JP2017121383A - Measurement system for biological activity attributed to respiration of subject - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement system for a biological activity attributed to the respiration in which a measurement condition for a biological activity is hardly affected by a surrounding environment.SOLUTION: A measurement system includes a light source 20, an imaging device 10 for generating a video image, and an image processing circuit for measuring a biological activity of a subject using the video image. A reflection marker 40 is disposed at a position where a body motion accompanying the respiration of the subject is generated. When a light is emitted toward the subject from the light source 20, the imaging device 10 receives the light reflected by the reflection marker 40 and generates a video image. The image processing circuit receives the video image from the imaging device 10, and measures the biological activity attributed to the respiration of the subject based on a change in a luminance value of a plurality of frame images. The reflection marker 40 includes a base 41 with a flat supporting surface 41a, and a plurality of reflection materials 42, each of which is inclined toward the same inclination direction at a predetermined inclination angle with respect to the supporting surface 41a, and is supported by the supporting surface 41a.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a technique for measuring a biological activity resulting from respiration, such as a subject's respiration rate, from a subject's video.

  A technique is known in which a subject is photographed with a camera, a change in luminance value due to a biological reaction such as body movement or blood flow is detected from the moving image, and a biological activity such as a subject's respiratory rate or heart rate is measured ( For example, Patent Documents 1 and 2). The image area in which the subject is shown is specified by an observer in advance or by using a contour extraction technique.

  The respiratory monitoring device of Patent Literature 1 divides an image obtained by photographing a subject into local regions, and analyzes lightness information of each local region. Then, using the three types of threshold values, it is determined whether the subject is observing movement around the chest or observing non-respiratory body movement such as turning over.

  The heart rate measuring device of Patent Document 2 captures the face of a subject with a camera equipped with an infrared light source, extracts a specific area between eyebrows from a face image for each frame, and corrects the average luminance. The heart rate measuring device obtains a waveform of a temporal change in corrected luminance from the corrected average luminance time series, and calculates the heart rate of the subject by filtering the waveform in a frequency band corresponding to the heart rate. .

Japanese Patent Laid-Open No. 11-276443 JP 2011-130996 A JP 2007-72589 A

  In the respiratory monitoring device of Patent Document 1, an appropriate threshold necessary for determining non-respiratory body movement varies greatly depending on the imaging environment. For example, the threshold value to be set can vary greatly depending on changes in the brightness of the observation location, the position of the indoor light source, the presence or absence of incident light from the outside, and the movement of people or objects other than the subject. Since there is no method for always obtaining an appropriate threshold value, an area for obtaining biological information such as respiration cannot be calculated if the threshold value is inappropriate.

  The heart rate measuring device of Patent Document 2 needs to capture the subject's face within the imaging range. Similar to Patent Document 1, when the shooting environment changes such as a change in illuminance, movement of a person, incidence of external light, etc., the luminance value of the image area in which the subject is photographed changes greatly due to a cause other than biological activity. When such disturbance noise occurs, the body movement location due to the biological reaction cannot be specified, and the biological information may not be extracted accurately.

  Furthermore, since the accuracy of acquiring the subject's biological information decreases when the subject's face moves away from the camera, the subject's face must be continuously imaged from a relatively short distance. As a result, a feeling of pressure is given to the subject, and there is a concern about the influence on the biological activity to be measured.

  The present invention has been made to solve the above-described problems, and is a measurement system for life activity caused by breathing (hereinafter referred to as “measurement system”) in which measurement conditions for life activity are not easily influenced by the surrounding environment. Provided.)

  A measurement system according to an embodiment of the present invention includes a light source that emits light, an imaging device that receives the light and generates a moving image, and an image processing circuit that measures a biological activity of a subject using the moving image. A reflection marker is disposed at a position where body movement occurs due to breathing of the subject, and when the light is emitted from the light source toward the subject, the imaging device is Receiving the light reflected by the reflective marker at a plurality of times, generating the moving image composed of a plurality of time-series frame images, and the image processing circuit receiving the moving image from the imaging device. Receiving and measuring a biological activity caused by respiration of the subject based on a change in luminance values of the plurality of frame images, and the reflective marker includes a base having a support surface and each of which is inclined with respect to the support surface. And, having a plurality of reflective material which is supported by the support surface.

  In one embodiment, the reflective marker may be a retroreflective marker, and the plurality of reflective materials may be a plurality of retroreflective materials.

  In one embodiment, when the reflective marker is disposed at a position where body movement occurs due to breathing of the subject, the inclination angle of each of the plurality of reflectors increases as the distance from the side closer to the light source increases. Also good.

  In one embodiment, a side surface of the reflective marker includes a saw-tooth structure including a plurality of saw teeth corresponding to the plurality of reflectors, and the height of each of the plurality of saw teeth is equal, and the reflective marker is the test marker. When the body movement is generated at the position where the body respiration occurs, the pitch of the sawtooth may be reduced as the distance from the side closer to the light source is increased.

  In one embodiment, each of the plurality of reflecting materials may have a curved reflecting surface.

  In one embodiment, the curved surface shape may be equal to the shape of a concave mirror defined by a parabola in which the incident angles of the light with respect to the normal at any point on the curved surface of two adjacent reflectors are all equal, A third direction orthogonal to a first direction parallel to an arrangement direction of the plurality of reflective materials, each of the second direction in which each reflective material extends, and a third direction orthogonal to both the first directions, and the first In the cross-section of the curved surface of each of the reflecting materials cut by a plane parallel to each direction, a point on the curved surface located at the first end of each reflecting material on the imaging device side is a point R, A point on the curved surface located at the second end of the reflector opposite to the imaging device is a point S, a focal length of the concave mirror is f, an object point is a point C, and an image point is a point C ′. Then, the perpendicular bisector of the line segment RS is the line segment C ′ at the midpoint of the line segment CC ′. And the focal point of the concave mirror is located on a perpendicular bisector of the line segment RS, and the distance between the line segment RS and the line segment CC ′ is 2f in length. Good.

  In one embodiment, the reflective marker further includes a cover including an opening having a predetermined marker shape, and the shapes of the plurality of reflective materials may coincide with the predetermined marker shape in a plan view. .

  In one embodiment, the predetermined marker shape may be a triangle, a diamond, or a rectangle.

  In one embodiment, the image processing circuit divides each frame image into a plurality of partial areas, and measures a biological activity caused by breathing of the subject based on a change in luminance value of the plurality of partial areas. Also good.

  In one embodiment, the light source is an infrared light source that emits infrared light, and the imaging device may include an optical filter that blocks a wavelength in a visible light region.

  ADVANTAGE OF THE INVENTION According to this invention, the measurement system of the biological activity resulting from the respiration which the measurement condition of a biological activity is hard to be influenced by the surrounding environment by using the reflective marker containing the several inclined reflective material is provided.

It is a schematic diagram for demonstrating the relationship between the incident angle of the light which injects into a retroreflection material, and a reflectance. 1 is a diagram showing a configuration of a measurement system 100 according to Embodiment 1. FIG. 3 is a perspective view of a retroreflective marker 40 according to Embodiment 1. FIG. 3 is a top view of a retroreflective marker 40 according to Embodiment 1. FIG. 4 is an exploded perspective view of a retroreflective marker 40 provided with a cover 43 according to Embodiment 1. FIG. 6 is a plan view of a retroreflective marker 40 provided with a cover 43 according to Embodiment 1. FIG. It is a schematic diagram which shows the state which is irradiating the infrared light 20a from the light source 10 to the retroreflection material 42 formed in the rhombus by the opening 44 of the cover 43. FIG. It is a figure which shows the frame image 102 which image | photographed the test subject 1 with which the retroreflection marker 40 was mounted | worn. It is a figure which shows the frame image 106 which image | photographed the test subject who does not mount | wear with the retroreflection marker 40. FIG. It is a graph which shows the vibration of the high-intensity area | region 104 measured based on the change of the luminance value of a some frame image. It is a graph which shows the change of the luminance value of the some frame image image | photographed in the dark imaging environment, without providing a retroreflection marker. 2 is a hardware configuration diagram mainly of an information processing apparatus 30 of the measurement system 100. FIG. 3 is a flowchart illustrating an example of a procedure of processing performed in the measurement system 100 according to Embodiment 1. It is a schematic diagram which shows the example of a setting of the partial area | region Q in a frame image for monitoring the luminance change of a high-intensity area | region. It is a schematic diagram which shows the camera 10 equipped with the optical filter 11 which interrupts | blocks the wavelength of visible light region. It is a schematic diagram which shows the luminance distribution of the reflection pattern area | region in a frame image at the time of using the retroreflection marker 40 containing the cover 44 by Embodiment 1. FIG. It is a perspective view of retroreflective marker 40A by Embodiment 2. FIG. It is a schematic diagram which shows the positional relationship of the camera 10 (or light source 20) and the two retroreflection materials 42. FIG. It is a schematic diagram which shows the luminance distribution of the reflection pattern area | region in a frame image at the time of using the retroreflection marker 40A containing the cover 44 by Embodiment 2. FIG. It is a perspective view of the retroreflection marker 40B by Embodiment 3. FIG. It is a schematic diagram which shows the mode of the light ray which injected into the boundary vicinity between the two adjacent retroreflection materials 42. FIG. It is a schematic diagram which shows a concave mirror, the focus of a concave mirror, an object point, and an image point.

  There is a demand for a measurement system in which measurement conditions for life activity are not easily influenced by the surrounding environment. For example, it has been proposed to use a retroreflective material to measure the biological activity resulting from the subject's breathing. More specifically, a flat retroreflecting material is arranged as a marker at a position where body movement accompanying breathing of the subject, for example, the chest, and infrared light is emitted from the infrared light source toward the marker. The camera captures a moving image including a marker, and the image processing circuit can measure a biological activity caused by the breathing of the subject based on a change in luminance values of a plurality of frame images constituting the acquired moving image. . By using the retroreflective material as a marker, the brightness of the marker region can be improved and the SN ratio (Signal Noise Ratio) can be ensured. Such a measurement system and measurement method are disclosed in, for example, Japanese Patent Application No. 2014-145476, which is an unpublished patent application by the present applicant. All of this disclosure is incorporated herein by reference. In the present specification, the subject is described as being a person, but may be an animal other than a person (a pet animal such as a dog or a cat, or an experimental animal such as a pig or a mouse). Animals (including people) as observation targets may be collectively referred to as “subjects”.

  According to the study by the present inventor, the reflectance of the retroreflective material strongly depends on the incident angle of light with respect to the retroreflective material. As the incident angle of light with respect to the retroreflective material increases, the reflectance can be significantly reduced. As a result, the luminance of a part of the marker area in the photographed image may decrease, and luminance unevenness may occur in the marker area.

  The incident angle at which light enters the retroreflecting material from the light source can vary depending on the positional relationship between the subject and the light source. FIG. 1A schematically shows the reflected light reflected by the retroreflecting material when the light incident angle α is relatively small, and FIG. 1B shows that the light incident angle α is relatively small. The reflected light reflected by the retroreflecting material in a large case is schematically shown, and FIG. 1C schematically shows a single marker arranged to be inclined with respect to the installation surface (for example, the chest). ing. As shown in the figure, the incident angle of light is an angle formed with respect to the normal line n. In the portion of the retroreflective material that is closer to the light source, as shown in FIG. 1A, the incident angle α of the light with respect to the retroreflective material is relatively small, and as a result, the reflectance of the light is high, Luminance can be ensured in that region. On the other hand, in the region of the retroreflective material that is away from the light source, the incident angle α of light with respect to the retroreflective material gradually increases as shown in FIG. For example, when the installation position of the light source is low, it is considered that the light incident angle α is further increased. As a result, the reflectance of light gradually decreases, and it is difficult to ensure luminance in that region. When the brightness of the marker is not sufficient, there is a possibility of affecting marker detection described later.

  Patent Document 3 discloses a coordinate input device including a retroreflecting material including a plurality of inclined surfaces and two sensor units in which a light source and a line sensor are integrated. The inclination angles of the plurality of inclined surfaces are determined in consideration of the incident angle of light from the light source. According to Patent Document 3, among retroreflective materials marketed for applications such as road signs, the retroreflective efficiency is relatively high, and even with the most wide-angle characteristics, When the incident angle is 30 ° to 45 ° or more, the retroreflection efficiency is drastically reduced.

  In order to solve such a problem, for example, as shown in FIG. 1 (c), by arranging the marker itself to be inclined, the incident angle of the light with respect to the retroreflecting material is relatively reduced, thereby increasing the luminance. It is conceivable to secure. However, according to such a configuration, the height of the marker is not only inconvenient to handle the marker, but the marker and the subject are not in close contact with each other, and the contact area thereof is reduced. May not be able to pick up body movements caused by biological activity. This leads to a failure to accurately measure the biological activity resulting from respiration.

  Based on the above findings, the inventor of the present application has found a reflective marker having a novel structure, and has reached the present invention. In the present specification, Embodiments 1 to 3 will be described using a measurement system mainly using a retroreflective marker as a measurement marker. However, as will be described later, under predetermined conditions, the measurement marker is not necessarily a retroreflective marker.

  Hereinafter, a measurement system according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the same reference numerals are assigned to the same or similar components. In addition, the measurement system by embodiment of this invention is not restricted to what is illustrated below. For example, it is possible to combine one embodiment with another embodiment.

(Embodiment 1)
FIG. 2 shows a configuration of the measurement system 100 according to the present embodiment. The measurement system 100 includes a camera 10, a light source 20, an information processing device 30, and a retroreflection marker 40. The measurement system 100 is used for observing the biological activity of the subject 1. In the present embodiment, it is assumed that the biological activity is the respiration of the subject 1, and the measurement system 100 measures the respiration rate within a predetermined time. Although the subject 1 is shown in FIG. 2, the subject 1 is not included in the measurement system 100.

  The camera 10 is a so-called imaging device that includes an image sensor and a lens optical system, and shoots the subject 1 to generate a moving image. The camera 10 sends moving image data to the information processing apparatus 30 by wire or wirelessly.

  The light source 20 is a light source that emits light 20a. The light may be visible light or invisible light (for example, infrared light). In this embodiment, infrared light will be described as an example. Hereinafter, the light 20a is described as “infrared light 20a”.

  The information processing apparatus 30 receives data of a moving image taken by the camera 10 and measures the respiration rate of the subject 1 using a change in the image between a plurality of frame images constituting the moving image. Details of the operation of the information processing apparatus 30 will be described later.

  FIG. 3 is a perspective view of the retroreflective marker 40. FIG. 4 is a top view of the retroreflective marker 40. FIG. 5 is an exploded perspective view of the retroreflective marker 40 provided with the cover 43. FIG. 6 is a plan view of the retroreflective marker 40 provided with the cover 43. FIG. 7 shows a state in which the retroreflecting material 42 formed in a rhombus shape by the opening 44 of the cover 43 is irradiated with the infrared light 20a from the light source 20.

  The retroreflective marker 40 has a base 41 having a flat support surface 41a and is inclined at a predetermined inclination angle with respect to the support surface 41a by facing the same inclination direction (Y direction in FIG. 3). A plurality of retroreflective members 42 supported by 41a. The support surface 41a is a surface that contacts the subject 1 when the retroreflective marker 40 is placed on the subject 1. In the present embodiment, the inclination angles of the retroreflecting material 42 are all set to be equal. However, the inclination angle can be set independently so that the incident angle of the light incident on each retroreflecting material 42 is optimized. In addition, the number of retroreflective materials 42 used can be appropriately determined according to product specifications and the like in consideration of the position where the camera 10 is disposed, the size of the subject 1, and the like.

  The shape of the retroreflecting material 42 may typically be substantially rectangular as shown in the figure, but may be, for example, circular or elliptical. The side surface of the retroreflective marker 40 viewed from the Z direction in FIG. 3 includes a saw-tooth structure including a plurality of saw teeth corresponding to the plurality of retroreflective members 42. In the present embodiment, the height h of the retroreflecting material 42, that is, the height h of the saw blade (the distance from the support surface 41a to the apex of the saw blade) is all made equal in consideration of ease of manufacture and the like. Yes. However, the height h of the retroreflecting material 42 may not be all equal.

  The retroreflective material 42 is a reflective material having an optical characteristic of reflecting incident light toward the incident direction. That is, the incident angle of light incident on the retroreflecting material 42 is equal to the emission angle of light reflected by the retroreflecting material 42. However, this property is ideal and can actually be reflected in a direction different from some incident directions. In the present embodiment, the optical axis of the light source 20 and the optical axis of the camera 10 are arranged close to each other. As a result, the infrared light 20a emitted from the light source 20 is reflected by the retroreflecting material 42, and most of the light enters the camera 10 as infrared light 20b. Therefore, the camera 10 can photograph the subject 1 with a sufficient amount of light. As the retroreflecting material 42, for example, a cloth coated with glass beads can be used.

  By using the retroreflective marker 40 including a plurality of inclined retroreflective materials 42, it becomes possible to reduce the incident angle of light incident on the retroreflective material 42 arranged away from the camera 10, A decrease in luminance in the region of the retroreflecting material 42 can be suppressed. In addition, by adopting a sawtooth structure of the retroreflecting material 42 as shown in the drawing, that is, a step structure, compared to the case where the marker itself is simply inclined as shown in FIG. The height of the retroreflection marker 40 can be suppressed. As a result, the inconvenience of handling the retroreflective marker 40 is eliminated, and the retroreflective marker 40 can be brought into close contact with the subject 1.

  As shown in FIG. 4, when the plurality of retroreflecting materials 42 are arranged to be inclined, the contours of the plurality of retroreflecting materials 42 are disturbed in a sawtooth shape. The outline becomes the marker shape of the retroreflective marker 40 and is recognized as a pattern in pattern recognition described later. For this reason, the position of the retroreflective marker 40 in the frame image may not be accurately specified using pattern recognition due to the disturbance. In particular, considering a detection method using pattern edge information, it is preferable to eliminate the influence as much as possible. As will be described below, the inventor of the present application has improved the retroreflective marker 40 in consideration of the influence of the disturbance of the outline.

  As shown in FIG. 5, the retroreflective marker 40 preferably further includes a cover 43 having an opening 44. The shape of the opening 44 may be a rhombus, for example, but may be a triangle or a rectangle. The shape of the opening 44 becomes a marker shape as it is. In other words, the shape of the opening 44 gives the retroreflection marker 40 a specific reflection pattern. By providing the cover 43 so as to cover the plurality of retroreflecting materials 42, the contours of the plurality of retroreflecting materials 42 are not disturbed in a sawtooth shape as shown in FIG. Can be. In the illustrated example, the shape of the reflection pattern can be made a rhombus by using the cover 43 including the opening 44 having a rhombus shape.

  As illustrated in FIG. 7, by using the retroreflective marker 40 including the cover 43, the information processing apparatus 30 can accurately capture the marker shape. As a result, the position of the retroreflection marker 40 is accurately specified in the frame image. In the frame image, there is a possibility that a shadow (a portion with low luminance) is generated between two adjacent retroreflective members 42 due to the influence of the step. However, since the brightness of the retroreflecting material 42 is high, the shadow can be made inconspicuous by suppressing the width of the shadow projected on the image sensor.

  As shown in FIG. 2, by using the retroreflecting material 42, disturbance light 21a incident on the retroreflecting material 42 is reflected in the incident direction as reflected light 21b. Since the reflected light 21b does not substantially enter the camera 10, the moving image photographed by the camera 10 is hardly affected by disturbance light.

  The overall operation of the measurement system 100 is outlined as follows.

  First, the observer or the subject 1 arranges the retroreflective marker 40 having the shape of a specific reflection pattern at the position where the body motion accompanying the breathing of the subject 1 occurs. When the light source 20 irradiates the subject 1 with infrared light, the camera 10 receives the infrared light reflected by the retroreflection marker 40 and captures a moving image of the subject 1.

  For example, FIG. 8 shows a frame image 102 taken of the subject 1 wearing the retroreflective marker 40. A high luminance area (white area) 104 in the center of the image is an area where the reflected light from the retroreflection marker 40 is detected. When the retroreflective marker 40 having a predetermined marker shape is used, a high-luminance region having a shape corresponding to the shape is visually recognized in the image. For reference, FIG. 9 shows a frame image 106 obtained by photographing a subject who does not wear the retroreflective marker 40. In the absence of the retroreflective marker 40, it can be said that the change in luminance in the captured frame image is very small. In FIG. 8 and FIG. 9, a plurality of vertical lines and horizontal lines are shown, which are border lines virtually provided for image processing. In this specification, an area of an image divided by a boundary line is referred to as a “partial area” of the image. FIG. 8 illustrates a partial region P. Note that the boundary lines of the partial areas P are highlighted for convenience of understanding.

  The information processing apparatus 30 analyzes each of a plurality of time-series frame images constituting the moving image as shown in FIG. 8, and determines the body movement of the subject 1 based on the change in the luminance value of the plurality of frame images. To detect. More specifically, the information processing apparatus 30 detects the high luminance area 104 shown in FIG. 8 over a plurality of frame images. Since the body movement of the subject 1 during calm occurs due to breathing, the position of the high-intensity region 104 changes (vibrates) in accordance with the breathing cycle. The information processing apparatus 30 can measure the respiration rate (bpm) of the subject 1 during that period by counting the number of respiration cycles over a predetermined period, where one period of vibration of the high luminance region 104 is one respiration period. it can. The respiration rate (bpm) is expressed as 60 / respiration cycle (s).

  In this specification, an example in which the respiratory rate is mainly measured will be described. However, the respiratory rate is an example of a biological activity resulting from the subject's breathing, and other biological activities resulting from the subject's breathing may be measured. In this specification, a subject's breathing motion is measured, and a waveform resulting from breathing (a waveform corresponding to the breathing waveform) is derived from body motion due to breathing. Typically, other biological activities that can be evaluated using the waveform, for example, biological activities such as breathing depth, turbulence, apnea periods, frequency of occurrence of apnea periods, This is the category of the biological activity to be measured.

  FIG. 10 shows the vibration of the high-intensity region 104 measured based on changes in the luminance values of a plurality of frame images. The waveform observed using the retroreflective marker 40 can accurately measure body movement due to respiration even in a dark imaging environment. That is, it is possible to measure body movement, that is, respiration, using the luminance value. As a reference, FIG. 11 shows changes in luminance values of a plurality of frame images shot in a dark shooting environment without providing a retroreflective marker. Due to the absence of the retroreflective marker, the luminance change in the image is originally small, and therefore the influence of noise is very large even if the change in the luminance value is observed over a plurality of frame images. Therefore, the body motion waveform that needs to be measured is buried in noise. Note that in FIG. 10 and FIG. 11, the scale of the vertical axis differs by several times. For convenience of understanding, the scale in FIG. 11 is larger than that in FIG. In other words, it means that the one using the retroreflective marker 40 (FIG. 10) is superior in signal-to-noise ratio (SNR) than the one not using it (FIG. 11).

  According to the measurement method of the present embodiment, by using the retroreflective marker 40, it is possible to perform imaging while ensuring a sufficient amount of reflected infrared light. As a result, the subject 1 and the camera 10 can be set apart by, for example, about 6 m. Moreover, the room to be measured can be darkened. As a result, while reducing the feeling of pressure on the subject 1, the environment is less susceptible to changes in the brightness of the observation location, the position of the indoor light source, and the presence or absence of incident light from outside, that is, an environment in which the influence of noise is small. It becomes possible to shoot with. Therefore, it becomes possible to measure the biological activity more accurately. Further, by using the retroreflective marker 40 having a saw-toothed side surface as described above, the incident angle of light incident on the retroreflective material 42 can be reduced, and the reflectance of the retroreflective material 42 is maintained. can do.

  FIG. 12 shows an example of the hardware configuration of the information processing apparatus 30 in the measurement system 100. In the present embodiment, the information processing apparatus 30 is connected to the camera 10 and the display 32. The information processing apparatus 30 receives captured moving image data from the camera 10. In addition, the display 32 displays a measurement result of the number of breaths that is the biological activity of the subject 1 as a result of the processing. For example, the information processing apparatus 30 may display a warning on the display 32 when it is determined that the shooting direction of the camera 10 is not appropriate because the high-luminance area is not detected.

  The information processing apparatus 30 includes a CPU 301, a ROM 302, a RAM 303, a hard disk drive (HDD) 304, an interface (I / F) 305, and an image processing circuit 306. The CPU 301 controls the operation of the information processing apparatus 30. The ROM 302 stores a computer program. The computer program is a group of instructions for causing the CPU 301 or the image processing circuit 306 to perform processing shown by a flowchart described later, for example. A RAM 303 is a work memory for developing a computer program when executed by the CPU 301. The HDD 304 is a storage device that stores moving image data received from the camera 10 or measured respiratory rate data of the subject 1.

  The I / F 305 is an interface for the information processing apparatus 30 to receive moving image data from the camera 10. When the information processing apparatus 30 receives moving image data via a wired network, the I / F 305 is, for example, an Ethernet (registered trademark) terminal. When the information processing apparatus 30 receives moving image data via a wireless network, the I / F 305 is a transmission / reception circuit that performs communication based on, for example, the Wi-Fi (registered trademark) standard. Alternatively, the I / F 305 may be a wired video input terminal.

  The image processing circuit 306 is a so-called graphics processor that analyzes moving image data. The image processing circuit 306 detects a high luminance area of each frame image of the moving image, detects a body movement based on the vibration of the high luminance area, and counts the respiration rate based on the vibration waveform of the body movement.

  In this embodiment, the image processing circuit 306 is provided separately from the CPU 301, but this is an example. For example, an integrated circuit in which the CPU 301 and the image processing circuit 306 are integrated may be used, or the CPU 301 may perform a part of the processing of the image processing circuit 306 described later.

  FIG. 13 shows an example of a processing procedure performed in the measurement system 100.

  In step S1, the camera 10 images the subject 1 on which the retroreflective marker 40 is arranged. The captured moving image is sent to the information processing apparatus 30.

  In step S <b> 2, the image processing circuit 306 of the information processing apparatus 30 divides each of a plurality of frame images constituting the captured moving image into a plurality of partial areas. The partial region (for example, the partial region P in FIG. 8) has a size of, for example, 64 pixels horizontally and 64 pixels vertically. Note that “divide” does not require division as an actual operation. For example, the operation of setting the size of the partial area as a unit for cutting out an image or a unit for performing processing may be included in the “dividing” operation described here.

  In step S <b> 3, the image processing circuit 306 identifies a partial region where the retroreflective marker 40 exists and a partial region including a body movement location due to a biological reaction based on the luminance value of each partial region. This will be described more specifically. The partial area where the retroreflective marker 40 exists can be specified in each frame image. On the other hand, the partial region including the body movement location can be specified over a plurality of frame images, that is, between the plurality of frame images.

  The partial area where the retroreflective marker 40 exists is specified by the following process. For example, the image processing circuit 306 holds in advance in the ROM 302 information on luminance values of partial areas observed when the retroreflective marker 40 is present. This information is used as a threshold value of the luminance value, and a partial region having a luminance value equal to or higher than the threshold value is specified as a partial region where the retroreflective marker 40 exists.

  The luminance value at this time may be an integrated value of the luminance values of the pixels included in the partial region, or may be an average value. Depending on whether the integrated value or the average value of the luminance values is adopted, the threshold value may also change.

  On the other hand, the partial region including the body movement location is specified by the following process. As described above, the region where the reflected light from the retroreflective marker 40 is observed fluctuates due to body movement due to a biological reaction (respiration). Now, with respect to each frame image, attention is paid to a partial region Q existing at a certain common coordinate position. FIGS. 14A and 14B show examples of partial areas Q in two frame images taken at different times. It is assumed that the region R shown in FIGS. 14A and 14B is a high-intensity region in which reflected light from the retroreflection marker 40 is detected. The partial area Q may or may not become a high luminance area due to body movement accompanying breathing.

  FIG. 14C shows a change in the luminance value of the partial region Q at this time. When the luminance of the partial area Q is observed in time series over a plurality of frame images, a group of frame images exceeding a certain threshold T and a group of frame images not exceeding exist alternately.

  In step S3 of FIG. 13, the partial area including the body movement location is specified as the partial area Q of the coordinate position indicating the luminance change shown in FIG. Then, a luminance value calculation (image processing) is performed with a group of pixels included in the partial region Q as a group.

  In step S4, the image processing circuit 306 calculates the average luminance value of the partial region Q including the body movement location for each frame image.

  In step S5, the image processing circuit 306 counts the respiration rate of the subject using the calculated average luminance value for each frame image. Each calculated average luminance value is expressed as a waveform shown in FIG. The image processing circuit 306 counts the number of breaths within a predetermined period, with one period of body movement specified by the average luminance value of the partial region Q oscillating as one breath.

  Through the above process, the measurement system 100 can acquire information on the respiration rate with high accuracy. Since the amount of infrared light reflected from the retroreflective marker 40 including the plurality of inclined retroreflective materials 42 is sufficiently large without depending on the distance from the light source 20 to the retroreflective material 42, the camera 10 When a captured moving image is used, it is easy to specify a partial region including body movement due to respiration from the retroreflective marker 40 in the image.

  As described above, when the retroreflective marker 40 includes the cover 43, the retroreflective marker 40 functions as a marker having a specific reflection pattern (for example, a rhombus). As shown in FIG. 8, the reflection pattern is confirmed as a high luminance region in the frame image. The image processing circuit 306 may receive a moving image from the camera 10 and specify the coordinate position of the retroreflective marker 40 in each frame image using, for example, a known pattern recognition method. The coordinate position means, for example, the coordinates of each vertex and the center of gravity of the reflection pattern (diamond) shown in FIG. For example, the reflection pattern in the frame image can be specified by the pattern matching process. The image processing circuit 306 holds information (for example, a template) indicating that the retroreflective marker 40 having a specific reflection pattern is used and the characteristics of the reflection pattern in advance in, for example, the ROM 302. The image processing circuit 306 can perform pattern matching processing on each frame image using the feature of the reflection pattern and specify the coordinate position of the retroreflection marker 40. A high luminance region can be detected more reliably and more easily by using the reflection pattern.

  Since the reflection pattern includes edge information, the coordinate position of the retroreflective marker 40 in the frame image can be specified by actively using the edge information. Specifically, the image processing circuit 306 may specify the coordinate position of the retroreflective marker 40 using a corner detection method and an edge detection method. Such a specifying method is described in Japanese Patent Application No. 2015-102726 which is an unpublished patent application by the present applicant. All of these disclosures are incorporated herein by reference.

  The image processing circuit 306 can designate a partial region (see FIG. 8) based on the coordinate position of the retroreflective marker 40 specified by the above-described pattern matching processing and processing using edge information. The partial area is an area for monitoring a change in luminance value associated with body movement, and can be set to include a body movement location. The image processing circuit 306 divides each frame image into two or more. At this time, the image processing circuit 306 sets a boundary line at a position across the reflection pattern. Further, the boundary line is set in a direction different from the body movement direction. For example, it is assumed that body movement is recognized in the vertical direction in the frame image. At this time, for example, the image processing circuit 306 sets a boundary line in the horizontal direction, divides each frame image into two or more, and sets a partial region.

  An example of setting the partial area will be specifically described. The image processing circuit 306 specifies a partial area including the edge of the high reflection area corresponding to the reflection pattern. As described above, the size of the partial region can be, for example, 64 pixels wide and 64 pixels vertical. For example, the image processing circuit 306 can obtain the edge information of the reflection pattern from the corner detection result. Then, the image processing circuit 306 designates an area including the edge of the reflection pattern as a partial area. In other words, the image processing circuit 306 sets a partial region so as to straddle the edge. The edge here refers to one edge when there are a plurality of edges facing each other with respect to the fluctuation direction.

  After specifying the partial area, the image processing circuit 306 calculates an average luminance value of the partial area for each frame image. In other words, the image processing circuit 306 generates a respiratory waveform based on the luminance value for each frame image. The image processing circuit 306 may count the respiration rate of the subject using the calculated average luminance value (respiration waveform) for each frame image.

[Modification of Camera 10]
FIG. 15 shows the camera 10 equipped with an optical filter 11 that blocks the wavelength in the visible light region. The optical filter 11 is generally called an infrared filter.

  The camera 10 may further include an optical filter 11. The optical filter 11 transmits infrared light emitted from the light source 20 and reflected by the retroreflective marker 40, but blocks visible light. By providing the optical filter 11, light other than infrared light, more specifically visible light, is prevented from entering the camera 10, thereby affecting the change in the luminance value of the captured moving image. Can be reduced. Since fluctuations in the luminance value of each frame image due to visible light can be suppressed, it is possible to reduce the occurrence of disturbance noise due to only visible light and not due to biological reactions.

  The inventor of the present application considers that it is very useful to provide the optical filter 11 that blocks the wavelength in the visible light region. This is because it is often difficult to realize a complete dark room environment during actual photographing. For example, when the life activity measurement system 100 is operated in a hospital, a night light, an evacuation guide light, etc. are lit in the hospital even at night. In such a photographing environment, it is preferable to block visible light by the optical filter 11.

  Furthermore, an optical filter that blocks not only visible light but also unnecessary infrared light may be provided as the optical filter 11 shown in FIG. In other words, a band pass filter that allows infrared light emitted from the light source 20 to pass therethrough may be provided as the optical filter 11.

  First, an LED light source having a steep wavelength characteristic is adopted as the light source 20. The wavelength is, for example, 850 nm or 940 nm and their vicinity. The “steep wavelength characteristic” means that the fluctuation of the wavelength of the emitted infrared light is small here.

  In correspondence with the light source 20, the optical filter 11 is provided with an optical filter having a band pass characteristic that allows infrared light emitted from the light source 20 to pass therethrough. For example, when the wavelength of infrared light emitted from the light source 20 is 850 nm, the optical filter 11 that transmits infrared light having a wavelength of 850 nm is provided.

  By matching the wavelength of the light source 20 with the pass band of the optical filter 11, the camera 10 has sensitivity only to light having the same wavelength as the wavelength of infrared light emitted from the light source 20. Since not only visible light but also unnecessary infrared light can be blocked, the captured moving image is not affected by disturbance light. Since the retroreflection marker 40 is used, the amount of infrared light emitted from the light source 20 and reflected by the retroreflection material 40 is large. Therefore, the ease of capturing the reflected light is the same as that described above.

The inventor of the present application measured the reflection performance of the retroreflecting material using the camera 10 having the optical filter 11 and the white light source and the infrared light source. The measurement results of the reflective performance (unit: cd / lx / m ² ) of the retroreflective material are shown in Table 1 below.

  It can be seen that when the incident angle of light incident on the retroreflective material increases, the reflective performance of the retroreflective material decreases. It can be seen that when the incident angle is changed from 5 ° to 30 °, the reflection performance becomes less than half. A decrease in reflection performance leads to a decrease in luminance during photographing. By using the retroreflective marker 40 according to the present embodiment, it is possible to suppress a decrease in luminance during photographing.

(Embodiment 2)
FIG. 16 schematically shows the luminance distribution of the reflection pattern area in the frame image when the retroreflection marker 40 including the cover 44 according to the first embodiment is used.

  In the first embodiment, the inclination angles of the retroreflecting material 42 are all equal. In that case, when the installation position of the camera 10 is very low, as shown in FIG. 16, the incident angle of the light incident on the retroreflective marker 40 is large as a whole, and the retroreflective material 42 (that is, the reflective pattern). Of these areas, the incident angle is assumed to be larger in an area farther from the camera 10. The retroreflective marker 40 according to the first embodiment may be slightly insufficient depending on the measurement system used in terms of ensuring uniform luminance in the high luminance region of the reflection pattern.

  In the retroreflective material 42 according to the present embodiment, a plurality of retroreflective materials 42 are devised so that the inclination angle gradually increases as the distance from the camera 10 increases. Hereinafter, the structure of the retroreflective marker 40A according to the present embodiment will be mainly described.

  FIG. 17 is a perspective view of a retroreflective marker 40A according to the present embodiment. The retroreflective marker 40A includes a base 41 and a plurality of retroreflective members 42. Similar to the first embodiment, the retroreflective marker 40A may further include a cover 43 including an opening. In the retroreflective marker 40 </ b> A, the inclination angle of each of the plurality of retroreflective members 42 increases gradually or stepwise as the distance from the side closer to the light source 20 increases. More specifically, the retroreflective marker 40A has a sawtooth structure when viewed from the Z direction, as in the first embodiment. The heights h of the retroreflecting materials 42 (that is, saw blades) are all equal, and as shown in FIG. 17, the length in the Y direction of the base 41 that supports the retroreflecting material 42 closest to the light source is d. If the lengths of the base 41 supporting the remaining retroreflecting material 42 in the Y direction are c, b and a, respectively, a <b <c <d is satisfied. Due to this geometrical relationship, the inclination angle of the retroreflecting material 42 closest to the light source 20 is the smallest, and the inclination angle of the retroreflecting material 42 farthest from the light source 20 is the largest. The lengths a, b, c and d can be set so as to decrease stepwise or gradually in this order. In other words, the pitch of the saw blade decreases stepwise or gradually as the distance from the side closer to the light source 20 increases. More specifically, the ratio of the lengths a, b, c and d is determined so that the incident angles of light incident on the respective retroreflecting materials 42 are substantially the same.

  With reference to FIG. 18, the ratio of the lengths of the retroreflective materials 42 in the Y direction will be specifically described by taking a retroreflective marker 40 including two retroreflective materials 42 as an example.

  FIG. 18 schematically shows the positional relationship between the camera 10 (or the light source 20) and the two retroreflective members 42. The point O in the figure is the origin of the XYZ coordinate system. A point C indicating the position of the camera 10 is located on the X axis, and one end of the inclined retroreflecting material 42 is located on the Y axis. L is the length of the retroreflective marker 40 in the Y-axis direction, and h is the length of the retroreflective material 42 in the X-axis direction, that is, the height of the retroreflective marker 40. x is the distance from the position (h / 2) half the height h of the retroreflective marker 40 to the point C on the X axis, and the coordinates of the point C are (h / 2 + x, 0). y is the distance from the origin O to the center point of the retroreflective marker 40 on the Y axis. The center point corresponds to a point whose length is L / 2 from the end of the retroreflective marker 40 on the camera 10 side. The coordinates of the center point can be represented by (h / 2, y).

  β indicates the difference between the length b in the Y-axis direction and the length L / 2 of the retroreflecting material 42 on the camera 10 side. Therefore, the length b can be expressed by L / 2 + β, and the length a in the Y-axis direction of the retroreflecting material 42 on the side opposite to the camera 10 can be expressed by L / 2−β. The point P indicates the center point of the retroreflective material 42 on the camera side, and the coordinates thereof can be represented by (h / 2, y−L / 4). The point Q indicates the center point of the retroreflecting material 42 on the side opposite to the camera 10, and the coordinates thereof can be represented by (h / 2, y + L / 4).

Here, assuming that y >> x and L >> h, β at which the incident angles to the point P and the point Q are equal is obtained. Here, the above-described “incident angles of light incident on the retroreflective material 42 substantially coincide” specifically means that “the incident angles of light incident on the center point of the retroreflective material 42 are plural. It means that they substantially coincide between the retroreflecting materials 42. ∠QCP can be obtained by equation (1).
∠QCP = tan ⁻¹ (y / (x−L / 4)) − tan ⁻¹ (y / (x + L / 4)) Equation (1)

∠QCP corresponds to the angle difference between the retroreflecting material 42 on the camera 10 side and the retroreflecting material 42 on the opposite side of the camera 10, so that ∠QCP can also be expressed by equation (2). it can.
QCP = tan ⁻¹ (h / (L / 2−β)) + tan ⁻¹ (h / (L / 2 + β)) Equation (2)

Since atan (θ) can be approximated as atan (θ) ≈θ when θ is small, Equation (3) is obtained from Equations (1) and (2).
y / (x−L / 4) −y / (x + L / 4) = h / (L / 2−β) + h / (L / 2 + β) Equation (3)

Further transforming equation (3) yields equation (4).
^{yL / (x 2 -L 2/} 16) = 4βh / (L 2/4-β 2) (4)

x ² >> L ^2/16, and, since L ^2/4 >> β ² is satisfied, the formula (4) is approximated to equation (5), and finally, the equation (6) is derived The
^{yL / x 2 = 4βh / (} L 2/4) Equation (5)
β = yL ³ / 16x ² formula (6)

Although an example in which two retroreflective materials 42 are included has been described above, β can be expanded even when n retroreflective materials 42 are included, and two adjacent retroreflective materials 42 can be expanded. The length difference β _n in the Y direction is generalized by the equation (7). The ratio of the length of the retroreflecting material 42 in the Y direction can be determined using β _n .
β _n = yL ³ / (2n ³ x ² ) Formula (7)

  By using the retroreflective marker 40A according to the present embodiment, it becomes possible to reduce the incident angle of light incident on the retroreflective member 42 located away from the light source 20, and the luminance can be reduced in the entire reflection pattern region. Can be secured.

(Embodiment 3)
FIG. 19 schematically shows the luminance distribution of the reflection pattern area in the frame image when the retroreflective marker 40A including the cover 44 according to the second embodiment is used.

  In the second embodiment, the brightness of the entire reflection pattern area is ensured by setting the inclination angle of the retroreflecting material 42 to increase as the distance from the camera 10 increases. However, since the inclination angle changes depending on the boundary between two adjacent retroreflective members 42, that is, the position of the step, as shown in the figure, there is a luminance difference in a part of the reflection pattern region, that is, in the vicinity of each boundary. Can occur.

  In the present embodiment, the shape of the retroreflecting material is devised in consideration of this. More specifically, the retroreflecting material according to the present embodiment has a curved reflecting surface. The curved surface can suppress a luminance difference that may occur near the step. Hereinafter, the structure of the retroreflection marker 40B according to the present embodiment will be mainly described.

  FIG. 20 is a perspective view of a retroreflective marker 40B according to the present embodiment. FIG. 21 schematically shows the state of light rays incident near the boundary between two adjacent retroreflective members 42.

  The retroreflective marker 40 </ b> B includes a base 41 and a plurality of retroreflective materials 42. The plurality of retroreflecting materials 42 have a plurality of curved reflecting surfaces 42S. In other words, each has a curved reflecting surface 42S. The shape of the curved surface is equal to the shape of a concave mirror defined by a parabola in which the incident angles of light with respect to the normal line at any point on the curved surface of two adjacent retroreflecting materials are all equal. Similar to the first embodiment, the retroreflection marker 40B may further include a cover 43 including an opening.

  The side surface of the retroreflective marker 40B viewed from the Z direction in FIG. 20 includes a saw-tooth structure including a plurality of saw teeth corresponding to the plurality of reflection surfaces 42S. Each of the cross sections of the retroreflective marker 40 cut along a plane parallel to the XY plane includes a saw-tooth structure identical to the shape of the side surface.

According to such a configuration, as shown in FIG. 21, in the vicinity of the boundary between two adjacent retroreflective materials 42, the incident angle α _{1 of} light incident on one retroreflective material 42 and the other The difference from the incident angle α _{2 of the} light incident on the retroreflecting material 42 can be reduced. As a result, the reflection angles of the reflected light at the two adjacent retroreflecting materials 42 can be made substantially equal, so that the luminance difference can be reduced in the vicinity of each boundary of the reflective marker region.

  With reference to FIG. 22, the curved surface shape of the retroreflection material 42 will be described in detail.

  FIG. 22 schematically shows the concave mirror, the focal point, the object point, and the image point of the concave mirror. The cross-sectional shape of the reflecting surface 42S in the XY plane matches the shape of the concave mirror shown in FIG. Point C (camera position) indicates an object point, point C ′ indicates a point (image point) where a light beam emitted from point C is collected to form a real image, F indicates a focal point of the concave mirror, and f indicates The focal length of the concave mirror is shown. Point R corresponds to a point on the concave mirror corresponding to the end of the retroreflecting material 42 on the camera side, and point S corresponds to a point on the concave mirror corresponding to the end of the retroreflecting material 42 opposite to the camera side. Equivalent to. Point T indicates the intersection of the perpendicular bisector of the line segment SR and the line segment CC ′.

  In the concave mirror described above, the light beam from the point C is collected at the point C ′ by the concave mirror. The focal point F is located on the vertical bisector of the line segment SR, the vertical bisector of the line segment SR and the line segment CC ′ are perpendicular to each other at the point T, and the point T is the line segment CC ′. It coincides with the midpoint, and the distance between the line segment SR and the line segment CC ′ is equal to twice the focal length f (2f). In other words, the length of the line segment connecting the midpoint of the line segment SR and the point T is 2f.

  The curved surface shape of the retroreflecting material 42 according to the present embodiment is determined by a parabola in which the point T coincides with the midpoint of the line segment CC ′. Under this condition, the incident angle of the light beam from the point C is constant on the concave mirror. For this reason, it is possible to make all the incident angles of light with respect to the normal at any point of the plurality of reflecting surfaces 42S equal.

  In Embodiments 1 to 3, the measurement system using a retroreflective marker has been mainly described. However, another embodiment according to the present invention may be a measurement system using a reflective marker composed of a plurality of reflective materials inclined with respect to the support surface. When the angle of inclination of the reflecting material is sufficiently large, for example, when the angle is close to 90 °, the incident angle of light incident on the reflecting material can be made sufficiently small. In that case, a sufficient amount of reflected light from the subject can be secured without using a retroreflecting material. As described above, a simple reflection marker can be used depending on the inclination angle of the reflecting material and the positional relationship between the camera and the reflection marker shown in FIG.

  The present specification discloses a measurement system for life activity resulting from respiration of a subject described in the following items.

[Item 1]
A light source that emits light;
An imaging device that receives the light and generates a moving image;
An image processing circuit for measuring a subject's biological activity using the moving image, and a measurement system comprising:
When a reflection marker is arranged at a position where a body movement accompanying breathing of the subject is performed, and the light is emitted from the light source toward the subject,
The imaging device receives the light reflected by the reflective marker at a plurality of times, generates the moving image composed of a plurality of time-series frame images,
The image processing circuit receives the moving image from the imaging device, measures a biological activity caused by breathing of the subject based on a change in luminance value of the plurality of frame images,
The reflective marker includes a base having a support surface, and a plurality of reflectors each inclined with respect to the support surface and supported by the support surface.

  According to the measurement system described in Item 1, there is provided a measurement system for life activity caused by respiration, in which measurement conditions for life activity are not easily affected by the surrounding environment.

[Item 2]
The measurement system according to item 1, wherein the reflective marker is a retroreflective marker, and the plurality of reflective materials are a plurality of retroreflective materials.

  According to the measurement system described in Item 2, since the light source and the retroreflective marker are used in combination, even if the surroundings are dark or bright and the distance between the subject and the imaging device is sufficiently separated, It is possible to capture body movements caused by biological activities such as from changes in a plurality of frame images. In particular, by using a retroreflective marker including a plurality of inclined retroreflective materials, the luminance can be maintained in the region of the retroreflective marker in the plurality of frame images.

[Item 3]
When the reflective marker is disposed at a position where body movement accompanying breathing of the subject occurs,
Item 3. The measurement system according to Item 1 or 2, wherein an inclination angle of each of the plurality of reflectors increases as the distance from the side closer to the light source increases.

  According to the measurement system described in Item 3, it is possible to reduce the incident angle of the light incident on the reflective material located away from the light source, and the luminance can be ensured in the entire reflection pattern region.

[Item 4]
The side surface of the reflective marker includes a sawtooth structure including a plurality of saw teeth corresponding to the plurality of reflectors, and each of the plurality of saw teeth has an equal height,
Item 4. The measurement system according to Item 3, wherein when the reflection marker is arranged at a position where body movement is generated due to breathing of the subject, the pitch of the sawtooth decreases as the distance from the side closer to the light source decreases.

  According to the measurement system described in Item 4, the inclination angle of the reflective material closest to the light source can be minimized, and the inclination angle of the reflective material farthest from the light source can be maximized.

[Item 5]
Item 5. The measurement system according to Item 4, wherein each of the plurality of reflecting materials has a curved reflecting surface.

  According to the measurement system described in Item 5, it is possible to suppress a luminance difference that may occur in the vicinity of a step between two adjacent reflectors.

[Item 6]
The curved surface shape is equal to the shape of a concave mirror defined by a parabola in which the incident angles of the light with respect to the normal at any point on the curved surface of two adjacent reflectors are all equal,
A third direction orthogonal to a first direction parallel to an arrangement direction of the plurality of reflective materials, each of the second direction in which each reflective material extends, and a third direction orthogonal to both the first directions, and the first In the cross-section of the curved surface of each of the reflecting materials cut by a plane parallel to each direction, a point on the curved surface located at the first end of each reflecting material on the imaging device side is a point R, A point on the curved surface located at the second end of the reflector opposite to the imaging device is a point S, a focal length of the concave mirror is f, an object point is a point C, and an image point is a point C ′. Then, the perpendicular bisector of the line segment RS is orthogonal to the line segment CC ′ at the midpoint of the line segment CC ′, and the focal point of the concave mirror is located on the vertical bisector of the line segment RS. And the measurement system of item 5 whose distance of said line segment RS and said line segment CC 'is the length of 2f.

  According to the measurement system described in item 6, it is possible to suppress a luminance difference that may occur in the vicinity of a step between two adjacent reflectors.

[Item 7]
The reflective marker further includes a cover including an opening having a predetermined marker shape,
7. The measurement system according to any one of items 1 to 6, wherein, in a plan view, the shapes of the plurality of reflecting materials coincide with the predetermined marker shape.

  According to the measurement system described in Item 7, the marker shape in the image can be accurately captured.

[Item 8]
Item 8. The measurement system according to Item 7, wherein the predetermined marker shape is a triangle, a diamond, or a rectangle.

  According to the measurement system according to item 8, variations in marker shape are provided.

[Item 9]
The image processing circuit divides each frame image into a plurality of partial areas, and measures a biological activity caused by respiration of the subject based on a change in luminance values of the plurality of partial areas. A measurement system according to any one of the above.

  According to the measurement system described in item 9, the efficiency of arithmetic processing can be improved by using a partial area as a processing unit.

[Item 10]
The light source is an infrared light source that emits infrared light,
10. The measurement system according to any one of items 1 to 9, wherein the imaging device includes an optical filter that blocks a wavelength in a visible light region.

  According to the measurement system described in Item 10, it is possible to reduce the generation of disturbance noise that is caused only by visible light and not caused by a biological reaction.

  INDUSTRIAL APPLICABILITY The present invention can be used as a measurement system that analyzes a moving image obtained by photographing a subject and measures a subject's life activity, particularly the number of breaths, in a non-contact manner.

DESCRIPTION OF SYMBOLS 1 Test subject 10 Camera 20 Light source 30 Information processing apparatus 32 Display 40, 40A, 40B Retroreflective marker 41 Base 42 Retroreflective material 42S Curved surface 43 Cover 44 Opening 100 Measurement system 301 CPU
302 ROM
303 RAM
304 HDD
305 I / F
306 Image processing circuit

A measurement system according to an embodiment of the present invention includes a light source that emits light, an imaging device that receives the light and generates a moving image, and an image processing circuit that measures a biological activity of a subject using the moving image. A reflection marker is disposed at a position where body movement occurs due to breathing of the subject, and when the light is emitted from the light source toward the subject, the imaging device is Receiving the light reflected by the reflective marker at a plurality of times, generating the moving image composed of a plurality of time-series frame images, and the image processing circuit receiving the moving image from the imaging device. Receiving and measuring a biological activity caused by respiration of the subject based on a change in luminance values of the plurality of frame images, and the reflective marker includes a base having a support surface and each of which is inclined with respect to the support surface. And, wherein the support surface a plurality of reflective material supported by, further comprising a cover including an opening having a predetermined marker shape, in plan view, the shape of the plurality of reflective material, to the predetermined marker shape Match .

In one embodiment, the shape of the first cross section obtained by cutting the reflective surface by a plane parallel to the side surface of the reflective marker matches the shape of the second cross section of the concave mirror, and the first shape obtained by cutting the reflective marker by the parallel surface is used. All three cross sections have the same shape as the side surface of the reflective marker .

In one embodiment, in the concave mirror, the focal point of the concave mirror is a first end point in the second cross section of the concave mirror on the light source side and a second end point in the second cross section of the concave mirror on the side opposite to the light source. The vertical bisector is an image point where the light emitted from the light source and the light source is condensed by the concave mirror to form a real image. And the distance between the first line segment and the second line segment is equal to twice the focal length of the concave mirror .

The side surface of the retroreflective marker 40B viewed from the Z direction in FIG. 20 includes a saw-tooth structure including a plurality of saw teeth corresponding to the plurality of reflection surfaces 42S. Each of the cross sections of the retroreflective marker 40B cut along a plane parallel to the XY plane includes a sawtooth structure identical to the shape of the side surface.

[Item 1]
A light source that emits light;
An imaging device that receives the light and generates a moving image;
An image processing circuit for measuring a subject's biological activity using the moving image, and a measurement system comprising:
When a reflection marker is arranged at a position where a body movement accompanying breathing of the subject is performed, and the light is emitted from the light source toward the subject,
The imaging device receives the light reflected by the reflective marker at a plurality of times, generates the moving image composed of a plurality of time-series frame images,
The image processing circuit receives the moving image from the imaging device, measures a biological activity caused by breathing of the subject based on a change in luminance value of the plurality of frame images,
The reflective marker further includes a base having a support surface, a plurality of reflectors each inclined with respect to the support surface and supported by the support surface, and a cover including an opening having a predetermined marker shape. And
In a plan view, the shape of the plurality of reflectors is a measurement system that matches the predetermined marker shape .

According to the measurement system described in Item 1, there is provided a measurement system for life activity caused by respiration, in which measurement conditions for life activity are not easily affected by the surrounding environment.
Moreover, according to the measurement system described in Item 1, the marker shape in the image can be accurately captured.

[Item 6]
The shape of the first cross section obtained by cutting the reflective surface with a plane parallel to the side surface of the reflective marker matches the shape of the second cross section of the concave mirror,
Item 6. The measurement system according to Item 5 , wherein any of the third cross sections obtained by cutting the reflective marker along the parallel plane has the same shape as the side surface of the reflective marker .

According to the measurement system according to item 6, in the vicinity of the boundary between two adjacent reflectors, the difference between the incident angle of light incident on one reflector and the incident angle of light incident on the other reflector Can be reduced. As a result, the reflection angle of the reflected light between the two adjacent reflectors can be made substantially equal, so that a luminance difference that can occur near the step of the reflection marker region can be suppressed.

[Item 7]
In the concave mirror, the focal point of the concave mirror is a first end connecting the first end point in the second cross section of the concave mirror on the light source side and the second end point in the second cross section of the concave mirror opposite to the light source. The vertical bisector is located on a vertical bisector of the line segment, and the vertical bisector connects the light source and an image point where a light emitted from the light source is collected by the concave mirror to form a real image. orthogonal at the midpoint of the line segment, and the distance of the first segment and the second segment is characterized by equal to twice the distance of the focal length of the concave mirror, according to item 6 Measurement system.

According to the measurement system described in Item 7, since the perpendicular bisector of the first line is orthogonal at the midpoint of the second line, the incident angle of the light beam from the light source is constant on the concave mirror. Therefore, all the incident angles of light with respect to the normal line at arbitrary points on the plurality of reflecting surfaces can be made equal.

Claims (8)

A light source that emits light;
An imaging device that receives the light and generates a moving image;
An image processing circuit for measuring a subject's biological activity using the moving image, and a measurement system comprising:
When a reflection marker is arranged at a position where a body movement accompanying breathing of the subject is performed, and the light is emitted from the light source toward the subject,
The imaging device receives the light reflected by the reflective marker at a plurality of times, generates the moving image composed of a plurality of time-series frame images,
The image processing circuit receives the moving image from the imaging device, measures a biological activity caused by breathing of the subject based on a change in luminance value of the plurality of frame images,
The reflective marker includes a base having a support surface, and a plurality of reflectors each inclined with respect to the support surface and supported by the support surface.   The measurement system according to claim 1, wherein the reflective marker is a retroreflective marker, and the plurality of reflective materials are a plurality of retroreflective materials. When the reflective marker is disposed at a position where body movement accompanying breathing of the subject occurs,
3. The measurement system according to claim 1, wherein an inclination angle of each of the plurality of reflecting materials increases as the distance from the side closer to the light source increases. The side surface of the reflective marker includes a sawtooth structure including a plurality of saw teeth corresponding to the plurality of reflectors, and each of the plurality of saw teeth has an equal height,
4. The measurement system according to claim 3, wherein when the reflection marker is disposed at a position where a movement of the subject accompanying breathing of the subject occurs, the pitch of the sawtooth decreases as the distance from the side closer to the light source decreases.   The measuring system according to claim 4, wherein each of the plurality of reflecting materials has a curved reflecting surface. The curved surface shape is equal to the shape of a concave mirror defined by a parabola in which the incident angles of the light with respect to the normal at any point on the curved surface of two adjacent reflectors are all equal,
A third direction orthogonal to a first direction parallel to an arrangement direction of the plurality of reflective materials, each of the second direction in which each reflective material extends, and a third direction orthogonal to both the first directions, and the first In the cross-section of the curved surface of each of the reflecting materials cut by a plane parallel to each direction, a point on the curved surface located at the first end of each reflecting material on the imaging device side is a point R, A point on the curved surface located at the second end of the reflector opposite to the imaging device is a point S, a focal length of the concave mirror is f, an object point is a point C, and an image point is a point C ′. Then, the perpendicular bisector of the line segment RS is orthogonal to the line segment CC ′ at the midpoint of the line segment CC ′, and the focal point of the concave mirror is located on the vertical bisector of the line segment RS. The measurement system according to claim 5, wherein a distance between the line segment RS and the line segment CC ′ is 2f. The reflective marker further includes a cover including an opening having a predetermined marker shape,
7. The measurement system according to claim 1, wherein in a plan view, the shapes of the plurality of reflecting materials coincide with the predetermined marker shape. The light source is an infrared light source that emits infrared light,
The measurement system according to claim 1, wherein the imaging device includes an optical filter that blocks a wavelength in a visible light region.

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