Optical concentration measurement device

Abstract

The invention provides a compact and high-precision optical concentration measurement device. In the optical concentration measurement device, the shape of at least a part of the inner surface of the light guide part is composed of a part of a pattern of an ellipsoid (E), the shape of at least a part of the other part of the inner surface of the light guide part is composed of a part of a pattern of a plane or a quadric surface, and at least 60% of the area of the light source region of the light emitting part is present in a region Rin. 60% or more of the area of the light-receiving region of the light-receiving unit is present in the region Rout.

Description

Technical Field

[0001] The present disclosure relates to an optical concentration measuring device. Background Art

[0002] Gas detection devices for detecting gas are used in various fields. For example, Patent Document 1 discloses a device that includes a light source emitting infrared rays and a detector detecting infrared rays of a specific wavelength in a housing having an ellipsoidal inner surface (ellipsoidal mirror), and introduces a gas to be detected into the housing.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-071816 Summary of the invention

[0006] Problems to be solved by the invention

[0007] Patent document 1 discloses a light path design in which a light emitting unit and a light receiving unit are arranged in an area outside the focus of an ellipsoidal mirror. When the size of the ellipsoidal mirror relative to the light emitting unit is not large, the light emitted from the light emitting unit can be concentrated to the light receiving unit placed in the outer area of ​​another ellipse.

[0008] On the other hand, with the recent trend toward miniaturization of gas detection devices, further miniaturization is required.

[0009] Therefore, it is required to further efficiently use the spatial volume to extend the optical path length per unit size, thereby improving the gas sensitivity per unit volume.

[0010] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide a compact and highly accurate optical concentration measuring device including an ellipsoidal mirror and a turning mirror.

[0011] Means for solving problems

[0012] (1) An optical concentration measuring device according to one embodiment of the present invention includes 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.

[0013] The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface,

[0014] The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points Fa and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in ,

[0015] will be contained in the ellipsoid E in The area in is set as area R in ,

[0016] The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out ,

[0017] More than 60% of the area of ​​the light source region of the light emitting portion is present in region R in ,

[0018] More than 60% of the area of ​​the light receiving region of the light receiving portion is present in region R out .

[0019] (2) As one embodiment of the present invention, in (1),

[0020] The entire area of ​​the light source region of the light emitting portion exists in region R in ,

[0021] The entire area of ​​the light receiving region of the light receiving portion exists in the region R out .

[0022] (3) As one embodiment of the present disclosure, in (1),

[0023] The plane or the quadratic surface passes through the ellipse E c Near a focal point.

[0024] (4) As one embodiment of the present disclosure, in (1),

[0025] The light receiving portion is located near the end of the ellipsoid E.

[0026] (5) As one embodiment of the present disclosure, in (1) or (2),

[0027] The angle formed by the elliptical symmetry plane existing in the central portion of the major axis of the ellipsoid E and the portion connecting the plane or the quadratic surface and the light guide portion is 1° or more.

[0028] (6) As one embodiment of the present disclosure, in any one of (1) to (5), the ellipse E c The ratio of the long radius a to the short radius b, i.e. (a / b), is greater than 1.2.

[0029] (7) As one embodiment of the present disclosure, in any one of (1) to (6),

[0030] The vicinity refers to the case where the maximum length of the ellipsoid E is set to L E The time distance to the one focus is (L E / 5) or less.

[0031] (8) As one embodiment of the present disclosure, in any one of (1) to (7),

[0032] When the maximum length of the light source area is set to L s , and the maximum length of the ellipsoid E is set to L E When L s ≥(L E / 50).

[0033] (9) As one embodiment of the present disclosure, in any one of (1) to (8),

[0034] When the maximum length of the light receiving area is set to L d , and the maximum length of the ellipsoid E is set to L E When L d ≥(L E / 50).

[0035] (10) As one embodiment of the present disclosure, in any one of (1) to (9), the light emitting unit and the light receiving unit are held by the same holding unit.

[0036] (11) As one embodiment of the present disclosure, in any one of (1) to (10),

[0037] The optical concentration measuring device further includes an auxiliary reflecting portion, and the auxiliary reflecting portion is composed of a pattern different from the ellipsoid E.

[0038] (12) As one embodiment of the present disclosure, in (11),

[0039] The auxiliary reflection portion exists in the region R in Inside.

[0040] (13) As one embodiment of the present disclosure, in any one of (1) to (12), the light emitting portion is a surface light source.

[0041] (14) As an embodiment of the present disclosure, in any one of (1) to (13), the ellipsoid E is a rotating ellipsoid.

[0042] (15) As one embodiment of the present disclosure, in any one of (1) to (14), at least a portion of the other portion of the inner surface of the light guide portion is in the shape of a plane.

[0043] (16) As one embodiment of the present disclosure, in any one of (1) to (14), at least a portion of the other portion of the inner surface of the light guide portion has a spherical shape.

[0044] (17) As one embodiment of the present disclosure, in (1),

[0045] Two or more reflecting surfaces formed by partial figures of a plane or a quadratic surface are connected to the symmetry plane of the ellipsoid E.

[0046] (18) As one embodiment of the present disclosure, in (17),

[0047] The angle formed by the portion connecting the two reflecting surfaces is greater than or equal to 10° and less than or equal to 90°.

[0048] (19) An optical concentration measuring device according to one embodiment of the present invention includes 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.

[0049] The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface,

[0050] The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in ,

[0051] will be contained in the ellipsoid E in The area in is set as area R in ,

[0052] The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out ,

[0053] Set the center of gravity of the light source area or the peak point of brightness as point G in , set the center of gravity of the light receiving area to point G out , click G in Exists in region R in , point Gout Exists in region R out .

[0054] (20) An optical concentration measuring device according to one embodiment of the present invention includes 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.

[0055] The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface,

[0056] The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in ,

[0057] will be contained in the ellipsoid E in The area in is set as area R in ,

[0058] The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out ,

[0059] More than 60% of the area of ​​the light source region of the light emitting portion is present in region R out ,

[0060] More than 60% of the area of ​​the light receiving region of the light receiving portion is present in region R in .

[0061] (21) An optical concentration measuring device according to one embodiment of the present invention includes 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.

[0062] The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface,

[0063] The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F bThe ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in ,

[0064] will be contained in the ellipsoid E in The area in is set as area R in ,

[0065] The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out ,

[0066] Set the center of gravity of the light source area or the peak point of brightness as point G out , set the center of gravity of the light receiving area to point G in , point G in Exists in region R in , point G out Exists in region R out .

[0067] Effects of the Invention

[0068] According to the embodiment of the present invention, it is possible to provide a compact and highly accurate optical concentration measuring device including an ellipsoidal mirror and a turning mirror. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is a diagram showing an example of ray tracing in an ellipsoidal mirror of the prior art.

[0070] Figure 2 It is a diagram showing a configuration example of a gas detection device according to an embodiment of the present disclosure.

[0071] Figure 3A It is a figure which shows an example of the ray tracing simulation result.

[0072] Figure 3B It is a figure which shows an example of the ray tracing simulation result.

[0073] Figure 4 This is a diagram showing an example of a ray tracing simulation result in the gas detection device according to one embodiment of the present disclosure.

[0074] Figure 5 It is a diagram showing another configuration example of the gas detection device according to one embodiment of the present disclosure.

[0075] Figure 6 It is a diagram showing another configuration example of the gas detection device according to one embodiment of the present disclosure.

[0076] Fig. 7A It is a plan view showing a configuration example of a gas detection device including a long-axis symmetrical surface reflector.

[0077] Figure 7B This is a front view showing a configuration example of a gas detection device including a longitudinally symmetrical surface reflector.

[0078] Figure 7C It is a side view showing a configuration example of a gas detection device including a long-axis symmetrical surface reflector.

[0079] Description of symbols

[0080] 10. Light-emitting part

[0081] 10A light emitting element

[0082] 20 Light receiving part

[0083] 20A light receiving element

[0084] 30 Light guide

[0085] 30C Steering Mirror

[0086] 30E Elliptical Mirror

[0087] 30H long axis symmetric reflector

[0088] 31 Gas Port

[0089] 40 Holding unit

[0090] 50 45° reflector DETAILED DESCRIPTION

[0091] <Gas Detection Device>

[0092] Figure 1 This is a diagram showing an example of ray tracing in an ellipsoidal mirror of the prior art. Figure 2 1 is a cross-sectional view of a gas detection device according to an embodiment of the present disclosure. As an example, the gas detection device is a small device having a length×width×height of 7.8 mm×9.0 mm×4.7 mm, and is also called a gas sensor.

[0093] In this embodiment, the gas detection device is a NDIR (Non Dispersive InfraRed) method device that measures the concentration of the detected gas based on infrared rays that pass through the 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 buildings, as a small portable measurement device installed in portable communication devices such as smartphones, and for detecting gas concentration indoors in mobile devices such as cars, trains, or airplanes.

[0094] The detected gas is carbon dioxide (CO2) in this embodiment, but is not limited thereto. As another example, it may be a combustible gas such as alcohol (ethanol, etc.), methane, propane, hydrogen, ethylene, MCH (methylcyclohexane), etc. In addition, the detected gas may be a toxic gas such as carbon monoxide, hydrogen sulfide, formaldehyde, ammonia, etc. Furthermore, the detected gas may be a greenhouse gas such as nitrous oxide, a refrigeration gas used in an air conditioner or a refrigerator, etc.

[0095] Furthermore, according to the structure of the gas detection device of the present embodiment, it can be applied as a light-receiving and light-emitting device for purposes other than gas detection. That is, the disclosure derived by replacing the "gas detection device" described above with "optical concentration measuring device", "optical physical quantity measuring device", "light-receiving and light-emitting device", "optical device", etc. is included in the scope of the present disclosure. For example, it is possible to detect the state of the optical path space (as an example other than gas, the presence or concentration of a specific component of the fluid, etc.). For example, it can be used for a component detection device or a component concentration measurement device for a substance (such as water or body fluid) present in the optical path space between the light-emitting part and the light-receiving part. For example, when the substance present in the optical path space is blood, the component detection device or the component concentration measurement device can be used for measuring the glucose concentration in the blood, etc.

[0096] The component detection device or the component concentration measuring device can measure the glucose concentration in blood glucose by measuring the absorption of light with a wavelength of 1 to 10 μm. In the measurement of the glucose concentration in blood glucose, it is preferred to measure the absorption of light at 1.6 μm, 2.0 to 2.3 μm, and 9.6 μm. A small, high-precision, and highly reliable non-invasive glucose concentration meter can be realized. With such a glucose concentration meter, for example, a diabetic patient can accurately investigate the blood glucose level by himself without causing damage to the skin caused by an invasive method. In addition, based on the investigated blood glucose level, more accurate management of medication (such as insulin) can be achieved.

[0097] The gas detection device of this embodiment includes a light emitting unit 10, a light receiving unit 20, and a light guiding unit 30, and the light guiding unit 30 guides the light from the light emitting unit 10 to the light receiving unit 20. In addition, the gas detection device may include: a control unit that controls the light emitting unit 10 and the light receiving unit 20 or performs signal conversion; a housing that has a gas port 31 and holds the light guiding unit 30; and a holding unit 40 that is a substrate that holds the light emitting unit 10, the light receiving unit 20, the control unit, and the housing.

[0098] At least a portion of the inner surface of the light guide 30 is formed by a whole or part of an ellipsoid. At least a portion of the other portion of the inner surface of the light guide 30 is formed by a part of a plane or quadratic surface.

[0099] Here, an ellipsoid constituting the shape of at least a part of the inner surface of the light guide portion 30 is sometimes referred to as an ellipsoid E. The ellipsoid E may be a rotational ellipsoid. Figure 2 30 is a diagram for explaining the detailed structure of the gas detection device. The light guide portion 30 includes a portion (a deflection mirror 30C, see FIG. 30 ) different from the portion corresponding to the ellipsoid E (elliptical mirror 30E). Figure 4 ). The light guide 30 may include another planar portion (long axis symmetric surface reflector 30H). The ellipse having the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in . will be contained in the ellipsoid E in The area in is set as area R in In addition, the inside of the ellipsoid E and not included in the ellipsoid E in The region is set as region R out The shape of at least a part of the other part (the turning mirror 30C) of the inner surface of the light guide 30 is formed by a plane or a part of a quadratic surface. In this embodiment, the reflecting surface Q of the turning mirror 30C is formed by a plane or a part of a quadratic surface. Figure 2 In the example, the gas detection device has a shape including only a portion of the ellipsoid E, but when describing an ellipsoid or an ellipse, the description is made assuming that there is an imaginary ellipsoid or ellipse formed by imaginarily extending the surface.

[0100] The gas detection device of the present embodiment is configured such that 60% or more of the area of ​​the light source region of the light emitting unit 10 exists in the region R in , more than 60% of the area of ​​the light receiving region of the light receiving unit 20 exists in the region R out .

[0101] In addition, the above-mentioned reflection surface Q is formed by passing through the ellipse E c Near a focal point.

[0102] The detailed principle will be described later, but by providing this structure, a small and high-precision gas detection device using an ellipsoidal mirror can be provided.

[0103] <Relationships among structural members>

[0104] As described above, the gas detection device includes the light emitting unit 10, the light receiving unit 20, and the light guiding unit 30. The gas detection device may further include a holding unit 40. Furthermore, the gas detection device may additionally include a control unit.

[0105] 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 guide unit 30 and the upper surface of the holding unit 40. In addition, the light guide unit 30 may include a gas port 31 that can introduce and export gas to the detection space. In addition, the holding unit 40 may include a gas port 31.

[0106] The light emitted from the light emitting unit 10 is reflected at least once on the inner surface of the light guiding unit 30 and reaches the light receiving unit 20 .

[0107] <Light Emitting Part>

[0108] The light emitting unit 10 is a component that emits light for detecting the gas to be detected. The light emitting unit 10 is not particularly limited as long as it outputs light including a wavelength absorbed by the gas to be detected. In the present embodiment, the light emitted by the light emitting unit 10 is infrared light, but the present invention is not limited thereto.

[0109] The light emitting unit 10 has a light emitting element. In the present embodiment, the light emitting element is composed of an LED (light emitting diode), but as other examples, it may also be a lamp, a laser (Light Amplification by Stimulated Emission of Radiation), an organic light emitting element or a MEMS (Micro Electro Mechanical Systems) heater. In addition, the light emitting unit 10 includes not only a light emitting element, but also a passive element that receives light emitted by the light emitting element and emits light passively. Passive elements are, for example, reflectors, optical filters, phosphors, optical images, optical fibers, optical waveguides, lenses or diffraction gratings.

[0110] The light emitting unit 10 has a light source region. The light source region refers to a component that generates photons of the light emitting element when light is guided from the light emitting element to the light guide unit 30 without passing through a passive element as in the present embodiment. For example, if the light emitting unit 10 is a quantum light emitting element, the light source region may be a region of the element itself or an active region. For example, if the light emitting unit 10 is a thermal light source, the light source region may be a region of the heat source element itself or a high temperature region. For example, if the light emitting unit 10 is a lamp, the light source region may be an internal region of a bulb (glass ball) or a filament.

[0111] In addition, the light emitting unit 10 includes a passive element, and when the light emitted by the light emitting element is guided to the light guide unit 30 via the passive element, the light source area is a collection of light emission ends of the passive element. For example, when the passive element is a reflector, the light source area is an area that reflects light.

[0112] In addition, for example, when the passive element is an optical filter having a wavelength selection function, the area where light passes on the surface connected to the space of the optical filter can be used as the light source area. In addition, for example, when the passive element is an optical fiber, an optical waveguide or a lens, the exit surface where light passes on the surface connected to the space can be used as the light source area.

[0113] In addition, when an optical image is formed by a lens, a reflector, or the like as the light emitting unit 10, the formed image can be used as the light source region.

[0114] Here, the light emitting unit 10 is preferably a planar surface light source such as an LED, a MEMS heater, a VCSEL (Vertical Cavity Surface Emitting LASER), etc. Since the light emitting surface is a plane, the volume of the optical image of the light source is concentrated to be small, and the light can be efficiently concentrated on the light receiving unit 20. Therefore, a small optical system can be formed.

[0115] <Light receiving part>

[0116] 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 including a wavelength absorbed by the detected gas. In the present embodiment, the light received by the light receiving unit 20 is infrared light, but the present invention is not limited thereto.

[0117] The light receiving unit 20 has a light receiving element. In the present embodiment, the light receiving element is a photodiode, but as another example, it may be a phototransistor, a thermopile, a thermoelectric sensor, a bolometer, or a photoacoustic detector. In addition, the light receiving unit 20 includes not only a light receiving element, but also an indirect element that guides light to the light receiving element. The indirect element is, for example, a reflector, 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 have a structure with an optical filter.

[0118] The light receiving unit 20 has a light receiving area. The light receiving area refers to an area in the light receiving element that has a function of converting received light into a signal when the light receiving element directly receives light without an indirect element as in the present embodiment. For example, if the light receiving element is a photodiode, the light receiving area is an active layer, and if the light receiving element is a thermopile, the light receiving area is a thermoelectric conversion unit.

[0119] In addition, when the light receiving unit 20 receives light via an indirect element, the light receiving area is an area in the indirect element that has an optical function of guiding the received light to the light receiving element and through which light passes. For example, when the indirect element is an optical filter having a wavelength selection function, the area through which light passes on the surface connected to the space of the optical filter can be used as the light receiving area. In addition, when the indirect element is an optical fiber, an optical waveguide, or a lens, the incident surface through which light passes on the surface connected to the space can be set as the light receiving area. In addition, when the indirect element is a reflector, the area that reflects light can be used as the light receiving area.

[0120] <Light guide section>

[0121] The light guide 30 is a member that guides the light emitted by the light emitting unit 10 to the light receiving unit 20 and is an optical system of the gas detection device. The light emitted from the light emitting unit 10 is reflected by the light guide 30 and reaches the light receiving unit 20. In other words, the light guide 30 optically connects the light emitting unit 10 and the light receiving unit 20.

[0122] In the present embodiment, the inner surface of the light guide 30 is a reflector (reflecting surface). The shape of at least a portion of its inner surface has an elliptical mirror 30E that is a figure of all or part of an ellipsoid. The light guide 30 may also be auxiliary with a 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 referred to as an auxiliary reflector. The gas detection device may, for example, further include an auxiliary reflector composed of a figure different from the ellipsoid E, or may be configured to have an auxiliary reflector in region R. in An auxiliary reflection part is provided inside.

[0123] In the present embodiment, the shape of the reflection surface Q of the turning mirror 30C, which is at least a part of the inner surface of the light guide 30, is formed by a plane or a part of a quadratic surface. c In the present embodiment, the light guide unit 30 further includes a long-axis symmetric surface reflector 30H, which is a plane mirror that is a part of the shape of the symmetry surface including the long axis of the ellipsoid E.

[0124] The material constituting the reflector may be, for example, metal, glass, ceramic, stainless steel, etc., but is not limited thereto.

[0125] In addition, the reflector may partially have the function of a wavelength filter.

[0126] From the viewpoint of improving the detection sensitivity, the material constituting these reflectors is preferably composed of a material with a small light absorption coefficient and high reflectivity. Specifically, it is preferred to implement a coated resin housing containing an alloy of aluminum, gold, silver, a dielectric or a laminate thereof. As the material of the resin housing, for example, 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), etc., and hard resins mixed with two or more of them, etc. can be listed. In addition, from the viewpoint of reliability and time-varying changes, it is preferred to coat a resin housing with gold or an alloy layer containing gold. Furthermore, in order to improve the reflectivity, it is preferred to form a dielectric laminated film on the surface of the metal layer. In the case where the inner surface of the light guide 30 is formed on the resin housing by evaporation or plating, compared with the case where it is formed by a metal material, it is possible to achieve high productivity and lightweight improvement. Furthermore, the difference in thermal expansion coefficient with the holding portion 40 is reduced, thermal deformation is suppressed, and sensitivity is unlikely to fluctuate.

[0127] In addition, the light guide 30 can be formed by cutting, but from the perspective of productivity, it is more preferably formed by injection molding. In the case where the light guide 30 is formed by injection molding, if the light guide 30 is a concave figure, the injection molding mold cannot be pulled out in one direction. Therefore, from the perspective of productivity, the light guide 30 is preferably a convex figure. The steering mirror 30C can be configured to be parallel to the symmetry plane existing in the central part of the major axis of the ellipsoid of the elliptical mirror 30E. At this time, the light guide 30 is a convex figure, and when the injection molding mold is pulled out in one direction, it can have an inclination relative to all surfaces. On the surface perpendicular to the extraction direction of the injection molding mold, deformation will occur during extraction due to the bonding of the mold and the resin, but if there is an inclination relative to the extraction direction, the deformation can be reduced. At this time, it can be formed with one set of molds, and the light guide 30 can also be made with one part, without the need for parts that connect the parts to each other. Therefore, a cheap, defective, small and high-precision gas detection device can be provided. From the viewpoint of good mold release properties, the angle formed by the elliptical symmetry plane existing in the central part of the major axis of the ellipsoid (elliptical mirror 30E) and the portion of the turning mirror 30C connected to the light guide 30 as a plane or quadratic surface is preferably 1° or more. Here, the portion of the turning mirror 30C connected to the light guide 30 refers to the contact point between the turning mirror 30C and the inner surface of the light guide 30 other than the turning mirror 30C when viewed in cross section. Figure 5 In the example, the portion of the turning mirror 30C connected to the light guide 30 is the contact point between the turning mirror 30C and the inner surface of the elliptical mirror 30E ( Figure 5"C"). In addition, the angle formed by the elliptical symmetry plane and the portion of the turning mirror 30C connected to the light guide portion 30 refers to the angle formed by the tangent and the elliptical symmetry plane when the tangent at the above-mentioned contact point of the turning mirror 30C is virtually extended when viewed in section. In addition, the angle is more preferably greater than 2°. In addition, the angle is further preferably greater than 5°. From the perspective of the optical principle described later, the turning mirror is required to be roughly parallel to the symmetry plane. Therefore, the angle is preferably less than 30°. In addition, the angle is more preferably less than 20°. In addition, the angle is further preferably less than 5°.

[0128] <Maintaining section>

[0129] The holding part 40 is a member for holding the light emitting part 10, the light receiving part 20 and the light guiding part 30. Holding means maintaining the relative positional relationship of each member with respect to external forces. The form of holding is not particularly limited, and mechanical holding is preferred. The form of holding can be electromagnetic or chemical holding.

[0130] When the gas detection device of the present embodiment includes a control unit, the control unit may be held by the holding unit 40 .

[0131] The holding part 40 is not particularly limited as long as it can hold the light receiving part 20, the light emitting part 10, and the light guiding part 30. In the present embodiment, the holding part 40 is a resin package, but as another example, it can also be a printed circuit board or a ceramic package. In addition, a semiconductor substrate can be used as the holding part 40, and the light receiving part 20 and the light emitting part 10 are formed on the same semiconductor substrate. In the case where the holding part 40 is a resin package, a lead frame can be built in, and the lead frame and the light emitting part 10, the light receiving part 20, and the control part can be electrically connected by wires or the like. In addition, in the case where the holding part 40 is a printed circuit board, the printed circuit board and the light receiving part 20 and the light emitting part 10 can be electrically and mechanically connected by solder. Moreover, the holding part 40 and the light guiding part 30 are mechanically held by adhesives, screws, claws, fittings, grommets, welding, etc. In addition, the holding part 40 can have a connection terminal for electrical connection with the outside. The same holding part (for example, a printed circuit board) can hold the light emitting part 10 and the light receiving part 20. In addition, the same holding part can also hold the control part.

[0132] <Control Unit>

[0133] The control unit is a component that controls at least one of the light emitting unit 10 and the light receiving unit 20. The control unit may include an analog-digital conversion circuit that converts an analog electrical signal output from the light receiving unit 20 into a digital electrical signal. In addition, the control unit may include a calculation unit that performs gas concentration calculation based on the converted digital electrical signal.

[0134] The control unit may include at least one of a general-purpose processor that executes functions corresponding to the read program and a dedicated processor dedicated to specific processing. The dedicated processor may include an IC (ASIC; Application Specific Integrated Circuit) for a specific purpose. The processor may include a programmable logic device (PLD; Programmable Logic Device).

[0135] <Dimensions of Gas Detection Device>

[0136] Generally, in an optical system in which the light emitting unit 10 and the light receiving unit 20 are respectively arranged at the two focal points of the ellipsoid mirror, when the size of the ellipsoid mirror is sufficiently large relative to the light emitting unit 10, the light emitted from the light emitting unit 10 can be concentrated to the light receiving unit 20. Here, the shape of a part of the light guide unit 30 is configured as an ellipsoid E, and the maximum length of the ellipsoid E is set to L E , set the maximum length of the light source area to L s In L s <(L E / 50) is satisfied, the size of the light emitting unit 10 is small enough relative to the ellipsoid mirror and is approximately regarded as a point light source. Therefore, the light emitted from one focal position is concentrated to the other focal position. That is, when the size of the light emitting unit 10 is not small enough relative to the ellipsoid mirror (L s ≥(L E / 50)), the light emitted from the light emitting portion 10 is dispersed toward the entire ellipsoidal mirror and cannot be concentrated on the light receiving portion 20.

[0137] The gas detection device of this embodiment has L s ≥(L E / 50), the effect is particularly significant.

[0138] Similarly, the gas detection device of this embodiment sets the maximum length of the light receiving area to L d If L d ≥(L E / 50) will have a particularly significant effect.

[0139] <Detailed principle>

[0140] In the following description, in order to make the description easier to understand, the ellipsoid E is assumed to be a rotating ellipsoid for description (that is, the ellipsoid E has a focus, which is equivalent to the focus F a 、F b ).

[0141] As shown in Patent Document 1, the light rays are emitted from the focal point F of the ellipsoid E. a 、Fb The outer area is area R out The light rays emitted from the point of the reflector are repeatedly reflected on the surface of the reflector. However, the light rays will not pass through the focus F connecting the ellipsoid E. a and focus F b The line segment ( Figure 3A ). In addition, the light from area R in When the light is emitted from the point, it is repeatedly reflected on the mirror surface, but it repeatedly passes through the focus F of the connecting ellipsoid. a and focus F b The reflection of the line segment ( Figure 3B ). The technology of Patent Document 1 is applied to this situation. In the area R out The region includes a light emitting unit 10 and a light receiving unit 20. out The light emitted from the point does not pass through the focal point F a and focus F b The line segment is repeatedly reflected and continues to stay in area R out The optical phenomenon in the region is called "external reflection mode". in The light rays emitted from the point repeatedly pass through the focal point F a and focus F b The reflection of the line segment continues to stay in area R in The optical phenomenon of the external reflection mode and the internal reflection mode being separated is called the “reflection mode separation phenomenon”.

[0142] Here, Figure 4 FIG. 2 shows a case where the shape of the reflection surface Q of the turning mirror 30C is set to a flat surface in the gas detection device according to one embodiment of the present disclosure. Figure 4 In the example, from the region R in The light emitted from the light emitting unit 10 initially repeats the internal reflection mode, but after multiple reflections, the light mode is transformed from the internal reflection mode to the external reflection mode by being reflected by the reflection surface Q. This transformation is caused by the following situation: in The light is reflected by the reflector of the reflecting surface Q and is regarded as mirror-like from the region R of the ellipsoid E. out The light emitted from the point of the reflection surface Q (light in the external reflection mode). The situation where the reflection mode of the light changes in this way is called "reflection mode transition". In addition, similarly, the light in the external reflection mode is reflected by the reflection surface Q, thereby becoming the light in the internal reflection mode. That is, through the reflection on the reflection surface Q, the "internal reflection mode" and the "external reflection mode" are transformed into each other.

[0143] By applying the reflection mode transition, the sensitivity of the gas detection device can be improved. When only the light in the external reflection mode is used, the optical path length is substantially equal to the arc length of the ellipsoidal mirror. In the gas detection device of this embodiment, the light emitting unit 10 is arranged in the region R. in , the light receiving unit 20 is arranged in the region R out , and the reflection mode changes. Thus, the number of reflections of the light in the light guide 30 can be set to approximately twice or more (extending the optical distance) by using either the internal reflection mode or the external reflection mode. A small and high-precision gas detection device with a long optical path length per unit size and improved gas sensitivity per unit volume can be provided.

[0144] The light source region of the light emitting unit 10 is locally present in the region R in The light receiving area of ​​the light receiving unit 20 is locally present in the area R out Therefore, as long as more than 60% of the light source area exists in the area R in , more than 60% of the light receiving area exists in area R out As another embodiment, when the light source area and the light receiving area are exchanged, it is configured so that 60% or more of the light receiving area exists in the area R in , more than 60% of the light source area exists in area R out From the viewpoint of improving gas sensitivity, it is preferred that 70% or more of the light source area exists in area R in In addition, it is more preferred that 80% or more of the light source area exists in area R in In addition, it is more preferable that all light source areas exist in area R in Similarly, from the viewpoint of improving gas sensitivity, it is preferred that 70% or more of the light receiving area exists in region R. out In addition, it is more preferred that 80% or more of the light receiving area exists in region R out In addition, it is more preferable that all the light receiving areas exist in the area R out Here, when the light source region and the light receiving region are exchanged, from the viewpoint of improving gas sensitivity, it is preferred that 70% or more of the light emitting region exists in region R. out In addition, it is more preferred that 80% or more of the light emitting area exists in region R out In addition, it is more preferable that the entire light emitting area exists in the area R out Similarly, from the viewpoint of improving gas sensitivity, it is preferred that 70% or more of the light receiving area exists in region R. in In addition, it is more preferred that 80% or more of the light receiving area exists in region R in In addition, it is more preferable that all the light receiving areas exist in the area Rin .

[0145] Furthermore, the light receiving portion may be located near the end of the ellipsoid E. Figure 4 , Figure 5 As shown in FIG. 1 , the external reflection mode of the light has a tendency that the light is concentrated at the end of the ellipsoid E (near the point where the ellipsoid E intersects with the major axis of the ellipsoid E). Therefore, the closer the light receiving area of ​​the light receiving unit 20 is to the end of the ellipsoid E, the more efficiently the light can be converged, and a small and high-precision gas detection device can be provided. More specifically, the ellipse with the largest area in the cross section of the ellipsoid E is set as the ellipse E. c , relative to the ellipse E c The major radius a and the minor radius b of the ellipse E c The shortest distance L between the focus of and the point where the ellipsoid E intersects the major axis of the ellipsoid E edg By a-(a 2 -b 2 ) 1 / 2 It is preferred that 60% or more of the area of ​​the light receiving region of the light receiving portion 20 exists at a distance L from the intersection of the ellipsoid E and the major axis of the ellipsoid E. edg More preferably, more than 80% of the area of ​​the light receiving region of the light receiving portion 20 exists at a distance of L edg It is further preferred that the entire light receiving area of ​​the light receiving unit 20 exists at a distance of less than 40% of L. edg In addition, it is preferred that more than 60% of the area of ​​the light receiving region of the light receiving portion 20 exists at a distance of less than 40% of L. edg More preferably, more than 80% of the area of ​​the light receiving region of the light receiving portion 20 exists at a distance of L edg It is further preferred that the entire light receiving area of ​​the light receiving unit 20 exists at a distance of less than 60% of L. edg Preferably, more than 60% of the area of ​​the light receiving region of the light receiving portion 20 exists at a distance of L. edg More preferably, more than 80% of the area of ​​the light receiving region of the light receiving portion 20 exists at a distance of L. edg It is further preferred that the entire light receiving area of ​​the light receiving unit 20 exists at a distance of less than 80% of L. edg At a distance below 80%.

[0146] In addition, if the ellipsoid E is a rotating ellipsoid, the light emitted from the vicinity of the rotation axis (if the ellipsoid E is a general ellipsoid, it is the axis of twice-rotational symmetry) cannot exist at a position away from the rotation axis due to the preservation of angular momentum around the axis of symmetry even if it is repeatedly reflected. Therefore, by making the light receiving area of ​​the light receiving part 20 and the light source area of ​​the light emitting part 10 exist near the rotation axis of the ellipsoid E, the light can be efficiently converged, and a small and high-precision gas detection device can be provided. More specifically, it is more preferred that more than 60% of the area of ​​the light receiving area of ​​the light receiving part 20 and the light source area of ​​the light emitting part 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 structure for efficiently converging the light is not limited to the light receiving part 20 and the light emitting part 10 being on the major axis. When viewed from the front or from above, the light receiving part 20 and the light emitting part 10 can overlap on the rotation axis.

[0147] That is, more than 60% of the area of ​​the light source region of the light emitting unit 10 exists in the region R. in , more than 60% of the area of ​​the light receiving region of the light receiving unit 20 exists in the region R out , thus realizing a small and high-precision gas detection device with an ellipsoid mirror and a turning mirror. The two foci of the ellipsoid are sufficiently separated to form a region R in In the case of the structure, the optical path length of the light in the internal reflection mode becomes longer, so the effect can be improved. c The ratio (a / b) of the major radius a to the minor radius b is preferably 1.2 or more.

[0148] Here, more than 60% of the light source area exists in the area R in , more than 60% of the light receiving area exists in area R out , but if we focus on the centroid or the peak point of brightness, the following holds. That is, when the centroid or the peak point of brightness of the light source area is set as point G in , Set the center of gravity of the light receiving area to point G out , click G in Exists in region R in , point G out Exists in region R out As another embodiment, when the light source area and the light receiving area are exchanged, the center of gravity of the light source area or the peak point of the brightness is set as point G. out , set the center of gravity of the light receiving area to point G in That's it.

[0149] Here, the reflection surface Q of the turning mirror 30C only needs to be a part of a general quadratic surface including a sphere or a parabola. In order to produce the effect of the gas detection device of this embodiment, when the light is reflected by the reflector of the reflection surface Q, it is necessary to regard it as a mirror image from the area R of the ellipsoid E. out However, if the reflecting surface Q is part of a general quadratic surface, then the condition is satisfied.

[0150] In addition, the reflecting surface Q may be arranged to pass through the focus of the ellipsoid E, but it is sufficient as long as it is arranged to pass near the focus. This is because even if the reflecting surface Q does not strictly pass through the focus, a large amount of light reflected by the reflecting surface Q is regarded as mirror-imaged from the area R of the ellipsoid E. out Here, the vicinity refers to the maximum length of the ellipsoid E as L. E The time distance from a focus is (L E / 4) or less. Nearby is preferably an area with a distance of (L E / 6) or less, and more preferably, a region of distance (L E / 8) or less.

[0151] The ellipsoid E may be a rotating ellipsoid having an axis of symmetry, or may be a general ellipsoid having different diameters. This is because even a general ellipsoid that is not a rotating ellipsoid causes the reflection mode separation phenomenon, and the orbits of the internal reflection mode and the external reflection mode are not mixed.

[0152] <Configuration of a reflector with a long-axis symmetric surface>

[0153] In addition, as described above, the gas detection device may include a long axis symmetrical reflector 30H. This is because 7A to 7C As shown, even if a plane mirror is added to the symmetry plane of the ellipsoid E, the light reflected by the light guide 30 can be processed to be simply folded in a mirror image, and the shape of the reflector does not change optically, causing the same reflection mode separation phenomenon. That is, the reflecting surfaces of two or more long-axis symmetric mirrors 30H can be connected on the symmetry plane of the ellipsoid E, and the angle between any two reflecting surfaces can be 10°≤θ≤180°. By folding the light path, the same light path length can be achieved with a smaller gas detection device. In addition, the shape of the reflecting surface can be composed of a partial graphic of a plane or a quadratic surface. Here, Fig. 7A It is a top view. Figure 7B is the main view, Figure 7C It is a side view. Figure 7CThe angle (θ) of the sector shown can be 10°≤θ≤180°, or 10°≤θ≤90°, but n is set to a natural number, preferably satisfying θ=360° / (2n). In addition, θ=360° / (2n+1) can 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 extended. However, the above formula may not be strictly satisfied with respect to the angle (θ) of the sector. The value of θ may, for example, have a deviation within the range of ±10% relative to the value of 360° / (2n) or 360° / (2n+1). The offset is more preferably within the range of ±5°%, and further preferably within the range of ±3°. In addition, similarly, it can be regarded that the ellipsoid E does not virtually change in the shape of the reflector, so there can be multiple plane mirrors containing the major axis of symmetry of the ellipsoid E.

[0154] <Configuration of light-emitting unit>

[0155] in addition, Figure 5 Another structural example of a gas detection device is shown. Figure 1 and Figure 4 The structure is different, and the light emitting unit 10 is arranged near the turning mirror 30C. Figure 5 The structure is also based on the above principle to realize a small and high-precision gas detection device.

[0156] Although the embodiments are described above based on the drawings and embodiments, 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.

[0157] Figure 6 Another configuration example of a gas detection device according to an embodiment of the present disclosure is shown. Figure 6 In the example of , the gas detection device comprises 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 a 45° reflector (50). As another structural example, the passive element and the indirect element can be a reflector such as a concave mirror, an optical filter, a phosphor, a lens, a diffraction grating, an optical fiber, or an optical waveguide.

Claims

1. An optical concentration measuring device comprising a light emitting unit, a light receiving unit, and a light guiding unit for guiding light from the light emitting unit to the light receiving unit, The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface, The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in , will be contained in the ellipsoid E in The area in is set as area R in , The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out , More than 60% of the area of ​​the light source region of the light emitting portion is present in region R in , More than 60% of the area of ​​the light receiving region of the light receiving portion is present in region R out .

2. The optical concentration measuring device according to claim 1, wherein: The entire area of ​​the light source region of the light emitting portion exists in region R in , The entire area of ​​the light receiving region of the light receiving portion exists in the region R out .

3. The optical concentration measuring device according to claim 1, wherein: The plane or the quadratic surface passes through the ellipse E c Near a focal point.

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

5. The optical concentration measuring device according to claim 1, wherein: The angle formed by the elliptical symmetry plane existing in the central portion of the major axis of the ellipsoid E and the portion connecting the plane or the quadratic surface and the light guide portion is 1° or more.

6. The optical concentration measuring device according to claim 1 or 2, wherein: The ellipse E c The ratio of the long radius a to the short radius b, i.e. (a / b), is greater than 1.

2.

7. The optical concentration measuring device according to claim 3, wherein: The near side refers to the situation where the maximum length of the ellipsoid E is set to L E The time distance to the one focus is (L E / 4) or less.

8. The optical concentration measuring device according to claim 1 or 2, wherein: When the maximum length of the light source area is set to L s , and the maximum length of the ellipsoid E is set to L E When L s ≥(L E / 50).

9. The optical concentration measuring device according to claim 1 or 2, wherein: When the maximum length of the light receiving area is set to L d , and the maximum length of the ellipsoid E is set to L E When L d ≥(L E / 50).

10. The optical concentration measuring device according to claim 1 or 2, wherein: The light emitting unit and the light receiving unit are held by the same holding unit.

11. The optical concentration measuring device according to claim 1 or 2, wherein: The optical concentration measuring device further includes an auxiliary reflecting portion, and the auxiliary reflecting portion is composed of a pattern different from the ellipsoid E.

12. The optical concentration measuring device according to claim 11, wherein: The auxiliary reflection portion exists in the region R in Inside.

13. The optical concentration measuring device according to claim 1 or 2, wherein: The light emitting part is a surface light source.

14. The optical concentration measuring device according to claim 1 or 2, wherein: The ellipsoid E is a rotating ellipsoid.

15. The optical concentration measuring device according to claim 1 or 2, wherein: At least a portion of the other portion of the inner surface of the light guide portion is in the shape of a plane.

16. The optical concentration measuring device according to claim 1 or 2, wherein: At least a portion of the other portion of the inner surface of the light guide portion has a spherical shape.

17. The optical concentration measuring device according to claim 1, wherein: Two or more reflecting surfaces formed by partial figures of a plane or a quadratic surface are connected to the symmetry plane of the ellipsoid E.

18. The optical concentration measuring device according to claim 17, wherein: The angle formed by the portion connecting the two reflecting surfaces is greater than or equal to 10° and less than or equal to 90°.

19. An optical concentration measuring device comprising a light emitting unit, a light receiving unit, and a light guiding unit, wherein the light guiding unit guides light from the light emitting unit to the light receiving unit. The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface, The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in , will be contained in the ellipsoid E in The area in is set as area R in , The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out , Set the center of gravity of the light source area or the peak point of brightness as point G in , set the center of gravity of the light receiving area to point G out , point G in Exists in region R in , point G out Exists in region R out .

20. An optical concentration measuring device comprising a light emitting unit, a light receiving unit, and a light guiding unit, wherein the light guiding unit guides light from the light emitting unit to the light receiving unit. The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface, The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in , will be contained in the ellipsoid E in The area in is set as area R in , The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out , More than 60% of the area of ​​the light source region of the light emitting portion is present in region R out , More than 60% of the area of ​​the light receiving region of the light receiving portion is present in region R in .

21. An optical concentration measuring device comprising a light emitting unit, a light receiving unit, and a light guiding unit, wherein the light guiding unit guides light from the light emitting unit to the light receiving unit. The shape of at least a part of the inner surface of the light guide portion is formed by a part of the figure of the ellipsoid E, and the shape of at least a part of the other part of the inner surface of the light guide portion is formed by a part of the figure of a plane or a quadratic surface, The ellipse with the largest area in the cross section of the ellipsoid E is defined as ellipse E. c , will pass through the ellipse E c The two focal points F a and F b The ellipsoid that does not rotate but is in a magnification-reduction relationship with the ellipsoid E and has the smallest volume is set as the ellipsoid E in , will be contained in the ellipsoid E in The area in is set as area R in , The inner part of ellipsoid E and not included in ellipsoid E in The area in is set as area R out , Set the center of gravity of the light source area or the peak point of brightness as point G out , set the center of gravity of the light receiving area to point G in , point G in Exists in region R in , point G out Exists in region R out .

Images