Gas detection device

Abstract

The present application provides a small gas detection device capable of high-precision measurement. The gas detection device is provided with a light emitting portion (10), a light receiving portion (20), and a light guide portion (30) for guiding light from the light emitting portion (10) to the light receiving portion (20). The light guide portion (30) includes a mirror (50) having a shape of a part of a rotating ellipsoid, the mirror (50) being disposed at or near a first focal point of the rotating ellipsoid, the light emitting portion (10) and the light receiving portion (20) being disposed at or near focal points other than the first focal point of the rotating ellipsoid, respectively, and the light emitting portion (10) and the light receiving portion (20) being arranged in parallel with a major axis direction of the rotating ellipsoid.

Description

Technical Field

[0001] This disclosure relates to gas detection devices. Background Technology

[0002] Gas detection devices for detecting gases are used in a wide variety of fields. For example, Patent Document 1 discloses a device configured to have a light source emitting infrared light and a detector for detecting infrared light of a specific wavelength inside a housing having an inner surface (ellipsoidal mirror) of an ellipsoid, into which the gas to be detected is introduced.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: U.S. Patent Application Publication No. 2018 / 0348121

[0006] Patent Document 2: Japanese Patent Application Publication No. 2004-257956 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Here, Figure 9 This diagram illustrates the problem of image blurring in a gas detection device with an ellipsoidal mirror. The light source (light-emitting unit 110) and the light-receiving unit 120 are positioned at the focal point of the ellipsoid within the housing. Light emitted from the light-emitting unit 110 of the gas detection device is reflected at multiple points on the inner surface of the ellipsoid, and multiple light rays are concentrated at the light-receiving unit 120. At this time, as... Figure 9 As shown, in one optical path, the distance from the light-emitting part 110 to the reflection point is 'a', and the distance after reflection to the light-receiving part 120 is 'b'. Furthermore, in other optical paths, the distance from the light-emitting part 110 to the reflection point is 'a', and the distance after reflection to the light-receiving part 120 is 'b'. The magnification of the image in the light-receiving surface of the light-receiving part 120 is related to the aforementioned optical path and is (b / a) and (b' / a'), respectively. When the light guide is constructed from an ellipsoidal mirror, multiple magnifications of images are formed in the light-receiving part 120; therefore, the image may sometimes be blurred.

[0009] For example, Patent Document 2 discloses an optical system with a double elliptical cylindrical mirror. Using a straight line passing through the three foci as the optical axis, a light source (light-emitting unit) and a detector (light-receiving unit) are arranged outside the double elliptical cylindrical mirror along the optical axis. Furthermore, a sample is arranged at the common focal point of the double ellipse, and an incident-side beam switching mirror and an exit-side beam switching mirror are arranged at the remaining two focal points. By controlling the orientation of these beam switching mirrors, an optical configuration can be obtained that allows light to enter at any incident angle relative to the sample, and the detector can detect the emitted light from any angle from the sample. In the optical system of Patent Document 2, although the optical path can be controlled, a beam switching mirror needs to be located inside the double elliptical cylindrical mirror. Therefore, if such an optical system is used, the gas detection device cannot be miniaturized. Furthermore, assuming the light-emitting unit and the light-receiving unit are located outside the double elliptical cylindrical mirror, such an optical system cannot be directly used for a small gas detection device that has the light-emitting unit and the light-receiving unit inside the housing.

[0010] The purpose of this disclosure, made in view of this point, is to provide a small gas detection device capable of high-precision measurement.

[0011] Solution for solving the problem

[0012] In one embodiment of the gas detection device of this disclosure, wherein...

[0013] The gas detection device includes a light-emitting unit, a light-receiving unit, and a light guide unit that guides light from the light-emitting unit to the light-receiving unit.

[0014] The light guide includes a mirror having the shape of a portion of one or more ellipsoidal bodies of revolution.

[0015] The mirror is positioned at or near the first focus of the elliptic of revolution.

[0016] The light-emitting part and the light-receiving part are respectively disposed at a position on the elliptic of rotation that is not the first focal point or near the focal point that is not the first focal point.

[0017] The light-emitting part and the light-receiving part are arranged parallel to the major axis of the rotating elliptic.

[0018] The effects of the invention

[0019] According to this disclosure, a small gas detection device capable of high-precision measurement can be provided. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating a structural example of a gas detection device according to one embodiment of the present disclosure.

[0021] Figure 2 It is used for explanation Figure 1 A diagram illustrating the configuration of the components of a gas detection device.

[0022] Figure 3 This is a diagram illustrating a structural example of a gas detection device according to other embodiments of the present disclosure.

[0023] Figure 4 It is used for explanation Figure 3 A diagram illustrating the configuration of the components of a gas detection device.

[0024] Figure 5 It is used for explanation Figure 3 A diagram showing the tilt and shape of the mirror in a gas detection device.

[0025] Figure 6 It is used for explanation Figure 3 A diagram showing an example of the configuration of the light-emitting part and the light-receiving part of a gas detection device.

[0026] Figure 7 It is used for explanation Figure 3 Figure 1 shows another example of the configuration of the light-emitting part and the light-receiving part of a gas detection device.

[0027] Figure 8 It means Figure 3 The figure shows the simulation results of the gas detection device.

[0028] Figure 9 This diagram illustrates the problem of image blurring in a gas detection device with an elliptical mirror.

[0029] Figure 10 This is an example Figure 3 Other tilted views of the mirror of the gas detection device.

[0030] Figure 11 This is a diagram used to illustrate a parallel configuration.

[0031] Explanation of reference numerals in the attached figures

[0032] 10. Light-emitting part; 20. Light-receiving part; 30. Light-guiding part; 31. Air inlet; 40. Holding part; 50, 50a, 50b. Mirror; 110. Light-emitting part; 120. Light-receiving part. Detailed Implementation

[0033] Hereinafter, a gas detection device according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same or equivalent parts are labeled with the same reference numerals. In the description of this embodiment, the description of the same or equivalent parts is appropriately omitted or simplified.

[0034] [First Implementation]

[0035] Figure 1 This is a block diagram of the gas detection device according to the first embodiment. The gas detection device is used to measure the concentration of a detected gas within a gas. In this embodiment, the gas detection device is an NDIR (Non-Dispersive Infrared) device that measures the concentration of the detected gas based on infrared light transmitted through the introduced gas. Examples of the detected gas include carbon dioxide, water vapor, carbon monoxide, nitric oxide, ammonia, sulfur dioxide, ethanol, formaldehyde, methane, and propane. As an example, the gas detection device is a small device with dimensions of 7mm x 9mm x 3mm (length x width x height), and is also referred to as a gas sensor.

[0036] The gas detection device includes a light-emitting unit 10, a light-receiving unit 20, and a light-guiding unit 30 that guides light from the light-emitting unit 10 to the light-receiving unit 20. The light-guiding unit 30 includes a mirror 50 and has the shape of a portion of one or more ellipsoids of revolution. In this embodiment, the ellipsoid of revolution is an ellipsoid (flattened ellipsoid) capable of rotating an ellipse about its major axis. The gas detection device may also include a gas inlet 31. Furthermore, the gas detection device may also include a holding unit 40. In addition, the gas detection device may also additionally include a control unit that controls at least one of the light-emitting unit 10 and the light-receiving unit 20.

[0037] Here, in Figure 1 In the accompanying drawings, which are referenced below, orthogonal coordinates are set corresponding to the orientation of the gas detection device. The x-axis is parallel to the major axis of the elliptical body of revolution that has a portion of the shape of the light guide 30. The z-axis is the height direction of the gas detection device. The y-axis corresponds to the minor axis of the elliptical body of revolution that is orthogonal to the x-axis and z-axis. Hereinafter, the positional relationships will be explained using the axes of this orthogonal coordinate system.

[0038] Figure 2 It is used for explanation Figure 1 A diagram illustrating the configuration of the components of a gas detection device. (See diagram for example.) Figure 1 and Figure 2 As shown, the gas detection device of this embodiment includes a light-emitting part 10, a light-receiving part 20, and a light-guiding part 30 held by a holding part 40. The gas detection device may also include a control part held by the holding part 40.

[0039] The light-emitting surface of the light-emitting part 10 and the light-receiving surface of the light-receiving part 20 are in contact with the space (detection space) between the inner surface of the light guide part 30 and the upper surface of the holding part 40. In addition, the light guide part 30 is provided with an air port 31 so as to introduce and export gas relative to the detection space.

[0040] The light emitted from the light-emitting part 10 is reflected at least once on the inner surface of the light guide part 30, which includes the reflective surface of the mirror 50, and reaches the light receiving part 20.

[0041] like Figure 2 As shown, in this embodiment, the mirror 50 is positioned at the first focus F1 of the elliptic of rotation. In this disclosure, the mirror 50 can be positioned at or near the first focus F1. A preferred range for the vicinity of the focus will be described later. In this embodiment, the light-emitting part 10 and the light-receiving part 20 are respectively positioned at locations on the elliptic of rotation that are not the first focus F1. Furthermore, the light-emitting part 10 and the light-receiving part 20 are arranged parallel to the major axis direction of the elliptic of rotation. In this disclosure, the light-emitting part 10 and the light-receiving part 20 can be respectively positioned at or near the focus of the elliptic of rotation. Figure 2 The example describes in detail that the light guide 30 has the shape of a portion of two rotating ellipsoids S1 and S2 that share a first focal point F1. The two rotating ellipsoids S1 and S2 share a major axis. Furthermore, when the focal point of one of the two rotating ellipsoids (rotating ellipsoid S1) that is not the first focal point F1 is designated as the second focal point F2, and the focal point of the other (rotating ellipsoid S2) that is not the first focal point F1 is designated as the third focal point F3, the light-emitting part 10 is positioned at the second focal point F2, and the light-receiving part 20 is positioned at the third focal point F3.

[0042] The following describes in detail the constituent components of the gas detection device according to this embodiment.

[0043] <Light-emitting part>

[0044] The light-emitting unit 10 is a component that emits light for detecting the gas being detected. There is no particular limitation on the light-emitting unit 10 as long as it outputs light with wavelengths that are absorbed by the gas being detected. In this embodiment, the light emitted by the light-emitting unit 10 is infrared light, but it is not limited to this.

[0045] The light-emitting unit 10 is configured to include a light-emitting element. In this embodiment, the light-emitting element is an LED (light-emitting diode). Other examples include lamps, lasers, organic light-emitting elements, or MEMS (Micro Electro Mechanical Systems) heaters. Furthermore, the light-emitting unit 10 may also include not only a light-emitting element but also a passive element that passively emits light by receiving light emitted from the light-emitting element. Examples of passive elements include mirrors, optical filters, phosphors, optical images, optical fibers, optical waveguides, lenses, and diffraction gratings. From a miniaturization perspective, it is preferable that the light-emitting unit 10 includes a semiconductor light-emitting element (e.g., an LED). Furthermore, it is preferable that the light-emitting element is a planar surface light source.

[0046] <Optical Receiver>

[0047] The light receiving unit 20 is a component that receives light transmitted through a gas introduced into the detection space. The light receiving unit 20 is not particularly limited to any component that has photosensitivity within the frequency band of light including wavelengths absorbed by the gas being detected. In this embodiment, the light received by the light receiving unit 20 is infrared light, but it is not limited to this.

[0048] The light receiving unit 20 is configured to include a light receiving element. In this embodiment, the light receiving element is a photodiode. Other examples include phototransistors, thermopile, thermoelectric sensors, calorimeters, or photoacoustic detectors. Furthermore, the light receiving unit 20 may also be configured to include not only the light receiving element but also indirect elements that guide light to the light receiving element. Indirect elements include, for example, mirrors, optical filters, phosphors, lenses, diffraction gratings, optical fibers, and optical waveguides. From a miniaturization perspective, it is preferable that the light receiving unit 20 includes a semiconductor light receiving element (e.g., a photodiode).

[0049] <Light Guide Section>

[0050] The light guide section 30 is a component that guides light emitted from the light-emitting section 10 to the light-receiving section 20, and is part of the optical system of the gas detection device. As described above, light from the light-emitting section 10 is reflected at least once on the inner surface of the light guide section 30, including the reflective surface of the mirror 50, before reaching the light-receiving section 20. Figure 2 As shown, in this embodiment, the mirror 50 is configured such that its reflecting surface is parallel to the major axis of the ellipsoid of revolution (parallel to the x-axis).

[0051] In this embodiment, the inner surface of the light guide portion 30 is a reflective surface. Furthermore, as described above, the inner surface of the light guide portion 30 has the shape of a portion of one or more ellipsoids of revolution. In addition to the mirror 50, the light guide portion 30 may also be supplemented with a reflector, a lens, a diffraction grating, an optical filter, etc. The mirror 50 may also be a wavelength-selective reflection filter.

[0052] Here, the materials constituting the inner surface of the light guide 30 and the reflective surface of the mirror 50 can be, for example, metal, glass, ceramic, stainless steel, etc., but are not limited to these. From the viewpoint of improving detection sensitivity, it is preferable that the materials constituting these reflective surfaces are composed of materials with low light absorption coefficients and high reflectivity. Specifically, it is preferable to have a resin housing coated with an alloy containing aluminum, gold, silver, a dielectric, or a laminate of the above. Examples of materials for the resin housing include, 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 (polyaryl ester resin), and rigid resins mixed with two or more of these. Furthermore, from the viewpoint of reliability and time-dependent changes, it is preferable to have a resin housing coated with a gold or gold-containing alloy layer. Moreover, to improve reflectivity, it is preferable to form a dielectric laminate on the surface of the metal layer. When the inner surface of the light guide portion 30 is formed on the resin housing by vapor deposition or plating, compared with the case where it is formed by metal material, it is possible to achieve improved productivity and weight reduction. Moreover, the difference in the coefficient of thermal expansion between the light guide portion 30 and the holding portion 40 is reduced, which can suppress thermal deformation and suppress changes in photosensitivity.

[0053] In addition, the light guide portion 30 can also be formed by machining, but from a production point of view, it is more preferable to form it by injection molding.

[0054] <Maintenance Section>

[0055] The holding part 40 is a component that holds 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 component relative to an external force. There are no particular limitations on the method of holding. If the gas detection device includes a control part, the holding part 40 may also hold the control part.

[0056] The holding portion 40 is not limited to a specific component as long as it can hold the light-emitting portion 10, the light-receiving portion 20, and the light-guiding portion 30. In this embodiment, the holding portion 40 is a resin encapsulation. In this embodiment, a lead frame is included inside the resin encapsulation, and the light-emitting portion 10 and the light-receiving portion 20 are electrically connected to the lead frame via cables or the like. Alternatively, if the gas detection device has a control unit, the light-emitting portion 10, the light-receiving portion 20, and the control unit can be electrically connected via the lead frame. As other examples, the holding portion 40 can also be a semiconductor substrate, a printed circuit board, or a ceramic package. For example, if the holding portion 40 is a semiconductor substrate, the light-emitting portion 10 and the light-receiving portion 20 can be formed on the semiconductor substrate. For example, if the holding portion 40 is a printed circuit board, the light-emitting portion 10 and the light-receiving portion 20 can be mechanically electrically connected to the holding portion 40 by solder. Furthermore, the light-guiding portion 30 is mechanically held in the holding portion 40 by adhesives, threaded parts, claws, mating parts, washers, or soldering. The holding part 40 may also have a connection terminal for making an electrical connection with an external device of the gas detection device.

[0057] <Control Department>

[0058] 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 also include an analog-to-digital converter circuit that converts the analog electrical signal output from the light-receiving unit 20 into a digital electrical signal. Furthermore, the control unit may also include a calculation unit that calculates the concentration of the detected gas based on the converted digital electrical signal. The control unit may be included in the gas detection device or may be provided as an external device electrically connected to the gas detection device.

[0059] The control unit may also have at least one of a general-purpose processor that performs functions corresponding to the read-in program and a dedicated processor that is specifically designed for a particular process. The dedicated processor may also include an Application Specific Integrated Circuit (ASIC). The processor may also include a Programmable Logic Device (PLD).

[0060] <Explanation of the Principle>

[0061] For reference Figure 9 As explained, in conventional gas detection devices with ellipsoidal mirrors, the image is sometimes blurred because multiple magnifications of the image are formed on the light-receiving surface. In the light guide section 30 of the gas detection device of this embodiment, as... Figure 2As shown, the light source has the shape of a portion of two ellipsoids S1 and S2 sharing a first focal point F1. Furthermore, the light-emitting unit 10 is positioned at the second focal point F2 (a point on ellipsoid S1 that is not the focal point of the first focal point F1), and the light-receiving unit 20 is positioned at the third focal point F3 (a point on ellipsoid S2 that is not the focal point of the first focal point F1). Light emitted from the light-emitting unit 10 is reflected at the reflection point (first reflection point) of ellipsoid S1, reflected on the reflecting surface of mirror 50, and reflected at the reflection point (second reflection point) of ellipsoid S2 before reaching the light-receiving unit 20.

[0062] In the gas detection apparatus of this embodiment, the distance from the light-emitting unit 10 to the first reflection point is 'a', and the distance from the first reflection point to the reflecting surface of the mirror 50 is 'b'. Furthermore, the distance from the reflecting surface of the mirror 50 to the second reflection point is 'b', and the distance from the second reflection point to the light-receiving unit 20 is 'a'. At this time, the magnification of the image in the mirror 50 is (b / a), and this image is magnified (a / b) times in the optical path from the mirror 50 to the light-receiving unit 20. In other words, in the gas detection apparatus of this embodiment, regardless of the position of the reflection point (and regardless of the optical path), a 1x image is formed in the light-receiving unit 20, thus suppressing image blurring. Image non-blurring means that a high-intensity light can be received within a certain range of the light-receiving surface, reducing the variation in light intensity relative to changes in the measurement environment. Therefore, high-precision measurements can be achieved in the concentration measurement of the detected gas.

[0063] Furthermore, the light-emitting part 10 and the light-receiving part 20 can each be configured to include semiconductor elements, realizing a compact gas detection device that includes the light-emitting part 10 and the light-receiving part 20 within a housing. Thus, the gas detection device of this embodiment is compact and capable of measuring the detected gas with high accuracy.

[0064] Here, in Figure 2 In the example, the light guide 30 has a structure having a portion of two rotating ellipsoids S1 and S2 sharing a first focal point F1. However, the number of rotating ellipsoids is not limited to two, as long as it is an even number. That is, the light guide 30 can have a shape having a portion of a total of an even number of rotating ellipsoids that share a focal point with adjacent rotating ellipsoids. The multiple rotating ellipsoids share a major axis. A mirror 50 is arranged at the position of the focal point shared by the adjacent rotating ellipsoids. A light-emitting part 10 is arranged on one side of the non-shared focal point (the focal points at both ends in the direction of the major axis of the rotating ellipsoid), and a light-receiving part 20 is arranged on the other side. If the number of rotating ellipsoids is even, then... Figure 2 Similarly, in the light receiving unit 20, an image of 1x magnification is formed, which can suppress image blurring.

[0065] [Second Implementation]

[0066] Figure 3 This diagram illustrates a structural example of the gas detection device according to the second embodiment. In the gas detection device of this embodiment, the mirror 50 is arranged such that its reflecting surface intersects the major axis direction of the elliptical body of rotation. Specifically, the mirror 50 includes not only the portion arranged parallel to the major axis direction of the elliptical body of rotation (hereinafter referred to as "mirror 50a") as in the first embodiment, but also the portion arranged intersecting the major axis direction of the elliptical body of rotation (hereinafter referred to as "mirror 50b"). Furthermore, in the gas detection device of this embodiment, the light-emitting part 10 and the light-receiving part 20 are respectively disposed near the focal point of the elliptical body of rotation that is not the first focal point F1. To avoid repetition, a structure different from that of the first embodiment will be described below.

[0067] Figure 4 It is used for explanation Figure 3 A diagram illustrating the configuration of the components of a gas detection device. (See diagram for example.) Figure 3 and Figure 4 As shown, in the gas detection device of this embodiment, the light guide 30 has a shape in which a focal point that is not the first focal point F1 is used as part of a rotating ellipsoid S1 as the second focal point F2. Figure 3 and Figure 4 In the example, mirror 50b is configured such that its reflecting surface intersects perpendicularly with the major axis of the ellipsoid of revolution. The reflected image of the ellipsoid of revolution S1 based on mirror 50b can serve as a virtual ellipsoid of revolution S2 (see reference). Figure 2 Therefore, in this embodiment, the light guide 30 has a shape consisting of a portion of an even number of actual and virtual ellipsoids of rotation. Furthermore, the actual size of the gas detection device in this embodiment is half that of the first embodiment in the direction of the major axis of the ellipsoid. The gas detection device in this embodiment includes a mirror 50b, thereby enabling further miniaturization.

[0068] Here, in Figure 3 and Figure 4 In this example, a mirror 50 is positioned at the first focal point F1, and the light-emitting part 10 and the light-receiving part 20 are respectively positioned near the second focal point F2. Similar to the first embodiment, the light-emitting part 10 and the light-receiving part 20 are arranged parallel to the major axis of the elliptic body S1. The second focal point F2 may also be located between the light-emitting part 10 and the light-receiving part 20. Furthermore, as... Figure 4As shown, when the distance between the light-emitting part 10 and the light-receiving part 20 is defined as d, it is acceptable as long as d is 0 or greater. That is, the light-emitting part 10 and the light-receiving part 20 can be arranged separately or adjacent to each other. When the light-emitting part 10 and the light-receiving part 20 are adjacent to each other, when viewed from a direction parallel to the major axis of the elliptic body S1, the portion of the light-emitting part 10 and the light-receiving part 20 that are in contact can also overlap with the position of the second focal point F2.

[0069] In this embodiment, the light emitted from the light-emitting unit 10 is reflected at the reflection point (first reflection point) of the rotating ellipsoid S1, reflected on the reflective surface of the mirror 50, and reflected again at the reflection point (second reflection point) of the rotating ellipsoid S1 before reaching the light-receiving unit 20. Here, as... Figure 4 As shown, the reflection at the reflective surface of mirror 50 includes reflection at mirror 50b and reflection at mirror 50a. Before and after reflection at the reflective surface of mirror 50, the light path is approximately the same. Therefore, in the gas detection device of this embodiment, regardless of the position of the reflection point (regardless of the light path), an image of approximately 1x size is formed in the light receiving unit 20, thus suppressing image blurring.

[0070] Here, mirror 50b is a plane mirror or a conical surface with a large radius of curvature that approaches a plane, as described later. Mirror 50b is not limited to a configuration where the reflecting surface intersects perpendicularly with the major axis of the elliptic of revolution, and can be inclined. Figure 5 This is a diagram used to illustrate the tilt and shape of mirror 50b. For example, as shown... Figure 5 As shown, when the heights of the light-emitting part 10 and the light-receiving part 20 (in other words, the positions of the light-emitting surface of the light-emitting part 10 and the light-receiving surface of the light-receiving part 20 in the z-axis direction) are different, adjustment can be made by tilting or paralleling the mirror 50b so that the image is imaged within the desired range of the light-receiving surface of the light-receiving part 20. The difference in height between the light-emitting part 10 and the light-receiving part 20 may occur, for example, when only one of the light-emitting part 10 and the light-receiving part 20 has an optical filter.

[0071] like Figure 5As shown, mirror 50b can be tilted to such an extent that it is contained within a space divided by a width w along the major axis of the elliptic of rotation, with the first focal point F1 as the base point. Mirror 50b can rotate and move parallel to the ground (including a combination of rotations centered on the z-axis, though this is not illustrated). w is not particularly limited, but needs to be determined in a way that establishes a paraxial approximation relative to the elliptic of rotation S1, suppresses aberrations, and images the optical image along the ray path. When the maximum diameter of the elliptic of rotation S1 is taken as Lmax, since it is on the order of approximately twice the radius of curvature Rtyp representing the elliptic of rotation S1, the separation distance between the optical image and its focal point must be sufficiently small compared to Rtyp; preferably, w is less than 1 / 10 of Lmax. In other words, mirror 50b can also be configured to be contained within a space divided by a width less than 1 / 10 of Lmax along the major axis of the elliptic of rotation, with the first focal point F1 as the base point. Alternatively, if mirror 50b is a conical surface, at a position away from b along the z-axis from the major axis, it can move within a range of w along the major axis with the first focus F1 as the center. Therefore, the radius of curvature can also be greater than b. 2 / W large. Here, the light guide 30 has a structure having the shape of a portion of the elliptic S1 of revolution, and the maximum diameter is not included in the light guide 30. However, the maximum diameter can be calculated based on the shape of the portion of the elliptic S1 included in the light guide 30, and the calculated value is used for Lmax mentioned above. Furthermore, the tilt of the mirror 50b is not limited to tilting around the first focal point F1. As long as the mirror 50b is contained within the space described above, it can also be accompanied by parallel movement in the x-axis direction, for example, as... Figure 10 Tilt mirror 50b as shown.

[0072] also, Figure 6 and Figure 7 This diagram illustrates an example of the configuration of the light-emitting part 10 and the light-receiving part 20. As described above, the light-emitting part 10 and the light-receiving part 20 are arranged parallel to the major axis direction (parallel to the x-axis) of the elliptic body of rotation, and the light emitted from the light-emitting part 10 is reflected by the inner surface of the light guide part 30 to reach the light-receiving part 20. However, the positions of the light-emitting part 10 and the light-receiving part 20 are not limited to the y-axis direction. Furthermore, when the sizes of the light-emitting part 10 and the light-receiving part 20 are different, the following cases also include situations where the light-emitting part 10 and the light-receiving part 20 are arranged parallel to the major axis direction of the elliptic body of rotation. Figure 11As shown, by comparing the sizes of the light-emitting part 10 and the light-receiving part 20 from a top view along the z-axis, the larger shape is designated as shape A, and the smaller shape as shape B. Furthermore, a shape Aex is defined, having an outer perimeter that is half the maximum length La of shape A relative to its outer perimeter. When shape B is moved parallel to the major axis of the elliptic body of rotation, and when shape B is included within shape Aex, the light-emitting part 10 and the light-receiving part 20 are arranged parallel to the major axis of the elliptic body of rotation. Figure 6 As shown in the example, the light-emitting part 10 and the light-receiving part 20 can also be configured to be located on the major axis of the rotating elliptic. Furthermore, as... Figure 7 As shown in the example, even when the light-emitting portion 10 and the light-receiving portion 20 are not located on the major axis of the elliptic of revolution, they are still included in a configuration near the second focal point F2. Furthermore, regardless of the position of the light-emitting portion 10 and the light-receiving portion 20 in the y-axis direction, the distance d between the light-emitting portion 10 and the light-receiving portion 20 can be set to 0. That is, the light-emitting portion 10 and the light-receiving portion 20 can be arranged adjacent to each other. Moreover, as long as the image can be imaged within a desired range of the light-receiving surface of the light-receiving portion 20, the second focal point F2 does not need to be located between the light-emitting portion 10 and the light-receiving portion 20; for example, the second focal point F2 can overlap with the light-emitting portion 10, and the second focal point F2 can also overlap with the light-receiving portion 20. Thus, setting the light-emitting portion 10 and the light-receiving portion 20 near the focal point means that the light-emitting portion 10 and the light-receiving portion 20 are arranged close to the focal point in a manner that allows the image to be imaged within a desired range of the light-receiving surface of the light-receiving portion 20. Furthermore, the light-emitting part 10 and the light-receiving part 20 are arranged within a range of v along the major axis direction with the x-axis coordinate of the second focal point F2 as the center (see reference). Figure 7 The value of v is not particularly limited, but it needs to be determined in a way that allows for paraxial approximation relative to the elliptic rotating body S1, suppresses aberrations, and enables the optical image to be formed along the light path. When the maximum diameter of the elliptic rotating body S1 is taken as Lmax, since it is on the order of approximately twice the radius of curvature Rtyp representing the elliptic rotating body S1, the separation distance between the optical image and its focal point needs to be sufficiently small compared to Rtyp, i.e., v is preferably less than 1 / 10 of Lmax. The light emission center of the light-emitting part 10 and the light receiving center of the light receiving part 20 can be arranged within the range of v in the major axis direction with the x-axis coordinate of the second focal point F2 as the base point.

[0073] Figure 8 This is a graph showing the simulation results of the gas detection device according to this embodiment. (In...) Figure 3In the gas detection device configured in this way, a simulation is performed to calculate the intensity of light emitted from the light-emitting unit 10 and the light-receiving unit 20. The center-to-center distance between the light-emitting unit 10 and the light-receiving unit 20 is set to 700 μm. Furthermore, the size of the light-emitting surface of the light-emitting unit 10 is set to 154 μm in the x-axis direction and 194 μm in the y-axis direction. Furthermore, the size of the light-receiving surface of the light-receiving unit 20 is set to 390 μm in both the x-axis and y-axis directions. Additionally, the major axis of the rotating elliptical body S1, including the light guide unit 30, is 18.00 mm, and the minor axis is 14.94 mm. The mirror 50 is a plane mirror, arranged perpendicular to the major axis of the rotating elliptical body at the position of the first focal point F1. Figure 8 As shown in the simulation results, it demonstrates that the central portion of the light-receiving surface can receive light of greater intensity. Here, the darker the color (the deeper the color), the greater the light intensity. Furthermore, in the context of... Figure 8 The light intensity was calculated for the area enclosed by the double-dotted line in the light receiving section 20. Regarding energy efficiency, it reached 96.3% when the reflectivity of the light guide section 30 was 100%, and 81.8% when the reflectivity of the light guide section 30 was 96%. Simulations show that the gas detection device of this embodiment can receive light with high intensity within a certain range of the light receiving surface, and also has high energy efficiency.

[0074] Here, further simulation experiments were conducted by changing the configuration of the light-emitting part 10 and the light-receiving part 20 of the gas detection device. The results clearly show that, in order to improve energy efficiency, it is preferable to position the light-emitting part 10 closer to the first focal point F1 than the light-receiving part 20. For example, when the light-emitting part 10 and the light-receiving part 20 are positioned across the second focal point F2, it is preferable not to position the light-emitting part 10 on the outer periphery of the rotating ellipsoid, but rather as follows: Figure 4 As shown, the light-emitting part 10 is arranged on the center side (near the first focal point F1).

[0075] The gas detection device of this embodiment images approximately one times larger in the light receiving unit 20, thus suppressing image blurring. Furthermore, the gas detection device of this embodiment includes a mirror 50b, allowing for miniaturization compared to the first embodiment. Therefore, the gas detection device of this embodiment is compact and capable of measuring the detected gas with high accuracy, making it particularly advantageous for applications requiring miniaturization.

[0076] Here, in Figure 4In the example, the light guide 30 has a structure having a portion of a rotating elliptic S1. However, the number of rotating elliptices is not limited to one. Here, in the first embodiment, it is necessary for the total number of multiple rotating elliptices to be even. In this embodiment, the number of rotating elliptices, including the virtual image, based on the reflected image of the mirror 50b is even. Therefore, in this embodiment, the number of rotating elliptices is not limited and may not be even. Here, in this embodiment, when there are multiple rotating elliptices, the major axis may also be shared.

[0077] While embodiments of this disclosure have been described with reference to the accompanying drawings and examples, it should be noted that those skilled in the art can readily make various modifications or alterations based on this disclosure. Therefore, such modifications or alterations are included within the scope of this disclosure. For example, the functions of each component can be reconfigured in a logically consistent manner, and multiple components can be combined into one or divided.

Claims

1. A gas detection device, wherein, The gas detection device includes a light-emitting unit, a light-receiving unit, and a light guide unit that guides light from the light-emitting unit to the light-receiving unit. The inner surface of the light guide has the shape of a portion of one or more ellipsoids of revolution, and the light guide also includes a mirror. The elliptic body of revolution is an elliptic body formed by rotating an ellipse about its major axis. The mirror is positioned at or near the first focus of the elliptic of revolution. The light-emitting part and the light-receiving part are disposed at a position on the elliptic of rotation that is not the first focal point or near the focal point that is not the first focal point. The light-emitting part and the light-receiving part are arranged parallel to the major axis of the rotating elliptic. The mirror is configured such that its reflecting surface is parallel to the major axis of the elliptic body.

2. The gas detection device according to claim 1, wherein, The mirror also includes a portion arranged such that its reflecting surface intersects the major axis of the elliptic body of revolution, with the maximum diameter of the elliptic body of revolution defined as Lmax. The portion of the mirror is configured to be contained within a space divided forward and backward along the major axis of the elliptic of revolution with the first focal point as the base point, by a width of 1 / 10 of Lmax.

3. The gas detection device according to claim 2, wherein, The portion of the mirror is either a plane mirror or a conical surface with a large radius of curvature that approximates a plane.

4. The gas detection device according to claim 2, wherein, The portion of the mirror is capable of rotation and parallel movement within the space.

5. The gas detection device according to claim 2, wherein, The portion of the mirror is configured such that its reflecting surface intersects perpendicularly with the major axis of the elliptic of revolution.

6. The gas detection device according to claim 2 or 5, wherein, The light guide portion has a shape that incorporates a focal point that is not the first focal point as a second focal point as part of an ellipsoid of revolution. The light-emitting part and the light-receiving part are respectively disposed near the second focal point.

7. The gas detection device according to claim 6, wherein, The light-emitting center of the light-emitting part and the light-receiving center of the light-receiving part are respectively arranged along the major axis direction with the second focal point as the base point in a space separated by a width of 1 / 10 of Lmax along the major axis direction of the rotating ellipse.

8. The gas detection device according to claim 6, wherein, The second focal point is located between the light-emitting part and the light-receiving part.

9. The gas detection device according to claim 6, wherein, The light-emitting part and the light-receiving part are arranged adjacent to each other.

10. The gas detection device according to claim 2 or 5, wherein, The light-emitting part is positioned closer to the first focal point than the light-receiving part.

11. The gas detection device according to claim 1, wherein, The light guide portion has the shape of a portion of two rotating ellipsoids sharing the first focal point. When the focus of one of the two rotating ellipsoids that is not the first focus is taken as the second focus, and the focus of the other of the two rotating ellipsoids that is not the first focus is taken as the third focus, the light-emitting part is disposed at the position of the second focus, and the light-receiving part is disposed at the position of the third focus.

12. The gas detection device according to any one of claims 1, 2, 5 and 11, wherein, The light-emitting part includes a semiconductor light-emitting element, and the light-receiving part includes a semiconductor light-receiving element.

13. The gas detection device according to claim 1, wherein, The gas detection device has a holding part for holding the light-emitting part, and the light-emitting surface of the light-emitting part and the light-receiving surface of the light-receiving part are in contact with the space between the inner surface of the light guide part and the upper surface of the holding part.

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