the distances are simultaneously detected). Is set to every other), it is possible to cause the plurality of distance sensors 11 to detect the distance at the same time. In this way, the time T of one cycle can be significantly reduced.
[0034]
Also, typically, the distance sensor 11 is installed in parallel to the housing 10, but the housing 10 may be curved as in a housing 10 'shown in the schematic diagram of FIG. In this case, the distance sensor 11 is installed along this curve. By using such a housing 10 ', a wide detection area 50 can be easily secured even if the size is reduced. Further, even if the housing 10 'is small, the distance sensor 11 can be easily installed so that the adjacent target points 5 do not overlap, so that the size of the apparatus can be reduced.
[0035]
An example of the configuration of the motion detection device 1 will be described with reference to FIG. The motion detection device 1 includes a housing 10 in which a plurality of distance sensors 11 are installed, and a control device 20. The control device 20 is typically a personal computer or a microcomputer. The plurality of distance sensors 11 are connected to the control device 20 and are configured to output the detected distance to the control device 20. Further, although the distance sensor 11 and the control device 20 are shown as separate bodies in the figure, they may be integrally formed. Further, for example, the plurality of distance sensors 11 and the control device 20 may be housed in the housing 10. In the present embodiment, the case where the housing 10 and the control device 20 are separate will be described. The distance sensor 11 is provided in the housing 10 in a 4 × 3 arrangement.
[0036]
Here, the distance sensor 11 will be further described. As the distance sensor 11 to be used, there are an infrared irradiation type distance sensor, an ultrasonic sensor, an electromagnetic wave pulse distance sensor, a passive type optical distance sensor, and the like. Among them, an infrared irradiation type distance sensor, an ultrasonic sensor, and an electromagnetic pulse distance sensor are irradiation type sensors. Further, as described above, it is preferable to use a relatively simple and inexpensive distance sensor 11 used for an autofocus camera, as described above. By using such a distance sensor 11, the motion detection device 1 can be configured simply and inexpensively. In this embodiment, a case where an infrared irradiation type distance sensor is used will be described.
[0037]
An infrared irradiation type distance sensor 30 (hereinafter, referred to as an infrared distance sensor 30) as an example of the distance sensor 11 will be described with reference to the block diagram of FIG. The infrared distance sensor 30 is a so-called active optical sensor. The infrared distance sensor 30 includes an infrared light irradiating unit 31 as a light irradiating unit that irradiates the person 2 with a light beam, an infrared light receiving unit 32, and a sensor control unit 33 that controls the entire infrared distance sensor 30. I have. Further, the sensor control unit 33 may be provided in the control unit 21 of the control device 20 (see FIG. 5). In this case, the infrared distance sensor 30 may output the photocurrent output from the electrode 36d of the PSD 36 described later with reference to FIG. 7 to the sensor control unit 33 in the control unit 21.
[0038]
The infrared light irradiating section 31 is provided with an infrared LED 34 and an irradiating lens 35. The luminous flux of the infrared light radiated from the infrared LED 34 irradiates the person 2 as a thin parallel luminous flux via the irradiating lens 35. Is done. Here, the parallel light beam may be substantially parallel, and includes a light beam that is nearly parallel. The infrared light receiving section 32 has a position detecting element 36 which receives a reflected light beam of the light beam reflected by the person 2 and outputs differently according to the light receiving position. Further, the infrared light receiving section 32 has a light receiving lens 37 as an image forming optical system for forming an image of a reflected light beam of the light beam reflected by the person 2 on the position detecting element 36. In the present embodiment, the position detecting element 36 is a PSD. Hereinafter, the position detection element 36 will be described in the case of PSD. The infrared distance sensor 30 using the PSD as the position detection element 36 is a distance sensor that detects the distance to the person 2 and has a detection element that outputs two values whose difference changes according to the distance. It is also a distance sensor. That is, in the present embodiment, a PSD is a PSD that outputs two values whose difference changes according to the distance.
[0039]
Further, the infrared distance sensor 30 has a position information output unit 39 as a distance calculation device that obtains a distance to the person 2 based on the output of the PSD 36 based on the principle of trigonometry. That is, the position information output unit 39 is configured to obtain light receiving position information as the distance by triangulation based on the light receiving position. The position information output unit 39 is provided in the sensor control unit 33. The infrared distance sensor 30 outputs a plurality of distances obtained by the position information output unit 39 during the first period.
[0040]
Further, the light receiving lens 37 is provided with a coating that transmits only light in the wavelength band of the irradiated light beam. Therefore, the position can be detected with little influence of disturbance light. In the above description, the light beam is a thin parallel light beam. However, the light beam may be a substantially parallel light beam, and may be a light beam that has been diffused or converged to some extent. In this case, the size (diameter) of the light beam incident on the PSD 36 described later is appropriate as long as it does not interfere with supplementing the position of the center of gravity.
[0041]
Further, the infrared distance sensor 30 may be configured such that the wavelength of the light beam emitted by the infrared light irradiating unit 31 is different for each sensor. In this case, the transmission wavelength band of the coating applied to the light receiving lens 37 is also set to the transmission wavelength band corresponding to the light beam to be irradiated. Accordingly, even when adjacent light beams described with reference to FIG. 3B overlap, there is no influence from the light beams of the adjacent sensors, and there is no need to perform control so as not to irradiate at the same time. Can be simplified. Further, the infrared distance sensor 30 may blink the infrared LED 34 (light source) at a constant frequency, and the infrared light receiving unit 32 may include an electric bandpass filter that extracts only a signal of that frequency. Thereby, the influence of disturbance light can be reduced. By changing the modulation frequency for each sensor, even when the light beams described with reference to FIG. 3B overlap, the influence of the light beam of the adjacent sensor is eliminated. Accordingly, even when the light beams overlap, it is not necessary to perform control so as not to simultaneously irradiate the light beams, and the motion detection device can be simplified. Further, it is preferable to perform synchronous detection in which the polarity of the amplifier of the infrared light receiving unit 32 is switched in synchronization with the irradiation timing of the infrared LED 34.
[0042]
The PSD 36 will be further described with reference to FIG. FIG. 7A is a schematic plan view, and FIG. 7B is a schematic front sectional view. As shown in FIG. 7A, the PSD 36 has a light receiving area larger than the diameter of the incident light beam, and has a required measurement in the moving direction (left and right direction in the figure) of the incident light beam due to a change in distance. Within the distance range, it has a length such that the light beam does not protrude due to the movement of the incident light beam.
[0043]
As shown in FIG. 7B, the PSD 36 has a P-layer 36a on the surface on the side where the light beam of the silicon plate is incident, an N-layer 36b on the surface opposite to the P-layer 36a, and the P-layer 36a and the N-layer. It is composed of an I layer 36c which is intermediate with the layer 36b. The light beam incident on the PSD 36 is configured to be photoelectrically converted and divided and output as a photocurrent from electrodes 36d provided at both ends of the P layer 36a. Here, the photocurrent output from each electrode 36d is represented by I _A , I _B And Where I _A , I _B Are two values whose difference changes according to the distance.
[0044]
The infrared distance sensor 30 calculates the output signal of the photocurrent output from both ends of the PSD 36 by the position information output unit 39 and outputs the position of the center of gravity of the incident light beam as the light receiving position information. 2 can be detected. In addition, the infrared distance sensor 30 uses infrared rays for the light beam to be irradiated, so that it is invisible to humans and does not give any discomfort.
[0045]
The sensor control unit 33 of the infrared distance sensor 30 performs modulation in order to distinguish it from disturbance light when detecting the position of the center of gravity of the incident light beam by the PSD 36. The modulation is, for example, an operation of repeatedly stopping light emission (irradiation) of a light beam periodically. In this case, the emission of the light beam may be stopped, for example, by stopping the emission of the light source or by rotating a light shielding plate or a slit. Further, in the modulation, in addition to the above, the output of the light beam may be changed depending on the intensity of the disturbance light. Then, the sensor control unit 33 calculates an output value obtained by subtracting the output value of the PSD 36 when the light beam is not irradiated from the output value of the PSD 36 when the light beam is irradiated. In order to ensure reliability, the sensor control unit 33 performs the modulation operation a plurality of times, and uses the average output value as a center-of-gravity supplementary signal (hereinafter, referred to as a ranging signal) as light-receiving position information. The sensor control unit 33 outputs the distance measurement signal value x, which is the value of the distance measurement signal, to the control device 20 as a distance.
[0046]
Note that the distance measurement signal value x is the I signal output from both electrodes 36d of the PSD 36. _A , I _B Is given by, for example,
Ix = (I _A −I _B ) / (I _A + I _B ) ……… (1)
Here, Ix is a current value corresponding to the distance measurement signal value x, ie, a distance.
[0047]
Further, as shown in the schematic diagram of FIG. 8, the distance value A to the target person 2 can be calculated by the following equation using triangulation based on the distance measurement signal value x.
A = f × w / (x−b) (2)
f is the focal length of the light receiving lens 37 of the infrared light receiving unit 32 when the lens is a single lens, w is the distance between the infrared LED 34 and the PSD 36, in other words, the irradiation lens 35 and the light receiving lens 37. Represents the distance between the optical axes (base line length), and b represents a bias value depending on the arrangement of the light receiving elements of the PSD 36. Note that f, w, and b are values expressed in the same dimension as the distance measurement signal value x. When a commonly used combination lens is used, the focal length here is the focal length of the combination lens. When calculating the distance value A as described above, the control unit 21 of the control device 20 may calculate the distance value A.
[0048]
In the above, the case where the infrared distance sensor 30 outputs the distance measurement signal value x as the distance has been described, but the infrared distance sensor 30 may be configured to output the distance value A itself calculated by the above method as the distance.
[0049]
As described above, since the infrared distance sensor 30 can be simply configured by using the PSD 36, an inexpensive and simple motion detection device can be provided. Hereinafter, the infrared distance sensor 30 will be described as the distance sensor 11.
[0050]
The distance sensor 11 outputs a plurality of distances in the first period. When detecting breathing of the person 2 as in the present embodiment, the first period is preferably set to about 10 to 20 seconds (s). With this setting, the respiration cycle of the person 2 is, for example, about 5 to 60 cycles per minute, so that the first period is a period in which approximately one respiration can be detected. In the present embodiment, a description will be given of a case where 15 s is set. The distance sensor 11 is set so as to output the distance at intervals of, for example, about 0.01 to 3 s, preferably about 0.01 to 0.5 s. In the present embodiment, a case will be described where the output interval is set to 0.1 s. That is, in the present embodiment, the distance sensor 11 outputs 150 distances in the first period. In the case where the distance sensor 11 continuously outputs the distance in an analog manner, the plurality of distance sensors 11 may be sampled by the control device 20 at the same interval as above, for example.
[0051]
Returning to FIG. 5, the motion detection device 1 will be further described. The control device 20 includes a control unit 21 and controls the entire motion detection device 1. The plurality of distance sensors 11 are connected to the control unit 21 and are controlled by the control unit 21. The control unit 21 is configured to acquire a plurality of distances output from the distance sensors 11 in time series from the respective distance sensors 11. Further, a storage unit 31 is connected to the control unit 21, and can store data such as calculated information. The storage unit 31 includes a distance storage unit 32 that stores the distances output from the distance sensor 11 in time series. The distance stored in the distance storage unit 32 in time series may be a distance at a past point in time, and may be, for example, a distance acquired one distance before the latest acquired distance. .
[0052]
In the control unit 21, a first value representing a variation in a plurality of distances output from the distance sensor 11 within a first period and a second value representing a small period obtained by subdividing the first period are provided. A calculation unit 22 as a calculation device for calculating an average value of a second value representing a variation within a period during the first period, a first value, and an average value of the second value within the first period; And a judging unit 23 as a judging device for judging the validity of the plurality of outputted distances based on the above. The second period is preferably, for example, about 0.5 to 2 seconds (s). In this embodiment, the second period is described as 1 s. That is, since the first period is 15 s here, the second period is obtained by dividing the first period into 15 equal parts.
[0053]
The first value representing the variation of the distance in the first period is, for example, a standard deviation or a variance of the distance in the first period, and the second value representing the variation of the distance in the second period. Is also the standard deviation or variance of the distance within the second period. In the present embodiment, both cases of the standard deviation will be described. Note that the first value representing the variation of the distance within the first period and the second value representing the variation of the distance within the second period are the difference between the maximum value and the minimum value of the distance within each period. However, by setting the standard deviation as described above, the first value representing the variation of the distance within the first period and the first value representing the second value representing the variation of the distance within the second period The difference from the average value during the period becomes clearer. This makes it easier to determine the fluctuation due to noise, particularly random noise.
[0054]
Further, the determination unit 23 determines that the first value is valid when the first value is larger than a mean value of the second value within the first period by more than a predetermined threshold, and invalid when the first value is equal to or smaller than the threshold. It is configured to judge. That is, the determination unit 23 determines that the standard deviation of a plurality of distances in 15 s, which is the first period, is the average value of the standard deviation of a plurality of distances in 1 s, which is the second period, in the first period. It is configured to be determined to be valid when it is larger than a predetermined threshold (for example, about 0.8) and to be invalid when it is equal to or smaller than the threshold. Here, the determination unit 23 determines based on the ratio of the average value of the first value and the second value in the first period. Further, here, a threshold value is set as described later, and when (the average value of the second value in the first period / the first value) <the threshold value, it is determined to be valid. The determination of effectiveness is not limited to the above, and may be, for example, a ratio of a difference between an average value of a first value and a second value in a first period and a first value. . Further, in this case, it is determined to be valid when ((first value−average value of second value in first period) / first value)> threshold. This threshold is different from the above threshold. Either of the above methods may be used, but if the ratio of the average value of the first value and the second value in the first period is 1 in the former case, and is invalid when the ratio is close to 0 in the latter case. It is good to judge. Hereinafter, the former case will be described.
[0055]
Here, the determination of the validity by the determination unit 23 will be described with reference to the diagram of FIG. FIG. 9 is a diagram in which the distances output from the distance sensor 11 are arranged in the time direction. FIG. 9A shows the case where the mixed noise is not dominant, that is, the case where the determination unit 23 determines that the noise is valid. (B) is a diagram showing an example where mixed noise is dominant, that is, a case where the determination unit 23 determines that the noise is invalid. FIG. 9A shows a case where the average value / first value of the second value in the first period (for example, 15 s) is about 0.3, and FIG. The average value / first value in the first period (for example, 15 s) is about 0.9.
[0056]
As shown in FIG. 9A, when the distance is valid, the standard deviation of the distance in the first period (for example, 15 s) is apparent as compared with the standard deviation of the distance in the second period (for example, 1 s). Big. That is, when valid, the average value of the standard deviation of the distance in the second period is less than the standard deviation of the distance in the first period. Further, the ratio between the standard deviation in the first period and the average value of the standard deviation in the second period is a small value (for example, 0.3) as compared with the ratio when the standard deviation is invalid. Further, as shown in FIG. 9B, when the distance is invalid, the contribution of the random noise increases, so that the relationship that the standard deviation in the first period of the distance (for example, 15 s) is large remains, but both of them remain. It will be a close value. That is, when invalid, the average of the standard deviations of the second period (for example, 1 s) does not become significantly larger than the standard deviation of the first period, and these ratios are close to 1 (for example, 0. 1). 9). Therefore, it is possible to judge how close to 1 is by taking the ratio of the two. That is, when a threshold value is set, the validity can be determined based on the threshold value or less. The threshold may be set to, for example, about 0.7 to 0.95.
[0057]
That is, the ratio of the average value of the first value and the second value in the first period is always smaller than 1 in the case of a change in distance due to the movement of the person 2, for example. When there is no movement, the noise becomes dominant and becomes 1 or close to 1.
[0058]
The calculation unit 22 also includes a first value representing a variation in the plurality of detection values output from the distance sensor 11 within the first period, and a second value representing a small period obtained by subdividing the first period. The average value of the detected values within the period is determined so as to obtain a third value indicating a variation in each small period, and the determination unit 23 determines the third value based on the first value and the third value. The configuration may be such that the validity of the plurality of output detection values is determined. Further, the determining unit 23 is configured to determine invalid when the first value is larger than the third value by more than a predetermined threshold value, and determine valid when the first value is equal to or smaller than the threshold value. . Here, when the ratio between the third value and the first value is smaller than a predetermined threshold value, it is determined to be valid. Further, here, a threshold value is set as described later, and when (third value / first value) <threshold value, it is determined to be invalid. That is, when a threshold value is set, invalidity can be determined based on the threshold value or less. The threshold may be set to, for example, about 0.7 to 0.95. Further, for example, a ratio of a difference between the first value and the third value and the first value may be used. Further, in this case, when ((first value−third value) / first value)> threshold, it is determined to be invalid. This threshold is different from the above threshold. The difference between the first value and the third value is an absolute value. Either of the above methods may be used, but it is good to judge that the ratio between the first value and the third value is valid when the ratio is close to 1 in the former case and close to 0 in the latter case. Hereinafter, the former case will be described.
[0059]
Further, in this case, as shown in FIG. 9A, when valid, the standard deviation of the average value in the second period of the distance (for example, 1 s) is equal to the standard deviation of the first period of the distance (for example, 15 s). , But these ratios are close to 1 (eg, 0.9). As shown in FIG. 9B, when the distance is invalid, the standard deviation of the average value of the distance in the second period (for example, 1 s) is smaller than the standard deviation of the first period (for example, 15 s). Further, the standard deviation of the average value in the second period is a relatively small value (for example, 0.3) since the average value is substantially constant. Then, these ratios are small values as compared with the ratios at the time of validity. That is, when the threshold value is set (for example, to a value such as 0.8), invalidity can be determined based on the threshold value or less.
[0060]
Either of the two configurations described above can be used to determine that a distance where noise is dominant is invalid. That is, the influence of noise can be reduced.
[0061]
Further, the determining unit 23 determines that the fourth value representing the variation within the first period (for example, 15 s) exceeds a predetermined threshold, and determines that the plurality of output values within the first period have been detected. It is configured to be an important matter that determines that the value is invalid. The fourth value may be the same value as the first value. That is, the fourth value may be a standard deviation of a plurality of distances within the first period. In the present embodiment, the case where the fourth value is the same as the first value will be described. That is, the determination unit 23 determines that the standard deviation of a plurality of distances in the first period output from the distance sensor 11 exceeds a predetermined threshold value, It is determined that the detection value is invalid. As a result, the noise is small, but the distance does not fluctuate or is very small because, for example, the person 2 does not move at all. As a result, the noise becomes dominant, and the distance is determined to be invalid. Disappears. Furthermore, it is possible to distinguish between a change in the distance where the noise is large and the person 2 seems to have a movement at first glance and a change in the distance where the noise is dominant but the person 2 does not actually move. . In this way, it is possible to prevent that the distance is determined to be invalid even if the person 2 does not move, for example, when breathing is stopped, and the breathing stop can be accurately detected.
[0062]
Further, when the infrared distance sensor 30 (see FIG. 6) having the PSD 36 (see FIG. 7) is used as the distance sensor 11 as in the present embodiment, the determination unit 23 outputs the two values output from the PSD 36. Photocurrent I as _A , I _B The configuration may be such that the validity of a plurality of distances output from the distance sensor 11 during the first period is determined based on the sum of the distances (see FIG. 7). In addition, in the case of such a configuration, it is not necessary to provide the arithmetic unit 22 described above. That is, it can be simply configured.
[0063]
In the distance sensor using the PSD, when the light amount of the light beam incident on the PSD decreases, the noise mixed in the output distance tends to increase (the noise tends to be dominant). Also, the photocurrent I output from both poles of the PSD _A , I _B Is calculated, the amount of light flux incident on the PSD can be detected. Thereby, the amount of light flux incident when the noise becomes more dominant, that is, the photocurrent I _A , I _B Is set as a threshold value, and the photocurrent I _A , I _B Is determined to be invalid when the sum is equal to or smaller than the threshold value, the influence of noise can be reduced.
[0064]
The determination of the validity of the distance within the first period output from the distance sensor 11 by the above-described determination unit 23 is performed for each distance sensor 11.
[0065]
Returning to FIG. 5, the description will be continued. Further, the control unit 21 includes a distance adopting unit 24 for selecting whether or not to adopt the determined distance within the first period based on the validity determined by the determining unit 23. I have. The distance adoption unit 24 performs a process of not employing the output of the distance sensor 11 within the first period, typically based on the validity determination. When a plurality of distance sensors 11 are provided as in the present embodiment, the outputs of the distance sensors 11 determined to have no validity in the first period are not used, and the outputs of the other distance sensors 11 are not used. Is adopted. Even when only one distance sensor 11 is provided, it is possible to select an output that can be temporally adopted and an output that cannot be adopted.
[0066]
The distance adoption unit 24 is configured not to adopt the output of the distance sensor 11 determined to be invalid, that is, the distance output from the distance sensor 11 among the plurality of distance sensors 11 based on the validity determination by the determination unit 23. ing. The outputs not adopted are those within the first period in which the validity was determined.
[0067]
Further, the distance adoption unit 24 employs the output of the distance sensor 11 having the largest change in the output of the distance sensor 11 during a certain period in the past among the distance sensors 11 determined to be effective by the determination of the validity by the determination unit 23. It is good to be constituted so that. The past fixed period may be, for example, a first period. As described above, by employing the output having the largest fluctuation, for example, an output in which the movement of the person 2 is reflected most can be employed. When the movement of the person 2 is reflected in the output, the fluctuation of the output is basically larger than the output in which the movement of the other person 2 is not reflected. Therefore, by performing the above, an output that most reflects the movement of the person 2 can be adopted.
[0068]
Further, the distance adoption unit 24 outputs the output of the distance sensor 11 in which the peak of the output spectrum is the clearest in the past certain period, from the distance sensors 11 determined to be valid by the determination of the validity by the determination unit 23. May be adopted.
[0069]
Whether the peak of the spectrum is clearest is evaluated by the sharpness of the peak of the spectrum. The sharpness of the peak (the sharpness of the peak) is, for example, a value obtained by dividing the height of the spectrum peak by the integrated value of the height of the spectrum at all frequencies. A value obtained by dividing the value obtained by adding the higher heights of the adjacent spectra by the sum of the spectrum heights of all the frequencies can be used as an index. By evaluating that the sharpness of the peak is equal to or more than a certain value, for example, the output of the distance sensor 11 that detects the respiration of the person 2 can be clearly adopted, so that the respiration of the person 2 is easily detected.
[0070]
The spectrum is evaluated by determining the validity of the distance sensors 11 of the predetermined number of distance sensors 11 in descending order of the output of the distance sensors 11 determined to be valid by the validity determination by the determining unit 23 in the past fixed period. The output is selected and evaluated by comparing the output of each selected distance sensor 11. The predetermined number is, for example, about 1 to 6, preferably about 2 to 4. Further, the evaluation of the spectrum is based on the validity of the distance sensor 11 among the outputs of the distance sensors 11 determined to be valid by the validity determination by the determining unit 23, in which the fluctuation of the output in the past fixed period exceeds the predetermined threshold value. The output may be selected and evaluated by comparing the output of each selected distance sensor 11.
[0071]
As described above, the motion detection device 1 is configured to detect the motion of the person 2 based on at least the output of the distance sensor 11 determined to be valid, based on the validity determination by the determination unit 23. That is, here, the movement of the person 2 is detected based on the distance within the first period adopted (selected) by the distance adopting unit 24. As described above, since the output determined to be valid by the determination unit 23 is employed, the motion of the person 2 is detected based on the output in which noise is dominant, thereby accurately detecting the motion without erroneously detecting the motion. The movement of the person 2 can be detected.
[0072]
Further, in the control unit 21, a distance calculation unit 25 that calculates a time change of the distance based on the output of the distance sensor 11, and based on the time change of the distance calculated by the distance calculation unit 25, And a motion detecting unit 26 for detecting a motion. Here, the time change of the calculated distance may be an absolute value of the time change. In this embodiment, the case of the absolute value of the time change of the distance will be described. The motion of the person 2 detected by the motion detection unit 26 is, for example, breathing, body motion, or movement.
[0073]
The distance calculation unit 25 is typically configured to calculate a time change of the distance based on the output of the distance sensor 11 adopted by the distance adoption unit 24. That is, the time change of the distance is calculated based on the plurality of distances within the first period that are determined to be valid by the determination unit 23 and that are adopted by the distance adoption unit 24.
[0074]
Calculating the time change based on the distance means that a plurality of distances output from the distance sensor 11 at a fixed time interval are acquired, and the distance acquired at the past time and the distance acquired at the current time are acquired. By taking the difference, the amount of change in distance within the past predetermined period is obtained. In other words, the difference between the distance acquired by the distance sensor 11 and the distance stored in the distance storage unit 32 in time series is obtained to obtain the distance change amount within the past predetermined period. Here, the time interval for acquiring the distance from the distance sensor 11 is, for example, about 0.01 to 3 seconds, and preferably about 0.01 to 0.5 seconds.
[0075]
Further, calculating the time change based on the distance means that a plurality of distances output from the distance sensor 11 at regular time intervals are acquired, and the maximum value of the distance obtained in the past predetermined period and the minimum value of the distance are obtained. By taking the difference (Max−Min) from the value, the distance change amount within a predetermined period in the past may be obtained. Also, the predetermined period here may be set to about 30 seconds, more preferably about 10 to 20 seconds, but may be set to a shorter time, for example, about 3 seconds. When the predetermined period is set to be longer, it is effective for detecting a relatively large body motion such as respiration or rising of the person 2 by the motion detection unit 26 described later. When the predetermined period is set shorter, it is similarly effective for detecting the body motion of the person 2.
[0076]
The former is particularly suitable for detecting the breathing of the person 2. The latter is suitable for determining breathing or body movement of the person 2 described later. Hereinafter, a description will be given of a case in which the time change of the former distance is used, but the time change of the latter distance may be used, and further, the time change of both the former and the latter may be used. In this case, a time change of each distance is selected and used by a motion detection unit 26 described later. It is not always necessary to use the difference in distance to calculate the time change of distance, and it is also possible to use means such as frequency analysis from the distance acquired in time series.
[0077]
Further, the distance calculation unit 25 sets a first predetermined period and a second predetermined period shorter than the first predetermined period, and calculates the distance change amount of the first predetermined period and the second predetermined period. It may be configured to obtain both the distance change amount. In this case, similarly to the above, the first predetermined period is set to about 30 seconds, more preferably about 10 to 20 seconds, and the second predetermined period is set to about 1 to 10 seconds, more preferably 3 to 6 seconds. Set to about seconds. By doing so, the motion detection unit 26 can more accurately detect the motion of the person 2. Further, in the above description, the predetermined period is described as time, but may be the number of acquired distances (for example, 10). The calculation of the distance change amount is performed for each output of the distance sensor 11. That is, the distance change amount is obtained for each distance sensor 11.
[0078]
The distance change amount in the past predetermined period obtained by calculating the time change of the distance by the distance calculation unit 25 is arranged in the time direction to form a waveform pattern.
FIG. 10 is a diagram illustrating an example of a waveform pattern.
[0079]
Further, the distance calculation unit 25 may calculate the time change of the distance by calculating a distance from a reference position within a past predetermined period. In this case, the calculation of the time change of the distance involves obtaining the distance from the reference position at regular time intervals. The obtained distances are arranged in the time direction. Here, the reference position is, for example, the upper surface of the bed 3, but may be set in advance as the position of the upper surface of the chest or abdomen of the person 2 having a standard body shape. The reference position may be stored in the distance storage unit 32 as a distance from the distance sensor 11 to the reference position.
[0080]
Further, the distance calculation unit 25 may be configured to calculate a moving average value or a period average value of distances acquired a certain number of times in the past from the output of the distance sensor 11 or acquired within a certain period of the past. Further, in this case, when the time change of the distance is calculated by the distance calculation unit 25, the moving average value or the period average value of the calculated distance is treated in the same manner as the distance output from the distance sensor 11. I do. In other words, the distance calculation unit 25 calculates the time change of the distance based on the moving average value or the period average value. Further, the moving average and the period average may be configured to be calculated by the distance sensor 11. In other words, the distance sensor 11 may be configured to calculate a moving average value or a period average value of the detected distance, and output the calculation result as the distance. By doing so, it is possible to reduce random noise or sudden noise due to flickering of sunlight coming in from a window, and to reduce erroneous determination of a peak position and erroneous determination of a zero-cross position (an intersection where a sign is inverted). . Although there are various methods for calculating each average value, fixed time intervals may be determined in advance, and data during that time may be averaged. Alternatively, the number of data to be averaged may be determined in advance, and the moving average may be determined in time series. A method of calculating a value may be used. In the former case, the number of data is small, and it is suitable for roughly grasping the state. In the latter case, although the number of data is slightly increased, fine behavior can be followed.
[0081]
Further, the motion detection unit 26 will be described. The motion detection unit 26 is configured to detect the motion of the person 2 based on the time change of the distance calculated by the distance calculation unit 25. That is, it is configured to detect the respiration, body movement, and movement of the person 2. Further, the motion detection unit 26 is configured to detect the motion of the person 2 based on a time change regarding one or a plurality of the selected distance sensors 11 among the plurality of the distance sensors 11.
[0082]
In addition, the motion detection unit 26 is configured to detect the respiration of the person 2 based on the temporal change of the calculated distance. Here, in the detection of respiration, the motion detection unit 26 detects a periodic change in the time change of the distance, and further detects the respiration of the person 2 based on the detected periodic change. The periodic change is a change having, for example, a respiratory cycle of the person 2, for example, a cycle of 5 to 60 cycles per minute. That is, in the present embodiment, the periodic change does not include a periodic change that greatly deviates from the respiratory cycle. By the way, the respiratory rate of an adult is in a range of about 5 to 30 times per minute, but the respiratory rate of an infant tends to be further increased. The motion detection unit 26 is configured to detect the respiration of the person 2 based on one or both of the period and the amplitude of the periodic change. Typically, the motion detection unit 26 detects the respiration of the person 2 from both the period and the amplitude of the periodic change. Further, the motion detection unit 26 may be configured to monitor the respiration rate from the detected respiration cycle. Here, monitoring the respiratory rate is also included in the concept of monitoring the cycle.
[0083]
In addition, the motion detecting unit 26 further selects, from among the time changes of the distance corresponding to the distance sensor 11 adopted by the distance adopting unit 24, those having a certain value or more, and periodically changes the time change of the selected distance. May be detected, and the presence / absence of respiration and the respiration rate may be detected from the periodic change having the clearest periodicity (representing respiration).
[0084]
Further, the motion detection unit 26 is configured to detect a body motion and a movement of the person 2 based on a temporal change of the calculated distance. The detection of the body motion or the movement of the person 2 fluctuates much more than the case where only the respiration is detected from the time change of the distance, so that the detection can be easily performed. In this case, the motion detection unit 26 further determines whether the person 2 is moving on the spot such as turning over, for example, based on each time change corresponding to the output of the distance sensor 11 adopted by the distance adoption unit 24. It is also possible to detect whether the user is moving on the bed by getting up or the like. Further, even when the person 2 makes periodic small movements such as convulsions, an abnormality can be detected from the waveform pattern. Further, by storing the waveform pattern in the state of being cramped in the storage unit 31, it is possible to detect that the person 2 is in a state of cramping.
[0085]
The movement detecting unit 26 detects the movement of the person 2 as described above. Further, the motion detection device 1 is configured to determine the state of the person 2 based on the detected movement of the person 2. The state of the person 2 is, for example, normal breathing, abnormal breathing and danger, physical movement such as turning over, movement such as landing on the floor, trying to get out of the floor, and the like. . Further, the motion detection unit 26 is configured to transmit a warning signal when it is determined that the person 2 is in a dangerous state. The alarm signal is transmitted to, for example, an alarm device 40 described below. For example, if the cycle of the breathing pattern is disturbed in a short time, or if the cycle of the breathing pattern changes rapidly, for example, spontaneous pneumothorax, lung disease such as bronchial asthma, heart disease such as congestive heart failure, Alternatively, it can be assumed that the disease is a cerebrovascular disease such as cerebral hemorrhage. Further, when the disappearance of the breathing pattern continues, it can be estimated that the breathing of the person 2 has stopped. Then, if the body motion of the person 2 occurs frequently instead of the breathing pattern in a short time, it can be estimated that the person 2 suffers for some reason and is rampaging. It is preferable that the motion detection unit 26 be set so as to comprehensively detect the state of the person 2 by using these facts.
[0086]
Here, examples of normal and abnormal breathing patterns will be described with reference to FIG. The normal breathing pattern stored in the breathing pattern storage unit 33 in the storage unit 31 is a periodic pattern, for example, as shown in FIG. However, in the case of an adult, the normal range of the respiratory rate per minute is about 10 to 20 times. The abnormal respiratory pattern stored in the respiratory pattern storage unit 33 is, for example, Cheyne-Stokes respiration, central hyperventilation, ataxic respiration, and large respiration of Kussmul (physical respiration). This is a respiratory pattern that is considered to occur when a failure has occurred in a subject.
[0087]
FIG. 11B shows the Cheyne-Stokes respiration pattern, FIG. 11C shows the central hyperventilation respiration pattern, and FIG. 11D shows the ataxia respiration respiration pattern.
Further, FIG. 12 shows disease names or disease locations when the above-mentioned abnormal breathing pattern occurs.
[0088]
The motion detection unit 26 determines that the breathing pattern of the person 2 belongs to which breathing pattern by utilizing the fact that the breathing frequency, the number of appearances, and the depth of each breathing pattern are different, and determines the state of the person 2. I do.
[0089]
Further, when the motion detecting unit 26 determines that the respiration of the person 2 belongs to a respiration pattern that is considered to occur physiologically when a disorder occurs in the body, the person 2 performs abnormal respiration. And judge that it is in a dangerous state. The detected state of the person 2 may be output from the output device 36 described later by the control unit 21. In this case, the output contents include the detected respiratory rate and movement frequency of the person 2, the name of an abnormal respiratory pattern, a disease name, a diseased organ, a diseased part, and the like which are considered to cause the respiration.
[0090]
Further, an input device 35 for inputting information for operating the motion detection device 1 and an output device 36 for outputting a result processed by the motion detection device 1 are connected to the control unit 21. The input device 35 is, for example, a touch panel, a keyboard, or a mouse, and the output device 36 is, for example, a display or a printer. Although the input device 35 and the output device 36 are shown as being externally attached to the control device 20 in this figure, they may be built in. The input device 35 may be, for example, a switch for starting or canceling the detection of the movement of the person 2, and the output device 36 may be, for example, an LED as an operation indicator. In this way, the motion detection device 1 can be simply configured. In addition, it is easy to configure integrally with the distance sensor 11 (housing 10).
[0091]
Further, the motion detection device 1 includes an alarm device 40 as alarm means for issuing an alarm. The alarm device 40 is connected to the control unit 21. The alarm device 40 is configured to generate an alarm by receiving an alarm signal transmitted from the motion detection unit 26. That is, the alarm device 40 is configured to issue an alarm when, for example, the motion detection unit 26 determines that the person 2 is in a dangerous state. Further, the alarm device 40 may be configured to issue an alarm even when an abnormality such as a failure of the motion detection device 1 occurs. By doing so, it is possible to promptly notify a third party that the person 2 is in a dangerous state, so that it is possible to quickly respond to the dangerous state. That is, the motion detection device 1 can increase the reliability of detecting the motion of the person 2. In this drawing, the alarm device 40 is shown as an external device, but may be built in.
[0092]
Further, the control device 20 may be configured to notify, via the interface 39, that an alarm has been issued to the outside when the alarm device 40 has issued an alarm. The outside is, for example, a place where the motion detection device 1 is managed, or in the case of a private house, for example, a living room or a fire station. The notification is based on, for example, the intensity of light including sound, characters, symbols, and indoor lighting, or vibration. The interface 39 has a function of connecting to a communication line such as a general telephone line, an ISDN line, a PHS line, or a mobile telephone line. In a private house, a report to another room such as a living room or another bedroom may be made via wireless or power line communication. Further, the control device 20 may be provided with a voice output function, and may notify the third party by voice via the interface 39 that the person is in a dangerous state.
[0093]
The control device 20 includes a human sensor 41 as presence detecting means for detecting the person 2 on the bed 3 or on the bed 3 and in the vicinity thereof. As the human sensor 41, for example, a pyroelectric sensor that can detect the presence of a human body by a heat ray, an ultrasonic sensor that detects the presence using ultrasonic waves, a motion sensor based on image processing, or the like can be used. It is preferable to use a pyroelectric sensor as the human sensor 41. By using the pyroelectric sensor, the motion detection device 1 can be configured to be small and inexpensive. The human sensor 41 operates as a motion sensor that captures a change in the detection level because it is difficult to distinguish between an environmental change and a change due to the presence or absence of the person 2 based on the absolute value of the detection level.
[0094]
It is preferable that the motion sensor 41 be installed in the housing 10. By doing so, the installation work of the motion detection device 1 becomes easy. Further, the size of the motion detection device 1 can be reduced. Further, the attachment position of the human sensor 41 is not limited to the above, and may be any position as long as it can detect the person 2 on the bed 3 or on the bed 3 and its vicinity.
[0095]
The motion detection device 1 further includes the motion sensor 41. For example, when the motion sensor 41 cannot detect the presence of the person 2 on the bed 3 or on the bed 3 and its vicinity, the motion detection device 1 Because you can turn off the power, you can save power. In other words, that is, the power of the motion detection device 1 can be turned on when necessary, and power can be saved. In addition, when the movement of the person 2 is not detected, it helps to determine whether the person 2 does not exist, exists, or does not move.
[0096]
Similarly, a pressure-sensitive sensor 43 may be installed as a device for detecting whether or not the person 2 exists. The pressure sensor 43 is, for example, a load sensor or a pressure sensor. The pressure-sensitive sensor 43 is located at a position where the load of the person 2 on the bed 3 is applied, for example, on the bed 3 on the upper body side of the person 2 or on the legs of the bed 3 on the upper body side (at the four corners of the rectangular bed 3). It is good to arrange in. In this case, by using the output from the pressure-sensitive sensor 43, for example, the reliability of the determination of the presence or absence from the bed increases.
[0097]
According to the motion detection device 1 described above, the determination unit 23 determines the validity of the distance output from the distance sensor 11 to determine, for example, that the output distance includes noise. it can. That is, for example, a change in distance due to noise and a change in distance due to the movement of the person 2 can be determined. Thereby, the distance when the noise is dominant can not be adopted, and the movement of the person 2 can be detected based on the distance with high effectiveness, so that the accurate movement of the person 2 can be detected. Furthermore, even when noise of the same or larger variation is mixed with the variation of the distance due to the movement of the small person 2, the motion detection device 1 determines that the noise is dominant by judging the validity of the distance. , The distance in that period is not used for detecting the motion of the person 2. Therefore, by detecting the motion of the person 2 based on the distance where the noise is dominant, the motion of the person 2 is not erroneously detected. That is, even a relatively small movement such as the breathing of the person 2 can be accurately detected.
[0098]
Furthermore, since the motion detection device 1 uses the distance sensor 11 and does not use image processing using a camera that is psychologically uncomfortable, high-speed processing can be performed with a simple device. Furthermore, even when the elderly or the sick are in a state of crisis, quick emergency response is possible.
[0099]
【The invention's effect】
As described above, according to the present invention, a distance sensor that detects a distance to an object and outputs a plurality of detection values representing the distance during a first period, and the plurality of output detection values A first value representing a variation within the first period and a second value representing a variation within a second period, which is a small period obtained by subdividing the first period, within the first period. Determining the validity of the plurality of output detection values based on an arithmetic unit for calculating an average value, and an average value of the first value and the second value within the first period. Since it has a determination device, by being able to determine the validity of the detection value representing the distance to the object, it is possible to remove the effect of noise, for example, a motion detection device that can accurately detect even relatively small movement of the object Can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing an outline of a motion detection device according to an embodiment of the present invention.
FIG. 2 is a schematic perspective view illustrating a case where the housing portion of FIG. 1 is installed on a ceiling.
FIG. 3 is a schematic plan view illustrating an example of an arrangement of target points (a) according to an embodiment of the present invention and an example of an arrangement (b) where target points overlap.
FIG. 4 is a schematic side view illustrating a case where the distance sensor according to the embodiment of the present invention is installed with a curve.
FIG. 5 is a block diagram illustrating a configuration example of a motion detection device used in the embodiment of the present invention.
FIG. 6 is a block diagram showing a configuration example of an infrared distance sensor which is an example of a distance sensor used in the embodiment of the present invention.
7A and 7B are a schematic plan view and a schematic front sectional view illustrating a PSD in the case of FIG. 6;
FIG. 8 is a schematic diagram illustrating a method for calculating a distance value to an object in the embodiment of the present invention.
FIG. 9 is a diagram illustrating a case where distances output from a distance sensor are arranged in a time direction according to an embodiment of the present invention, and FIG. 9A is a diagram illustrating an example in which mixed noise is not dominant (B) is a diagram showing an example in which mixed noise is dominant.
FIG. 10 is a diagram illustrating an example of a waveform pattern formed by a temporal change in distance used in the embodiment of the present invention.
FIG. 11 is a diagram showing waveform patterns of normal and abnormal respiration in the case of FIG. 10;
12 is a diagram showing a table of disease names or disease locations corresponding to abnormal breathing waveform patterns in the case of FIG. 11;
[Explanation of symbols]
1 Motion detection device
2 people
3 beds
4 Bedding
5 Target points for ranging
6 beds
7 stand
10 Case
11 Distance sensor
20 Control device
21 Control unit
22 Operation part
23 Judgment unit
24 Distance adoption department
25 Distance calculator
26 Motion detector
31 Memory
32 Distance storage
33 breathing pattern storage
35 Input device
36 Output device
39 Interface
30 Infrared distance sensor
31 Infrared light irradiator
32 infrared light receiver
36 Position detection element (PSD)
39 Position information output unit
40 alarm device
41 Human Motion Sensor
50 detection area

Claims (7)

A distance sensor that detects a distance to the target object and outputs a plurality of detection values representing the distance during a first period;
A first value representing a variation in the output plurality of detected values within the first period, and a second value representing a variation within a second period which is a small period obtained by subdividing the first period. An arithmetic unit for determining an average value of the values within the first period;
A determination device that determines the validity of the plurality of output detection values based on the first value and an average value of the second value within the first period;
Motion detection device. When the first value is larger than a mean value of the second value within the first period by more than a predetermined threshold value, it is determined to be valid, and when it is equal to or smaller than the threshold value, it is determined to be invalid. ;
The motion detection device according to claim 1. A distance sensor that detects a distance to the target object and outputs a plurality of detection values representing the distance during a first period;
A first value representing a variation in the plurality of output detection values in the first period, and an average value of detection values in a second period which is a small period obtained by subdividing the first period. An arithmetic unit for obtaining a third value indicating a variation in each small period;
A determination device that determines the validity of the plurality of output detection values based on the first value and the third value;
Motion detection device. If the first value is greater than the third value by more than a predetermined threshold, it is determined to be invalid; if it is equal to or smaller than the threshold, it is determined to be valid;
The motion detection device according to claim 3. The distance sensor,
Light irradiation means for irradiating the object with a light beam;
A position detecting element that receives a reflected light beam of the light beam reflected by the object and outputs differently according to the light receiving position;
A distance calculation device for obtaining a detection value indicating the distance to the object based on the principle of trigonometry based on an output from the position detection element;
The distance calculated by the distance calculation device as the plurality of outputs;
The motion detection device according to claim 1. A distance sensor that detects a distance to the object, the distance sensor having a detection element that outputs two values whose difference changes according to the distance;
A determination device that determines the validity of the output detection value based on a sum of the two output values;
Motion detection device. An important matter that determines that the plurality of output values detected in the first period are invalid when the fourth value representing the variation within the first period exceeds a predetermined threshold value. Said;
The motion detection device according to claim 1.

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