Optical concentration measurement device

Abstract

To provide a compact, highly accurate optical concentration measurement device with an ellipsoid mirror and a folding mirror.SOLUTION: An optical concentration measurement device has a light guide part in which at least a portion of an inner surface is composed of a figure which is a portion of an ellipsoid E. At least a portion of another part of the inner surface of the light guide part is composed of a figure which is a portion of a plane surface or a quadratic surface. At least 60% of a light-emitting region of a light-emitting part is located in a region Rin, and at least 60% of a light-receiving region of a light-receiving part is located in a region Rout.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to optical concentration measuring devices. [Background technology]

[0002] Gas detection devices for detecting gases are used in various fields. For example, Patent Document 1 discloses a device that includes a light source that emits infrared rays and a detector that detects infrared rays of a specific wavelength in a case having an ellipsoidal inner surface (ellipsoidal mirror), and is configured so that a gas to be detected is introduced into the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-071816 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses an optical path design in which a light emitting unit and a light receiving unit are arranged in the outer region of the focal point of an ellipsoidal mirror. When the ellipsoidal mirror is not large compared to the size of the light emitting unit, the light emitted from the light emitting unit can be collected at the light receiving unit placed in the outer region of the other ellipse.

[0005] On the other hand, with the recent trend towards miniaturization of gas detection devices, there is a demand for further miniaturization.

[0006] Therefore, there is a demand for more efficient use of spatial volume to increase the optical path length per unit size and to increase the gas sensitivity per unit volume.

[0007] In view of the above, an object of the present disclosure is to provide a small-sized, highly accurate optical concentration measuring device that includes an ellipsoidal mirror and a folding mirror. [Means for solving the problem]

[0008] (1) An optical concentration measuring device according to an embodiment of the present disclosure, A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. c Let E be the ellipse c The two foci of F a , F b Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation. in year, Ellipsoid E in The area included in the region R in year, Inside ellipsoid E, inside ellipsoid E in The area not included in is the area R out year, 60% or more of the area of ​​the light source region of the light-emitting part is the region R in exists in 60% or more of the area of ​​the light receiving region of the light receiving unit is region R out exists.

[0009] (2) As an embodiment of the present disclosure, in (1), The entire area of ​​the light source region of the light emitting unit is within the region R in exists in The entire area of ​​the light receiving region of the light receiving unit is within the region R out exists.

[0010] (3) As an embodiment of the present disclosure, in (1), The plane or the quadric surface is an ellipse E c It passes near one of the foci of

[0011] (4) As an embodiment of the present disclosure, in (1), The light receiving portion is located near the end of the ellipsoid E.

[0012] (5) As an embodiment of the present disclosure, in (1) or (2), The angle between the elliptical symmetry plane present in the center of the major axis of the ellipsoid E and the portion where the plane or the quadric surface is connected to the light guiding portion is 1° or more.

[0013] (6) As an embodiment of the present disclosure, in any one of (1) to (5), The ellipse E c The ratio of the semimajor axis a to the semiminor axis b (a / b) is 1.2 or greater.

[0014] (7) As an embodiment of the present disclosure, in any one of (1) to (6), The vicinity is defined as the maximum length of the ellipsoid E, L E When the distance from the one focus (L E / 5) or less.

[0015] (8) As an embodiment of the present disclosure, in any one of (1) to (7), The maximum length of the light source area is L s The maximum length of the ellipsoid E is L E When L s ≧(L E / 50).

[0016] (9) As an embodiment of the present disclosure, in any one of (1) to (8), The maximum length of the light receiving area is L d The maximum length of the ellipsoid E is L E When L d ≧(L E / 50).

[0017] (10) As an embodiment of the present disclosure, in any one of (1) to (9), The same holder holds the light emitting portion and the light receiving portion.

[0018] (11) As an embodiment of the present disclosure, in any one of (1) to (10), The reflecting surface 10 further includes an auxiliary reflecting portion having a shape different from that of the ellipsoid E.

[0019] (12) As an embodiment of the present disclosure, in (11), The region R in The auxiliary reflecting portion is located within the

[0020] (13) As an embodiment of the present disclosure, in any one of (1) to (12), The light emitting portion is a surface light source.

[0021] (14) As an embodiment of the present disclosure, in any one of (1) to (13), The ellipsoid E is a spheroid.

[0022] (15) As an embodiment of the present disclosure, in any one of (1) to (14), At least a part of another portion of the inner surface of the light guiding portion has a flat shape.

[0023] (16) As an embodiment of the present disclosure, in any one of (1) to (14), At least a part of another portion of the inner surface of the light guiding portion has a spherical shape.

[0024] (17) As an embodiment of the present disclosure, in (1), Two or more reflecting surfaces, each of which is a part of a plane or a quadric surface, are connected to the symmetric plane of the ellipsoid E.

[0025] (18) As an embodiment of the present disclosure, in (17), The angle between the two reflecting surfaces is 10° or more and 90° or less.

[0026] (19) An optical concentration measuring device according to an embodiment of the present disclosure, A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. c Let E be the ellipse c The two foci of F a , F b Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation. in year, Ellipsoid E in The area included in the region R in year, Inside ellipsoid E, inside ellipsoid E in The area not included in is the area R out year, The center of gravity of the light source area or the peak point of brightness is point G in , the center of gravity of the light receiving area is point G out Then, point G in is the region R in exists at point G out is the region R out exists.

[0027] (20) An optical concentration measuring device according to an embodiment of the present disclosure, A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. c Let E be the ellipse c The two foci of F a , F b Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation. in year, Ellipsoid E in The area included in the region R in year, Inside ellipsoid E, inside ellipsoid E in The area not included in is the area Rout year, 60% or more of the area of ​​the light source region of the light-emitting part is the region R out exists in 60% or more of the area of ​​the light receiving region of the light receiving unit is region R in exists.

[0028] (21) An optical concentration measuring device according to an embodiment of the present disclosure, A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. c Let E be the ellipse c The two foci of F a , F b Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation. in year, Ellipsoid E in The area included in the region R in year, Inside ellipsoid E, inside ellipsoid E in The area not included in is the area R out year, The center of gravity of the light source area or the peak point of brightness is point G out , the center of gravity of the light receiving area is point G in Then, point G in is the region R in exists at point G out is the region R out exists. Effect of the Invention

[0029] According to an embodiment of the present disclosure, it is possible to provide a small-sized, highly accurate optical concentration measurement device including an ellipsoidal mirror and a folding mirror. [Brief description of the drawings]

[0030] [Figure 1]FIG. 1 is a diagram showing an example of ray tracing in a prior art ellipsoidal mirror. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of a gas detection device according to an embodiment of the present disclosure. [Figure 3A] FIG. 3A is a diagram showing an example of a ray tracing simulation result. [Figure 3B] FIG. 3B is a diagram showing an example of a ray tracing simulation result. [Figure 4] FIG. 4 is a diagram showing an example of a ray tracing simulation result for the gas detection device according to the embodiment of the present disclosure. [Diagram 5] FIG. 5 is a diagram showing another configuration example of the gas detection device according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram showing another configuration example of a gas detection device according to an embodiment of the present disclosure. [Figure 7A] FIG. 7A is a perspective view showing an example of the configuration of a gas detection device including a long-axis symmetric surface mirror. [Figure 7B] FIG. 7B is a front view showing an example of the configuration of a gas detection device including a long-axis symmetric surface mirror. [Figure 7C] FIG. 7C is a side view showing an example of the configuration of a gas detection device including a long-axis symmetric surface mirror. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] <Gas detection equipment> Fig. 1 is a diagram showing an example of ray tracing in a conventional ellipsoidal mirror. Fig. 2 is a cross-sectional view of a gas detection device according to an embodiment of the present disclosure. The gas detection device is a small device having dimensions of, for example, 7.8 mm x 9.0 mm x 4.7 mm in length x width x height, and is also called a gas sensor.

[0032] In this embodiment, the gas detection device is an NDIR (Non Dispersive InfraRed) type device that measures the concentration of a gas to be detected based on infrared rays transmitted through an introduced gas. The gas detection device in this embodiment can be applied to various devices. For example, it can be used for environmental measurement in a building, for installation in a mobile communication device such as a smartphone as a portable small measurement device, and for detecting gas concentrations inside a vehicle such as an automobile, a train, or an airplane.

[0033] In this embodiment, the gas to be detected is carbon dioxide (CO2), but is not limited thereto, and may be, as another example, a combustible gas such as alcohol (ethanol, etc.), methane, propane, hydrogen, ethylene, MCH (methylcyclohexane), etc. The gas to be detected may also be a toxic gas such as carbon monoxide, hydrogen sulfide, formaldehyde, ammonia, etc. Furthermore, the gas to be detected may be a greenhouse gas such as nitrous oxide or a refrigerant gas used in an air conditioner or refrigerator, etc.

[0034] Furthermore, according to the configuration of the gas detection device in this embodiment, it can be applied as a light receiving and emitting device for purposes other than gas detection. That is, the disclosure derived by replacing the above-described "gas detection device" with "optical concentration measuring device", "optical physical quantity measuring device", "light receiving and emitting device", "optical device", etc., is included in the scope of this disclosure. For example, it becomes possible to detect the state of the optical path space (existence or concentration of a specific component of a fluid, as an example other than gas). For example, it can be used as a component detection device or component concentration measurement device for a substance (e.g., water or body fluid) present in the optical path space between the light emitting unit and the light receiving unit. For example, the component detection device or component concentration measurement device can be used to measure the glucose concentration in blood when the substance present in the optical path space is blood.

[0035] The component detection device or component concentration measurement device can measure the glucose concentration in blood glucose by measuring the absorption of light with a wavelength of 1 to 10 μm. In measuring the glucose concentration in blood glucose, it is preferable to measure the absorption of light with wavelengths of 1.6 μm, 2.0 to 2.3 μm, and 9.6 μm. A small, highly accurate, and highly reliable non-invasive glucose concentration measurement device can be realized. With such a glucose concentration measurement device, for example, a diabetic patient can accurately check his or her own blood glucose level without causing damage to the skin that occurs with invasive methods. Furthermore, more accurate management of medication (e.g., insulin) can be realized based on the blood glucose level thus measured.

[0036] The gas detection device of the present embodiment includes a light-emitting unit 10, a light-receiving unit 20, and a light-guiding unit 30 that guides light from the light-emitting unit 10 to the light-receiving unit 20. The gas detection device may further include a control unit that controls or converts signals of the light-emitting unit 10 and the light-receiving unit 20, a housing that has a gas port 31 and holds the light-guiding unit 30, and a holding unit 40 that is a substrate or the like that holds the light-emitting unit 10, the light-receiving unit 20, the control unit, and the housing.

[0037] At least a part of the shape of the inner surface of light guiding section 30 is configured as all or part of an ellipsoid. At least a part of another part of the inner surface of light guiding section 30 is configured as a part of a plane or a quadric surface.

[0038] Here, the ellipsoid constituting the shape of at least a portion of the inner surface of light-guiding section 30 may be referred to as ellipsoid E. Ellipse E may be a spheroid. FIG. 2 is a diagram for explaining the details of the configuration of the gas detection device. Light-guiding section 30 includes a portion corresponding to ellipsoid E (ellipsoid mirror 30E) and another portion (folding mirror 30C, see FIG. 4). Light-guiding section 30 may include yet another planar portion (long-axis symmetric mirror 30H). The ellipse that has the maximum area in the cross section of ellipsoid E is referred to as ellipse E. c Let E be the ellipse c The two foci of F a , F b The ellipsoid with the smallest volume that passes through and has a scaling relationship with ellipsoid E without rotation is ellipsoid E. inIt is said that the ellipsoid E in The area included in is region R in In addition, inside the ellipsoid E, in The area not included in is region R out It is assumed that the shape of at least a part of another portion (folding mirror 30C) of the inner surface of light guiding section 30 is configured with a partial figure of a plane or a quadratic curved surface. In this embodiment, it is assumed that reflecting surface Q of folding mirror 30C is configured with a partial figure of a plane or a quadratic curved surface. Here, in the example of FIG. 2, the gas detection device has a shape that includes only a part of an ellipsoid E, but when explaining an ellipsoid or ellipse, it is explained that there is a virtual ellipsoid or ellipse configured by virtually extending the surface.

[0039] In the gas detection device of this embodiment, 60% or more of the area of ​​the light source region of the light-emitting unit 10 is the region R in and 60% or more of the area of ​​the light receiving region of the light receiving section 20 is in the region R out It is configured to be present in

[0040] Moreover, the above reflecting surface Q is an ellipse E c The optical axis is configured to pass near one of the foci.

[0041] Although the detailed principle will be described later, by adopting this configuration, it is possible to provide a small-sized, highly accurate gas detection device that uses an ellipsoidal mirror.

[0042] <Interrelationships between components> As described above, the gas detection device includes the light emitting section 10, the light receiving section 20, and the light guiding section 30. The gas detection device may further include a holding section 40. The gas detection device may additionally include a control section.

[0043] The surfaces of the light-emitting unit 10 and the light-receiving unit 20 are in contact with the space (detection space) between the inner wall of the light-guiding unit 30 and the upper surface of the holding unit 40. The light-guiding unit 30 may be provided with a gas port 31 capable of introducing and emitting gas into and from the detection space. The holding unit 40 may be provided with the gas port 31.

[0044] The light emitted from the light-emitting section 10 is reflected at least once on the inner surface of the light-guiding section 30 and reaches the light-receiving section 20 .

[0045] <Light emitting part> The light emitting unit 10 is a component that emits light used to detect the gas to be detected. There are no particular limitations on the light emitting unit 10 as long as it outputs light that includes a wavelength that is absorbed by the gas to be detected. In this embodiment, the light emitted by the light emitting unit 10 is infrared light, but is not limited thereto.

[0046] The light-emitting unit 10 has a light-emitting element. In this embodiment, the light-emitting element is an LED (light emitting diode), but other examples may include a lamp, a laser (Light Amplification by Stimulated Emission of Radiation), an organic light-emitting element, or a MEMS (Micro Electro Mechanical Systems) heater. The light-emitting unit 10 may include not only a light-emitting element, but also a passive element that passively emits light upon receiving light emitted by the light-emitting element. The passive element is, for example, a mirror, an optical filter, a phosphor, an optical image, an optical fiber, an optical waveguide, a lens, or a diffraction grating.

[0047] The light-emitting unit 10 has a light source region. The light source region is a component that generates photons of the light-emitting element when light is guided from the light-emitting element to the light-guiding unit 30 without passing through a passive element as in this embodiment. For example, if the light-emitting unit 10 is a quantum-type light-emitting element, the light source region may be the region of the element itself, or it may be an active region. For example, if the light-emitting unit 10 is a thermal light source, the light source region may be the region of the heat source element itself, or it may be a high-temperature region. For example, if the light-emitting unit 10 is a lamp, the light source region may be the internal region of a bulb (glass bulb), or it may be a filament.

[0048] Furthermore, when the light-emitting unit 10 includes passive elements and guides the light emitted by the light-emitting elements to the light-guiding unit 30 via the passive elements, the light source region is a collection of the light emitting ends of the passive elements. For example, when the passive elements are mirrors, the light source region is a region that reflects the light.

[0049] For example, when the passive element is an optical filter having a wavelength selection function, the light source area may be a surface of the optical filter that is in contact with the space and through which light passes. For example, when the passive element is an optical fiber, an optical waveguide, or a lens, the light source area may be a light source area.

[0050] Furthermore, when an optical image is formed as the light emitting unit 10 by a lens or a mirror, the formed image may be regarded as the light source area.

[0051] Here, the light emitting unit 10 is preferably a planar surface light source, such as an LED, a MEMS heater, or a VCSEL (Vertical Cavity Surface Emitting LASER). Since the light emitting surface is planar, the volume of the optical image of the light source is small and concentrated, and light can be efficiently collected at the light receiving unit 20. This makes it possible to configure a small optical system.

[0052] <Light receiving section> The light receiving unit 20 is a component that receives light that has passed through the introduced gas. The light receiving unit 20 is not particularly limited as long as it has sensitivity to a band of light that includes a wavelength that is absorbed by the gas to be detected. In this embodiment, the light received by the light receiving unit 20 is infrared light, but is not limited thereto.

[0053] The light receiving unit 20 has a light receiving element. In this embodiment, the light receiving element is a photodiode, but as another example, it may be a phototransistor, a thermopile, a pyroelectric sensor, a bolometer, or a photoacoustic detector. The light receiving unit 20 may include not only the light receiving element, but also an indirect element that guides light to the light receiving element. The indirect element is, for example, a mirror, an optical filter, a phosphor, a lens, a diffraction grating, an optical fiber, or an optical waveguide. Here, at least one of the light receiving unit 20 and the light emitting unit 10 may be configured to include an optical filter.

[0054] The light receiving unit 20 has a light receiving region. The light receiving region is a region of the light receiving element that has a function of converting the received light into a signal when the light receiving element receives light directly without passing through an indirect element as in this embodiment. For example, the light receiving region is an active layer if the light receiving element is a photodiode, and is a thermoelectric conversion section if the light receiving element is a thermopile.

[0055] In addition, when the light receiving element of the light receiving unit 20 receives light through an indirect element, the light receiving region is a region of the indirect element that has an optical function of guiding the received light to the light receiving element and through which the light ray passes. For example, when the indirect element is an optical filter having a wavelength selection function, the light receiving region may be a region through which the light ray passes on a surface of the optical filter that is in contact with the space. In addition, when the indirect element is an optical fiber, an optical waveguide, or a lens, the light receiving region may be an incident surface through which the light ray passes on a surface that is in contact with the space. In addition, when the indirect element is a mirror, the region that reflects the light ray may be the light receiving region.

[0056] <Light guide section> The light guiding section 30 is a member that guides the light emitted by the light emitting section 10 to the light receiving section 20, and is an optical system of the gas detection device. The light emitted from the light emitting section 10 is reflected by the light guiding section 30 and reaches the light receiving section 20. In other words, the light guiding section 30 optically connects the light emitting section 10 and the light receiving section 20.

[0057] In this embodiment, the inner surface of the light guiding unit 30 is a mirror (reflective surface). At least a part of the shape of the inner surface has an elliptical mirror 30E that is the whole or part of an ellipsoid. The light guiding unit 30 may further include an auxiliary plane mirror, a concave mirror or a convex mirror, a lens, or a diffraction grating. The auxiliary plane mirror, concave mirror or convex mirror is called an auxiliary reflecting unit. The gas detection device may further include an auxiliary reflecting unit that is configured with a different shape from the ellipsoid E, for example, and the region R in The auxiliary reflector may be arranged to be present within the

[0058] In this embodiment, the shape of the reflecting surface Q of the folding mirror 30C, which is at least a part of the inner surface of the light guide unit 30, is configured as a plane or a part of a quadric curved surface. c In this embodiment, the light guiding unit 30 further includes a long-axis symmetric mirror 30H which is a plane mirror that is part of the shape of a symmetric plane including the long axis of the ellipsoid E.

[0059] The material constituting the mirror may be, for example, metal, glass, ceramics, stainless steel, etc., but is not limited to these.

[0060] Furthermore, the mirror may partially have a wavelength filter function.

[0061] From the viewpoint of improving the detection sensitivity, it is preferable that the material constituting these mirrors is composed of a material having a small light absorption coefficient and a high reflectance. Specifically, a resin housing coated with an alloy containing aluminum, gold, or silver, a dielectric, or a laminate of these is preferable. Examples of materials for the resin housing include LCP (liquid crystal polymer), PP (polypropylene), PEEK (polyether ether ketone), PA (polyamide), PPE (polyphenylene ether), PC (polycarbonate) or PPS (polyphenylene sulfide), PMMA (polymethyl methacrylate resin), PAR (polyarylate resin), and hard resins containing two or more of these. In addition, from the viewpoint of reliability and change over time, a resin housing coated with gold or an alloy layer containing gold is preferable. Furthermore, it is preferable to form a dielectric laminate film on the surface of the metal layer to increase the reflectance. When the inner surface of the light guide unit 30 is formed on the resin housing by deposition or plating, it is possible to improve productivity and weight reduction compared to when it is formed from a metal material. Furthermore, the difference in thermal expansion coefficient with the holding portion 40 is reduced, thermal deformation is suppressed, and sensitivity fluctuations are less likely to occur.

[0062] The light guide 30 may be formed by cutting, and from the viewpoint of productivity, it is more preferable to form it by injection molding. When the light guide 30 is formed by injection molding, if the light guide 30 is a concave shape, the injection mold cannot be pulled out in one direction. Therefore, from the viewpoint of productivity, the light guide 30 is preferably a convex shape. The folding mirror 30C may be arranged so as to be parallel to the symmetrical plane present in the center of the long axis of the ellipsoid of the elliptical mirror 30E. At this time, the light guide 30 is a convex shape, and when the injection mold is pulled out in one direction, it can have an inclination with respect to all faces. On a face perpendicular to the pull-out direction of the injection mold, distortion occurs during removal due to the adhesion between the mold and the resin, but if there is an inclination with respect to the pull-out direction, the distortion can be reduced. At this time, it can be molded with one set of molds, and the light guide 30 can also be made with one part, and there is no need for a part for connecting the parts together. Therefore, it is possible to provide a small, highly accurate gas detector that is inexpensive and has few defective products. From the viewpoint of easy mold release, the angle between the elliptical symmetry plane present in the center of the long axis of the ellipsoid (elliptical mirror 30E) and the part of the folding mirror 30C that is a plane or a quadric surface and that is connected to the light guide section 30 is preferably 1° or more. Here, the part of the folding mirror 30C that is connected to the light guide section 30 is the contact point between the folding mirror 30C and the inner surface of the light guide section 30 excluding the folding mirror 30C in a cross-sectional view. In the example of FIG. 5, the part of the folding mirror 30C that is connected to the light guide section 30 is the contact point between the folding mirror 30C and the inner surface of the elliptical mirror 30E ("C" in FIG. 5). In addition, the angle between the elliptical symmetry plane and the part of the folding mirror 30C that is connected to the light guide section 30 is the angle that the tangent to the elliptical symmetry plane forms with the folding mirror 30C when the tangent to the contact point of the folding mirror 30C is virtually extended in a cross-sectional view. Moreover, the angle is more preferably 2° or more. Moreover, the angle is even more preferably 5° or more. From the viewpoint of the optical principle described later, the folding mirror is required to be approximately parallel to the symmetry plane. Therefore, the angle is preferably 30° or less. Moreover, the angle is more preferably 20° or less. Moreover, the angle is even more preferably 5° or less.

[0063] <Holding part> The holding section 40 is a member that holds the light emitting section 10, the light receiving section 20, and the light guiding section 30. Holding means attempting to maintain the relative positional relationship of each member against external forces. The form of holding is not particularly limited, but mechanical holding is preferable. The form of holding may be electromagnetic or chemical.

[0064] When the gas detection device of the present embodiment has a control unit, the control unit may be held by the holding unit 40.

[0065] The holding unit 40 is not particularly limited as long as it can hold the light receiving unit 20, the light emitting unit 10, and the light guiding unit 30. In this embodiment, the holding unit 40 is a resin package, but as another example, it may be a printed circuit board or a ceramic package. Also, a semiconductor substrate may be used as the holding unit 40, and the light receiving unit 20 and the light emitting unit 10 may be formed on the same semiconductor substrate. When the holding unit 40 is a resin package, a lead frame may be built in, and the lead frame may be electrically connected to the light emitting unit 10, the light receiving unit 20, and the control unit by wires or the like. Also, when the holding unit 40 is a printed circuit board, the printed circuit board may be electrically and mechanically joined to the light receiving unit 20 and the light emitting unit 10 by solder. Furthermore, the holding unit 40 and the light guiding unit 30 are mechanically held by adhesive, screws, claws, fitting, grommets, welding, or the like. Also, the holding unit 40 may have a connection terminal for electrically connecting to the outside. The same holding unit (for example, one printed circuit board) may hold the light emitting unit 10 and the light receiving unit 20. Moreover, the same holding unit may also hold a control unit.

[0066] <Control Unit> The control unit is a member that controls at least one of the light-emitting unit 10 and the light-receiving unit 20. The control unit may have an analog-to-digital conversion circuit that converts an analog electrical signal output from the light-receiving unit 20 into a digital electrical signal. Furthermore, the control unit may have a calculation unit that performs gas concentration calculation based on the converted digital electrical signal.

[0067] The control unit may have at least one of a general-purpose processor that executes functions according to a loaded program and a dedicated processor specialized for a specific process. The dedicated processor may include an application specific integrated circuit (ASIC). The processor may include a programmable logic device (PLD).

[0068] <Gas detector size> In general, in an optical system in which a light emitting unit 10 and a light receiving unit 20 are arranged at two focal points of an ellipsoidal mirror, if the ellipsoidal mirror is sufficiently large with respect to the size of the light emitting unit 10, the light emitted from the light emitting unit 10 can be collected at the light receiving unit 20. Here, the shape of a part of the light guiding unit 30 is configured as an ellipsoid E, and the maximum length of the ellipsoid E is L. E Let the maximum length of the light source area be L s Let us assume that L s <(L E When the condition (L / 50) is satisfied, the size of the light emitting unit 10 is sufficiently small relative to the ellipsoidal mirror and it is approximately regarded as a point light source. Therefore, the light emitted from one focal position is gathered at the other focal position. In other words, when the size of the light emitting unit 10 is not small enough relative to the ellipsoidal mirror (L s ≧(L E / 50)), the light emitted from the light-emitting unit 10 is scattered over the entire ellipsoidal mirror and cannot be collected by the light-receiving unit 20.

[0069] The gas detection device of this embodiment is L s ≧(L E / 50), the effect is particularly noticeable.

[0070] Similarly, in the gas detection device of this embodiment, the maximum length of the light receiving region is L d When L d ≧(L E / 50) the effect is particularly pronounced.

[0071] <Detailed principle> In the following description, for ease of understanding, the ellipsoid E will be described as a spheroid of revolution (i.e., the ellipsoid E has a focus and the focus F a , F b is equal to).

[0072] As shown in Patent Document 1, the focus F of an ellipsoid E a , F b The area R is the area outside out When a ray of light is emitted from the point F, it is repeatedly reflected by the mirror surface. However, at the focus F of the ellipsoid E, a and the focus F b No ray passes through the line segment connecting the two (Figure 3A). in When a ray of light is emitted from the point, it is repeatedly reflected by the mirror surface, but at the focal point F of the ellipsoid, a and the focus F b The light is reflected repeatedly through the line segment connecting the regions R (Fig. 3B). out The region R is provided with a light emitting section 10 and a light receiving section 20. out A ray of light emitted from point F reaches the focal point F. a and the focus F b The light does not pass through the line segment connecting the two, but is repeatedly reflected, forming an area R out The optical phenomenon that remains in the region R is called the "external reflection mode". in The light ray emitted from point F reaches the focal point F. a and the focus F b Repeated reflection through the line segment connecting the in The optical phenomenon in which the reflection mode remains constant is called the "internal reflection mode." The optical phenomenon in which the reflection mode and the internal reflection mode exist separately is called the "reflection mode separation phenomenon."

[0073] 4 illustrates a gas detection device according to an embodiment of the present disclosure, in which the shape of the reflecting surface Q of the folding mirror 30C is a flat surface. inThe light emitted from the light emitting unit 10 in the region R1 initially repeats the internal reflection mode, but after several reflections, the light transits from the internal reflection mode to the external reflection mode when it is reflected by the reflecting surface Q. This transition occurs in the region R2, which is the internal reflection mode. in The light from the mirror on the reflecting surface Q is reflected by the mirror on the ellipsoid E in the region R. out This occurs when the reflection mode of a light ray can be considered as a light ray emitted from point Q (a light ray in external reflection mode). This change in the reflection mode of a light ray is called "reflection mode transition". Similarly, a light ray in external reflection mode becomes a light ray in internal reflection mode when reflected by reflecting surface Q. In other words, the reflection on reflecting surface Q causes a transition between "internal reflection mode" and "external reflection mode".

[0074] By applying the reflection mode transition, the sensitivity of the gas detector can be improved. When only light in the external reflection mode is used, the optical path length is approximately equal to the arc length of the ellipsoidal mirror. In the gas detector according to this embodiment, the light emitting unit 10 is arranged in the region R in and the light receiving unit 20 is disposed in the region R out and configured to cause a reflection mode transition. This makes it possible to use both the internal reflection mode and the external reflection mode to roughly double the number of reflections of a light beam within the light guiding section 30 (extend the optical path). It is possible to provide a small, highly accurate gas detection device with a long optical path length per size and increased gas sensitivity per volume.

[0075] The light source area of ​​the light emitting unit 10 is area R in and the light receiving area of ​​the light receiving unit 20 is in the area R out Even if the light source area is partially present in the region R, the effect of this embodiment can be achieved in that partial area. in and 60% or more of the light receiving area is in area R out In another embodiment, when the light source area and the light receiving area are interchanged, 60% or more of the light receiving area is in the area R. in , and more than 60% of the light source area is in area R outFrom the viewpoint of improving gas sensitivity, 70% or more of the light source area may be located in the area R in It is preferable that 80% or more of the light source area is in the area R in It is more preferable that the entire light source area is within the region R. in Similarly, from the viewpoint of improving gas sensitivity, it is more preferable that 70% or more of the light receiving area is in the region R out It is preferable that 80% or more of the light receiving area is in the region R. out It is more preferable that the entire light receiving area is located in the region R. out It is more preferable that, when the light source region and the light receiving region are interchanged, 70% or more of the light emitting region is located in the region R from the viewpoint of improving the gas sensitivity. out It is preferable that 80% or more of the light-emitting region is in the region R out It is more preferable that the entire light-emitting region is located in the region R. out Similarly, from the viewpoint of improving gas sensitivity, it is more preferable that 70% or more of the light receiving area is in the region R in It is preferable that 80% or more of the light receiving area is in the region R. in It is more preferable that the entire light receiving area is located in the region R. in It is more preferred that the .alpha.-amino acid is present in the

[0076] Furthermore, the light receiving section may be located near the end of the ellipsoid E. As shown in Figs. 4 and 5, in the external reflection mode of light rays, light rays tend to concentrate at the end of the ellipsoid E (near the point where the major axes of the ellipsoid E and the ellipsoid E intersect). Therefore, the closer the light receiving region of the light receiving section 20 is to the end of the ellipsoid E, the more efficiently the light rays can be collected, making it possible to provide a small-sized, highly accurate gas detection device. More specifically, the ellipse with the largest area in the cross section of the ellipsoid E is called the ellipse E. c Let E be the ellipse c For the semimajor axis a and the semiminor axis b of the ellipse E c The shortest distance L between the foci of the ellipsoid E and the point where the major axis of the ellipsoid E intersects edg is a-(a 2 -b 2 ) 1 / 2From the intersection of the major axis of the ellipsoid E and the major axis of the ellipsoid E, L edg It is preferable that 60% or more of the area of ​​the light receiving region of the light receiving section 20 is present at a distance of 40% or less of L edg It is more preferable that 80% or more of the area of ​​the light receiving region of the light receiving section 20 is present at a distance of 40% or less of L edg It is more preferable that the entire light receiving area of ​​the light receiving section 20 is located within a distance of 40% or less of L. edg It is preferable that 60% or more of the area of ​​the light receiving region of the light receiving section 20 is present at a distance of 60% or less of L edg It is more preferable that 80% or more of the area of ​​the light receiving region of the light receiving section 20 is present within a distance of 60% or less of L edg It is more preferable that the entire light receiving area of ​​the light receiving section 20 is located within a distance of 60% or less of the L edg It is preferable that 60% or more of the area of ​​the light receiving region of the light receiving section 20 is present at a distance of 80% or less of L edg It is more preferable that 80% or more of the area of ​​the light receiving region of the light receiving section 20 is present at a distance of 80% or less of L edg It is more preferable that the entire light receiving area of ​​the light receiving section 20 is located within a distance of 80% or less of the total light receiving area.

[0077] Furthermore, if the ellipsoid E is a spheroid, the light beam emitted from the vicinity of the axis of rotation (the axis of two-fold rotational symmetry if the ellipsoid E is a general ellipsoid) cannot exist at a position away from the axis of rotation even if it is repeatedly reflected due to the conservation of angular momentum around the axis of symmetry. Therefore, by having the light receiving area of ​​the light receiving unit 20 and the light source area of ​​the light emitting unit 10 exist near the axis of rotation of the ellipsoid E, the light beam can be efficiently collected, and a small-sized, highly accurate gas detection device can be provided. More specifically, it is more preferable that 60% or more of the area of ​​the light receiving area of ​​the light receiving unit 20 and the light source area of ​​the light emitting unit 10 exist at a distance of 10% of the short radius of the ellipsoid E from the axis of symmetry of the ellipsoid E. Here, the configuration for efficiently collecting the light beam is not limited to one in which the light receiving unit 20 and the light emitting unit 10 exist on the major axis. It is sufficient that the light receiving unit 20 and the light emitting unit 10 overlap on the axis of rotation when viewed from the front or in a plan view.

[0078] That is, 60% or more of the area of ​​the light source region of the light-emitting unit 10 is the region R in and 60% or more of the area of ​​the light receiving region of the light receiving section 20 is in the region R out The presence of the ellipsoid in the region R allows the realization of a small, highly accurate gas detection device equipped with an ellipsoid mirror and a folding mirror. in This effect can be enhanced when the ellipse E is formed, since the optical path length of the light in the internal reflection mode is longer. c It is preferable that the ratio of the major axis a to the minor axis b (a / b) is 1.2 or more.

[0079] Here, more than 60% of the light source area is in the area R in and 60% or more of the light receiving area is in area R out However, if we focus on the center of gravity or the peak point of brightness, the following holds true. That is, if the center of gravity or the peak point of brightness of the light source area is located at point G in , the center of gravity of the light receiving area is point G out Then, point G in is the region R in exists at point G out is the region R out In another embodiment, when the light source area and the light receiving area are interchanged, the center of gravity or the peak point of brightness of the light source area is located at point G out , the center of gravity of the light receiving area is point G in This should be the case.

[0080] Here, the reflecting surface Q of the folding mirror 30C may be a part of a general quadratic surface including, for example, a sphere or a parabola. In order to produce the effect of the gas detection device of this embodiment, when a light ray is reflected by the mirror of the reflecting surface Q, the light ray is reflected by the region R of the ellipsoid E in a mirror-like manner. out However, this is satisfied if the reflecting surface Q is part of a general quadratic surface.

[0081] The reflecting surface Q may be arranged so as to pass through the focal point of the ellipsoid E, but it is sufficient if the reflecting surface Q is arranged so as to pass through the vicinity of the focal point. Even if the reflecting surface Q does not strictly pass through the focal point, most of the light rays reflected by the reflecting surface Q will be reflected by the region R of the ellipsoid E. outHere, the neighborhood is defined as the maximum length of the ellipsoid E, L E As a result, from one focus (L E / 4) from one focus. E It is preferable that the distance is within 1 / 6 of one focus. E It is even more preferable that the distance be within a range of 0.1 mm to 1.5 mm (0.1 mm to 0.5 mm) or less.

[0082] In addition, the ellipsoid E may be a spheroid having an axis of symmetry, but may also be a general ellipsoid with different diameters. This is because even if the ellipsoid is not a spheroid, the orbits of the internal reflection mode and the external reflection mode do not intermingle, and the reflection mode separation phenomenon occurs.

[0083] <Arrangement with a long axis symmetric mirror> As described above, the gas detector may include a long-axis symmetric surface mirror 30H. As shown in Figs. 7A to 7C, even if a flat mirror is added to the symmetric surface of the ellipsoid E, the light reflected by the light guide 30 is simply folded mirror-like, and the mirror shape can be treated as optically unchanged, and a similar reflection mode separation phenomenon occurs. That is, two or more reflecting surfaces of the long-axis symmetric surface mirror 30H may be connected to the symmetric surface of the ellipsoid E, and the angle between any two reflecting surfaces may be 10°≦θ≦180°. By folding back the optical path, the same optical path length can be achieved with a smaller gas detector. The shape of the reflecting surface may be a part of a plane or a quadratic curved surface. Here, Fig. 7A is a bird's-eye view, Fig. 7B is a front view, and Fig. 7C is a side view. The angle (θ) of the sector shown in FIG. 7C may be 10°≦θ≦180° or 10°≦θ≦90°, but it is preferable that θ=360° / (2n), where n is a natural number, is satisfied. Also, θ=360° / (2n+1) may be satisfied. For example, when θ is 120°, 90°, 60°, 45°, 30°, or 20°, the multiple of θ is 360°, so the optical path length per unit volume can be increased. However, the above formula does not need to be strictly satisfied for the angle (θ) of the sector. The value of θ may deviate within a range of ±10% from the value of, for example, 360° / (2n) or 360° / (2n+1). It is more preferable that the deviation is within a range of ±5°%, and more preferably within a range of ±3°. Similarly, since the virtual mirror shape of the ellipsoid E can be treated as being unchanged, there may be multiple plane mirrors including the major axis of symmetry of the ellipsoid E.

[0084] <Light emitting part placement> Fig. 5 shows another example of the configuration of the gas detection device. Unlike the configurations of Fig. 1 and Fig. 4, the light emitting unit 10 is disposed near the folding mirror 30C. Even with the configuration of Fig. 5, a small-sized, highly accurate gas detection device can be realized according to the above principle.

[0085] Although the embodiment has been described above based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these modifications and corrections are included in the scope of the present disclosure.

[0086] Fig. 6 shows another example of a configuration of a gas detection device according to an embodiment of the present disclosure. In the example of Fig. 6, the gas detection device includes a light-emitting unit 10 including a light-emitting element (10A) and a passive element, and a light-receiving unit 20 including a light-receiving element (20A) and an indirect element, and the passive element and the indirect element are 45° mirrors (50). As yet another example of a configuration, the passive element and the indirect element may be a mirror such as a concave mirror, an optical filter, a phosphor, a lens, a diffraction grating, an optical fiber, or an optical waveguide. [Explanation of symbols]

[0087] 10 Light emitting unit 10A Light Emitting Device 20 Light receiving section 20A Photodetector 30 Light guide section 30C Folding Mirror 30E elliptical mirror 30H Long axis symmetric mirror 31 Gas Port 40 Holding part 50 45° mirror

Claims

1. A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. ｃ Let E be the ellipse ｃ The two foci F ａ , F ｂ Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation as ellipsoid E. ｉｎ year, Ellipsoid E ｉｎ The area included in the region R ｉｎ year, Inside the ellipsoid E, the ellipsoid E ｉｎ The area not included in ｏｕｔ year, 60% or more of the area of ​​the light source region of the light emitting unit is the region R ｉｎ exists in 60% or more of the area of ​​the light receiving region of the light receiving part is region R ｏｕｔ An optical density measuring device that exists in.

2. The entire area of ​​the light source region of the light emitting unit is within the region R ｉｎ exists in The entire area of ​​the light receiving region of the light receiving unit is within the region R ｏｕｔ 2. The optical concentration measuring device according to claim 1 .

3. The plane or the quadric surface is an ellipse E ｃ 2. The optical concentration measuring device according to claim 1, wherein the optical concentration measuring device passes near one of the foci.

4. 2. The optical concentration measurement device according to claim 1, wherein the light receiving portion is located near an end of the ellipsoid E.

5. 2. The optical concentration measuring device according to claim 1, wherein an angle between an elliptical symmetry plane existing at the center of the major axis of the ellipsoid E and a portion where the plane or the quadric surface is connected to the light guiding portion is 1° or more.

6. The ellipse E ｃ 3. The optical concentration measurement device according to claim 1, wherein a ratio (a / b) of a major axis a to a minor axis b is 1.2 or more.

7. The vicinity is defined as the maximum length of the ellipsoid E, L Ｅ When the distance from the one focus point is (L Ｅ 4. The optical concentration measuring device according to claim 3, wherein the distance between the optical axis and the target object is within a range of 0.1 mm to 0.5 mm.

8. The maximum length of the light source area is L ｓ The maximum length of the ellipsoid E is L Ｅ When this is done, L ｓ ≧(L Ｅ 3. The optical concentration measuring device according to claim 1, wherein the optical concentration measuring device is a concentration measuring device having a concentration of 1 / 50.

9. The maximum length of the light receiving area is L ｄ The maximum length of the ellipsoid E is L Ｅ When this is done, L ｄ ≧(L Ｅ 3. The optical concentration measuring device according to claim 1, wherein the optical concentration measuring device is a concentration measuring device having a concentration of 1 / 50.

10. 3. The optical concentration measurement device according to claim 1, wherein a same holder holds the light emitting section and the light receiving section.

11. 3. The optical concentration measurement device according to claim 1, further comprising an auxiliary reflecting portion having a shape different from that of the ellipsoid E.

12. The region R ｉｎ The optical concentration measurement device according to claim 11 , wherein the auxiliary reflecting portion is located within a first reflecting portion.

13. 3. The optical concentration measurement device according to claim 1, wherein the light emitting section is a surface light source.

14. The optical concentration measurement device according to claim 1 , wherein the ellipsoid E is a spheroid.

15. The optical concentration measurement device according to claim 1 , wherein at least a part of the other portion of the inner surface of the light guiding portion has a flat shape.

16. The optical concentration measurement device according to claim 1 , wherein the shape of at least a part of the other portion of the inner surface of the light guiding portion is spherical.

17. 2. The optical concentration measurement device according to claim 1, wherein two or more reflecting surfaces each formed of a part of a plane or a quadric surface are connected to a symmetrical plane of the ellipsoid E.

18. 18. The optical concentration measurement device according to claim 17, wherein an angle formed by a portion where the two reflecting surfaces are connected is equal to or greater than 10 degrees and equal to or less than 90 degrees.

19. A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. ｃ Let E be the ellipse ｃ The two foci F ａ , F ｂ Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation as ellipsoid E. ｉｎ year, Ellipsoid E ｉｎ The area included in the region R ｉｎ year, Inside the ellipsoid E, the ellipsoid E ｉｎ The area not included in ｏｕｔ year, The center of gravity or the peak point of brightness of the light source area is point G ｉｎ , the center of gravity of the light receiving area is point G ｏｕｔ Then, point G ｉｎ is the region R ｉｎ exists at point G ｏｕｔ is the region R ｏｕｔ An optical density measuring device that exists in.

20. A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. ｃ Let E be the ellipse ｃ The two foci F ａ , F ｂ Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation as ellipsoid E. ｉｎ year, Ellipsoid E ｉｎ The area included in the region R ｉｎ year, Inside the ellipsoid E, the ellipsoid E ｉｎ The area not included in ｏｕｔ year, 60% or more of the area of ​​the light source region of the light emitting unit is the region R ｏｕｔ exists in 60% or more of the area of ​​the light receiving region of the light receiving part is region R ｉｎ An optical density measuring device that exists in.

21. A light emitting unit, a light receiving unit, and a light guiding unit that guides light from the light emitting unit to the light receiving unit, a shape of at least a part of an inner surface of the light guiding unit is configured with a part of the figure of an ellipsoid E, and a shape of at least a part of another part of the inner surface of the light guiding unit is configured with a part of the figure of a plane or a quadric surface, The ellipse with the largest area in the cross section of ellipsoid E is called ellipse E. ｃ Let E be the ellipse ｃ The two foci F ａ , F ｂ Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E without rotation as ellipsoid E. ｉｎ year, Ellipsoid E ｉｎ The area included in the region R ｉｎ year, Inside the ellipsoid E, the ellipsoid E ｉｎ The area not included in ｏｕｔ year, The center of gravity or the peak point of brightness of the light source area is point G ｏｕｔ , the center of gravity of the light receiving area is point G ｉｎ Then, point G ｉｎ is the region R ｉｎ exists at point G ｏｕｔ is the region R ｏｕｔ An optical density measuring device that exists in.

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