Light detection device and booth for sleeping

Abstract

A light detection device according to the present disclosure comprises: a sensor that receives light from a user and outputs a signal to a processing circuit that generates biological information of the user; and a mask member. The sensor is a single pixel sensor having one photodiode. The mask member scatters visible wavelength range light which is included in light from a user and incident on the single pixel sensor, thereby reducing the visibility of the single pixel sensor.

Description

Light detection device and sleep booth

[0001] This disclosure relates to a light detection device and a sleep booth.

[0002] Conventionally, technologies have been known that use optical sensors or imaging devices to measure biological information such as pulse rate and heart rate of a subject. In such technologies, measurements are generally performed on exposed skin areas such as the face.

[0003] International Publication No. 2019 / 176535, Japanese Patent Publication No. 2006-162465

[0004] This disclosure provides an optical detection device and a sleep booth that can measure biometric information while protecting the privacy of the subject.

[0005] The light detection device according to this disclosure comprises a sensor that receives light from a user and outputs a signal to a processing circuit that generates the user's biological information, and a mask member. The sensor is a single-pixel sensor having one photodiode. The mask member reduces the visibility of the single-pixel sensor by scattering light in the visible wavelength range contained in the light incident from the user toward the single-pixel sensor.

[0006] Figure 1 is a schematic diagram showing an example of the configuration of a biological information measurement system according to an embodiment. Figure 2 is a block diagram showing an example of the hardware configuration of a signal processing device according to an embodiment. Figure 3 is a cross-sectional view showing an example of the position and shape of each component of a non-contact sensor according to an embodiment. Figure 4 is a cross-sectional view showing another example of the position and shape of each component of a non-contact sensor according to an embodiment. Figure 5 is a table showing an example of the visual evaluation results regarding the thickness of the mask member and the distance of the gap between the mask member and the hood according to an embodiment. Figure 6 is a table showing an example of the relationship between the combination of the thickness of the mask member and the distance between the mask member and the sensor according to an embodiment and the measurement accuracy of the information corresponding to the pulse wave. Figure 7 is a cross-sectional view showing yet another example of the position and shape of each component of a non-contact sensor according to an embodiment. Figure 8 is a diagram showing an example of the relationship between the shape of the hood of a non-contact sensor according to an embodiment and the maximum sensor incidence angle. Figure 9 is a diagram showing an example of the light range detected by a non-contact sensor according to an embodiment. Figure 10 is a graph showing an example of the relationship between the hood angle of a non-contact sensor according to an embodiment and the detection rate. Figure 11 is a diagram showing an example of the configuration of a sensor equipped with a lens hood and lens in a comparative example. Figure 12 is a graph showing an example of the instantaneous pulse measurement results according to an embodiment. Figure 13 shows an example of a sleep booth to which the bio-information measurement system according to the embodiment is applied. Figure 14 shows another application example of the bio-information measurement system according to the embodiment. Figure 15 shows an example of a reinforcing member according to Modification 1.

[0007] (Item 1) The light detection device according to Item 1 of this disclosure comprises a sensor that receives light from a user and outputs a signal to a processing circuit that generates the user's biological information, and a mask member. The sensor is a single-pixel sensor having one photodiode. The mask member reduces the visibility of the single-pixel sensor by scattering light in the visible wavelength range contained in the light incident from the user toward the single-pixel sensor.

[0008] (Item 2) In the light detection device described in Item 1, a hood having a cavity may be provided between the single-pixel sensor and the mask member. The hood may be provided surrounding the outer circumference of the sensor. The light that has passed through the mask member may pass through the cavity without passing through a lens that refracts light and enter the single-pixel sensor.

[0009] (Item 3) In the light detection device described in Item 2, a gap may exist between the mask member and the hood.

[0010] (Item 4) In the light detection device described in any of Items 1 to 3, if the thickness of the mask member in the direction from the mask member to the single-pixel sensor is t (mm), the distance between the mask member and the hood is d (mm), the distance between the single-pixel sensor and the hood is d2 (mm), and the sum of d (mm) and d2 (mm) is d' (mm), then the values ​​of t (mm), d (mm), and d' (mm) may satisfy the following two equations: 1 mm ２ ≦t・d t・d'≦40mm ２

[0011] (Item 5) In the photodetector described in any of Items 1 to 4, the thickness of the mask member may be 1 mm or less.

[0012] (Item 6) In the light detection device described in Item 2, the hood may be substantially cylindrical in shape with the single-pixel sensor as the center of the circle. When the aperture radius of the hood is r, the maximum radius of the sensor is a, the effective field of view incident on the single-pixel sensor is θ, and the height from the point where the straight line of the outermost ray of the effective field of view intersects the optical axis to the aperture surface is h, then r may satisfy the following equation: a ≤ r ≤ h * tanθ

[0013] (Item 7) In the photodetector described in any of Items 1 to 6, the mask member may include a translucent resin or a diffusion member having irregularities on the side facing the user.

[0014] (Item 8) In the light detection device described in Item 2, the hood angle, which is the inclination angle of the surface through which light toward the single-pixel sensor passes in the hood, may satisfy the following formula: 0 degrees ≤ α < 60 degrees

[0015] (Item 9) The sleep booth according to Item 9 of this disclosure comprises a light detection device as described in any of Items 1 to 8, and a sleep space in which the user sleeps. The light detection device is positioned on the ceiling corresponding to the position of the user's head when the user sleeps.

[0016] Hereinafter, embodiments of the photodetector and sleep booth related to this disclosure will be described with reference to the drawings.

[0017] The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, steps, and order of steps shown in the following embodiments are examples and are not intended to limit the art of this disclosure. Components in the following embodiments that are not described in the independent claim representing the highest-level concept are described as optional components. The figures are schematic and not necessarily strictly illustrative. Furthermore, substantially identical or similar components are denoted by the same reference numerals in each figure. Duplication of explanation may be omitted or simplified.

[0018] Figure 1 is a schematic diagram showing an example of the configuration of the biological information measurement system 1 of this embodiment. The biological information measurement system 1 is a system that measures the biological information of user P. User P is the person whose biological information is measured by the biological information measurement system 1.

[0019] Biological information refers to information that changes over time according to the state of user P. In this embodiment, we will explain assuming that the biological information is information relating to user P's pulse wave. The information corresponding to the pulse wave may be, for example, pulse rate, pulse wave interval, heart rate, RRI (heart rate interval: R-R Interval), LF (Low Frequency), HF (High Frequency), LF / HF, or CvRR (Coefficient of variation of R-R intervals).

[0020] The signal processing device 10 may also generate information related to respiration as biological information. That is, the biological information may be information indicating the respiratory rate or respiratory cycle. Alternatively, the biological information may be information related to user body movements. The biological information may include multiple of the above-mentioned types of information.

[0021] The biological information measurement system 1 comprises a signal processing device 10, a non-contact sensor 11, a lighting device 12, and a display device 13. The non-contact sensor 11 and the display device 13 and the signal processing device 10 are communicated with each other by wire or wireless means. The lighting device 12 may be, for example, a light fixture installed on the ceiling of the room where the biological information measurement system 1 is installed.

[0022] The lighting device 12 is a device that illuminates the user P. When the lighting device 12 illuminates the user P, the non-contact sensor 11 detects the light reflected by the user P.

[0023] The illumination device 12 can be any known illumination device that emits visible light or near-infrared light. The illumination device 12 is, for example, a near-infrared LED (Light Emitting Diode) illumination that emits near-infrared light. By using near-infrared light as illumination for user P, the non-contact sensor 11 can acquire light reflected from user P even when the environment around user P is dark, such as at night or while sleeping, with an illumination level below a predetermined level. Furthermore, the illumination device 12 may also be capable of emitting visible light.

[0024] Furthermore, when irradiating with near-infrared light by the lighting device 12, a filter that blocks visible light (a visible light cut filter, a bandpass filter that only passes the near-infrared light band) may be installed in front of the non-contact sensor 11 to prevent detection of visible light. By providing a filter that blocks visible light, even in environments where the illuminance fluctuates due to the swaying of curtains or other factors, it is possible to prevent the influx of ambient light components with fluctuating intensity from entering the non-contact sensor 11, thereby enabling stable signal measurement.

[0025] The display device 13 is a display that shows various types of information. The display device 13 displays the user P's biometric information generated by the signal processing device 10. Furthermore, when the signal processing device 10 transmits biometric information to another information processing device, the display device 13 may be a display provided on that other information processing device.

[0026] The signal processing device 10 generates biological information based on the signal output from the non-contact sensor 11. The signal processing device 10 may also generate biological information based on the time-dependent change in the intensity of the output signal. The signal processing device 10 is an example of a treatment circuit.

[0027] Figure 2 is a block diagram showing an example of the hardware configuration of the signal processing device 10 of this embodiment.

[0028] The signal processing unit 10 consists of a CPU (Central Processing Unit) 10A, a ROM (Read Only Memory) 10B, a RAM (Random Access Memory) 10C, and an I / F (Interface) 10D, which are interconnected via a bus 10E, and has a hardware configuration that utilizes a typical computer.

[0029] The CPU 10A is an arithmetic unit that controls the signal processing device 10 of this embodiment. The ROM 10B stores programs and the like that realize various processes performed by the CPU 10A. The RAM 10C stores data necessary for various processes performed by the CPU 10A. The I / F 10D is an interface for sending and receiving data.

[0030] The program for executing the information processing performed by the signal processing device 10 of this embodiment is provided pre-installed in a ROM 10B or the like. Alternatively, the program executed by the signal processing device 10 of this embodiment may be provided as a file in a format installable or executable by the signal processing device 10, recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, or DVD (Digital Versatile Disc).

[0031] Note that the configuration shown in Figure 2 is just one example, and the signal processing device 10 may, for example, include multiple processors. Furthermore, the signal processing device 10 may include, for example, flash memory or a non-volatile, non-temporary storage medium such as an HDD (Hard Disk Drive).

[0032] Returning to Figure 1, the signal processing device 10 has a functional configuration that includes, for example, a control unit 101, a storage unit 102, and an arithmetic unit 103. The control unit 101 and the arithmetic unit 103 are realized by a processor such as a CPU 10A executing a program stored in, for example, a ROM 10B. Note that the control unit 101 and the arithmetic unit 103 may be realized by different processors. The storage unit 102 is composed of, for example, a RAM 10C or other storage medium.

[0033] The control unit 101 controls the non-contact sensor 11 to detect a signal. The control unit 101 may control, for example, the start and end of light detection by the non-contact sensor 11. When the signal processing device 10 and the lighting device 12 are communicably connected, the control unit 101 may control the lighting and extinguishing of the lighting device 12. Further, when the lighting device 12 can irradiate both near-infrared light and visible light, the control unit 101 may control the type of light irradiated by the lighting device 12. Further, the control unit 101 may control the lighting device 12 to switch the type of light (near-infrared light, visible light) to be irradiated and the irradiation / non-irradiation of light according to the generated biometric information of the user P. For example, when it is specified from the generated biometric information of the user P that the user P is sleeping, the control unit 101 may control the lighting device 12 to irradiate near-infrared light, and when it is specified that the user P is not sleeping, to irradiate visible light.

[0034] The storage unit 102 stores the signal output from the non-contact sensor 11. Specifically, the signal output from the non-contact sensor 11 is the light detection result by the sensor 111 described later. The light detection result by the sensor 111 represents the state of the user P that changes over time.

[0035] The arithmetic unit 103 generates biometric information by executing arithmetic processing based on the detection signal output from the non-contact sensor 11. A method of generating a pulse wave and other biometric information based on the detection signal output from the non-contact sensor 11 can adopt a known method. For example, the arithmetic unit 103 may calculate a pulse value by processing a plurality of comb filters that process the light detection result, which is an input signal, for each time window of a predetermined length along the time series in parallel with different periods (intervals). Further, the arithmetic unit 103 may remove noise from the detection signal by various filters before calculating the pulse value.

[0036] The non-contact sensor 11 includes a sensor 111, a hood 112, and a mask member 113. The non-contact sensor 11 is preferably provided at a position where reflected light from an exposed part of the body surface of the user P enters. For example, the non-contact sensor 11 is provided at a position facing the face of the user P. The non-contact sensor 11 is an example of a light detection device.

[0037] The sensor 111 receives the light from the user P and outputs a signal to the signal processing device 10 that generates the biological information of the user P. More specifically, the sensor 111 is a single-pixel sensor having one photodiode, and detects the reflected light from the face of the user P. In other words, the sensor 111 has one pixel and does not have a plurality of pixels. Also, the sensor 111 can detect light from visible to near infrared, for example. In the present embodiment, the sensor 111 detects at least near infrared light.

[0038] Also, the shape of the sensor 111 may be circular or rectangular. In the present embodiment, the case where the sensor 111 is circular will be described as an example.

[0039] Also, the sensor 111 does not have a lens. Since there is no lens, light from all directions is superimposed and detected by the sensor 111. More specifically, the light from the user P passes through the mask member 113 and then enters the sensor 111 through the cavity in the hood 112 without passing through a lens that refracts the light.

[0040] The hood 112 is located between the sensor 111 and the mask member 113 and is provided so as to surround the outer periphery of the sensor 111. The hood 112 has a cavity at least in the direction facing the user P of the sensor 111. In the present embodiment, the case where the inner and outer peripheral shapes of the hood 112 are circular will be given as an example, but when the sensor is rectangular, the inner peripheral shape of the hood 112 may be rectangular. Also, the outer peripheral shape of the hood 112 is not limited to circular or rectangular.

[0041] The hood 112 increases the detection rate of reflected light from the user P by blocking light rays that enter the sensor 111 from unwanted angles. In other words, the hood 112 controls the angle of light rays that enter the sensor 111. The signal-to-noise ratio of the sensor 111 can be improved by blocking light with the hood 112. The material of the hood 112 may be resin. For example, it may include at least one of ABS resin, polycarbonate (PC), polypropylene (PP), polystyrene (PS), and polyethylene (PE). The material of the hood 112 may also be metal. For example, it may include at least one of duralumin, aluminum alloy, and stainless steel (SUS). Details of the shape of the hood 112 will be described later.

[0042] The mask member 113 is provided so as to cover the sensor 111 and the hood 112 in the direction of the sensor 111 facing the user P. The mask member 113 reduces the visibility of the sensor 111 by scattering light in the visible wavelength range contained in the light incident on the sensor 111 from the user P. The visibility of the sensor 111 refers to its visibility when the user P looks at the sensor 111 from the outside. In this embodiment, since the mask member 113 covers the hood 112 as well as the sensor 111, the visibility of the hood 112 is also reduced. The lower the visibility of the sensor 111 and the hood 112, the less likely the user P is to notice the presence of the sensor 111 and the hood 112, and the lower the possibility of mistaking the non-contact sensor 11 for a camera.

[0043] For example, the mask member 113 may be made of a scattering material with a cloudy interior. More specifically, the mask member 113 may be made of a translucent resin. When the mask member 113 is placed between the user P and the sensor 111, some of the light traveling from the user P to the sensor 111 is scattered (Mie scattering, etc.) inside the resin and returns to the user P's eyes. As a result, the visibility from the user P to the sensor 111, etc., is reduced.

[0044] In this embodiment, as an example, the material of the mask member 113 is a translucent white resin. The translucent white resin can be, for example, a fluoropolymer film (PTFE: Poly Tetra Fluoro Etherene). The mask member 113 made of PTFE is produced by cutting (skiving) a compression-molded block to form a sheet. The mask member 113 produced in this way is a milky white sheet.

[0045] The thickness of the mask member 113 in the direction from the mask member 113 toward the sensor 111 may be 1 mm or less, or 0.5 mm or less. Alternatively, the thickness may be 0.2 mm or less. In this embodiment, the thickness of the mask member 113 is 1 mm or less. Making the mask member 113 thicker makes it possible to make the hood 112 and sensor 111 less visible to the user P, but if it is too thick, the scattering of reflected light to the sensor 111 will increase. If the scattering of reflected light becomes too large, the detection rate of reflected light from the user P's skin will decrease, which can be a factor in the decrease in the S / N ratio of biological information. For this reason, by making the thickness of the mask member 113 thin to 1 mm or less, the transmittance of near-infrared light will increase, the proportion of reflected light from the user P will increase, and the S / N ratio in pulse detection can be improved.

[0046] Examples of fluororesins other than PTFE that can be used as materials for the mask component 113 include PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene hexafluoropropylene copolymer), ETFE (tetrafluoroethylene ethylene copolymer), PVDF (polyvinylidene fluorophosphate), PCTFE (polychlorotrifluoroethylene), and ECTFE (chlorotrifluoroethylene ethylene copolymer).

[0047] In addition to fluororesin, acrylic, polyacetal, polyethylene, polycarbonate, ABS resin, rigid polyvinyl chloride, PET resin, polystyrene resin, and AS resin can also be used as materials for the mask component 113.

[0048] Regardless of which of the above-mentioned resins or other materials is used, it is desirable that the mask member 113 be milky white and semi-transparent. A property of milky white resin is that it scatters visible light well and reflects some light. Therefore, by forming the mask member 113 from a milky white and semi-transparent resin, it appears white to the user P's eye, making it difficult to see the sensor 111 placed behind it. On the other hand, near-infrared light has a longer wavelength and is therefore less scattered than visible light, so the light reflected from the person can easily pass through the resin and reach the sensor 111 in a relatively straight line. Therefore, when the illumination device 12 irradiates near-infrared light, even if a resin is placed between the sensor 111 and the user P, the biological information measurement system 1 can measure the pulse while maintaining a high signal-to-noise ratio.

[0049] The translucent resin used as the material for the mask component 113 may, for example, be a resin with a haze of 20% or more, or a resin with a haze of 30% or more. Haze represents the degree of light scattering and can be measured using a haze meter or the like.

[0050] Next, the details of the position and shape of the mask member 113 and the hood 112 in this embodiment will be described.

[0051] Figure 3 is a cross-sectional view showing an example of the position and shape of each component of the non-contact sensor 11 according to this embodiment. In the example shown in Figure 3, the mask member 113 of the non-contact sensor 11 is integrated with, for example, a lighting panel and is not directly joined to the hood 112. In this case, for example, the mask member 113 may be replaced with a lighting panel of indoor lighting such as a ceiling light. In this case, the sensor 111, hood 112, and lighting device 12 may be attached to the light source side of the ceiling light.

[0052] In the example shown in Figure 3, the hood 112 has an opening 3 at a position opposite the sensor 111 in the detection direction of the sensor 111. The size of the opening 3 is the same as or larger than the sensor 111. In the example shown in Figure 3, the size of the opening 3 is approximately the same as the sensor 111.

[0053] Furthermore, as described above, since the sensor 111 does not have a lens, there is a cavity 30 between the mask member 113 and the sensor 111. It is sufficient that at least the space between the opening 3 of the hood 112 and the sensor 111 is a cavity 30; the space between the opening 3 and the sensor 111 in the hood 112 may not be a cavity 30, but rather a solid structure made of resin or the like. In other words, the hood 112 may have a substantially cylindrical shape with a cavity 30 between the opening 3 and the sensor 111.

[0054] A gap of distance d exists between the mask member 113 and the hood 112. This gap is an example of a gap between the mask member 113 and the hood 112. This gap makes it difficult for the user P to see the opening 3 of the hood 112 and the sensor 111 through the mask member 113. Therefore, by providing a gap between the mask member 113 and the hood 112, the possibility of the non-contact sensor 11 being mistaken for a camera is reduced compared to when the mask member 113 and the hood 112 are in close contact.

[0055] The gap distance d between the mask member 113 and the hood 112 may be, for example, 1 mm or more and 70 mm or less. The appropriate gap distance d also depends on the thickness and opacity of the mask member 113. For example, if the mask member 113 is thick and highly opaque, the opening 3 of the hood 112 and the sensor 111 may be difficult to see through the mask member 113, so the gap may be 5 mm or less. The relationship between the thickness of the mask member 113 and the gap distance d will be described later using Figures 5 and 6. Also, in Figure 3, the distance from the hood 112 to the sensor 111 is denoted as d2. In the shape of the hood 112 shown in Figure 3, more specifically, d2 is the distance from the end of the opening 3 of the hood 112 on the mask member 113 side to the sensor 111. Also, the sum of distance d and distance d2 is denoted as d'. As shown in Figure 3, d' is, in other words, the distance between the mask member 113 and the sensor 111.

[0056] As shown in Figure 3, in the configuration where the mask member 113 and the hood 112 are not joined, depending on the thickness and opacity of the mask member 113 and the distance d of the gap between the mask member 113 and the hood 112, it is possible to completely shield the hood 112 and the sensor 111 so that they are not visible to the user P.

[0057] Figure 4 is a cross-sectional view showing another example of the position and shape of each component of the non-contact sensor 11 according to this embodiment. As shown in Figure 4, a part of the hood 112 of the non-contact sensor 11 may be joined to the mask member 113. In this case, the gap distance d between the mask member 113 and the hood 112 is defined with respect to the surface of the hood 112 where the opening 3 is provided (opening surface).

[0058] In Figure 4, the outer periphery of the hood 112 is joined to the mask member 113 by rising higher than the area where the opening 3 is provided. However, the means of joining the hood 112 and the mask member 113 are not limited to this. For example, one or more other members that join the hood 112 and the mask member 113 may be provided between the hood 112 and the mask member 113.

[0059] Next, we will explain in detail the relationship between the thickness of the mask member 113 and the gap distance d between the mask member 113 and the hood 112.

[0060] Generally, the thickness of the mask member 113 exponentially scatters and attenuates the light incident from the user P toward the sensor 111. Similarly, the distance between the sensor 111 and the mask member 113 also exponentially attenuates the light.

[0061] The following equations (1) to (3) define the relationship between the thickness of the mask member 113, the distance d between the mask member 113 and the hood 112, and the distance d2 between the hood 112 and the sensor 111. In the following equations (1) to (3), as in Figure 3, the thickness of the mask member 113 is t (mm), the gap distance between the mask member 113 and the hood 112 is d (mm), and the distance between the mask member 113 and the sensor 111 is d2 (mm). Also, as shown in equation (3), d' (mm) is the sum of distance d (mm) and distance d2 (mm). d' (mm) is the distance between the mask member 113 and the sensor 111. In this case, the value of A in the following equation (1) is 1, preferably 3, and even more preferably 6. Also, the value of B in the following equation (2) is 40, preferably 25, and even more preferably 10. The symbol "・" represents multiplication. A≦t・d...(1) t・d'≦B...(2) d'=d+d2...(3)

[0062] Furthermore, by rearranging equations (1) to (3), we obtain the following equation (4): A ≤ t・d ≤ B - t・d² ... (4)

[0063] The value of "t・d" is the lower limit A = 1 (mm ２ If the value falls below ), there is a high possibility that the hood 112 or sensor 111 will pass through the mask member 113 and be visible to the user P. Also, the value of "t・d'" is the upper limit B = 40 (mm ２ If the value exceeds this limit, the signal-to-noise ratio of the light detection signal from sensor 111 decreases, and the accuracy of detecting biological information deteriorates.

[0064] In other words, the gap distance d is the distance between the mask member 113 and the object to be concealed by the mask member 113. The object to be concealed is something that could be mistaken for a camera if seen by the user P, such as the opening 3 of the hood 112 in the configuration example shown in Figures 3 and 4.

[0065] The value of A will be explained in detail using Figure 5. Figure 5 is a table showing an example of the visual evaluation results regarding the thickness t of the mask member 113 and the gap distance d between the mask member 113 and the hood 112 according to this embodiment.

[0066] Figure 5 shows the results of evaluating whether the hood 112 or the sensor 111 can be visually recognized through the mask member 113 for a plurality of combinations of thickness t and distance d, in four levels: "◎: cannot be seen at all", "○: hardly visible", "△: faintly visible", and "×: visible". The material of the mask member 113 used in the visual evaluation of Figure 5 is PTFE. Also, in the visual evaluation of Figure 5, the same hood 112 and sensor 111 are used for all combinations.

[0067] For example, like the combination of thickness t = 0.2 mm and distance d = 2 mm shown in Figure 5, when the value of "t·d" is less than 1 (mm ２ ), the result is that the hood 112 or the sensor 111 can be seen through the mask member 113, i.e., "×: visible". Also, for combinations where the value of "t·d" is 1 (mm ２ ) or more, the result is that the hood 112 or the sensor 111 can hardly be seen through the mask member 113, either "◎: cannot be seen at all", "○: hardly visible", or "△: faintly visible". Also, for combinations where the value of "t·d" is 3 (mm ２ ) or more, the result is that the hood 112 or the sensor can hardly be seen through the mask member 113, either "◎: cannot be seen at all" or "○: hardly visible". Also, for combinations where the value of "t·d" is 6 (mm ２ ) or more, the result is that the hood 112 or the sensor 111 cannot be seen at all through the mask member 113, i.e., "◎: cannot be seen at all".

[0068] From such visual evaluation results, it was specified that by setting the value of "t·d" to 1 (mm ２ ) or more, the hood 112 or the sensor 111 on the back side of the mask member 113 can be hidden at least to the extent of being faintly visible.

[0069] Next, the value of B will be specifically explained using Figure 6. Figure 6 is a table showing an example of the relationship between the combination of the thickness t of the mask member 113 according to the present embodiment and the distance d' between the mask member 113 and the sensor 111, and the measurement accuracy of information corresponding to the pulse wave.

[0070] In the measurement results shown in Figure 6, the same hood 112 and sensor 111 are used in all combinations. Also, in Figure 6, the value of d' is fixed at 50 (mm).

[0071] Specifically, the graph in Figure 6(a) shows experimental heart rate values ​​of user P measured based on the signal detected by the non-contact sensor 11, when the thickness t = 0.2 mm of the mask member 113 and the value of "t・d" is 10. In the case shown in Figure 6(a), the heart rate error with the electrocardiograph was in the low 1% range on a 1-minute average, demonstrating experimentally good accuracy. Specifically, the average error between the measurement results of the non-contact sensor 11 and the measurement results of the electrocardiograph in Figure 6(a) is 1.1%. This average error value is comparable in accuracy to that of a typical finger-contact pulse meter.

[0072] Furthermore, the graphs in Figure 6(b) to (d) show estimated results (simulation values, SIM values) calculated by adding noise corresponding to the thickness t of the mask member 113 to the measurement results shown in Figure 6(a). For example, in Figure 6(b), noise has been added to achieve a similar error based on the experimental values ​​in Figure 6(e). The experimental values ​​in Figure 6(e) are the same as the simulation conditions in Figure 6(b), with t = 0.2 (mm), d' = 50 (mm), and t・d: 25 (mm) ２ These are values ​​measured under the following conditions.

[0073] As shown in the graph of Figure 6(b), the thickness t of the mask member 113 is 0.5 mm, and the value of "t・d'" is 25 (mm ２ When this occurred, the heart rate error with the electrocardiograph was in the high 1% range on average per minute. Therefore, “t・d'” = 25 (mm ２ The combination of values ​​in this case is presumed to be a condition where the accuracy for detecting heart rate variability begins to become insufficient.

[0074] Furthermore, as shown in the graph in Figure 6(c), the thickness t of the mask member 113 is 0.8 mm, and the value of "t・d'" is 40 (mm ２ At this point, the average error is estimated to be close to 3%, and the accuracy of detecting the heart rate itself begins to become insufficient.

[0075] Furthermore, as shown in the graph of Figure 6(d), the thickness t of the mask member 113 is 0.85 mm, and the value of "t・d'" is 43 (mm ２ It is estimated that when this occurs, a large amount of noise is generated, and a regular heartbeat may not be obtained.

[0076] Therefore, the upper limit B of “t・d'” defined in equation (2) above is no more than 40 (mm ２ Preferably 25 (mm) ２ ), more preferably 10 (mm ２ This allows the accuracy of the measurement results of the non-contact sensor 11 to be maintained at a certain level or higher.

[0077] Furthermore, in the examples shown in Figures 3 and 4, the size of the opening 3 of the hood 112 was approximately the same as that of the sensor 111, but the opening 3 may be larger than that of the sensor 111.

[0078] For example, Figure 7 is a cross-sectional view showing yet another example of the position and shape of each component of the non-contact sensor 11 according to this embodiment. As shown in Figure 7, the hood 112 may have a tapered cavity 30 that is inclined toward the sensor 111.

[0079] In the example shown in Figure 7, the portion of the hood 112 facing the mask member 113 is an opening 3, except for the joint with the mask member 113. In such a case, as shown in Figure 7, "d (distance of the gap between the mask member 113 and the hood 112) = 0", so "d2 = d'".

[0080] Next, we will describe the details of the hood 112's configuration.

[0081] Figure 8 shows an example of the relationship between the shape of the hood 112 of the non-contact sensor 11 according to this embodiment and the maximum sensor incidence angle θ. Note that the mask member 113 is omitted in Figure 8 for illustrative purposes. Also, in Figure 8, as an example, a substantially cylindrical hood 112 surrounding the outer circumference of the sensor 111 is shown. The corner of the hood 112 on the inner circumference side (i.e., the sensor 111 side) is cut off, and it has a tapered slope toward the sensor 111.

[0082] As shown in Figure 8, it is desirable that the aperture radius r (mm) of the hood 112, the radius or maximum effective radius a (mm) of the sensor 111, the maximum sensor incidence angle (effective field of view) θ incident on the sensor 111, and the height h from the point where the straight line of the outermost ray of the effective field of view θ intersects the optical axis to the aperture surface satisfy the following equation (5). The maximum sensor incidence angle θ is the angle of the ray with the largest incidence angle among the ray rays incident on the sensor 111 from outside the hood 112. Note that the symbol "*" means multiplication, similar to the symbol "•". a ≤ r ≤ h * tanθ ... (5)

[0083] The maximum sensor incidence angle (effective field of view) θ is basically determined by the design specifications of the biological information measurement system 1.

[0084] If the aperture radius r of the hood 112 satisfies equation (5), the light incident from the aperture 3 of the hood 112 is included in the effective field of view θ of the sensor 111.

[0085] Furthermore, if the opening radius r of the hood 112 exceeds the upper limit h * tanθ specified in equation (5), the amount of unwanted light incident on the sensor 111 from undesirable angles will increase. Also, the hood 112 may become unnecessarily large, which may cause inconvenience in terms of installation and other aspects.

[0086] Equation (5) applies not only to the hood 112 with the shape shown in Figure 8, but also to the hood 112 with the shape described in Figures 3, 4, and 7, or to hoods 112 with other shapes. Although the mask member 113 is omitted in Figure 8, it is desirable that equation (5) be satisfied even when the mask member 113 is provided.

[0087] One method for verifying whether the non-contact sensor 11 satisfies equation (5) is to measure the maximum sensor incidence angle θ using a laser with an adjusted incidence angle. More specifically, the laser is shone multiple times from outside the hood 112 toward the sensor 111 while changing the incidence angle. In this case, the maximum sensor incidence angle θ can be calculated from the laser angle at which light is no longer detected by the sensor 111. Furthermore, the point where the straight line of the outermost ray of the effective field of view intersects the optical axis can be calculated from the mechanical positional relationship between the sensor 111 and the hood 112.

[0088] Furthermore, as described above, the hood 112 increases the detection rate of reflected light from the user P by blocking light rays that enter the sensor 111 from unnecessary angles. Here, we will explain the relationship between the inclination angle of the surface through which light toward the sensor 111 passes in the hood 112 and the detection rate of reflected light from the user P in the sensor 111. The inclination angle of the surface through which light toward the sensor 111 passes in the hood 112 is also called the hood angle.

[0089] Figure 9 shows an example of the light range detected by the non-contact sensor 11 according to this embodiment. The region 40 shown in Figure 9 is the range within the hemispherical space 4 surrounding the sensor 111 in which light is incident on the sensor 111 without being blocked by the hood 112. In other words, the hood 112 blocks light incident from outside the region 40. The region 40 includes the face of user P. Also, r_obj indicates the radius of user P's face.

[0090] If sensor 111 were to capture all the light from the hemispherical space 4, it would capture a large amount of light incident from a space where user P is not present. Light incident from a space where user P is not present is unnecessary for measuring biological information.

[0091] The hood 112 blocks light with a large angle of incidence, limiting the amount of light incident on the sensor 111, thereby improving the detection rate of reflected light from user P's face relative to the total incident light. The detection rate of reflected light from user P's face relative to the total incident light is calculated as the ratio of reflected light from user P's face to the total amount of light taken in by the sensor 111 (the amount of light incident from region 40), as shown in equation (6) below. Hereinafter, the detection rate of reflected light from user P's face relative to the total incident light will simply be referred to as the detection rate.

[0092]

[0093] The detection rate depends on the hood angle of the hood 112. Figure 10 is a graph showing an example of the relationship between the hood angle α of the non-contact sensor 11 according to this embodiment and the detection rate. In calculating the detection rate in Figure 10, let a be the sensor radius or maximum effective radius, h be the height from the sensor surface to the opening surface, α be the hood angle, r be the distance from the sensor 111 to the user P's face, and r_obj be the radius of the user P's face. The calculation conditions for the detection rate shown in Figure 10 are 2a = 9.5 mm, h = 150 mm, r = 750 mm, and r_obj = 100 mm.

[0094] α = 0 degrees is the hood angle when, for example, the inner wall of the opening 3 of the hood 112 is positioned perpendicular to the sensor 111, as shown in Figures 3 and 4.

[0095] Furthermore, α = 90 degrees corresponds to a state where the hood 112 is not provided. Under conditions where the hood 112 is not provided, the detection rate is approximately 1.7%.

[0096] By providing the hood 112, the detection rate can be increased by several to tens of times compared to the state without the hood 112. The amplitude of the pulse waveform is a very small signal change, about 0.1% of the detected value of reflected light from the face using near-infrared light. Therefore, in the case of a detection rate of 1.7% without the hood 112, if the detected signal is 100,000, the signal change due to the pulse will be a very small 1.7, and without the hood 112, it takes 100,000 gradations to finally be able to detect the pulse.

[0097] Furthermore, as shown in Figure 10, when the hood angle α exceeds 60 degrees, the detection rate becomes almost the same as when the hood angle α is 0 degrees. Therefore, it is desirable that the hood angle α be within the range shown in equation (7) below: 0 degrees ≤ α < 60 degrees ... (7)

[0098] Next, we will describe the configuration of the non-contact sensor 11 according to this embodiment and a sensor that detects light incident through a lens as a comparative example.

[0099] Figure 11 shows an example of the configuration of a sensor 90 equipped with a lens hood 91 and lenses 92a to 92d in a comparative example. Note that the sensor 90 shown in Figure 11 is a known image sensor, the lens hood 91 is a known camera lens hood, and the lenses 92a to 92d are known camera lenses.

[0100] Generally, the aperture radius r1 of the lens hood 91 in such comparative examples is determined to satisfy the following equation (8): h1 * tanθ1 < r ... (8)

[0101] The effective field of view θ1 of the sensor 90 shown in Figure 11 is the angle between the light ray 910 with the maximum field of view incident on the sensor 90 and the optical axis 920. Also, h1 is the distance from the intersection of the light ray 910 with the maximum field of view and the optical axis 920 to the opening of the lens hood 91. In other words, in this comparative example, the aperture radius r1 of the lens hood 91 is set to be greater than the product of h1 and tanθ1.

[0102] In the comparative example, the role of the lens hood 91 is to reduce flare caused by the reflection of light from angles greater than the effective angle of view θ1. As shown in Figure 11, in the comparative example, the aperture radius r1 of the lens hood 91 is greater than h1 * tanθ1. Also, due to the refraction of light by lenses 92a to 92d, light (rays) 902 outside the effective angle of view θ1 are basically focused outside the sensor 90. Light (rays) 901 within the effective angle of view θ1 are incident on the sensor 90. Note that although Figure 11 illustrates light incident from the left half of the lens hood 91, the same applies to light incident from the right half.

[0103] In this comparative example, because light outside the effective field of view θ1 is imaged outside the sensor 90 via lenses 92a to 92d, unwanted light does not enter the sensor 90. Furthermore, if the aperture radius r1 is narrowed to a size close to the effective field of view, the incident range of light will coincide with the effective area of ​​the sensor 90, so if there is a manufacturing error, there is a possibility that light within the effective field of view θ1 will not reach the sensor 90.

[0104] Therefore, in such comparative examples, the aperture radius r1 is generally configured to allow light with an effective field of view θ1 or greater to enter, so that even if the image on the sensor 90 shifts due to manufacturing errors, an image is formed across the entire surface of the sensor 90.

[0105] In contrast, as described above, the non-contact sensor 11 according to this embodiment does not have a lens. Also, as explained in Figure 8, the aperture radius r of the hood 112 and the height h from the point where the straight line of the outermost ray of the effective field of view θ intersects the optical axis to the aperture surface are configured to satisfy the above-described equation (5). For this reason, the configuration of the non-contact sensor 11 according to this embodiment differs from the comparative example using the conventional technology which includes lenses 92a to 92d.

[0106] Next, we will describe an actual measurement example using the biological information measurement system 1 according to this embodiment, which is configured as described above.

[0107] Figure 12 is a graph showing an example of instantaneous pulse rate measurement results according to this embodiment. More specifically, Figure 12 shows the results of simultaneously measuring the heart rate of user P using the bio-information measurement system 1 and a comparative electrocardiograph according to this embodiment.

[0108] The dashed graph in Figure 12 shows the heart rate measured by the electrocardiogram (ECG) obtained with a comparison electrocardiograph. The comparison heart rate is the true value used to evaluate the measurement results of the biological information measurement system 1 according to this embodiment.

[0109] The solid line graph in Figure 12 shows the results of simultaneous measurement of the user P's heart rate by the biometric information measurement system 1 according to this embodiment.

[0110] The two measurement results shown in Figure 12 were measured simultaneously in the same environment. Specifically, user P was lying on their back in bed. The non-contact sensor 11 of the biometric information measurement system 1 was installed on the ceiling. The distance from user P's face to the sensor 111 was 75 cm. The hood angle α was 30 degrees. The lighting device 12 was installed next to the non-contact sensor 11 on the ceiling and emitted near-infrared light towards user P. Specifically, the illumination wavelength was 940 nm. The visible light in the room where the measurement was performed was turned off.

[0111] As shown in Figure 12, the measurement results obtained by the biometric information measurement system 1 according to this embodiment closely match the true value. Specifically, the 1-minute average pulse rate measurement error in the measurement test was 1.2%. The biometric information measurement system 1 according to this embodiment is capable of such highly accurate measurements.

[0112] The highly accurate measurement results obtained by the biological information measurement system 1 according to this embodiment make it possible, for example, to determine the sleep stage of user P and to understand the arousal and sedation state of the autonomic nervous system by analyzing heart rate variability.

[0113] Figure 13 shows an example of a sleep booth 5 to which the bio-information measurement system 1 according to this embodiment is applied. In the example shown in Figure 13, a non-contact sensor 11 and a sleep space 50 where user P sleeps are provided.

[0114] Furthermore, the non-contact sensor 11 is positioned, for example, on the ceiling of the sleeping booth 5. In the example shown in Figure 13, the mask member 113 of the non-contact sensor 11 also serves as a lighting panel 60 and is installed on the ceiling. The non-contact sensor 11 and the lighting device 12 are provided within the lighting panel 60.

[0115] The lighting device 12 may be an integrated near-infrared and visible light illuminator.

[0116] The signal processing device 10 may be installed inside the sleeping booth 5 or outside the sleeping booth 5. The display device 13 is generally installed outside the sleeping booth 5.

[0117] The sleeping space 50 where user P sleeps may be, for example, a bed, futon, or reclining chair.

[0118] Sleeping booth 5 can be a bedroom in a home, a nap booth for medical personnel in a hospital, or a hotel room. Sleeping booth 5 can support the health of user P.

[0119] For example, in the sleep booth 5, the biometric information measurement system 1 can measure the pulse rate of user P during sleep. In addition, the calculation unit 103 of the signal processing device 10 of the biometric information measurement system 1 may measure information related to user P's respiration by frequency filtering the detection signal of the non-contact sensor 11. Furthermore, the calculation unit 103 of the signal processing device 10 of the biometric information measurement system 1 may detect user P's body movements based on large fluctuations in the detection signal. The signal processing device 10 may improve the accuracy of sleep stage estimation by measuring information on respiration and body movements in addition to pulse rate.

[0120] The sleep booth 5 configured in this way can, for example, detect whether user P has fallen asleep and provide support for falling asleep. For example, the calculation unit 103 of the signal processing device 10 of the biological information measurement system 1 may determine that the user has fallen asleep if the heart rate drops to a predetermined value (e.g., 8-10%) in a short time (a time less than or equal to a predetermined length). Alternatively, the control unit 101 of the signal processing device 10 may control the illumination device 12 to emit near-infrared light if it is determined from the generated biological information of user P that user P is asleep, and visible light if it is determined that user P is not asleep. The signal processing device 10 may generate user P's biological information based on near-infrared light if it determines from the generated biological information of user P that user P is asleep. The signal processing device 10 may generate user P's biological information based on visible light if it determines from the generated biological information of user P that user P is not asleep. The visible light used to generate the biological information may be reflected light from the user based on light from a light source different from the illumination device 12.

[0121] Furthermore, the calculation unit 103 of the signal processing device 10 may visualize the sleep depth of user P from the generated biometric information of user P. The control unit 101 of the signal processing device 10 may output the visualization result of user P's sleep depth to, for example, the display device 13 or an information processing device such as user P's smartphone. In addition, the control unit 101 of the signal processing device 10 may improve the quality of sleep by linking it with the intervention of sensory stimulation according to the sleep level. For example, the control unit 101 of the signal processing device 10 may control the air conditioning system of the sleep booth 5 to adjust the room temperature according to user P's sleep state.

[0122] Since the non-contact sensor 11 is not a camera, it does not acquire images of user P using the sleeping booth 5, thus protecting user P's privacy. Furthermore, because the non-contact sensor 11 does not need to be attached to user P's body, it does not cause user P any inconvenience or feeling of constraint, and therefore does not disturb user P's sleep. In addition, because the non-contact sensor 11 does not come into contact with user P's body, a hygienic condition can be maintained even when the sleeping booth 5 is used by multiple users P.

[0123] Figure 14 shows another application example of the biological information measurement system 1 according to this embodiment. In the example shown in Figure 14, the sleeping booth 5 is a hospital room or a room in a nursing care facility (hereinafter referred to as "hospital room, etc."). The user P shown in Figure 14 is a hospital patient or a resident of a nursing care facility. Also, the sleeping space 50 shown in Figure 14 is a bed provided in the hospital room, etc.

[0124] In the example shown in Figure 14, the non-contact sensor 11 is attached to a support member 70 and installed on the bed. It is desirable that the non-contact sensor 11 be positioned above the user P's face. The non-contact sensor 11 and the support member 70 may be part of the bed, or they may be removable devices attached to the bed. For example, the non-contact sensor 11 and the support member 70 may be retrofitted to an existing bed without requiring any installation work. Alternatively, the non-contact sensor 11 and the support member 70 may be installed on the wall on the user P's face side.

[0125] Furthermore, the lighting device 12 that emits near-infrared light may be installed on the support member 70 together with the non-contact sensor 11, or it may be installed on the ceiling of a hospital room or the like.

[0126] For example, if the sleeping booth 5 is a hospital room, the vital signs measurement system 1 is used to monitor the patient's condition. The vital signs measurement system 1 can also be applied to measuring the body movements or other vital signs of newborns to prevent sudden neonatal death syndrome (SIDS).

[0127] Furthermore, for example, if the sleeping booth 5 is a room in a nursing care facility, the biometric information measurement system 1 records the resident's sleep state, allowing caregivers to understand whether the resident slept well the previous day.

[0128] As a comparative example, in heart rate measurement devices that are attached to the user P's body, dementia patients and infants may remove them. In contrast, this method does not have such a risk because it is a non-contact measurement method. Another comparative example is a technology that measures body movement or other vital signs using a sensor pad placed under the bed sheet, but this requires changing the sensor or repositioning it due to sheet changes or urine leaks. In contrast, with this method, changing the sheet or the user P's clothes does not affect the placement of the non-contact sensor 11, thus reducing the burden on administrators. Furthermore, compared to contact methods, non-contact measurement like this method does not pose hygiene risks or require cleaning.

[0129] It should be noted that the applications of the biometric information measurement system 1 according to this embodiment are not limited to the examples shown in Figures 13 and 14. For example, a non-contact sensor 11 may be placed inside a vehicle. In this case, the non-contact sensor 11 may monitor users P in the front seats, including the driver's seat and passenger seat, or it may monitor users P in the rear seats.

[0130] As described above, the non-contact sensor 11 of this embodiment comprises at least a sensor 111 that receives light from user P and outputs a signal to a signal processing device 10 that generates user P's biological information, and a mask member 113. Sensor 111 is a single-pixel sensor having one photodiode. The mask member 113 reduces the visibility of sensor 111 by scattering light in the visible wavelength range contained in the light incident from user P toward sensor 111. Therefore, with the non-contact sensor 11 of this embodiment, biological information can be measured while protecting user P's privacy.

[0131] Furthermore, the non-contact sensor 11 of this embodiment includes a hood 112 having a cavity 30 between the sensor 111 and the mask member 113. The hood 112 surrounds the outer circumference of the sensor 111. Light that has passed through the mask member 113 passes through the cavity 30 without going through a lens that refracts light and enters the sensor 111. Therefore, with the non-contact sensor 11 of this embodiment, the hood 112 restricts the direction of incidence of light entering the sensor 111, thus improving the signal-to-noise ratio of the light detection result.

[0132] Furthermore, in the non-contact sensor 11 of this embodiment, a gap exists between the mask member 113 and the hood 112. Therefore, the non-contact sensor 11 of this embodiment reduces the possibility that user P can see the hood 112 through the mask member 113. This reduces the possibility that user P may mistake the non-contact sensor 11 for a camera or feel insecure about their privacy.

[0133] Furthermore, in the non-contact sensor 11 of this embodiment, if the thickness of the mask member 113 in the direction from the mask member 113 toward the sensor 111 is t (mm), the distance between the mask member 113 and the hood 112 is d (mm), and the sum of d (mm) and d2 (mm) is d', then the values ​​of t, d, and d' satisfy the above-described equations (1) to (3), for example, the value of A in equation (1) is 1 (mm ２ ), the value of B in equation (2) is 40 (mm ２It is desirable that the following conditions are met. According to the non-contact sensor 11 of this embodiment that satisfies these conditions, the possibility of the user P viewing the hood 112 through the mask member 113 is reduced, and the signal-to-noise ratio of the light detection result and the biological information based thereon can be maintained at a high level.

[0134] Furthermore, in the non-contact sensor 11 of this embodiment, the thickness t of the mask member 113 is 1 mm or less. Therefore, the mask member 113 does not scatter the light incident from the user P to the sensor 111 excessively, and a high signal-to-noise ratio can be maintained for the light detection result and the biological information based thereon.

[0135] Furthermore, in the non-contact sensor 11 of this embodiment, the hood 112 is substantially cylindrical in shape with the sensor 111 as its center. When the aperture radius of the hood 112 is r, the maximum radius of the sensor 111 is a, the effective field of view incident on the sensor 111 is θ, and the height from the point where the straight line of the outermost ray of the effective field of view θ intersects the optical axis to the aperture surface is h, the aperture radius r satisfies the above-described equation (5). Therefore, the non-contact sensor 11 of this embodiment reduces the incidence of light from areas unnecessary for measuring biological information, and also reduces the need for the hood 112 to become unnecessarily large.

[0136] Furthermore, in the non-contact sensor 11 of this embodiment, the material of the mask member 113 is a translucent resin. Therefore, with the non-contact sensor 11 of this embodiment, the sensor 111 and the like, which are positioned behind the mask member 113, can be made less visible to the user P, and the signal-to-noise ratio of the light detection result by the sensor 111 and the biological information based thereon can be maintained at a high level.

[0137] Furthermore, in the non-contact sensor 11 of this embodiment, the hood angle α satisfies the above-described equation (7). Therefore, the non-contact sensor 11 of this embodiment can maintain a high detection rate of reflected light from the user P's face relative to the total incident light.

[0138] (Modification 1) In the above embodiment, the thickness of the mask member 113 was set to 1 mm or less. However, if the mechanical strength of the mask member 113 is insufficient due to its thin form, a reinforcing member may be superimposed on the mask member 113.

[0139] Figure 15 shows an example of a reinforcing member 114 according to Modification 1. The reinforcing member 114 may be, for example, a transparent plastic plate or a transparent glass plate that is thicker than the mask member 113. The reinforcing member 114 may be bonded to the mask member 113 or it may be closely superimposed on it. If the reinforcing member 114 has a higher mirror-like surface than the mask member 113, the reinforcing member 114 may be installed facing the user P from a design perspective.

[0140] (Modification 2) In the above embodiment, the mask member 113 was made of a translucent resin, but the material of the mask member 113 is not limited to this. For example, the mask member 113 may include a diffusion member having irregularities on the surface facing the user P.

[0141] Specifically, the mask member 113 may be a diffuser plate with an uneven surface on the user P side. Due to the uneven surface of the diffuser plate, some of the light traveling from user P to sensor 111 is scattered and returns to user P's eyes. This reduces the visibility of the hood 112 and sensor 111 from the user P's perspective.

[0142] The diffuser plate may have a textured surface on both sides, or the side facing user P may be mirror-finished to prevent dust from adhering, while only the surface opposite user P is textured. Furthermore, the material used before the textured surface is processed may be, for example, transparent glass or acrylic. Alternatively, the diffuser plate may be produced by forming a textured surface on a smooth substrate using nanoimprinting.

[0143] (Modification 3) In the above embodiment, an example was given in which the lighting device 12 is a light fixture installed on the ceiling of the room where the biological information measurement system 1 is installed, but the lighting device 12 is not limited to this. For example, the lighting device 12 may be a light fixture installed separately from the room's lighting and dedicated to the biological information measurement system 1. In this case, the lighting device 12 may be connected to the signal processing device 10 in a communicative manner, or it may be installed independently without being connected to the signal processing device 10.

[0144] Furthermore, if the non-contact sensor 11 is used in a state where the user P is sufficiently exposed to natural light, the biometric information measurement system 1 does not need to include the lighting device 12.

[0145] The lighting device 12 may be controlled to switch on and off by the signal processing device 10. The lighting device 12 may also be controlled by the signal processing device 10 to switch the type of light emitted between visible light and near-infrared light. Furthermore, when the biological information measurement system 1 measures a user P inside a vehicle, the interior lights or ambient lights installed in the vehicle may be used as the lighting device 12.

[0146] Furthermore, the measurement of user P's biological information by the non-contact sensor 11 may be performed in an environment where it is not illuminated by the lighting device 12. For example, the measurement of user P's biological information by the non-contact sensor 11 may be performed under ambient light such as sunlight or existing indoor lighting. Ambient light includes light in the visible light wavelength range. When ambient light is used, there is no need to provide dedicated lighting, which reduces costs. Also, if the visible light illuminance is stable at a constant value, the absorbance of hemogolobin is higher than that of near-infrared light, which can improve the signal-to-noise ratio of the measurement.

[0147] Furthermore, when the lighting device 12 emits visible light, it may be provided as a separate lighting source specifically for the biological information measurement system 1, distinct from the room lighting. This is because the built-in light sources in rooms, etc., may not be stable. Generally, since pulse rate changes account for about 0.001 to 0.01% of the signals detected by a single-pixel sensor, the temporal variation in the illuminance of the lighting should be at least 0.01%, preferably 0.001%, and even more preferably 0.0001%. In this case, the temporal variation in illuminance refers to, for example, the standard deviation over a 10-second period. Specifically, in an environment where no user P is present, a reflective object equivalent to a living organism is used as the measurement target, and the time-series data of the detection signal detected by the non-contact sensor 11 is passed through a 4th-order Butterworth filter with a cutoff frequency of 0.5 Hz and a high-pass filter, and the standard deviation over a 10-second period is taken as the temporal variation in illuminance. This evaluation method makes it possible to stably calculate the amount of variation by removing monotonically increasing / decreasing components and the effects of low-frequency fluctuations.

[0148] (Modification 4) In the above embodiment, a single-pixel sensor having one photodiode was given as an example of the sensor 111, but other sensors may be used as the sensor 111. For example, the sensor 111 may be a photodetector, a silicon sensor, an InGaAs sensor, etc.

[0149] (Modification 5) The non-contact sensor 11 may also be equipped with an image sensor having multiple pixels as sensor 111, instead of a single-pixel sensor. Even when an image sensor is used as sensor 111 in the non-contact sensor 11, the visibility of the image sensor can be reduced by providing a mask member, allowing for monitoring of biometric information while respecting the privacy of the user P.

[0150] (Modification 6) The non-contact sensor 11 may also be composed of a hood 112 and a sensor 111 without a mask member 113. For example, if the sensor 111 is rectangular instead of circular, or if a filter that blocks visible light (a visible light cut filter, a bandpass filter that only passes the near-infrared light band) that looks like a mirror is installed between the sensor 111 and the user P, the possibility of the sensor 111 being mistaken for a camera is low. In such cases where the possibility of the sensor 111 being mistaken for a camera is low, the possibility of the sensor 111 being configured without a mask member 113 is low, and the possibility of causing the user P to feel insecure about their privacy is low. The filter that blocks visible light may be directly above the sensor 111, or it may be installed inside the hood 112 or on the side facing the user P.

[0151] (Modification 7) When the non-contact sensor 11 is composed of a mask member 113 and a sensor 111 without a hood 112, the thickness t (mm) of the mask member 113 and the distance d' (mm) between the mask member 113 and the sensor 111 may satisfy the following formula (9): 1 mm ２ <t・d'<40mm ２ ... (9)

[0152] If the value of "t・d'" is too small, there is a high possibility that the sensor 111 will pass through the mask member 113 and be visible to the user P. Also, if the value of "t・d'" is too large, the signal-to-noise ratio of the light detection signal from the sensor 111 will decrease, and the accuracy of detecting biological information will deteriorate. For this reason, it is desirable that the value of "t・d'" falls within the range shown in equation (9). Furthermore, even when the non-contact sensor 11 is equipped with a hood 112, if the hood 112 has a tapered cavity 30 that is inclined toward the sensor 111 as explained in Figure 7, the thickness t (mm) of the mask member 113 and the distance d' (mm) between the mask member 113 and the sensor 111 may satisfy equation (9).

[0153] While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0154] 1. Biological information measurement system 3. Aperture 4. Space 5. Sleeping booth 10. Signal processing unit 10A. CPU 10B. ROM 10C. RAM 10D. I / F 10E. Bus 11. Non-contact sensor 12. Lighting device 13. Display device 30. Cavity 40. Area 50. Sleeping space 60. Lighting panel 70. Support member 90, 111. Sensor 91. Lens hood 92a, 92b, 92c, 92d Lens 101. Control unit 102. Memory unit 103. Calculation unit 112. Hood 113. Mask member 114. Reinforcement member 901, 902, 910. Light ray 920. Optical axis

Claims

1. A light detection device comprising: a sensor that receives light from a user and outputs a signal to a processing circuit that generates the user's biological information; and a mask member, wherein the sensor is a single-pixel sensor having one photodiode, and the mask member reduces the visibility of the single-pixel sensor by scattering light in the visible wavelength range contained in the light incident from the user toward the single-pixel sensor.

2. The light detection device according to claim 1, wherein a hood having a cavity is provided between the single-pixel sensor and the mask member, the hood is provided surrounding the outer circumference of the sensor, and the light that has passed through the mask member passes through the cavity without passing through a lens that refracts light and enters the single-pixel sensor.

3. The light detection device according to claim 2, wherein a gap exists between the mask member and the hood.

4. When the thickness of the mask member in the direction from the mask member toward the single-pixel sensor is t (mm), the distance between the mask member and the hood is d (mm), the distance between the single-pixel sensor and the hood is d2 (mm), and the sum of d (mm) and d2 (mm) is d' (mm), then the values ​​of t (mm), d (mm), and d' (mm) satisfy the following equations (1) and (2): 1 mm ２ ≦t・d...(1) t・d'≦40mm ２ ... (2) The light detection device according to claim 3.

5. The photodetector according to claim 4, wherein the thickness of the mask member is 1 mm or less.

6. The hood is substantially cylindrical in shape with the single-pixel sensor as its center, and when the aperture radius of the hood is r, the maximum radius of the sensor is a, the effective field of view incident on the single-pixel sensor is θ, and the height from the point where the straight line of the outermost ray of the effective field of view intersects the optical axis to the aperture surface is h, then r satisfies the following equation (2): a ≤ r ≤ h * tanθ ... (2) The light detection device according to claim 2.

7. The light detection device according to claim 1, wherein the mask member includes a translucent resin or a diffusion member having irregularities on the surface facing the user.

8. The hood angle, which is the inclination angle of the surface through which light toward the single-pixel sensor in the hood passes, satisfies the following equation (3): 0 degrees ≤ α < 60 degrees ... (3) The light detection device according to claim 2.

9. A sleeping booth comprising: a light detection device according to claim 1; and a sleeping space in which the user sleeps, wherein the light detection device is positioned on the ceiling corresponding to the position of the user's head when the user sleeps.

Images