JP2021162577A - Gas detection device - Google Patents

Abstract

To provide a gas detection device capable of suppressing the occurrence of distortion of an optical path.SOLUTION: A gas detection device 1 includes a substrate 2, a light-emitting element 3 provided to a main surface 20 of the substrate and emitting light, a light-receiving element 4 provided to the main surface 20 of the substrate and receiving light, a light guide member 5 that guides the light emitted from the light-emitting element to the light-receiving element, a first bonding member 6, and a second bonding member 7. The first bonding member bonds between the substrate and the light guide member, and when external force is applied to the light guide member, the first bonding member suppresses the movement in a direction parallel and/or perpendicular to the main surface 20 of the substrate. The second bonding member bonds between the substrate and the light guide member, and when external force is applied to the light guide member or distortion due to thermal expansion occurs, the second bonding member suppresses the movement of the light guide member in the direction parallel to the main surface of the substrate and/or suppresses the movement within a plane perpendicular to the main surface of the substrate. At least one of the first bonding member and the second bonding member can move in the plane parallel to the main surface of the substrate or the plane perpendicular to the main surface of the substrate.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a gas detector.

Gas detectors that detect gas are used in various fields. For example, Patent Document 1 discloses an apparatus in which a light source that emits infrared rays and a detector that detects infrared rays of a specific wavelength are provided in the same case, and a gas to be detected is introduced into the case. do.

Japanese Unexamined Patent Publication No. 2015-184211

Here, in the gas detection device described in Patent Document 1, the optical path tube is firmly joined to the substrate and the case by the groove and the fixture of the substrate fixing portion. Therefore, for example, the distortion of the substrate and the case due to thermal expansion is transmitted to the optical path tube, causing distortion of the optical path, or the relative position of the optical surface may change, and the gas detection sensitivity may fluctuate.

An object of the present disclosure made in view of such a point is to provide a gas detection device capable of suppressing the occurrence of distortion of an optical path.

The gas detection device according to the embodiment of the present disclosure is
With the board
A light emitting element provided on the main surface of the substrate and emitting light,
A light receiving element provided on the main surface of the substrate and receiving the light,
A light guide member that guides the light emitted by the light emitting element to the light receiving element, and
With the first joining member,
With a second joining member
The first joining member joins the substrate and the light guide member, and suppresses movement in a direction parallel to and / or perpendicular to the main surface of the substrate when an external force is applied to the light guide member. death,
The second joining member joins the substrate and the light guide member in a direction parallel to the main surface of the substrate when an external force is applied to the light guide member or distortion occurs due to thermal expansion. Suppressing the movement of the light guide member and / or suppressing the movement in a plane perpendicular to the main surface of the substrate.
At least one of the first joining member and the second joining member can move in a direction parallel to the main surface of the substrate or in a plane perpendicular to the main surface of the substrate.

The gas detection device according to the embodiment of the present disclosure is
A substrate on which a light emitting element that emits light and a light receiving element that receives the light are provided on the main surface, and
A light guide member that guides the light emitted by the light emitting element to the light receiving element, and
A first joining member that joins the substrate and the light guide member,
A second joining member that joins the substrate and the light guide member and has a lower joining degree than the first joining member is provided.

The gas detection device according to the embodiment of the present disclosure is
With the board
A light emitting element provided on the main surface of the substrate and emitting light,
A light receiving element provided on the main surface of the substrate and receiving the light,
A light guide member that guides the light emitted by the light emitting element to the light receiving element, and
With the first joining member,
With a second joining member
The first joining member places the substrate and the light guide member in a first direction parallel to the plane of the substrate with a first restraint degree, and a second direction parallel to the plane of the substrate and perpendicular to the one direction. With a second degree of restraint, and with a third degree of restraint in the third direction perpendicular to the plane of the substrate, constrained in each translational direction.
The second joining member holds the substrate and the light guide member in the first direction with a fourth degree of restraint, in the second direction with a fifth degree of restraint, and in the third direction with a sixth degree of restraint. So, restrain in each translation direction,
At least one of the first restraint degree to the sixth restraint degree is zero, and one of the first restraint degree and the fourth restraint degree is not zero, and the second restraint degree and the fifth restraint degree are not zero. One of the restraint degrees is not zero, and one of the third restraint degree and the sixth restraint degree is not zero.

According to one embodiment of the present disclosure, a gas detection device capable of suppressing the occurrence of distortion of the optical path can be provided.

FIG. 1 is a perspective view showing a part of the gas detection device according to the embodiment of the present disclosure. FIG. 2 is a diagram showing an example of a cross section of the gas detection device. FIG. 3 is a diagram showing an example of the arrangement and shape of the first and second joining members. FIG. 4 is a diagram showing another example of the arrangement of the first joining member. FIG. 5 is an enlarged cross-sectional view of the second joining member. FIG. 6 is a diagram showing another example of the cross section of the gas detection device. FIG. 7 is a diagram showing another example of the arrangement and shape of the first joining member. FIG. 8 is a diagram showing another example of the shape of the first joining member. FIG. 9 is a diagram showing another example of the shape of the first joining member. FIG. 10 is a diagram showing another configuration example of the light guide member. FIG. 11 is a diagram for explaining an elongated hole. FIG. 12 is a diagram for explaining the intensity distribution on the object surface (light emitting surface) and the illuminance distribution on the image surface (light receiving surface). FIG. 13 is a diagram for explaining the relationship between the restraint point and the strain. FIG. 14 is a diagram showing another example of the shape of the first joining member. FIG. 15 is a diagram illustrating the arrangement of the first and second joining members.

(First Embodiment)
FIG. 1 is a perspective view showing a part of the gas detection device 1 according to the embodiment of the present disclosure. The gas detection device 1 is, for example, a small device having a size of 30 mm × 20 mm × 10 mm, and is also referred to as a gas sensor. In the present embodiment, the gas detection device 1 is an NDIR (Non Dispersive InfraRed) type device that measures the concentration of the gas to be detected based on the infrared rays transmitted through the introduced gas. The gas to be detected is, for example, carbon dioxide, water vapor, methane, propane, formaldehyde, carbon monoxide, nitric oxide, ammonia, sulfur dioxide or alcohol.

The gas detection device 1 includes a substrate 2, a light emitting element 3, a light receiving element 4, a light guide member 5, a first joining member 6, and a second joining member 7. FIG. 1 shows a configuration example of the gas detection device 1 by transmitting a part of the light guide member 5, and the light emitting element 3 and the light receiving element 4 provided on the main surface 20 of the substrate 2 are visible. In the present embodiment, the main surface 20 is a surface facing the light guide member 5 among the surfaces having the largest area of the substrate 2.

Hereinafter, as shown in FIG. 1, the 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 a direction perpendicular to the main surface 20 of the substrate 2. The x-axis direction and the y-axis direction are parallel to the side of the main surface 20 of the substrate 2. Here, the y-axis direction corresponds to the direction in which the first reflecting portion 51 and the second reflecting portion 52, which will be described later, face each other.

The substrate 2 is a plate-shaped member on which the components of the gas detection device 1 are mounted and the mounted electronic components are electrically connected. The substrate 2 is provided with a light emitting element 3 and a light receiving element 4 on the main surface 20. Yet another electronic component may be mounted on the substrate 2. For example, the substrate 2 may be provided with a controller for controlling at least one of the light emitting element 3 and the light receiving element 4 on the main surface 20 or the bottom surface opposite to the main surface 20. Further, the substrate 2 may be provided on the main surface 20 or the bottom surface with a calculation unit that executes a calculation in calculating the gas concentration. The arithmetic unit may include at least one of a general-purpose processor that executes a function according to a program to be read and a dedicated processor specialized in a specific process. Dedicated processors may include application specific integrated circuits (ASICs). The processor may include a programmable logic device (PLD). The arithmetic unit may be integrated with the above controller.

The light emitting element 3 is a component that emits light used for detecting a gas to be detected. The light emitting element 3 is not particularly limited as long as it outputs light including a wavelength absorbed by the gas to be detected. In the present embodiment, the light emitted by the light emitting element 3 is infrared rays, but the light is not limited to this. In the present embodiment, the light emitting device 3 is an LED (light emitting diode), but another example may be a semiconductor laser, an organic light emitting device, a MEMS (Micro Electro Mechanical Systems) heater, or the like. The light emitting element 3 is provided in the first region 21 of the main surface 20 of the substrate 2. The first region 21 is defined at a position facing the first mirror 511, which will be described later, in the z-axis direction.

The light receiving element 4 is a component that receives light transmitted through the introduced gas. The light receiving element 4 is not particularly limited as long as it has sensitivity in the band of light including the wavelength absorbed by the gas to be detected. In the present embodiment, the light received by the light receiving element 4 is infrared rays, but the light is not limited to this. In the present embodiment, the light receiving element 4 is a photodiode, but another example may be a phototransistor or a thermopile, a pyroelectric sensor, a bolometer, or the like. 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 detected gas based on the light transmittance and the like. The light receiving element 4 is provided in the second region 22 of the main surface 20 of the substrate 2. The second region 22 is defined at a position facing the fifth mirror 513, which will be described later, in the z-axis direction. The light receiving element 4 may include an optical filter having a wavelength selection function.

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

In the present embodiment, the light guide member 5 includes a first reflecting portion 51 and a second reflecting portion 52. The first reflecting unit 51 includes a first mirror 511, a third mirror 512, and a fifth mirror 513 as optical members. The first reflecting unit 51 has a mirror that first reflects the light emitted from the light emitting element 3, and has a mirror that finally reflects the light received by the light receiving element 4. The second reflecting unit 52 includes a second mirror 521 and a fourth mirror 522 as optical members. The light guide member 5 reflects the light emitted by the light emitting element 3 in the order of the first mirror 511, the second mirror 521, the third mirror 512, the fourth mirror 522, and the fifth mirror 513. It leads to the light receiving element 4. The optical path is configured to pass through the cell 54 into which the gas is introduced, which is provided between the light guide member 5 and the substrate 2. As another example, the number of mirrors included in the light guide member 5 may be one or more other than five. Further, the light guide member 5 may be configured to include a lens in a part of the optical path.

In the light guide member 5, the position of the first reflecting portion 51 with respect to the second reflecting portion 52 is fixed. 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 metal-plated after being integrally formed. As another example, the first reflective portion 51 and the second reflective portion 52 may be individually formed and strongly fixed by an adhesive, screws, claws, fittings, grommets, welding or the like.

The first mirror 511 is a condensing mirror that reflects the light emitted from the light emitting element 3 at the focal point. The first mirror 511 is, for example, a concave mirror. An ellipsoidal surface may be used as the shape of the first mirror 511. In the present embodiment, the first mirror 511 reflects the light emitted from the focal light emitting element 3 in the z-axis direction in the xy plane direction. Here, the xy plane direction is a direction having components in at least one direction in the x-axis direction and the y-axis direction. However, the xy plane direction may have a z-axis direction component.

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 condensing mirror having a condensing 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.

The fifth mirror 513 is a condensing mirror that condenses the incident light on the light receiving element 4. The fifth mirror 513 is, for example, a concave mirror. An ellipsoidal surface may be used as the shape of the fifth mirror 513. In the present embodiment, the fifth mirror 513 reflects the incident light from the fourth mirror 522 in the xy plane direction so as to have a component in the z-axis direction. Specifically, the fifth mirror 513 reflects the incident light so as to be focused by the light receiving element 4 at the focal position.

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, or the like. , Not limited to this. From the viewpoint of improving the detection sensitivity, the material constituting these mirrors is preferably made 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 thereof is preferable. From the viewpoint of reliability and aging, a resin housing coated with gold or an alloy layer containing gold is preferable. Further, it is preferable to form a dielectric laminated film on the surface of the metal layer in order to increase the reflectance and avoid deterioration over time. When the first mirror 511 and the fifth mirror 513 are formed by vapor deposition or plating on a resin housing, it is possible to improve productivity and weight reduction as compared with the case where the first mirror 511 and the fifth mirror 513 are formed of a metal material. can. Further, the difference in the coefficient of thermal expansion from the substrate 2 is reduced, thermal deformation is suppressed, and fluctuations in sensitivity are suppressed. Further, the light guide member 5 may be molded by cutting, and it is more preferable that the light guide member 5 is molded by injection molding from the viewpoint of productivity.

The first joining member 6 is a member that joins the substrate 2 and the light guide member 5. In the present embodiment, the first joining member 6 is a single pillar body, and the first bottom surface portion 61 (see FIG. 2) joined to the substrate 2 and the second joining member 6 to be joined to the light guide member 5. It has a bottom surface portion 62 and. The first bottom surface portion 61 and the substrate 2 are joined by, for example, an adhesive, grommets or screws, welding, claws, fitting, or the like. The same applies to the joining of the second bottom surface portion 62 and the light guide member 5. Further, from the viewpoint of productivity, it is desirable that the first joining member 6 and the light guide member 5 are integrally molded in order to reduce the number of constituent members.

The second joining member 7 is a member that joins the substrate 2 and the light guide member 5 at a position different from that of the first joining member 6. The insertion portion 7a (see FIG. 2) of the second joining member 7 is connected to the light guide member 5. The insertion portion 7a of the second joining member 7 may be firmly connected to the light guide member 5 by, for example, an adhesive, a grommet or a screw, a welding claw, a fitting or the like. As another example, the insertion portion 7a of the second joining member 7 may be made of the same material as the light guide member 5 and may be integrally formed with the light guide member 5. When integrally formed with the light guide member 5, the number of constituent members is reduced, so that productivity is improved. As shown in FIG. 1, the first reflecting portion 51 is joined to the substrate 2 by the first joining member 6, and the second reflecting portion 52 is joined to the substrate 2 by the second joining member 7.

FIG. 2 is a diagram showing an example of a cross section of the gas detection device 1. FIG. 2 shows a cross section of the substrate 2, the light guide member 5 including the third mirror 512, the first joining member 6, and the second joining member 7 cut along a plane parallel to the yz plane. Has been done. The cell 54 is formed inside the gas detection device 1 sandwiched between the substrate 2 and the light guide member 5. The light guide member 5 includes a vent 53 for introducing a gas into the cell 54. The vent 53 can also be used to expel gas from the cell 54. In the present embodiment, the first joining member 6 is a hollow cylinder. The first bottom surface portion 61 is joined to the substrate 2 by inserting a screw into the hollow portion 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 the second bottom surface portion 62. As another example, the first joining member 6 may be a solid cylinder. The first bottom surface portion 61 and the substrate 2, and the second bottom surface portion 62 and the light guide member 5 may be joined by an adhesive, welding, claws, fitting, or the like.

The second joining member 7 includes an insertion portion 7a and a fastener 7b. As described above, a part of the insertion portion 7a is firmly connected to the light guide member 5. At least a part of the insertion portion 7a is inserted into the hole 25 of the substrate 2. As another example, at least a portion of the fastener 7b may be inserted into the hole 25. The hole 25 is a hole provided in the substrate 2. In the present embodiment, the hole 25 penetrates the substrate 2 in the z-axis direction, that is, in the thickness direction. In the present embodiment, the insertion portion 7a is a cylindrical body. The insertion portion 7a has a hole on the surface opposite to the surface connected to the light guide member 5 into which the fastener 7b is inserted. The fastener 7b is inserted through the hole 25 on the bottom surface of the substrate 2 to fasten the insertion portion 7a. In this embodiment, the fastener 7b is a screw, but may be a pin, a grommet, or the like as another specific example. The holes of the fastener 7b and the insertion portion 7a have threads corresponding to each other. In other words, the fastener 7b screwed the insertion portion 7a. Here, as another example, the second joining member 7 may have a configuration without the fastener 7b. That is, the second joining member 7 may be composed only of the insertion portion 7a having no hole for the fastener 7b. In this case, the hole 25 may be a hole provided on the main surface 20 and does not penetrate the substrate 2 in the z-axis direction. Since the first mirror 511 of FIG. 2, the main surface 20 of the substrate 2, and the light emitting element 3 are the same as the elements with the same numbers in FIG. 1, description thereof will be omitted. The reason will be described later, but the hole 25 may be an elongated hole extending in one direction. Further, preferably, the hole 25 may be a hole extending in the direction connecting the centers of the vertical projection images of the first joining member and the second joining member on the main surface of the substrate 2. Here, the extending direction is a direction having a major axis in the elongated hole. When the hole 25 is a long hole and the second joining member 7 is fastened by the fastener 7b, the second joining member is subjected to an external force applied to the light guide member 5 or due to thermal expansion. When distortion occurs, the movement of the light guide member other than one direction, which is parallel to the main surface 20 of the substrate 2 and is the direction in which the elongated hole extends, is suppressed. As an example of the external force, the substrate 2 of the gas detection device 1 is fixed to the base, and the representative point of the light guide member 5 is pushed to apply a twist in the z-axis direction. Specifically, as a representative point, for example, one point of the light guide member 5 other than the first joining member, or a point on the surface of the light guide member 5 farthest from the first joining member is selected, and an external force is applied thereto. In addition, as a representative point, the geometric center of each surface of the light guide member 5 may be selected. The direction of the external force is parallel to the main surface 20 of the substrate 2 and perpendicular to the direction connecting the representative point and the first joint. Further, when the second joining member 7 has no fastener 7b, the second joining member 7 can freely move in the direction perpendicular to the main surface 20 of the substrate 2. Therefore, when an external force is applied to the light guide member 5 or when distortion occurs due to thermal expansion, the second joining member 7 is suppressed from moving in a plane perpendicular to the main surface 20 of the substrate 2. Here, the elongated hole is a hole having a shape including two line segments parallel to the outer circumference of the hole, as shown in FIG. As a specific example, the elongated hole may be a hole of a figure in which circles having the same diameter are continuously arranged and overlapped so that their centers are lined up on a line segment, or a rectangular hole. However, those in which the first joining member and the second joining member suppress the movement in the directions parallel to and perpendicular to the main surface of the substrate, respectively, may be excluded from the embodiments of the present disclosure.

FIG. 3 is a diagram showing an example of the arrangement and shape of the first joining member 6. In FIG. 3, the main surface 20 of the substrate 2 viewed in the negative direction of the z-axis is shown. The vertical projection image 6i is an image in which the first joining member 6 is projected perpendicularly to the main surface 20 of the substrate 2. In the present embodiment, the vertical projection image 6i on the main surface 20 of the substrate 2 is a hollow circle. As another example, when the first joining member 6 is a solid cylinder, the vertical projection image 6i is a solid circle. Here, in FIG. 3, the midpoint 24 of the line segment connecting the center 21c of the first region 21 and the center 22c of the second region 22 is shown. Further, in FIG. 3, a vertical bisector 23 of a line segment connecting the center 21c of the first region 21 and the center 22c of the second region 22 is shown. Further, it is shown that the second joining member 7 including the insertion portion 7a and the fastener 7b is inserted with a gap with respect to the hole 25. In the present embodiment, the first joining member 6 is arranged so that the vertical projection image 6i on the main surface 20 of the substrate 2 is on the vertical bisector 23. Further, as will be described in detail later, the second joining member 7 is substantially joined to the substrate 2 and the light guide member 5 in order to join the light guide member 5 in a direction in which the light guide member 5 can move freely, that is, with a degree of freedom. Is joined by the first joining member 6. Here, the vertical projection image 6i may be a cross-sectional shape of the first joining member 6 directly above the main surface 20 of the substrate 2.

For the first joining member 6 and the second joining member 7, a material having a large elastic modulus and being hard to be deformed can be used. For example, the materials of the first joining member 6 and the second joining member 7 are LCP (liquid crystal polymer), PP (polypropylene), PEEK (polyetheretherketone), PA (polyether), PPE (polyphenylene ether), PC ( Polypropylene), PPS (polyphenylene sulfide), PMMA (polymethylmethacrylate resin), etc., and a hard resin in which two or more of these are mixed, or a metal from the viewpoint of heat resistance may be used. Further, the first joining member 6, the second joining member 7, and the light guide member 5 may be made of the same material. If the materials of the first joining member 6 and the second joining member 7 and the light guide member 5 are the same, there is no difference in thermal expansion, so that thermal strain can be suppressed. The substrate 2 and the light guide member 5 are substantially joined by the first joining member 6. Therefore, even if the substrate 2 is deformed due to thermal expansion, for example, the light guide member 5 is not affected by the deformation of the substrate 2 because there is only one restraint point and the substrate 2 is not over-constrained. For example, when the substrate 2 is deformed so as to spread in the y-axis direction, the light guide member 5 is connected to the substrate 2 at substantially only one point, so that the optical members are similar to each other around one point without causing distortion. Shrink (expand). In that case, the optical performance is not affected.

Further, if the second joining member 7 does not exist and different forces act on the substrate 2 and the light guide member 5, the first joining member 6 is hard to be deformed in the axial direction, but on the other hand, it is twisted and deformed. Bending deformation can occur. Therefore, for example, when the second joining member 7 does not restrain the light guide member 5 in the x direction, the light guide member 5 may rotate with respect to the substrate 2 with the first joining member 6 as the rotation axis. could be. That is, the first joining member 6 becomes a rotation axis when an external force is applied to the light guide member 5 in a direction parallel to the main surface 20 of the substrate 2. In other words, when the light guide member 5 moves with respect to the substrate 2, it can be a rotation axis. Moving here means that when the substrate 2 is fixed and a shear stress parallel to the main surface of the substrate 2 is applied to the side surface of the light guide member 5, the light guide member 5 and the substrate 2 rotate relatively. It may be. However, as shown in FIG. 12, the intensity distribution on the object surface (light emitting surface) and the illuminance distribution on the image surface (light receiving surface) are point-symmetrically distributed with respect to the rotation axis. Therefore, even if the light guide member 5 deforms and moves with respect to the substrate 2 (that is, the light emitting surface), the movement vector of the illuminance distribution on the light receiving surface formed by the light emitting surface matches the moving vector of the light receiving portion. Therefore, the illuminance distribution received by the light receiving surface does not change, and the fluctuation of the gas detection sensitivity is further suppressed. Here, the object surface (light emitting surface) is a surface that comes into contact with a gas in the light emitting portion of the light emitting element 3 and is made of a material having optical transparency. The image plane (light receiving surface) is a surface that comes into contact with gas in the sensitive portion of the light receiving element 4 and is made of a material having optical transparency.

Here, FIG. 4 is a diagram showing another example of the arrangement of the first joining member 6. Since each element of FIG. 4 is the same as the element having the same reference numeral in FIG. 3, the description thereof will be omitted. As shown in FIG. 4, the first joining member 6 may be provided at different positions on the main surface 20 of the substrate 2. That is, the first joining member 6 may be arranged so that the vertical projection image 6i is not on the vertical bisector 23 on the main surface 20 of the substrate 2. Further, the first joining member 6 may be arranged at a position closer to the second mirror 521 and the fourth mirror 522 than the first mirror 511 and the fifth mirror 513 in the y-axis direction. However, as described above, in order to maintain the optical path, it is necessary for the light emitting element 3 and the light receiving element 4 to directly receive and emit light from the first reflecting portion 51. Therefore, the first joining member 6 is provided at a position where the amount of movement of the first reflecting portion 51 is smaller than the amount of movement of the second reflecting portion 52 when the light guide member 5 moves with respect to the substrate 2. Is preferable. That is, it is preferable that the first joining member 6 serving as the rotation axis is provided at a position closer to the first reflecting portion 51 than to the second reflecting portion 52. Specifically, it is preferable that the vertical projection image 6i of the first joining member 6 is close to the midpoint 24.

Here, also in the case of FIG. 4, the second joining member 7 is in a direction other than the direction parallel to the main surface 20 of the substrate 2 when an external force is applied to the light guide member 5 or when distortion occurs due to thermal expansion. The movement of the light guide member 5 is suppressed. In other words, the second joining member 7 suppresses movement in the direction perpendicular to the main surface 20 of the substrate 2.

As an example, a straight line connecting the start point and the first joint portion in a direction parallel to the main surface 20 of the substrate 2 with respect to the light guide portion, starting from a point on the surface of the light guide member 5 farthest from the first joint member. When the first joining member becomes the axis of rotation when an external force is applied in the vertical direction of the substrate 2, the second joining member moves in the direction perpendicular to the main surface 20 of the substrate 2 and the first joining member and the first joining member. The movement of the second joining member in the direction connecting the centers of the vertical projection images on the main surface 20 of the substrate 2 is suppressed.

As another example, when distortion occurs due to thermal expansion, the second joining member moves in a direction perpendicular to the main surface 20 of the substrate 2, and the substrate 2 of the first joining member and the second joining member The movement other than the direction connecting the centers of the vertical projection images on the main surface 20 is suppressed.

FIG. 5 is an enlarged cross-sectional view of the second joining member 7. In the present embodiment, the second joining member 7 including the insertion portion 7a and the fastener 7b has a gap in the direction parallel to the xy plane with respect to the hole 25. As shown in FIG. 5, at least a part of the side surface 7as of the portion of the insertion portion 7a inserted into the hole 25 does not come into contact with the side surface 2s of the hole 25 of the substrate 2. In the example of FIG. 5, even if the second joining member 7 moves to the maximum in the positive direction of the y-axis and the side surface 7as of the insertion portion 7a and the side surface 2s of the hole 25 come into contact with each other, there is a gap on the negative side of the y-axis. Occurs. On the other hand, the first bottom surface portion 61, that is, the portion of the first joining member 6 to be joined to the substrate 2 does not have a space between the first bottom surface portion 61 and the substrate 2. The second joining member 7 having a gap in the xy plane direction has a lower joining degree than the first joining member 6. Here, the degree of joining means the difficulty of moving the object to be joined. In the present embodiment, a high degree of bonding means a state in which the light guide member 5 is strongly bonded to the substrate 2 or is closely bonded to the substrate 2 so that it is difficult to move to the substrate 2. .. A low degree of bonding means that the light guide member 5 is weakly bonded to the substrate 2, or is bonded so that there is a gap, or the side surface 7as and the side surface 2s are partially in contact with each other but friction. It shows a state in which there is little and it is easy to move with respect to the substrate 2.

As described above, the light guide member 5 may rotate with respect to the substrate 2 with the first joining member 6 as the rotation axis. The second joining member 7 suppresses free rotational movement with the z-axis as the rotation axis, but allows minute rotational movement by having a gap between the second joining member 7 and the hole 25. Here, the permissible minute rotational movement can be determined by the size of the gap. As described above, as long as the first reflecting unit 51 can directly reflect the light emitted from the light emitting element 3 and the light received by the light receiving element 4, the optical path is maintained as before the rotational movement. Is done. Therefore, the gap between the second joining member 7 and the hole 25 is set so that the optical path for the light guide member 5 is maintained even if the light guide member 5 moves to the maximum with respect to the substrate 2. Further, when the mounting tolerances of the second joining member 7 and the first joining member 6 are the same, the larger the distance between the two joining members, the smaller the angular deviation of the optical members, and the mass production yield. Good from the point of view of. In particular, it is preferable that the distance between the centers of the vertical projection images of the first joining member and the second joining member on the main surface 20 of the substrate 2 is longer than half of the maximum distance on the substrate 2. Here, the difference in coefficient of thermal expansion between dissimilar resin materials is about 100 ppm, and the maximum temperature difference in the general usage environment of electronic devices is about 150 ° C. Therefore, the amount of strain due to thermal expansion is the product of each of the light guide members 5. It is estimated to be 1.5% of the maximum length of. Therefore, the gap may be designed to be 1.5% or more of the maximum length of the light guide member 5.

Further, as shown in FIG. 5, the hole 25 of the substrate 2 is provided with a step in which the head of the screw, which is the fastener 7b, comes into contact with the hole 25. By screwing the fastener 7b to the insertion portion 7a connected to the light guide member 5, the substrate 2 and the light guide member 5 are strongly joined in the z-axis direction. Therefore, the movement of the light guide member 5 with respect to the substrate 2 in the z-axis direction is further restricted, and the translational freedom in the z-direction is lost. Further, regarding the degree of freedom of rotation with respect to the shaft connecting the two restraint points, since the first joining member 6 and the substrate are in surface contact with each other, rotation is suppressed and the degree of freedom of rotation is lost. In other words, the light guide member 5 does not have a degree of freedom of rotation about an axis connecting the contact points between the first joining member 6, the second joining member 7, and the substrate 2.

Further, the first joining member 6 constrains the degree of freedom in the translation direction with respect to each of the x-axis, y-axis, and z-axis of the light guide member 5 with respect to the substrate 2. On the other hand, as described above, the second joining member 7 suppresses the movement of the light guide member 5 in the direction perpendicular to the main surface 20 of the substrate 2. The second joining member 7 preferably has a gap between it and the hole 25, so that the degree of freedom is not constrained in the direction in which the gap exists. As shown in FIG. 13, over-constraint generally occurs when two or more restraint points and the same degree of freedom are constrained to an object. When the object is deformed due to thermal expansion or the like, distortion may occur along the line segment connecting the restraint points. In the case of over-constraint, the strain cannot be freely extended by the restraint points, so that the strain deviates in a direction different from the direction in which the restraint points are connected, resulting in deformation other than the overall similarity reduction (expansion).

Therefore, as shown in FIG. 11, the hole 25 is not in an over-restrained state because it is a long hole. Therefore, the second joining member 7 can move freely in the direction in which the elongated hole extends, and the strain due to thermal expansion is reduced. In particular, when the first joining member and the second joining member extend in the direction connecting the centers of the vertical projection images of the substrate 2 on the main surface 20, the gas detection device 1 is optical due to expansion. It is possible to suppress the deterioration of performance. This is because distortion can occur between restraint points, but when there is no constraint in the direction connecting the restraint points, all the distortion can be eliminated by moving freely, and deformation other than similarity reduction (expansion) due to temperature changes can be achieved. Because it does not bring.

As described above, in the gas detection device 1 according to the present embodiment, even if the substrate 2 is distorted due to thermal expansion due to the above configuration, the light guide member 5 is not affected by the deformation. Further, as described above, even if the light guide member 5 moves to the maximum with respect to the substrate 2, the optical path is appropriately maintained by the second joining member 7. Therefore, the gas detection device 1 can suppress deterioration of optical performance due to deformation other than similarity reduction (expansion).

Further, in the gas detection device 1, the vertical projection image 6i on the main surface 20 of the substrate 2 is located on the perpendicular bisector of the line segment connecting the center of the first region 21 and the center of the second region 22. By arranging in, the illuminance distribution on the image plane (light receiving plane) is not changed, and the fluctuation of the gas detection sensitivity is suppressed. As shown in FIG. 12, the intensity distribution on the object surface (light emitting surface) and the illuminance distribution on the image surface (light receiving surface) are distributed point-symmetrically with respect to the rotation axis, and when the substrate 2 is deformed by thermal expansion, Deformation occurs symmetrically with respect to the above vertical bisector. This is because the movement of the illuminance distribution on the light receiving surface formed by the light emitting surface coincides with the movement of the light receiving surface in the direction and amount.

Further, as shown in FIG. 15, if the vertical projection images of the first joining member 6 and the second joining member 7 on the main surface of the substrate are arranged in the region Rt, the substrate 2 is deformed by thermal expansion. For the same reason, the illuminance distribution on the image plane (light receiving plane) is less likely to change, and fluctuations in gas detection sensitivity are suppressed. Here, the straight line Lp is a vertical bisector 23 of a line segment connecting the center of the first region 21 and the center of the second region 22. The straight line Le is a straight line passing through the first region 21 parallel to the straight line Lp. The straight line Ld is a straight line passing through the second region 22 parallel to the straight line Lp. The region Rt is the largest region in the main surface of the substrate sandwiched between the straight line Le and the straight line Ld.

(Second Embodiment)
FIG. 6 is a diagram showing an example of a cross section of the gas detection device 1 according to another embodiment of the present disclosure. The gas detection device 1 according to the present embodiment has a different configuration of the first joining member 6 from the gas detection device 1 according to the first embodiment described above. Other components are the same as those of the gas detection device 1 according to the first embodiment. For example, a perspective view of the gas detection device 1 according to the present embodiment is shown in FIG. 1 as in the first embodiment. Further, the same components as those of the gas detection device 1 according to the first embodiment are designated by the same reference numerals as those in FIGS. 1 to 4, and detailed description thereof will be omitted.

As shown in FIG. 6, in the present embodiment, the first joining member 6 is not a pillar body. The first 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, a first portion 6a, a second portion 6b, and the like. A coupling portion 63 for coupling the third mirror 512 is provided. By connecting the third mirror 512 to the first joining member 6, the relative position of the first reflecting portion 51 with respect to the second reflecting portion 52 is more firmly fixed.

FIG. 7 is a diagram showing an example of the arrangement and shape of the first joining member 6 in the present embodiment. In FIG. 7, the main surface 20 of the substrate 2 viewed in the negative direction of the z-axis is shown. In the present embodiment, the vertical projection image 6i on the main surface 20 of the substrate 2 is arcuate. In the first joining member 6, the vertical projection image 6i on the main surface 20 of the substrate 2 includes the midpoint 24 of the line segment connecting the center 21c of the first region 21 and the center 22c of the second region 22. Is placed in. As described above, since the vertical projection image 6i of the first joining member 6 is close to the midpoint 24, the amount of movement of the first reflecting portion 51 can be made smaller than the amount of movement of the second reflecting portion 52. , Contributes to keeping the deviation of the optical path parameters small.

As described above, the gas detection device 1 according to the present embodiment has the same effect as that of the first embodiment by the above configuration. Further, the gas detection device 1 according to the present embodiment includes a first joining member 6 having a coupling portion 63 to which the third mirror 512 is also coupled, whereby the second reflecting portion 52 of the first reflecting portion 51 is provided. The relative position to the relative can be fixed more firmly.

(Modification example)
Although the embodiments have been described above based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and modifications based on the present disclosure. It should be noted, therefore, that these modifications and modifications are within the scope of this disclosure. For example, the functions included in each member, each means, and the like can be rearranged so as not to be logically inconsistent, and a plurality of means and the like can be combined or divided into one.

For example, in the first joining member 6, the vertical projection image 6i may have a polygonal shape. As one modification, as shown in FIG. 8, the vertical projection image 6i may be a quadrangle, and the first joining member 6 may be a quadrangular prism.

For example, in the above embodiment, it has been described that the first joining member 6 is composed of one component. The first joining member 6 may be composed of a plurality of parts. Here, although the plurality of parts are separated from each other, they are close to each other to some extent so as to become a rotation axis as a whole when an external force is applied to the light guide member 5 in a direction parallel to the main surface 20 of the substrate 2. Is arranged. As one modification, as shown in FIG. 9, the vertical projection image 6i may be a plurality of solid circles. At this time, the first joining member 6 can join the substrate 2 and the light guide member 5 more firmly.

For example, in the above embodiment, it has been explained that the position of the first reflecting portion 51 with respect to the second reflecting portion 52 is fixed by integral formation or an adhesive or the like. As one modification, as shown in FIG. 10, the second reflecting portion 52, together with the first reflecting portion 51, has the second bottom surface portion 62 of the first joining member 6, and the adhesive, screws, claws, and the like. It may be strongly bonded by fitting, grommet, welding or the like. At this time, the second reflecting portion 52 may include an extension portion 523 that is integrally formed with the second mirror 521 and the fourth mirror 522 and extends to the first reflecting portion 51.

For example, in the above embodiment, the first joining member 6 has a shape having a long side in the z-axis direction, but may have a shape having a long side in a direction other than the z-axis. For example, as shown in FIG. 14, the first joining member 6 may be a pillar body having a long side in the x-axis direction. The first joining member 6 may be connected to one side of the main surface 20 of the substrate 2 parallel to the x-axis and to each of the bottom surface portion of the first reflecting portion 51 facing the one side with an adhesive or the like. At this time, the light guide member 5 can move in the z-axis positive direction with the first joining member 6 as the rotation axis with respect to the substrate 2. However, if the substrate 2 and the light guide member 5 are strongly joined by the fastener 7b in the z-axis direction, the movement of the light guide member 5 can be suppressed.

For example, in the above embodiment, the first reflecting portion 51 is joined to the substrate 2 by the first joining member 6 having a high joining degree, and the second reflecting portion 52 is joined to the substrate 2 by a second joining member having a low joining degree. It is joined to the substrate 2 by the member 7. Here, the combination of the first joining member 6 and the second joining member 7 and the first reflecting portion 51 and the second reflecting portion 52 is not limited to the example of the above embodiment. For example, the first reflecting portion 51 may be joined to the substrate 2 by the second joining member 7, and the second reflecting portion 52 may be joined to the substrate 2 by the first joining member 6. Further, for example, the first joining member 6 and the second joining member 7 may join the desired reflecting portion of the first reflecting portion 51 or the second reflecting portion 52 to the substrate 2.

Another way of thinking about the above-described embodiment is that the gas detection device of the present embodiment is provided on the substrate, the main surface 20 of the substrate, the light emitting element 3 that emits light, and the main surface 20 of the substrate. A light receiving element 4 that receives light, a light guide member that guides the light emitted by the light emitting element 3 to the light receiving element 4, a first joining member, and a second joining member are provided. The substrate and the light guide member have a first degree of restraint in the first direction parallel to the plane of the substrate, a second degree of restraint in the second direction parallel to the plane of the substrate and perpendicular to one direction, and perpendicular to the plane of the substrate. The substrate and the light guide member are constrained in the third direction by the third restraint in the translational direction, respectively, and the second joining member holds the substrate and the light guide member in the fourth restraint in the first direction, the fifth restraint in the second direction, and the second. Constrained in the translational direction with the sixth restraint in each of the three directions, at least one of the restraints is zero, and one of the first and fourth restraints is not zero, but the second restraint. One of the fifth restraint degree is not zero, and one of the third restraint degree and the sixth restraint degree is a gas detection device which is not zero.

Here, the degree of restraint is an index indicating whether or not the object can move freely in translation with respect to a certain direction, and the degree of restraint of zero means that the object can move freely in that direction. As a specific method for measuring the degree of restraint, there is a method in which one point of the object is displaced by a specified amount X and the average displacement amount Y of the entire object is measured at that time. At this time, the degree of restraint is an absolute value of (XY) / X. However, if the degree of restraint is 0.01 or less, it is set to zero.

Since at least one of the first to sixth restraint degrees is zero, at least one of the first joining member and the second joining member is free to move in any one of the first to third directions. Will be possible.

Further, either one of the first restraint degree and the fourth restraint degree is not zero, one of the second restraint degree and the fifth restraint degree is not zero, and one of the third restraint degree and the sixth restraint degree is not zero. Since one of them is not zero, the entire light guide member is prevented from being separated from the substrate.

That is, the light guide member and the substrate are fixed as a whole, and are free to move in either the first to third directions when an external force is applied to the light guide member or when distortion occurs due to thermal expansion. Since it can move, it is possible to suppress the occurrence of distortion of the optical path while maintaining the reliability of the device.

The method of setting each degree of restraint to zero is not particularly limited, but as shown in the above-described embodiment, a method of removing the fastener in the form of inserting the insertion portion of the joining member into the hole (thus, the third and sixth restraint degrees). Can be zero), and a method in which the insertion portion does not come into contact with the side surface of the hole (thus, the first, second, fourth, and fifth restraint degrees can be zero).

In order to suppress the occurrence of distortion of the optical path due to external force and stress in the plane direction of the substrate, the fourth restraint degree and / or the fifth restraint degree may be set to zero (in this case, the second joining member side is attached to the substrate. Freely move in at least one direction in parallel planes). Alternatively, the first degree of restraint and / or the second degree of restraint may be set to zero (in this case, the first joining member side freely moves in at least one direction in the plane direction parallel to the substrate).

In order to suppress the occurrence of distortion of the optical path due to external force and stress in the vertical direction of the substrate, the sixth restraint degree may be set to zero (in this case, the second joining member side freely moves in the direction perpendicular to the substrate). ). Alternatively, the third degree of restraint may be set to zero (in this case, the first joining member side freely moves in the direction perpendicular to the substrate).

From the viewpoint of reliability and ease of assembly, it may be preferable that the first to third restraints are not zero.

1 Gas detector 2 Substrate 2s Side of hole 3 Light emitting element 4 Light receiving element 5 Light guide member 6 First joining member 6a First part 6b Second part 6i Vertical projection image 7 Second joining member 7a Insertion part 7as Side of insertion 7b Fastener 20 Main surface 21 First area 21c Center of first area 22 Second area 22c Center of second area 23 Vertical bisector 24 Midpoint 25 Hole 51 First reflection Part 52 Second reflective part 53 Vent 54 Cell 61 First bottom part 62 Second bottom part 63 Joint part 511 First mirror 512 Third mirror 513 Fifth mirror 521 Second mirror 522 Fourth Mirror 523 extension

Claims (25)

With the board
A light emitting element provided on the main surface of the substrate and emitting light,
A light receiving element provided on the main surface of the substrate and receiving the light,
A light guide member that guides the light emitted by the light emitting element to the light receiving element, and
With the first joining member,
With a second joining member
The first joining member joins the substrate and the light guide member, and suppresses movement in a direction parallel to and / or perpendicular to the main surface of the substrate when an external force is applied to the light guide member. death,
The second joining member joins the substrate and the light guide member in a direction parallel to the main surface of the substrate when an external force is applied to the light guide member or distortion occurs due to thermal expansion. Suppressing the movement of the light guide member and / or suppressing the movement in a plane perpendicular to the main surface of the substrate.
A gas detection device in which at least one of the first joining member and the second joining member can move in a direction parallel to the main surface of the substrate or in a plane perpendicular to the main surface of the substrate. The first joining member fixes the substrate and starts from a point on the surface of the light guide member farthest from the first joining member in a direction parallel to the main surface of the substrate with respect to the light guide portion. The gas detection device according to claim 1, which serves as a rotation axis when an external force is applied in the vertical direction of a straight line connecting the start point and the first joint. The substrate has holes
The gas detection device according to claim 1 or 2, wherein the second joining member is connected to the light guide member and includes an insertion portion in which at least a part thereof is inserted into the hole. The hole penetrates the substrate and
The gas detection device according to claim 3, wherein the second joining member is inserted from the hole on the bottom surface opposite to the main surface of the substrate and includes a fastener for fastening the insertion portion. The gas detection device according to claim 4, wherein the fastener is screwed to the insertion portion. The gas detection device according to any one of claims 3 to 5, wherein at least a part of the side surface of the insertion portion inserted into the hole does not come into contact with the side surface of the hole. The gas detection device according to claim 6, wherein the portion of the first joining member to be joined to the substrate does not have a space between the first joining member and the substrate. The gas detection device according to any one of claims 3 to 7, wherein the hole is an elongated hole. The long hole is a hole extending in a direction connecting the centers of the vertical projection images of the first joining member and the second joining member on the main surface of the substrate. 8. The gas detection device according to 8. When the second joining member is distorted due to thermal expansion, the direction other than the direction in which the centers of the first joining member and the vertical projection image of the second joining member on the main surface of the substrate are connected to each other. The gas detection device according to any one of claims 1 to 9, wherein the movement of the gas detection device is suppressed. The gas detection device according to any one of claims 1 to 10, wherein the light guide member includes a first reflecting portion and a second reflecting portion. The gas detection device according to claim 11, wherein the position of the first reflecting portion is fixed relative to the second reflecting portion. The first reflecting portion is joined to the substrate by the first joining member, and is joined to the substrate.
The gas detection device according to claim 11 or 12, wherein the second reflecting portion is joined to the substrate by the second joining member. The gas detection device according to any one of claims 1 to 13, wherein the first joining member is composed of a plurality of parts. The gas detection device according to any one of claims 1 to 13, wherein the first joining member is composed of one component. The gas detection device according to claim 15, wherein the first joining member has a solid circular shape, a hollow circular shape, a bow shape, or a polygonal shape as a vertical projection image on the main surface of the substrate. The perpendicular bisector of the line connecting the center of the light receiving element and the center of the light emitting element is defined as a straight line Lp, and the straight line passing through the light receiving element and parallel to the straight line Lp is defined as a straight line Ld. A straight line passing through and parallel to the straight line Lp is defined as a straight line Le, a maximum region in the main surface of the substrate sandwiched between the straight line Ld and the straight line Le is defined as a region Rt, and the substrate of the first joining member is defined as a region Rt. The gas detection device according to any one of claims 1 to 16, wherein a vertical projection image of the above on the main surface exists in the region Rt. The gas detection device according to claim 17, wherein the first joining member is arranged so that a vertical projection image of the first joining member on the main surface of the substrate is arranged on the straight line Lp. Claims 1 to claim that the distance between the centers of the first joining member and the vertical projection image of the second joining member on the main surface of the substrate is longer than half of the maximum distance on the substrate. 18. The gas detector according to any one of 18. A substrate on which a light emitting element that emits light and a light receiving element that receives the light are provided on the main surface, and
A light guide member that guides the light emitted by the light emitting element to the light receiving element, and
A first joining member that joins the substrate and the light guide member,
A gas detection device comprising a second joining member that joins the substrate and the light guide member and has a joining degree lower than that of the first joining member. The gas detection device according to any one of claims 1 to 19, wherein the degree of joining of the second joining member is smaller than the degree of joining of the first joining member. With the board
A light emitting element provided on the main surface of the substrate and emitting light,
A light receiving element provided on the main surface of the substrate and receiving the light,
A light guide member that guides the light emitted by the light emitting element to the light receiving element, and
With the first joining member,
With a second joining member
The first joining member places the substrate and the light guide member in a first direction parallel to the plane of the substrate with a first restraint degree, and a second direction parallel to the plane of the substrate and perpendicular to the one direction. With a second degree of restraint, and with a third degree of restraint in the third direction perpendicular to the plane of the substrate, constrained in each translational direction.
The second joining member holds the substrate and the light guide member in the first direction with a fourth degree of restraint, in the second direction with a fifth degree of restraint, and in the third direction with a sixth degree of restraint. So, restrain in each translation direction,
At least one of the first restraint degree to the sixth restraint degree is zero, and one of the first restraint degree and the fourth restraint degree is not zero, and the second restraint degree and the fifth restraint degree are not zero. A gas detection device in which one of the restraint degrees is not zero and one of the third restraint degree and the sixth restraint degree is not zero. The gas detection device according to claim 22, wherein the fourth degree of restraint and / or the fifth degree of restraint is zero. The gas detection device according to claim 22, wherein the sixth degree of restraint is zero. The gas detection device according to any one of claims 22 to 24, wherein the first degree of restraint, the second degree of restraint, and the third degree of restraint are not zero.

Images