Gas detection equipment

Abstract

To provide a compact and high accuracy gas detector using an elliptical mirror.SOLUTION: The gas detector comprises a light emission part 10, a light reception part 20, and a light guide part 30. The shape of at least a portion of inner surface of the light guide part is composed of entire or partial diagram of n ellipsoids, and when it is assumed, using n ellipsoids E1 to En, an ellipse Eci having a maximum area in the cross section of an ellipsoid Ei, and an ellipsoid Esi passing through two focal points Fai, Fbi of the ellipse Eci and having a minimum area in an expansion / contraction relationship with the ellipsoid Ei, not being rotated, that the region inside of the ellipsoid Ei and not including the ellipsoid Esi is a region Ri, that the ellipsoid Ei including the light source region of the light emission part is an ellipsoid Es, that the ellipsoid Ei including the light reception region of the light reception part is an ellipsoid Ed, that the region Ri of the ellipsoid Es is a region Rin, and that the region Ri of the ellipsoid Ed is a region Rout, 60% or more of the light source region exists in the region Rin, and 60% or more of the light reception region exists in the region Rout.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to gas detection 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] US Patent Application Publication No. 2018 / 0348121 Summary of the Invention [Problem to be solved by the invention]

[0004] 1 and 2 are examples of ray tracing in an optical path design in which the centers of the light emitting unit and the light receiving unit are located at the focal position of an ellipsoidal mirror as in Patent Document 1. When the ellipsoidal mirror is sufficiently large compared to the size of the light emitting unit as in Fig. 1, the light beam emitted from the light emitting unit located at the focal position can be collected at the light receiving unit located at the other focal position. In other words, since the light emitting unit can be approximately regarded as a point light source, the light beam emitted from one focal position is collected at the other focal position according to the general properties of an ellipsoid.

[0005] On the other hand, if the ellipsoidal mirror is not large enough compared to the size of the light-emitting part, as shown in Figure 2, the light emitted from the light-emitting part scatters over the entire ellipsoidal mirror and cannot be collected at the light-receiving part of the light-receiving element. This is because the physical image of the light-emitting part approximately behaving as a point source breaks down, and the aberration of the ellipsoidal mirror due to the size of the light-emitting part becomes more pronounced.

[0006] With the recent trend towards miniaturization of gas detection devices, the ratio of the size of the light emitting part to the size of the ellipsoidal mirror has become smaller.

[0007] In view of the above, an object of the present disclosure is to provide a small-sized, highly accurate gas detection device that uses an ellipsoidal mirror. [Means for solving the problem]

[0008] A gas detection device according to an embodiment includes: The light emitting device includes a light receiving section, and a light guiding section that guides light from the light emitting section to the light receiving section. The shape of at least a part of the inner surface of the light guiding section is composed of all or part of n (n: a natural number of 1 or more) ellipsoids, The n ellipsoids are divided into ellipsoids E1, E2, ..., E (n-1) , E n year, Ellipsoid E i The ellipse with the largest area in the cross section of (i: natural number satisfying 1≦i≦n) is called the ellipse Ec i Let Ec be the ellipse i The two foci of F ai , F bi Pass through the ellipsoid E without rotating it. i Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E. si When Ellipsoid E i Inside the ellipsoid E si The region that does not include i year, An ellipsoid E including the light source region of the light-emitting unit i Let E be the ellipsoid s year, An ellipsoid E including the light receiving area of ​​the light receiving unit i Let E be the ellipsoid d year, The ellipsoid E s Region R i Let R be the region in year, The ellipsoid E d Region R i Let R be the region out When 60% or more of the light source area is in the area R in and 60% or more of the light receiving area is in the area R out exists.

[0009] A gas detection device according to an embodiment includes: The light emitting device includes a light receiving section, and a light guiding section that guides light from the light emitting section to the light receiving section. The shape of at least a part of the inner surface of the light guiding section is composed of all or part of n (n: a natural number of 1 or more) ellipsoids, The n ellipsoids are divided into ellipsoids E1, E2, ..., E (n-1) , E n year, Ellipsoid E i The ellipse with the largest area in the cross section of (i: a natural number satisfying 1≦i≦n) is called the ellipse Ec i Let Ec be the ellipse i The two foci of F ai , F bi Pass through the ellipsoid E without rotating it. i Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E. si When Ellipsoid E i Inside the ellipsoid E si The region that does not include i year, An ellipsoid E including the light source region of the light-emitting unit i Let E be the ellipsoid s year, An ellipsoid E including the light receiving area of ​​the light receiving unit i Let E be the ellipsoid d year, The ellipsoid E s Region R i Let R be the region in year, The ellipsoid E d Region R i Let R be the region out When 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 year, point G in is the region R in exists at point Gout is the region R out exists. Effect of the Invention

[0010] According to the embodiments of the present disclosure, it is possible to provide a small-sized, highly accurate gas detection device using an ellipsoidal mirror. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of ray tracing in an ellipsoidal mirror. [Diagram 2] FIG. 2 is a diagram showing another example of ray tracing in an ellipsoidal mirror. [Diagram 3] FIG. 3 is a partially see-through perspective view of the gas detection device according to one embodiment. [Figure 4] FIG. 4 is a diagram showing the results of a ray tracing simulation for a spheroidal mirror. [Diagram 5] FIG. 5 is a diagram for explaining the region Ri. [Figure 6] FIG. 6 is a diagram showing an example of the configuration of the gas detection device according to this embodiment. [Figure 7] FIG. 7 is a diagram showing a modified example of the gas detection device according to the present embodiment. [Figure 8] FIG. 8 is a diagram showing the results of a light ray simulation for a general ellipsoid. [Figure 9] FIG. 9 is a diagram showing a configuration example of a light-emitting section including a passive element and a light-receiving section including an indirect element. [Figure 10] FIG. 10 is a diagram showing another example of the configuration of a light-emitting section including a passive element and a light-receiving section including an indirect element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Gas detection device of this embodiment> The gas detection device of this embodiment includes a light emitting section, a light receiving section, and a light guiding section that guides light from the light emitting section to the light receiving section.

[0013] At least a part of the shape of the inner surface of the light guiding part is configured with the figure of all or part of n pieces of spheroids (n: a natural number of 1 or more).

[0014] Let n spheroids be ellipsoids E1, E2, …, E (n-1) , E n We define the ellipsoid E i Two foci F (i: natural number satisfying 1≦i≦n) ai , F bi Passing through the ellipsoid E i has the same axis of rotational symmetry as that of the ellipsoid E i The ellipsoid that is in a similar contraction relationship with is the ellipsoid E si We define the ellipsoid E i Inside the ellipsoid E si The region that does not include i The ellipsoid E that contains the light source area of ​​the light emitting part is defined as i Let E be the ellipsoid s The ellipsoid E that contains the light receiving area of ​​the light receiving part is defined as i Let E be the ellipsoid d (When there is one ellipsoid, that is, n = 1, E s =E d ) The ellipsoid E s Region R i Let R be the region in We define the ellipsoid E d Region R i Let R be the region out It is defined as:

[0015] In the gas detection device of this embodiment, 60% or more of the area of ​​the light source region is within the region R in and 60% or more of the area of ​​the light receiving region is in region R out exists.

[0016] 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.

[0017] <An example of a specific configuration of the gas detection device according to this embodiment> 3 is a partially see-through perspective view of a gas detection device according to an embodiment of the present disclosure. The gas detection device is, for example, a small device having dimensions of 7 mm x 5 mm x 3 mm in length x width x height, and is also called a gas sensor.

[0018] 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.

[0019] The gas to be detected may be, for example, carbon dioxide, water vapor, carbon monoxide, nitrogen monoxide, ammonia, sulfur dioxide, or a hydrocarbon gas such as alcohol, formaldehyde, methane, or propane.

[0020] <Architecture (interrelationships between components)> The gas detection device includes a light emitting section, a light receiving section, and a light guiding section. The gas detection device may further include a holding section. The gas detection device may additionally include a control section. The gas detection device according to one embodiment of the present disclosure shown in FIG. 3 includes a light receiving section 20 and a light emitting section 10 held by a holding section 40, and a light guiding section 30 held by the holding section 40. Although not shown, a control section that controls at least one of the light emitting section 10 and the light receiving section 20 may be provided within the holding section 40.

[0021] 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 also includes a gas port 31 that can introduce and extract gas into and from the detection space.

[0022] 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 .

[0023] Next, the components of the gas detection device of this embodiment will be described in detail.

[0024] <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.

[0025] The light-emitting unit 10 has a light-emitting element 10A. In this embodiment, the light-emitting element 10A is an LED (light emitting diode), but as another example, the light-emitting element 10A may 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. The light-emitting unit 10 may include not only the light-emitting element 10A, but also a passive element that passively emits light upon receiving light emitted by the light-emitting element 10A. Specifically, the passive element is a mirror, an optical filter, a phosphor, an optical image, an optical fiber, an optical waveguide, a lens, or a diffraction grating.

[0026] In this embodiment, the light-emitting section 10 only has the light-emitting element 10A, and therefore the light-emitting section 10 and the light-emitting element 10A are synonymous.

[0027] The light-emitting unit 10 has a light source region. The light source region is a region where photons of the light-emitting element 10A are generated when light is guided directly from the light-emitting element 10A to the light-guiding unit 30 without passing through a passive element as in this embodiment. Specifically, it is an active region in the case of a quantum-type light-emitting element 10A, and a high-temperature region in the case of a thermal light source. For example, it is a filament in the case of a lamp.

[0028] Furthermore, when the light-emitting unit 10 includes passive elements and the light emitted by the light-emitting element 10A is guided 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. Specifically, when the passive elements are mirrors, the light source region is a region that reflects light rays.

[0029] In addition, when the passive element is an optical filter having a wavelength selection function, the area through which the light ray passes on the surface of the optical filter that is in contact with the space may be regarded as the light source area, and when the passive element is an optical fiber, an optical waveguide, or a lens, the exit surface through which the light ray passes on the surface that is in contact with the space may be regarded as the light source area.

[0030] Furthermore, when an optical image is formed as the light-emitting unit 10 by a lens, a mirror, or the like, the formed image may be regarded as the light source area.

[0031] Here, the light emitting element 10A is preferably a planar surface light source such as an LED, a MEMS heater, or a VCSEL (Vertical Cavity Surface Emitting LASER).

[0032] <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.

[0033] The light receiving unit 20 has a light receiving element 20A. In this embodiment, the light receiving element 20A 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 20A, but also an indirect element that guides light to the light receiving element 20A. Specifically, the indirect element is a mirror, an optical filter, a phosphor, a lens, a diffraction grating, an optical fiber, or an optical waveguide.

[0034] In this embodiment, since the light receiving section 20 has only the light receiving element 20A, the light receiving section 20 and the light receiving element 20A are synonymous.

[0035] The light receiving unit 20 has a light receiving region. When the light receiving element 20A receives light directly without an indirect element as in this embodiment, the light receiving region is a region of the light receiving element 20A that has a function of converting the received light into a signal. Specifically, when the light receiving element 20A is a photodiode, the light receiving region is an active layer, and when the light receiving element 20A is a thermopile, it is a thermoelectric conversion section.

[0036] In addition, when 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 for guiding the received light to the light receiving element 20A and through which the light ray passes. Specifically, when the indirect element is an optical filter having a wavelength selection function, the region through which the light ray passes on the surface of the optical filter that contacts the space may be regarded as the light receiving region. In addition, when the indirect element is an optical fiber, an optical waveguide, or a lens, the incident surface through which the light ray passes on the surface that contacts the space may be regarded as the light receiving region. In addition, when the indirect element is a mirror, the light receiving region is a region that reflects the light ray.

[0037] <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.

[0038] 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 is a figure of all or part of a spheroid. The light guiding unit 30 may further include a plane mirror, a concave mirror, a convex mirror, a lens, and a diffraction grating as auxiliary components.

[0039] The material constituting the mirror may be, for example, metal, glass, ceramics, stainless steel, etc., but is not limited to these.

[0040] 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.

[0041] Furthermore, the light guiding section 30 may be formed by cutting, and from the viewpoint of productivity, it is more preferable that the light guiding section 30 be formed by injection molding.

[0042] <Holding part> The holding section 40 is a member that holds the light receiving section 20, the light emitting section 10, 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.

[0043] When the gas detection device of the present embodiment has a control unit, the control unit may be held by the holding unit 40.

[0044] 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. Alternatively, the holding unit 40 may be a semiconductor substrate, 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. 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. The holding unit 40 may also have a connection terminal for electrically connecting to the outside.

[0045] <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.

[0046] 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).

[0047] <Gas detector size> In FIGS. 1(a) and 1(b), it is shown that when the ellipsoidal mirror is sufficiently larger than the size of the light emitting part 10, the light rays emitted from the light emitting part 10 can be collected by the light receiving part 20. Here, as the size of the light guiding part 30, a part of the shape of the light guiding part 30 is configured as an ellipsoid. Among them, the maximum length of the ellipsoid including the light emitting part 10 is defined as Lms, and the maximum length of the light source region is defined as Ls. When the condition of Ls < Lms / 50 is satisfied, the size of the light emitting part 10 is sufficiently smaller than the ellipsoidal mirror and can be approximately regarded as a point light source. Therefore, the light rays emitted from one focal position converge at the other focal position. On the other hand, as shown in FIGS. 2(a) and 2(b), when the ellipsoidal mirror is not sufficiently larger than the size of the light emitting part 10 (Ls ≧ Lms / 50), the light rays emitted from the light emitting part 10 are scattered over the entire ellipsoidal mirror and cannot be collected by the light receiving part 20.

[0048] Although not particularly limited, the gas detection device of the present embodiment exhibits a particularly remarkable effect when Ls ≧ Lms / 50.

[0049] Although not particularly limited, similarly, the gas detection device of the present embodiment exhibits a particularly remarkable effect when Ld ≧ Lmd / 50, where the maximum length of the ellipsoid including the light receiving part 20 is defined as Lmd and the maximum length of the light receiving part 20 is defined as Ld.

[0050] Next, the principle of the gas detection device of the present embodiment will be described in detail with reference to the drawings.

[0051] <Explanation of the principle> FIG. 4 is a diagram for explaining the basic principle in the present embodiment, and is a result of a ray tracing simulation in a plane passing through the rotation axis of the ellipsoidal mirror. As described above, the gas detection device may be configured by a plurality of ellipsoids, but one ellipsoid will be used for explaining the basic principle. When the n (n: a natural number of 1 or more) ellipsoids constituting the gas detection device are denoted as ellipsoids E1,..., E i ,..., E n (i: a natural number satisfying 1 ≦ i ≦ n), the ellipsoids in FIGS. 4(a), 4(b) and 5 are one ellipsoid Ei (i=n=1).

[0052] In Fig. 4(a), the focus F of the ellipsoid ai , F bi The area R is the area outside i This is the result of a simulation of a ray of light emitted from the point. In this case, the ray of light is repeatedly reflected on the mirror surface. However, in the region R INTER No light penetrates into the

[0053] Also, Fig. 4(b) shows the area R INTER This is the result of a simulation of a ray of light emitted from the focal point F of a spheroid. ai , F bi The outermost two regions are the regions R EDGE No light penetrates into the

[0054] This region R i and region R INTER The phenomenon of separation of the penetration area of ​​light rays in the mirror (hereafter referred to as the area separation phenomenon) can be explained by considering the trajectory of the light rays to be the same as the trajectory of a hard sphere that repeatedly elastically collides with a wall of the same shape as the mirror surface. For the motion of a hard sphere in free space that is elastically reflected by an ellipsoidal wall, ai Angular momentum L around Fai and the focus F bi Angular momentum L around Fbi The general angular momentum J=L Fai L Fbi is preserved. In this case, the region R i In the orbit of a rigid ball emitted from the point, it rotates in the same direction as seen from each focus, so the angular momentum L Fai and L Fbi are in the same direction and the general angular momentum J is positive (J>0). On the other hand, in the region R INTER In the case of an orbit that passes through, the direction of rotation as seen from each focus is opposite, so the general angular momentum J is negative (J<0).

[0055] In other words, according to the law of conservation of general angular momentum J, first, iThe trajectory (ray) of the rigid ball emitted from the mirror has a positive general angular momentum J, and no matter how many times it is reflected by the wall of the mirror, it remains in the region R with a negative general angular momentum J. INTER Conversely, the region R where the general angular momentum J is negative cannot be a trajectory (ray) of a hard sphere. INTER The trajectory (light ray) of the hard ball emitted from the mirror is reflected by the wall of the mirror many times, but it remains in the region R where the general angular momentum J is positive. i The trajectory (ray of light) of a hard sphere passing through the center of the sphere does not become a trajectory (ray of light). In this way, the phenomenon of domain separation occurs. Here, in the case of generalized angular momentum J = 0, it corresponds to a trajectory emitted from a focal point and reaching the other focal point, and this separates the phase space of the motion of the hard sphere.

[0056] Here, the ellipsoid E i The ellipse with the largest area in the cross section of (i: natural number satisfying 1≦i≦n) is called the ellipse Ec i In this case, if the ellipse is a spheroid, the foci are uniquely determined, and the maximum area is the cross section passing through two of the foci. i The two foci of F ai , F bi Pass through the ellipsoid E without rotating it. i Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E. si If the object is an ellipsoid, the focal point is uniquely determined. Therefore, the above principle is generally applied to the "ellipsoid E i The ellipse with the largest area in the cross section of (i: natural number satisfying 1≦i≦n) is called the ellipse Ec i Let Ec be the ellipse i The two foci of F ai , F bi Pass through the ellipsoid E without rotating it. i Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E. si This holds true when...

[0057] Next, a configuration of the gas detection device of this embodiment will be described taking into consideration the above-mentioned phenomenon of separation of the light beam entrance region.

[0058] 5 is a diagram illustrating an embodiment in which the region separation phenomenon is applied to the inner surface of the light guide unit 30 including a single spheroid shape. i By placing the light source in the area R, the light emitted from the light source at this position will always be within the area R even if it is repeatedly reflected by the mirror. i In this case, the same region R i By placing the light receiving area in the INTER In the region R i Since the light remains within the aperture, the light can be efficiently collected onto the light receiving area.

[0059] This improves the gas sensitivity of the detector. i Even if the light source area is in the region R, the effect of the present embodiment is exerted in the partial region. i The effect is realized by the presence of the complementary expression, but less than 40% of the light source area and the light receiving area are in the area R INTER From the viewpoint of improving gas sensitivity, the effect is realized by having more than 70% of the light source area in the region R i It is preferable that 80% or more of the light source area is in the area R i It is more preferable that the entire light source area is in the region R i Similarly, from the viewpoint of improving gas sensitivity, it is preferable that 70% or more of the light receiving area is in the region R i It is preferable that 80% or more of the light receiving area is in the area R i It is more preferable that the entire light receiving area is in the region R. i It is preferred that the .alpha.-

[0060] That is, the shape of at least a part of the inner surface of the light guiding section 30 is an ellipsoid E i The two foci of F ai , F bi Passing through the ellipsoid E i has the same axis of rotational symmetry as that of the ellipsoid E i The ellipsoid that is in a similar contraction relationship with is the ellipsoid E si Then, the ellipsoid Ei Inside the ellipsoid E si The region that does not include i The light source area of ​​the light-emitting unit 10 and the light-receiving area of ​​the light-receiving unit 20 are 60% or more of the area of ​​the region R i The existence of the ellipsoidal mirror in the region R allows the realization of a small, highly accurate gas detection device. INTER Specifically, this effect is remarkable when the ratio "a / b" of the minor axis b to the major axis a of the spheroid is 1.2 or more.

[0061] 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 In this case, point G in is the region R in exists at point G out is the region R out exists.

[0062] <Positioning on multiple ellipsoids> Although an embodiment in which there is one spheroid mirror (i=1) has been described above, the gas detection device of this embodiment also exhibits the same effects when it is provided with a light-guiding section 30 having a plurality of spheroid mirrors.

[0063] Fig. 6 is a diagram illustrating a gas detection device according to this embodiment in the case where three light guiding units 30 each having an inner surface (reflective surface) of a spheroid shape are used. Fig. 6(a) is a schematic diagram. Fig. 6(b) shows the results of a ray tracing simulation.

[0064] In FIG. 6(a), the region R1 of the ellipsoid E1 that contains the light source region is defined as the region R in The adjacent ellipsoid E2 includes the area R2. The light source area is the area R in If the ray is in the ellipsoid Es1 The other end of the region R in The light is transported without scattering to the region R2. By regarding the region to which this light is transported as the light source of the ellipsoid E2, the light can move through the region R2 without scattering. In order to realize this efficiently, it is preferable to further have an auxiliary reflecting section 50 as shown in Figs. 6(a) and 6(b) as a light guiding section 30 to an adjacent ellipsoid for turning back the light. The shape of the auxiliary reflecting section 50 is not particularly limited, and examples include a plane mirror, a concave mirror, and a convex mirror. The auxiliary reflecting section 50 may be configured with a shape different from that of the ellipsoid. From the viewpoints of simplicity and efficiency, it is preferable that the auxiliary reflecting section 50 is a plane mirror. Furthermore, the auxiliary reflecting section 50 may have a wavelength selection function. The auxiliary reflecting section 50 is configured to guide the light to the region R2 of the ellipsoid. i It is preferably located within the

[0065] By repeating this process, the light beam can move without scattering, as shown in the ray tracing simulation results in Fig. 6(b). Finally, the light receiving area is shifted to the area R3 of the ellipsoid E3, which is the area R. out By arranging the mirrors in this way, light can be collected as efficiently as with a single spheroidal mirror.

[0066] 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 a spheroidal mirror in the spheroidal mirror makes it possible to realize a small, highly accurate gas detection device. Compared to the case where a single spheroidal mirror is used, it is possible to design a longer optical path length, which may be preferable from the viewpoint of detection accuracy.

[0067] FIG. 7 shows a modified example in which there are two spheroids. The light guide 30 is made up of a mirror formed by combining two spheroids and one flat mirror, and the major axes of the two spheroids intersect at right angles. In this case, the region R i By providing auxiliary reflecting portion 50 in the same manner as in the case of FIG. 6, a small-sized, highly accurate gas detection device using an ellipsoidal mirror can be realized.

[0068] Although the light guide unit 30 has been described above as a spheroid, it may be a general ellipse, that is, one that does not have rotational symmetry and has three different diameters. This is because a system of hard spheres that elastically reflect inside the ellipsoid wall (the so-called billiard problem) is also an integrable system, so there exists a conserved quantity similar to the general angular momentum J, and a similar domain separation phenomenon follows. Figure 8 shows the focus F of a general ellipsoid. ai , F bi The area R is the area outside i The simulation result of the light ray emitted from the focal point F shown in FIG. ai , F bi is the focus of the plane ellipse that has the largest area when the ellipsoid is cut by a plane, and the area R i Even if the light rays emitted from the area R are repeatedly reflected, i This can also be understood from the fact that when the smallest diameter of the ellipse becomes 0 in the limit, it becomes the same as the area separation phenomenon caused by the focus of light rays in a plane ellipse, and a general ellipse is positioned in between the case of the ellipsoid of revolution explained so far and this plane ellipse.

[0069] Although the embodiment has been described above based on the drawings and examples, it should be noted that a person 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. For example, the functions included in each member, each means, etc. can be rearranged so as not to be logically inconsistent, and multiple means, etc. can be combined into one or divided.

[0070] 9 and 10 are diagrams showing an example of the configuration of a light-emitting unit 10 including a passive element and a light-receiving unit 20 including an indirect element in another embodiment. In the example of FIG. 9, the light-emitting unit 10 includes a light-emitting element 10A and a passive element that is a 45° mirror. Also, in the example of FIG. 9, the light-receiving unit 20 includes a light-receiving element 20A and an indirect element that is a 45° mirror. In the example of FIG. 10, the light-emitting unit 10 includes a light-emitting element 10A and a passive element that is a lens. Also, in the example of FIG. 10, the light-receiving unit 20 includes a light-receiving element 20A and an indirect element that is a concave mirror.

[0071] (Additional Note) A gas detection device according to an embodiment includes: The light emitting device includes a light receiving section, and a light guiding section that guides light from the light emitting section to the light receiving section. At least a part of the shape of the inner surface of the light guiding section is composed of all or part of n (n: a natural number of 1 or more) spheroids, The n number of spheroids are divided into ellipsoids E1, E2, ..., E (n-1) , E n year, Ellipsoid E i Two foci F (i: natural number satisfying 1≦i≦n) ai , F bi Passing through the ellipsoid E i has the same axis of rotational symmetry as that of the ellipsoid E i The ellipsoid that is in a similar contraction relationship with is the ellipsoid E si When Ellipsoid E i Inside the ellipsoid E si The region that does not include i year, An ellipsoid E including the light-emitting surface of the light-emitting unit i Let E be the ellipsoid s year, An ellipsoid E including the light receiving surface of the light receiving unit i Let E be the ellipsoid d year, The ellipsoid E s Region R i Let R be the region in year, The ellipsoid E d Region R iLet R be the region out When 60% or more of the area of ​​the light-emitting surface is in the region R in and 60% or more of the area of ​​the light receiving surface is in region R out may be present in [Explanation of symbols]

[0072] 10 Light emitting unit 20 Light receiving section 30 Light guide section 31 Gas Port 40 Holding part 50 Auxiliary reflector

Claims

1. The light emitting device includes a light receiving section, and a light guiding section that guides light from the light emitting section to the light receiving section. At least a part of the shape of the inner surface of the light guiding section is composed of all or part of n (n: a natural number of 1 or more) ellipsoids, The n ellipsoids are divided into an ellipsoid E １ , E ２ , … , E （ｎ－１） , E ｎ year, Ellipsoid E ｉ The ellipse with the largest area in the cross section of (i: natural number satisfying 1≦i≦n) is called the ellipse Ec ｉ Let Ec be the ellipse ｉ The two foci F ａｉ , F ｂｉ Without rotating it, we pass through the ellipsoid E ｉ Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E. ｓｉ When Ellipsoid E ｉ Inside, ellipsoid E ｓｉ The region that does not include ｉ year, An ellipsoid E including the light source region of the light-emitting unit ｉ Let E be the ellipsoid E. ｓ year, An ellipsoid E including the light receiving region of the light receiving unit ｉ Let E be the ellipsoid E. ｄ year, The ellipsoid E ｓ Region R ｉ Let R be the region ｉｎ year, The ellipsoid E ｄ Region R ｉ Let R be the region ｏｕｔ When 60% or more of the light source area is in the area R ｉｎ and 60% or more of the light receiving area is in the area R ｏｕｔ A gas detection device present in.

2. The ellipsoid E ｓ and the ellipsoid E ｄ 2. The gas detection device according to claim 1, wherein a ratio a / b of the major axis a to the minor axis b of each of said first and second electrodes is 1.2 or more.

3. The maximum length of the light source region is Ls, and the ellipsoid E ｓ 3. The gas detection device according to claim 1, wherein Ls≧Lms / 50, where Lms is the maximum length of the detection electrode.

4. The maximum length of the light receiving portion is Ld, and the ellipsoid E ｄ 4. The gas detection device according to claim 1, wherein Ld≧Lmd / 50, where Lmd is a maximum length of the first electrode.

5. The gas detection device according to claim 1 , wherein a same holder holds the light-emitting section and the light-receiving section.

6. 6. The gas detection device according to claim 5, wherein the same holding portion further holds a control portion.

7. 7. The gas detection device according to claim 1, wherein at least one of the light receiving portion and the light emitting portion is provided with an optical filter.

8. 8. The gas detection device according to claim 1, further comprising an auxiliary reflecting portion configured in a shape different from the n number of ellipsoids.

9. The region R ｉ The gas detection device according to claim 8 , wherein the auxiliary reflector is present within a first reflector.

10. The gas detection device according to claim 1 , wherein the light emitting portion is a surface light source.

11. The gas detection device according to claim 1 , wherein the n ellipsoids are spheroids.

12. The light emitting device includes a light receiving section, and a light guiding section that guides light from the light emitting section to the light receiving section. At least a part of the shape of the inner surface of the light guiding section is composed of all or part of n (n: a natural number of 1 or more) ellipsoids, The n ellipsoids are divided into an ellipsoid E １ , E ２ , … , E （ｎ－１） , E ｎ year, Ellipsoid E ｉ The ellipse with the largest area in the cross section of (i: natural number satisfying 1≦i≦n) is called the ellipse Ec ｉ Let Ec be the ellipse ｉ The two foci F ａｉ , F ｂｉ Without rotating it, we pass through the ellipsoid E ｉ Let us define the ellipsoid with the smallest volume that has a scaling relationship with ellipsoid E. ｓｉ When Ellipsoid E ｉ Inside, ellipsoid E ｓｉ The region that does not include ｉ year, An ellipsoid E including the light source region of the light-emitting unit ｉ Let E be the ellipsoid E. ｓ year, An ellipsoid E including the light receiving region of the light receiving unit ｉ Let E be the ellipsoid E. ｄ year, The ellipsoid E ｓ Region R ｉ Let R be the region ｉｎ year, The ellipsoid E ｄ Region R ｉ Let R be the region ｏｕｔ When 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 year, Point G ｉｎ is the region R ｉｎ exists at point G ｏｕｔ is the region R ｏｕｔ A gas detection device present in.

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