Gas detection equipment

Abstract

To provide a gas detector with a stable precision.SOLUTION: A gas detector 1 includes: a light emitting element 3 on a main surface 20 of a substrate 2, the light emitting element emitting light from a light emission surface 31; a light reception element 4 on the main surface 20 of the substrate 2, the light reception element receiving light at a light reception surface 41; and a light guiding member 5 for guiding light emitted from the light emission surface 3 to the light reception element 4. The light emission surface 31 and the light reception surface 41 have a shape with a corner when the main surface 20 of the substrate 2 is viewed planarly. The sides of the light emission surface 31 do not overlap with the sides of the light reception surface 41 when the light emission surface is enlarged or reduced, or is moved in parallel.SELECTED DRAWING: Figure 1

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 the same case, and is configured so that a gas to be detected is introduced into the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-184211 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the gas detection device described in Patent Document 1 performs multiple reflections with multiple mirrors to increase the optical path length. Here, when multiple optical members are arranged in the optical system, the image of the light received by the light receiving element may differ from the original image of the light emitted by the light emitting element due to transformations such as enlargement / reduction and rotation, as well as the effects of optical aberration and diffraction. Such changes in the image of the light may hinder stable and highly accurate gas detection.

[0005] In addition, gas detectors have traditionally used lamps as light sources, but in recent years (since 2018), SMD-type (Surface Mount Device) mid-infrared LED light sources have been developed and mass-produced, and light sources with light-emitting element sizes significantly smaller than lamps are now being used. In conventional lamps, the size of the light shape incident on the light-receiving element (cross-sectional area of ​​the incident light beam) is sufficiently larger than the size of the light-receiving element, and the cross-section of the incident light beam spreads in a rotationally symmetric shape (typically circular). However, by using an LED light source, the cross-sectional area of ​​the incident light beam is equal to or smaller than the size of the light-receiving element, and the cross-section of the incident light beam changes to a rectangle with corners according to the shape of the light source, and the corners of the cross-section of the incident light beam deviate from the light-receiving element, resulting in a problem of a decrease in the SNR (Signal to Noise Ratio) of the light-receiving element.

[0006] The present disclosure has been made in consideration of the above-mentioned conventional unsolved problems, and aims to realize a stable, highly accurate gas detection device. [Means for solving the problem]

[0007] A gas detection device according to an embodiment of the present disclosure includes: a light emitting element provided on a main surface of the substrate and emitting light from a light emitting surface; a light receiving element provided on a main surface of the substrate, the light receiving element receiving the light on a light receiving surface; a light guiding member for guiding the light emitted by the light emitting element to the light receiving element, When the main surface of the substrate is viewed in plan, The light emitting surface and the light receiving surface have a shape having corners, The sides of the light emitting surface do not overlap with the sides of the light receiving surface due to enlargement or reduction and translation.

[0008] The light-emitting surface is the surface of the light-emitting part of the element that comes into contact with the gas and is made of an optically transparent material, while the light-receiving surface is the surface of the sensor part of the element that comes into contact with the gas and is made of an optically transparent material.

[0009] A gas detection device according to an embodiment of the present disclosure includes: a light emitting element provided on a main surface of the substrate and emitting light from a light emitting surface; a light receiving element provided on a main surface of the substrate, the light receiving element receiving the light on a light receiving surface; a light guiding member for guiding the light emitted by the light emitting element to the light receiving element, When the main surface of the substrate is viewed in plan, The light emitting surface and the light receiving surface have a shape having corners, Each side of the light-emitting surface is not parallel to any side of the light-receiving surface.

[0010] A gas detection device according to an embodiment of the present disclosure includes: A substrate having a rectangular main surface; a light emitting element provided on a main surface of the substrate and emitting light from a rectangular light emitting surface; a light receiving element provided on a main surface of the substrate and having a rectangular light receiving surface for receiving the light; a light guiding member for guiding the light emitted by the light emitting element to the light receiving element, When the main surface of the substrate is viewed in plan, each side of the light receiving surface or the light emitting surface is not parallel to any side of the main surface of the substrate. Effect of the Invention

[0011] According to one embodiment of the present disclosure, a stable and highly accurate gas detection device can be realized. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a partially see-through perspective view of a gas detection device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of a cross section of the gas detection device. [Diagram 3] FIG. 3 is a diagram showing an example of an arrangement of light emitting elements and light receiving elements. [Figure 4] FIG. 4 is a diagram showing a margin of a light receiving element in a comparative example. [Diagram 5]FIG. 5 is a diagram showing a margin of the light receiving element in this embodiment. [Figure 6] FIG. 6 is a diagram for explaining the rotated image. [Figure 7] FIG. 7 is a diagram showing another example of the arrangement of light emitting elements and light receiving elements. [Figure 8] FIG. 8 is a diagram showing another example of the arrangement of light emitting elements and light receiving elements. [Figure 9] FIG. 9 is a diagram for explaining the cause of rotation of the light image. [Figure 10] FIG. 10 is a diagram for explaining the cause of rotation of the light image. [Figure 11] FIG. 11 is a diagram for explaining the suppression of the influence of optical aberration when an off-axis optical system is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 1 is a partially see-through perspective view of a gas detection device 1 according to an embodiment of the present disclosure. Gas detection device 1 is, for example, a small device measuring 30 mm×20 mm×10 mm, and is also referred to as a gas sensor. In this embodiment, gas detection device 1 is an NDIR (Non Dispersive InfraRed) type device that measures the concentration of a detection target gas based on infrared light that has passed through an introduced gas. The detection target gas is, for example, carbon dioxide, water vapor, methane, propane, formaldehyde, carbon monoxide, nitric oxide, ammonia, sulfur dioxide, alcohol, or the like.

[0014] Gas detection device 1 includes a substrate 2, a light-emitting element 3, a light-receiving element 4, a light-guiding member 5, and a bonding member 6. Fig. 1 shows an example of the configuration of gas detection device 1 through a portion of light-guiding member 5, and shows light-emitting element 3 and light-receiving element 4 provided on main surface 20 of substrate 2. In this embodiment, main surface 20 is the surface of substrate 2 that has the largest area and faces light-guiding member 5. Main surface 20 is rectangular.

[0015] 1, orthogonal coordinates are set so that the xy plane is parallel to the main surface 20 of the substrate 2. The z-axis direction is perpendicular to the main surface 20 of the substrate 2. The x-axis and y-axis directions are parallel to the sides of the main surface 20 of the substrate 2. Here, the y-axis direction corresponds to the direction in which a first reflecting portion 51 and a second reflecting portion 52, which will be described later, face each other.

[0016] The substrate 2 is a plate-like member on which the components of the gas detection device 1 are mounted and which electrically connects the mounted electronic components. The substrate 2 has the light-emitting element 3 and the light-receiving element 4 provided on the main surface 20. The substrate 2 may further have other electronic components mounted thereon. For example, the substrate 2 may have a controller for controlling at least one of the light-emitting element 3 and the light-receiving element 4 provided on the main surface 20 or the bottom surface opposite to the main surface 20. The substrate 2 may also have a calculation unit on the main surface 20 or the bottom surface that performs calculations for calculating the gas concentration. The calculation unit may include at least one of a general-purpose processor that performs 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). The calculation unit may be integrated with the controller.

[0017] The light-emitting element 3 is a component that emits light used to detect the gas to be detected. The light-emitting element 3 is not particularly limited as long as it outputs light including a wavelength that is absorbed by the gas to be detected. In this embodiment, the light emitted by the light-emitting element 3 is infrared light, but is not limited thereto. In this embodiment, the light-emitting element 3 is an LED (light emitting diode), but as another example, it may be an incoherent light source such as an organic light-emitting element or a MEMS (Micro Electro Mechanical Systems) heater. The light-emitting element 3 is provided at a position facing a first mirror 511 described later in the z-axis direction.

[0018] The light-emitting element 3 has a rectangular light-emitting surface 31. The light-emitting element 3 is a surface light source that emits light from the entire light-emitting surface 31. As shown in FIG. 1, the light-emitting element 3 emits light from the light-emitting surface 31 in the z-axis direction, that is, in the thickness direction of the substrate 2.

[0019] The light receiving element 4 is a component that receives light that has passed through the introduced gas. The light receiving element 4 is not particularly limited as long as it has sensitivity to a band of light including a wavelength absorbed by the gas to be detected. In this embodiment, the light received by the light receiving element 4 is infrared light, but is not limited thereto. In this embodiment, the light receiving element 4 is a photodiode, but may be a phototransistor, a thermopile, a pyroelectric sensor, a bolometer, or the like as another example. The light receiving element 4 converts the received light into an electric signal and outputs the converted electric signal. The electric signal is output to, for example, a calculation unit. The calculation unit that receives the electric signal calculates the concentration of the gas to be detected based on the transmittance of the light, etc. The light receiving element 4 is provided at a position facing a fifth mirror 513 described later in the z-axis direction. The light receiving element 4 may be provided with an optical filter having a wavelength selection function.

[0020] The light receiving element 4 has a rectangular light receiving surface 41. As shown in Fig. 1, the light receiving element 4 receives light in the z-axis direction, that is, the thickness direction of the substrate 2, at the light receiving surface 41.

[0021] The light guiding member 5 is a member that guides the light emitted by the light emitting element 3 to the light receiving element 4. The light guiding member 5 is an optical system of the gas detection device 1. The light guiding member 5 includes optical members and constitutes an optical path from the light emitting element 3 to the light receiving element 4. In other words, the light guiding member 5 optically connects the light emitting element 3 and the light receiving element 4. Here, the optical members are, for example, a mirror, a lens, etc.

[0022] In this embodiment, the light guide member 5 includes a first reflecting portion 51 and a second reflecting portion 52. The first reflecting portion 51 includes a first mirror 511, a third mirror 512, and a fifth mirror 513 as optical members. The first reflecting portion 51 directly reflects the light emitted from the light emitting element 3 and the light received by the light receiving element 4. The second reflecting portion 52 includes a second mirror 521 and a fourth mirror 522 as optical members. The second reflecting portion 52 reflects light between itself and the first reflecting portion 51. The light guide member 5 reflects the light emitted by the light emitting element 3 multiple times and emits the light to the light receiving element 4. Specifically, the light guiding member 5 reflects the light emitted by the light emitting element 3 off of the first mirror 511, the second mirror 521, the third mirror 512, the fourth mirror 522, and the fifth mirror 513 in this order, and guides the light to the light receiving element 4. The light path is configured to pass through a cell 54, into which a gas is introduced, provided between the light guiding member 5 and the substrate 2. As another example, the number of mirrors included in the light guiding member 5 is not limited to five, and may be one or more. Furthermore, the light guiding member 5 may be configured to include a lens in a part of the light path.

[0023] In the light guide member 5, the first reflecting portion 51 is fixed in a relative position with respect to the second reflecting portion 52. For example, the first reflecting portion 51 and the second reflecting portion 52 may be made of resin and integrally formed. The mirrors of the first reflecting portion 51 and the second reflecting portion 52 may be processed by metal plating after integral formation. As another example, the first reflecting portion 51 and the second reflecting portion 52 may be formed separately and strongly fixed by adhesive, screws, claws, fitting, grommets, welding, or the like.

[0024] The first mirror 511 is a collecting mirror that reflects the light from the focal point that is incident thereon. The first mirror 511 is, for example, a concave mirror. The shape of the first mirror 511 may be an ellipsoid. In this embodiment, the first mirror 511 reflects the light emitted in the z-axis direction from the light-emitting element 3 at the focal point, in an xy plane direction perpendicular to the z-axis direction. Here, the xy plane direction is a direction having at least one component in the x-axis direction and the y-axis direction. However, the xy plane direction may have a z-axis component.

[0025] The second mirror 521, the third mirror 512, and the fourth mirror 522 reflect the incident light. At least one of the second mirror 521, the third mirror 512, and the fourth mirror 522 may be a light-collecting mirror having a light-collecting function. At least one of the second mirror 521, the third mirror 512, and the fourth mirror 522 may be, for example, a concave mirror. As shown in FIG. 1, the second mirror 521 reflects the incident light from the first mirror 511 to the third mirror 512. The third mirror 512 reflects the incident light from the second mirror 521 to the fourth mirror 522. The fourth mirror 522 reflects the incident light from the third mirror 512 to the fifth mirror 513.

[0026] The fifth mirror 513 is a focusing mirror that focuses the incident light on a focal point. The fifth mirror 513 is, for example, a concave mirror. The shape of the fifth mirror 513 may be an ellipsoid. In this embodiment, the fifth mirror 513 reflects the incident light in the xy plane direction from the fourth mirror 522 so as to have a z-axis component. Specifically, the fifth mirror 513 reflects the incident light so as to focus it on the light receiving element 4 at the focal point.

[0027] The materials constituting the first mirror 511, the second mirror 521, the third mirror 512, the fourth mirror 522, and the fifth mirror 513 may be, for example, metal, glass, ceramics, stainless steel, etc., but are not limited thereto. From the viewpoint of improving the detection sensitivity, it is preferable that the materials constituting these mirrors are 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. 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 first mirror 511 and the fifth mirror 513 are formed on the resin housing by deposition or plating, it is possible to improve high productivity and weight reduction compared to when they are formed from a metal material. Furthermore, the difference in thermal expansion coefficient with the substrate 2 is reduced, thermal deformation is suppressed, and sensitivity is less likely to fluctuate. In addition, the light guide member 5 may be formed by cutting, and from the viewpoint of productivity, it is more preferable to form it by injection molding.

[0028] The joining member 6 is a member that joins the substrate 2 and the light guiding member 5. In this embodiment, the joining member 6 has a first bottom surface portion 61 (see FIG. 2) that is joined to the substrate 2, and a second bottom surface portion 62 that is joined to the light guiding member 5. The first bottom surface portion 61 and the substrate 2 are joined by, for example, an adhesive, a grommet or a screw, welding, a claw, a fit, or the like. The second bottom surface portion 62 and the light guiding member 5 are joined in the same manner. Furthermore, from the viewpoint of productivity, it is desirable that the joining member 6 and the light guiding member 5 are integrally molded in order to reduce the number of components.

[0029] Fig. 2 is a diagram showing an example of a cross section of gas detection device 1. Fig. 2 shows a cross section of substrate 2, light guiding member 5 including third mirror 512, and bonding member 6 cut along a plane parallel to the yz plane. Cell 54 is formed inside gas detection device 1, sandwiched between substrate 2 and light guiding member 5. Light guiding member 5 includes vent 53 for introducing gas into cell 54. Vent 53 can also be used to exhaust gas from cell 54.

[0030] The joining member 6 includes a first portion 6a including a first bottom surface portion 61, a second portion 6b including a second bottom surface portion 62, and a joining portion 63 that joins the first portion 6a, the second portion 6b, and the third mirror 512. The first portion 6a and the second portion 6b include a hollow cylindrical body. The first bottom surface portion 61 is joined to the substrate 2 by inserting a screw from the bottom surface of the substrate 2. The second bottom surface portion 62 is joined to the light guide member 5 by inserting a grommet into the hollow portion and expanding it. In addition, as shown in FIG. 2, the relative position of the first reflecting portion 51 to the second reflecting portion 52 is further firmly fixed by joining the third mirror 512 to the joining member 6. As another example, the first portion 6a and the second portion 6b may be a solid cylindrical body. The first bottom surface portion 61 and the substrate 2, and the second bottom surface portion 62 and the light-guiding member 5 may be joined by adhesive, screws, tabs, fitting, grommets, welding, etc. Here, the first mirror 511, the main surface 20 of the substrate 2, and the light-emitting element 3 in Fig. 2 are the same as the elements with the same numbers in Fig. 1, and therefore descriptions thereof will be omitted.

[0031] Fig. 3 is a diagram showing an example of the arrangement of the light-emitting element 3 and the light-receiving element 4. Fig. 3 shows the main surface 20 of the substrate 2 as viewed in the negative direction of the z-axis. In other words, the arrangement of the light-emitting element 3 and the light-receiving element 4 when the main surface 20 of the substrate 2 is viewed in plan view is shown.

[0032] As shown in Fig. 3, the light emitting surface 31 is rectangular and has sides 32a, 32b, 32c, and 32d. Also, the light receiving surface 41 is rectangular and has sides 42a, 42b, 42c, and 42d. The light emitting surface 31 and the light receiving surface 41 in this embodiment are shaped with corners. Generally speaking, a shape S having corners means that the shape S can be approximated by a polygon with six or fewer sides. When a polygon P having N vertices (an integer where 2 < N < 7) is defined on the shape S so that the area mismatch rate is minimized, the area mismatch rate is 5% or less. Here, the area mismatch rate is the area of the region included in the shape S but not included in the polygon P, plus the area of the region not included in the shape S but included in the polygon P, divided by the area of the shape S. For comparison here, the minimum area mismatch rate of a regular hexagon with respect to a circle is 7.4%, and a circle does not have a shape with corners.

[0033] The light emitting element 3 emits light from the entire surface of the light emitting surface 31. The shape of the emitted light L0 when the main surface 20 of the substrate 2 is viewed in plan is the same as that of the light emitting surface 31. Each of the sides 32a, 32b, 32c, and 32d of the light emitting surface 31 is parallel to the x-axis or the y-axis. That is, when the main surface 20 of the substrate 2 is viewed in plan, each of the sides 32a, 32b, 32c, and 32d of the light emitting surface 31 is parallel to any side of the main surface 20 of the substrate 2.

[0034] The light receiving element 4 receives the rectangular incident light L1 on the light receiving surface 41. The incident light L1 has a shape obtained by reducing, rotating, shear-transforming, and trapezoidally deforming the emitted light L0 in the xy plane. For reasons described later, the light receiving surface 41 is arranged in accordance with the rotation of the incident light L1 so as to increase the minimum distance between the edge of the incident light L1 and the sides 42a, 42b, 42c, and 42d of the light receiving surface 41. As shown in Fig. 3, each of the sides 42a, 42b, 42c, and 42d of the light receiving surface 41 is not parallel to the x-axis and not parallel to the y-axis either. That is, when the main surface 20 of the substrate 2 is viewed in plan, each of the sides 42a, 42b, 42c, and 42d of the light receiving surface 41 is not parallel to any side of the main surface 20 of the substrate 2.

[0035] In gas detection device 1 in which light is reflected multiple times in the optical system, rotation of the light image generally occurs except in certain arrangements. As an example, the rotation angle is non-zero, for example, 45° or less. Therefore, when main surface 20 of substrate 2 is viewed in plan, the direction of the side of incident light L1 does not coincide with the original emitted light L0, but coincides with the emitted light L0 after rotation.

[0036] FIG. 4 is a diagram showing an example of the arrangement of the light receiving element 4 in the comparative example. The light receiving element 4 in the comparative example is arranged so that the sides of the light receiving surface 41 are parallel to the x-axis or y-axis. That is, in the comparative example, the light receiving element 4 is arranged so that the sides of the light receiving surface 41 are parallel to the sides of the main surface 20 of the substrate 2. As described above, since the incident light L1 rotates, the minimum margin m0 of the light receiving area is small in the light receiving surface 41 of the light receiving element 4 in the comparative example. If the margin m0 is small, the total amount of light received by the light receiving surface 41 changes due to an error in the arrangement of the light receiving element 4 on the main surface 20, a deviation of the incident light L1 due to the use environment or aging, etc., and this may affect the accuracy of gas detection. Here, if the light receiving surface 41 is made larger, that is, the light receiving element 4 is made larger in order to increase the margin m0, the manufacturing cost of the gas detection device 1 increases, and noise also increases, making it difficult to miniaturize the device. In addition, the effects of optical aberration and diffraction are another factor that reduces the margin m0.

[0037] FIG. 5 is a diagram showing an example of the arrangement of the light receiving element 4 of the gas detection device 1 according to this embodiment. As described above, in this embodiment, the light receiving surface 41 is rotated and arranged on the xy plane in accordance with the incident light L1. Therefore, it is possible to make the minimum margin m1 of the light receiving region larger than the margin m0 of the comparative example. Since the gas detection device 1 according to this embodiment has a large margin m1, the accuracy of gas detection is less susceptible to the effects of errors in the arrangement of the light receiving element 4 on the main surface 20, deviations of the incident light L1 due to the usage environment or aging, and the like. Therefore, the gas detection device 1 according to this embodiment is capable of stable and highly accurate gas detection.

[0038] Here, the cause of the rotation of the light image (incident light L1) is as follows. As an example, as shown in Figs. 9 and 10, a case will be described in which the third mirror 512 among the second mirror 521, the third mirror 512, and the fourth mirror 522 is a light-collecting mirror having a light-collecting function. The rotation of the image is determined by the tilt direction of the first mirror 511 and the fifth mirror 513. The light emitted from the light-emitting surface 31 is reflected by the first mirror 511 toward the second mirror 521. At this time, the light emitted from the focal point of the first mirror 511 is imaged on the second mirror 521 at the other focal point of the ellipse. In addition, the Z-axis positive direction is the rotation axis, and the long side of the ellipse of the first mirror 511 is tilted at an angle A with respect to one side of the rectangular light-emitting surface 31 parallel to the Y-axis, assuming the direction of a right-handed screw as positive. For this reason, the image that is formed has the positive Z-axis direction facing upward, and is an image that has been rotated +A° from the inverted real image around the axis of the light's travel direction, with the right-handed screw direction as the positive direction.

[0039] Here, if we change our perspective and consider the relationship between the light intensity distribution on the light-emitting surface 31 and the image inversely, we emphasize that with the direction of the right-handed screw being positive, the light emission intensity distribution image (emitted light L0) of the light-emitting surface 31 is an image rotated by -A° with respect to the image on the second mirror 521 (this property will be used in the description of the fifth mirror 513).

[0040] The third mirror 512 forms the image reflected by the second mirror 521 again as an inverted real image on the fourth mirror 522. That is, the image formed on the fourth mirror 522 is an image in which the positive direction of the Z axis is upward, and the image formed on the second mirror 521 is rotated by A°+180° around the axis of the light travel direction, with the right-handed screw direction being positive.

[0041] The elliptical mirror of the fifth mirror 513 forms an image of the light reflected from the fourth mirror 522 on the light receiving surface 41 arranged at the focal point. The long side of the ellipse of the fifth mirror 513, which has the positive Z-axis direction as the rotation axis, is inclined at an inclination of -B with respect to one side of the rectangular light emitting surface 31 parallel to the Y-axis, with the right-handed screw direction being positive, and the traveling direction of the light relative to the reflecting surface of the fifth mirror 513 is opposite to the relationship between the reflecting surface of the first mirror 511 and the traveling direction of the light. Therefore, the light incident on the light receiving surface 41 becomes an image rotated 180°+A°+B° from the inverted real image around the traveling direction of the light as the axis, with the right-handed screw direction being positive, using the positive direction of the light intensity distribution on the light emitting surface 31 as the reference.

[0042] FIG. 6 is a diagram for explaining a rotated image. As shown in FIG. 6, in the light guide member 5, when a concave mirror or a plane mirror facing the light emitting surface 31 is inclined in the second direction, the image rotates in the upward positive direction. Here, the first direction is a specific direction of the image (emitted light L0) of the light emitting surface 31 (for example, the direction of a specific side if the shape of the light emitting surface 31 is rectangular). The second direction is a direction perpendicular to the first direction in the light emitting surface 31 and in a right-handed system. Similarly, in the light receiving surface 41, when a mirror facing the light receiving surface 41 is inclined, the light guide member 5 rotates the image of the light. Here, inclination in the second direction refers to a vector in the direction of the rotational symmetry axis of the concave mirror (particularly in the case of a plane mirror, a local rotation axis exists at any part, so it is the same as a normal direction vector) that is not perpendicular to the second direction, that is, the inner product of the unit vector of the second direction and the second direction is not 0, and has a projected component in the second direction. In other words, when the light-emitting surface 31 and the light-receiving surface 41 are rectangular, the gas detection device 1 having a light-guiding member 5 constituted by a mirror surface (or a mirror surface of an off-axis optical system) that is inclined with respect to the direction of one side of the light-emitting surface 31 or the light-receiving surface 41 and the direction perpendicular to that plane will experience rotation of the image (incident light L1).

[0043] Therefore, even if the light-emitting element 3 is rotated, the direction of the emitted light L0 and the direction of the incident light L1 do not coincide. Therefore, when the main surface 20 of the substrate 2 is viewed in plan, the arrangement of the light-receiving element 4 of the gas detection device 1 according to this embodiment can be described as follows based on the arrangement of the light-emitting element 3. The sides 32a, 32b, 32c, and 32d of the light-emitting surface 31 of the light-emitting element 3 do not overlap with the sides 42a, 42b, 42c, and 42d of the light-receiving surface 41 of the light-receiving element 4 due to the enlargement or reduction of the light-emitting surface 31 and the translation. In other words, each of the sides 32a, 32b, 32c, and 32d of the light-emitting surface 31 of the light-emitting element 3 is not parallel to any side of the light-receiving surface 41 of the light-receiving element 4. The sides 32a, 32b, 32c, and 32d of the light-emitting surface 31 of the light-emitting element 3 overlap with the sides 42a, 42b, 42c, and 42d of the light-receiving surface 41 of the light-receiving element 4 due to the enlargement or reduction, the translation, and the rotation. In other words, each of the sides 32a, 32b, 32c, and 32d of the light-emitting surface 31 of the light-emitting element 3 that has been rotated is parallel to any one of the sides of the light-receiving surface 41 of the light-receiving element 4.

[0044] As described above, the incident light L1 may rotate in the light-guiding member 5 using the mirror surface of the off-axis optical system, but the arrangement relationship between the light-emitting element 3 and the light-receiving element 4 suppresses the decrease in the margin m0 due to the rotation of the incident light L1 occurring in the light-guiding member 5, thereby realizing stable and high-precision gas detection. In the off-axis optical system and the free-form surface optical system, the decrease in the minimum margin m0 of the light-receiving area on the light-receiving surface 41 due to optical aberration is suppressed. For this reason, it is desirable that the light-guiding member 5 is an off-axis optical system or a free-form surface optical system. Here, the off-axis optical system is an optical system that uses a lens, a mirror surface, or a lens and a mirror surface that does not include a mirror surface at the position of the rotation center axis in a lens, a spherical mirror, an ellipsoidal mirror, etc. On the other hand, an optical system that uses a mirror surface that includes the position of the rotation center axis is called a coaxial optical system or a symmetric optical system. FIG. 11 is a diagram of the light-receiving surface 41 and the image of the incident light when an off-axis optical system and a coaxial optical system with the same magnification are used as the light-guiding member 5. When the total light amount of the image of the incident light incident on the light receiving surface 41 is 100%, the area of ​​the image of the incident light where the light amount is 99% when an off-axis optical system is used as the light-guiding member 5 is defined as SOA, and the area of ​​the image of the incident light where the light amount is 99% when a coaxial optical system is used as the light-guiding member 5 is defined as SA. In this case, the area of ​​the area SA is 2.3 times that of the area SOA, and the effect of optical aberration is observed to be greater when a coaxial optical system is used than when an off-axis optical system is used. For the above reasons, an off-axis optical system is desirable for the light-guiding member 5 to achieve small, stable, and highly accurate gas detection.

[0045] As described above, the gas detection device 1 according to this embodiment is capable of stable, highly accurate gas detection due to the above-described configuration.

[0046] 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.

[0047] For example, in the above embodiment, the light-emitting element 3 is arranged so that each of the sides 32a, 32b, 32c, and 32d of the light-emitting surface 31 is parallel to the x-axis or the y-axis. As one modified example, as shown in FIG. 7, the light-receiving element 4 may be arranged so that each of the sides 42a, 42b, 42c, and 42d of the light-receiving surface 41 is parallel to the x-axis or the y-axis. At this time, the light-emitting element 3 is arranged so that each of the sides 32a, 32b, 32c, and 32d of the light-emitting surface 31 is not parallel to the x-axis or the y-axis so that the side of the incident light L1 is parallel to the x-axis or the y-axis. As another modified example, as shown in FIG. 8, the light-emitting element 3 and the light-receiving element 4 may be arranged so that each of the sides 32a, 32b, 32c, and 32d of the light-emitting surface 31 and the sides 42a, 42b, 42c, and 42d of the light-receiving surface 41 are not parallel to the x-axis or the y-axis. [Explanation of symbols]

[0048] 1 Gas detection equipment 2. Board 3 Light emitting element 4 Photodetector 5 Light guide member 6 Joining materials 6a First Part 6b Second Part 20 Main Surface 31 Light-emitting surface 32a, 32b, 32c, 32d Edges of the light-emitting surface 41 Photosensitive surface 42a, 42b, 42c, 42d Edges of the light receiving surface 51 First reflector 52 Second reflector 53 Vent 54 Cells 61 First bottom part 62 Second bottom part 63 Joint 511 First Mirror 512 The Third Mirror 513 The Fifth Mirror 521 Second Mirror 522 The Fourth Mirror L0 emission light L1 incident light

Claims

1. a light emitting element provided on a main surface of the substrate and emitting light from a light emitting surface; a light receiving element provided on a main surface of the substrate, the light receiving element receiving the light on a light receiving surface; a light guiding member for guiding the light emitted by the light emitting element to the light receiving element, the light guiding member is an off-axis optical system, the light guiding member is composed of the first mirror surface, a direction of one side of the light emitting surface being a first direction, a direction perpendicular to the first direction in the plane being a second direction, and a unit vector in the direction of the rotational symmetry axis of the first mirror surface having a projected component in both the first direction and the second direction; and the second mirror surface, a direction of one side of the light receiving surface being a third direction, a direction perpendicular to the third direction in the plane being a fourth direction, and a unit vector in the direction of the rotational symmetry axis of the second mirror surface having a projected component in both the third direction and the fourth direction; When the main surface of the substrate is viewed in plan, The light emitting surface and the light receiving surface have a shape having corners, A gas detection device, wherein the sides of the light-emitting surface do not overlap with the sides of the light-receiving surface by enlarging or reducing and translating.

2. 2 . The gas detection device according to claim 1 , wherein, when the main surface of the substrate is viewed in plan, a side of the light emitting surface overlaps a side of the light receiving surface due to enlargement or reduction, translation, and rotation.

3. a light emitting element provided on a main surface of the substrate and emitting light from a light emitting surface; a light receiving element provided on a main surface of the substrate, the light receiving element receiving the light on a light receiving surface; a light guiding member for guiding the light emitted by the light emitting element to the light receiving element, the light guiding member is an off-axis optical system, the light guiding member is composed of the first mirror surface, a direction of one side of the light emitting surface being a first direction, a direction perpendicular to the first direction in the plane being a second direction, and a unit vector in the direction of the rotational symmetry axis of the first mirror surface having a projected component in both the first direction and the second direction; and the second mirror surface, a direction of one side of the light receiving surface being a third direction, a direction perpendicular to the third direction in the plane being a fourth direction, and a unit vector in the direction of the rotational symmetry axis of the second mirror surface having a projected component in both the third direction and the fourth direction; When the main surface of the substrate is viewed in plan, The light emitting surface and the light receiving surface have a shape having corners, A gas detection device, wherein each side of the light-emitting surface is not parallel to any side of the light-receiving surface.

4. 4. The gas detection device according to claim 3, wherein, when the main surface of the substrate is viewed in plan, each of the sides of the light-emitting surface that has been rotated is parallel to any one of the sides of the light-receiving surface.

5. A substrate having a rectangular main surface; a light emitting element provided on a main surface of the substrate and emitting light from a rectangular light emitting surface; a light receiving element provided on a main surface of the substrate and having a rectangular light receiving surface for receiving the light; a light guiding member for guiding the light emitted by the light emitting element to the light receiving element, the light guiding member is an off-axis optical system, the light guiding member is composed of the first mirror surface, a direction of one side of the light emitting surface being a first direction, a direction perpendicular to the first direction in the plane being a second direction, and a unit vector in the direction of a rotational symmetry axis of the first mirror surface having a projected component in both the first direction and the second direction; and the second mirror surface, a direction of one side of the light receiving surface being a third direction, a direction perpendicular to the third direction in the plane being a fourth direction, and a unit vector in the direction of a rotational symmetry axis of the second mirror surface having a projected component in both the third direction and the fourth direction; A gas detection device, wherein when the main surface of the substrate is viewed in plan, each side of the light receiving surface or the light emitting surface is not parallel to any side of the main surface of the substrate.

6. 6. The gas detection device according to claim 5, wherein, when the main surface of the substrate is viewed in plan, each side of the light emitting surface or the light receiving surface is parallel to one of the sides of the main surface of the substrate.

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

8. The light guiding member is a first reflecting portion that directly reflects the light emitted from the light-emitting element and the light received by the light-receiving element; 8. The gas detection device according to claim 1, further comprising: a second reflecting portion whose position relative to the first reflecting portion is fixed and which reflects the light between the second reflecting portion and the first reflecting portion.

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