JP7569712B2 - Gas detection equipment - Google Patents

Description

This disclosure relates to a gas detection device.

Gas detection devices that detect gases are used in a variety of 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 the gas to be detected is introduced into the case.

JP 2015-184211 A

In the gas detection device described in Patent Document 1, the optical path tube is firmly joined to the substrate and case by the groove and fastener of the substrate fixing part. Therefore, for example, distortion of the substrate and case due to thermal expansion may be transmitted to the optical path tube, causing distortion of the optical path or changing the relative position of the optical surfaces, which may cause fluctuations in gas detection sensitivity.

In view of the above, the objective of this disclosure is to provide a gas detection device that can suppress the occurrence of distortion in the optical path.

A gas detection device according to an embodiment of the present disclosure includes:
A substrate;
A light emitting element that is provided on a main surface of the substrate and emits light;
a light receiving element provided on a main surface of the substrate and receiving the light;
a light guiding member that guides the light emitted by the light emitting element to the light receiving element;
A first bonding member;
A second joining member,
the first bonding member bonds the substrate and the light guiding member and suppresses movement of the light guiding member in a direction parallel to and/or perpendicular to a main surface of the substrate when an external force is applied to the light guiding member;
the second bonding member bonds the substrate and the light guiding member, and when an external force is applied to the light guiding member or when distortion occurs due to thermal expansion, suppresses movement of the light guiding member in a direction parallel to a main surface of the substrate and/or suppresses 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 may move in a direction parallel to a major surface of the substrate or in a plane perpendicular to the major surface of the substrate.

A gas detection device according to an embodiment of the present disclosure includes:
A substrate having a light emitting element that emits light and a light receiving element that receives the light provided on a main surface thereof;
a light guiding member that guides the light emitted by the light emitting element to the light receiving element;
a first bonding member that bonds the substrate and the light guide member;
a second bonding member that bonds the substrate and the light guide member and has a bonding strength lower than that of the first bonding member.

A gas detection device according to an embodiment of the present disclosure includes:
A substrate;
A light emitting element that is provided on a main surface of the substrate and emits light;
a light receiving element provided on a main surface of the substrate and receiving the light;
a light guiding member that guides the light emitted by the light emitting element to the light receiving element;
A first bonding member;
A second joining member,
the first bonding member constrains the substrate and the light guide member in each translation direction with a first degree of constraint in a first direction parallel to a plane of the substrate, a second degree of constraint in a second direction parallel to the plane of the substrate and perpendicular to the first direction, and a third degree of constraint in a third direction perpendicular to the plane of the substrate;
the second bonding member constrains the substrate and the light guiding member in each translation direction at a fourth constraint degree in the first direction, a fifth constraint degree in the second direction, and a sixth constraint degree in the third direction;
At least one of the first constraint degree to the sixth constraint degree is zero, one of the first constraint degree and the fourth constraint degree is not zero, one of the second constraint degree and the fifth constraint degree is not zero, and one of the third constraint degree and the sixth constraint degree is not zero.

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

FIG. 1 is a partially see-through perspective view of a gas detection device according to an 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 joint members. FIG. 4 is a diagram showing another example of the arrangement of the first joint members. FIG. 5 is an enlarged cross-sectional view of the second joining member. FIG. 6 is a diagram showing another example of a cross section of a gas detection device. FIG. 7 is a diagram showing another example of the arrangement and shape of the first joint members. FIG. 8 is a diagram showing another example of the shape of the first joint member. FIG. 9 is a diagram showing another example of the shape of the first joint member. FIG. 10 is a diagram showing another configuration example of the light guide member. FIG. 11 is a diagram for explaining the slot. FIG. 12 is a diagram for explaining the intensity distribution on the object plane (light-emitting surface) and the illuminance distribution on the image plane (light-receiving surface). FIG. 13 is a diagram for explaining the relationship between the constraint points and the distortion. FIG. 14 is a diagram showing another example of the shape of the first joint member. FIG. 15 is a diagram illustrating the arrangement of the first and second joint members.

First Embodiment
1 is a partially transparent perspective view of a gas detection device 1 according to an embodiment of the present disclosure. The gas detection device 1 is, for example, a small device measuring 30 mm×20 mm×10 mm, and is also called a gas sensor. In this embodiment, the gas detection device 1 is an NDIR (Non Dispersive InfraRed) type device that measures the concentration of a detection target gas based on infrared rays transmitted 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.

The gas detection device 1 comprises a substrate 2, a light-emitting element 3, a light-receiving element 4, a light-guiding member 5, a first bonding member 6, and a second bonding member 7. In FIG. 1, an example of the configuration of the gas detection device 1 is shown with a portion of the light-guiding member 5 being transparent, 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 this embodiment, the main surface 20 is the surface of the substrate 2 that has the largest area and faces the light-guiding member 5.

As shown in FIG. 1, below, 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 perpendicular to the main surface 20 of the substrate 2. The x-axis direction and the y-axis direction 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 the first reflecting section 51 and the second reflecting section 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 which electrically connects the mounted electronic components. The substrate 2 has the light-emitting element 3 and the light-receiving element 4 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 on the main surface 20 or the bottom surface opposite 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 in calculating the gas concentration. The calculation unit may include at least one of a general-purpose processor that performs functions according to a program to be loaded 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.

The light-emitting element 3 is a component that emits light used to detect the gas to be detected. There are no particular limitations on the light-emitting element 3 as long as it outputs light that includes a wavelength that is absorbed by the gas to be detected. In this embodiment, the light emitted by the light-emitting element 3 is infrared light, but is not limited to this. In this embodiment, the light-emitting element 3 is an LED (light emitting diode), but other examples include a semiconductor laser, an organic light-emitting element, or a MEMS (Micro Electro Mechanical Systems) heater. The light-emitting element 3 is provided in a first region 21 of the main surface 20 of the substrate 2. The first region 21 is positioned in the z-axis direction opposite a first mirror 511, which will be described later.

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 that includes the 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 to this. In this embodiment, the light receiving element 4 is a photodiode, but other examples may include a phototransistor, a thermopile, a pyroelectric sensor, a bolometer, etc. 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 light transmittance, etc. 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 determined to be opposite the fifth mirror 513 described later in the z-axis direction. The light receiving element 4 may be equipped with an optical filter having a wavelength selection function.

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 the optical system of the gas detection device 1. The light-guiding member 5 includes optical members and forms 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, mirrors and lenses.

In this embodiment, the light-guiding 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 has a mirror that first reflects the light emitted from the light-emitting element 3, and a mirror that finally reflects 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 light-guiding 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, and guides the light to the light-receiving element 4. The light path is configured to pass through a cell 54, which is provided between the light-guiding member 5 and the substrate 2 and into which gas is introduced. As another example, the number of mirrors provided in the light-guiding member 5 may be one or more other than five. Also, the light-guiding member 5 may be configured to include a lens in part of the optical path.

In the light-guiding member 5, the first reflecting portion 51 is fixed in position relative 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 adhesives, screws, claws, fittings, grommets, welding, etc.

The first mirror 511 is a collecting 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. 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 the xy plane direction. Here, the xy plane direction is a direction that has components in at least one of the x-axis and y-axis directions. However, the xy plane direction may have a z-axis 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 focusing mirror having a focusing 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 focusing mirror that focuses the incident light on the light receiving element 4. 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 that it has a z-axis component. Specifically, the fifth mirror 513 reflects the incident light so that it is focused on 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, 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 materials with a small light absorption coefficient and 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 and avoid deterioration over time. When the first mirror 511 and the fifth mirror 513 are formed by deposition or plating on the resin housing, 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 fluctuations in sensitivity are suppressed. The light guide member 5 may be formed by cutting, and from the standpoint of productivity, it is more preferable that it be formed by injection molding.

The first joining member 6 is a member that joins the substrate 2 and the light-guiding member 5. In this embodiment, the first joining member 6 is a single column, and 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, adhesive, grommets or screws, welding, tabs, fitting, etc. The same applies to the joining of the second bottom surface portion 62 and the light-guiding member 5. In addition, from the viewpoint of productivity, it is desirable that the first joining member 6 and the light-guiding member 5 are integrally molded in order to reduce the number of components.

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, adhesive, grommets or screws, welding tabs, 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 components is reduced, thereby improving productivity. 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.

2 is a diagram showing an example of a cross section of the gas detection device 1. In FIG. 2, a cross section of the substrate 2, the light guide member 5 including the third mirror 512, the first joint member 6, and the second joint member 7 is shown cut along a plane parallel to the yz plane. 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 has a vent 53 for introducing gas into the cell 54. The vent 53 may also be used to exhaust gas from the cell 54. In this embodiment, the first joint 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 it. As another example, the first joint 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-guiding member 5 may be joined by adhesive, welding, nails, fitting, etc.

The second joint member 7 includes an insertion portion 7a and a fastener 7b. As described above, a portion of the insertion portion 7a is firmly connected to the light-guiding member 5. At least a portion 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 this embodiment, the hole 25 penetrates the substrate 2 in the z-axis direction, i.e., the thickness direction. In this embodiment, the insertion portion 7a is a cylindrical body. The insertion portion 7a has a hole into which the fastener 7b is inserted on the surface opposite to the surface connected to the light-guiding member 5. The fastener 7b is inserted from 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 other specific examples may include a pin or a grommet. The fastener 7b and the hole of the insertion portion 7a have corresponding threads. In other words, the fastener 7b screws the insertion portion 7a. Here, as another example, the second joining member 7 may be configured without the fastener 7b. That is, the second joining member 7 may be configured only with the insertion portion 7a without a hole for the fastener 7b. In this case, the hole 25 may be a hole provided on the main surface 20 and not penetrating the substrate 2 in the z-axis direction. 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, so their explanations are omitted. The reason will be described later, but the hole 25 may be an elongated hole extending in one direction. Also, preferably, the hole 25 may be a hole extending in a direction connecting the centers of the vertical projection images of the first joining member and the second joining member onto the main surface of the substrate 2. Here, the extended direction refers to the direction in which the elongated hole has a major diameter. In the case where the hole 25 is an elongated hole and the second joint member 7 is fastened by a fastener 7b, the second joint member suppresses the movement of the light guide member in a direction 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, when an external force is applied to the light guide member 5 or when distortion occurs due to thermal expansion. One example of the external force is to fix the substrate 2 of the gas detection device 1 to a base and press a representative point of the light guide member 5 to apply a twist in the z-axis direction. In detail, for example, a point on the light guide member 5 other than the first joint member or a point on the surface of the light guide member 5 farthest from the first joint member is selected as the representative point, and an external force is applied to this point. Alternatively, the geometric center of each surface of the light guide member 5 may be selected as the representative point. 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. In addition, when the second bonding member 7 is configured without the fastener 7b, the second bonding member 7 can freely move in a 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 bonding member 7 is restricted from moving in a plane perpendicular to the main surface 20 of the substrate 2. Here, the long hole refers to a hole having a shape including two line segments parallel to the periphery of the hole, as shown in FIG. 11. As a specific example, the long hole may be a hole having a shape in which circles of the same diameter are continuously arranged and superimposed so that their centers are aligned on the line segments, or a rectangular hole. However, the first bonding member and the second bonding member that restrict the movement in the direction parallel to and perpendicular to the main surface of the substrate, respectively, may be excluded from the embodiments of the present disclosure.

Figure 3 is a diagram showing an example of the arrangement and shape of the first joining member 6. In Figure 3, the main surface 20 of the substrate 2 viewed toward the negative direction of the z axis is shown. The vertical projection image 6i is an image of the first joining member 6 projected perpendicularly onto the main surface 20 of the substrate 2. In this embodiment, the vertical projection image 6i onto 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 Figure 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. Also, in Figure 3, the perpendicular bisector 23 of the line segment connecting the center 21c of the first region 21 and the center 22c of the second region 22 is shown. Also, the second joining member 7 having the insertion portion 7a and the fastener 7b is shown being inserted into the hole 25 with a gap therebetween. In this embodiment, the first bonding member 6 is disposed so that a vertical projection image 6i onto the main surface 20 of the substrate 2 is on the perpendicular bisector 23. In addition, as will be described in detail later, the second bonding member 7 bonds the light guide member 5 in a direction that allows it to move freely, that is, with a degree of freedom, so that the substrate 2 and the light guide member 5 are essentially bonded by the first bonding member 6. Here, the vertical projection image 6i may be the cross-sectional shape of the first bonding member 6 directly on the main surface 20 of the substrate 2.

The first bonding member 6 and the second bonding member 7 can be made of a material that has a large elastic modulus and is difficult to deform. For example, the material of the first bonding member 6 and the second bonding member 7 may be LCP (liquid crystal polymer), PP (polypropylene), PEEK (polyether ether ketone), PA (polyamide), PPE (polyphenylene ether), PC (polycarbonate), PPS (polyphenylene sulfide), PMMA (polymethyl methacrylate resin), etc., or a hard resin made by mixing two or more of these, or a metal from the viewpoint of heat resistance. In addition, the first bonding member 6, the second bonding member 7, and the light guide member 5 may be made of the same material. If the first bonding member 6, the second bonding member 7, and the light guide member 5 are made of the same material, no difference in thermal expansion occurs, and thermal distortion can be suppressed. The substrate 2 and the light guide member 5 are substantially bonded by the first bonding member 6. Therefore, even if the substrate 2 deforms due to, for example, thermal expansion, the light-guiding member 5 is not affected by the deformation of the substrate 2 because there is only one constraint point and it is not over-constrained. For example, if the substrate 2 deforms so as to expand in the y-axis direction, the optical member shrinks (expands) similarly around the one point without distortion, because the light-guiding member 5 is essentially connected to the substrate 2 at only one point. In that case, there is no effect on the optical performance.

In addition, if the second joint member 7 does not exist and different forces act on the substrate 2 and the light-guiding member 5, the first joint member 6 is unlikely to deform in the axial direction, but may be twisted or bent. Therefore, for example, if the second joint member 7 does not restrain the light-guiding member 5 in the x-direction, the light-guiding member 5 may rotate with the first joint member 6 as the rotation axis relative to the substrate 2. That is, the first joint member 6 becomes the rotation axis when an external force is applied to the light-guiding member 5 in a direction parallel to the main surface 20 of the substrate 2. In other words, it can become the rotation axis when the light-guiding member 5 moves relative to the substrate 2. Here, movement may mean that the light-guiding member 5 and the substrate 2 rotate relatively when the substrate 2 is fixed and a shear stress parallel to the main surface of the substrate 2 is applied to the side of the light-guiding member 5. However, as shown in FIG. 12, the intensity distribution on the object plane (light-emitting surface) and the illuminance distribution on the image plane (light-receiving surface) are distributed point-symmetrically with respect to the rotation axis. Therefore, even if the light-guiding member 5 deforms and moves relative to the substrate 2 (i.e., the light-emitting surface), the movement vector of the illuminance distribution on the light-receiving surface created by the light-emitting surface coincides with the movement vector of the light-receiving section. This causes no change in the illuminance distribution received by the light-receiving surface, further suppressing fluctuations in gas detection sensitivity. Here, the object surface (light-emitting surface) is the surface in the light-emitting section of the light-emitting element 3 that comes into contact with the gas and is made of an optically transparent material. The image surface (light-receiving surface) is the surface in the sensing section of the light-receiving element 4 that comes into contact with the gas and is made of an optically transparent material.

Here, FIG. 4 is a diagram showing another example of the arrangement of the first bonding member 6. Each element in FIG. 4 is the same as the element with the same reference numeral in FIG. 3, so the description is omitted. As shown in FIG. 4, the first bonding member 6 may be provided at a different position on the main surface 20 of the substrate 2. That is, the first bonding member 6 may be arranged so that the vertical projection image 6i onto the main surface 20 of the substrate 2 is not on the perpendicular bisector 23. In addition, the first bonding 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 between the first reflecting portion 51. Therefore, it is preferable that the first bonding member 6 is provided at a position where the movement amount of the first reflecting portion 51 is smaller than the movement amount of the second reflecting portion 52 when the light-guiding member 5 moves relative to the substrate 2. In other words, the first joint member 6 that serves as the axis of rotation is preferably 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 joint member 6 is closer to the midpoint 24.

Here, even in the case of FIG. 4, the second bonding member 7 suppresses movement of the light-guiding member 5 in directions other than those parallel to the main surface 20 of the substrate 2 when an external force is applied to the light-guiding member 5 or when distortion occurs due to thermal expansion. In other words, the second bonding member 7 suppresses movement in a direction perpendicular to the main surface 20 of the substrate 2.

As an example, when an external force is applied to the light guide section in a direction parallel to the main surface 20 of the substrate 2 and perpendicular to the line connecting the starting point and the first joint, starting from a point on the surface of the light guide member 5 farthest from the first joint member, and the first joint member serves as the axis of rotation, the second joint member suppresses movement in a direction perpendicular to the main surface 20 of the substrate 2 and movement in a direction connecting the centers of the vertical projection images of the first and second joint members onto the main surface 20 of the substrate 2.

As another example, when distortion occurs due to thermal expansion, the second bonding member suppresses movement in a direction perpendicular to the main surface 20 of the substrate 2 and movement in a direction other than the direction connecting the centers of the perpendicular projection images of the first bonding member and the second bonding member onto the main surface 20 of the substrate 2.

Figure 5 is an enlarged cross-sectional view of the second joining member 7. In this embodiment, the second joining member 7, which includes 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 Figure 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 contact the side surface 2s of the hole 25 of the substrate 2. In the example of Figure 5, even if the second joining member 7 moves to the maximum in the positive y-axis direction and the side surface 7as of the insertion portion 7a contacts the side surface 2s of the hole 25, a gap is generated on the negative y-axis side. In contrast, the first bottom surface portion 61, i.e., the portion of the first joining member 6 that is joined to the substrate 2, does not have a space between it and the substrate 2. The second joining member 7, which has a gap in the xy plane direction, has a lower degree of joining than the first joining member 6. Here, the degree of joining means the difficulty of moving the object to be joined. In this embodiment, a high degree of bonding indicates that the light guide member 5 is strongly bonded to the substrate 2, or is bonded closely with no gaps, making it difficult to move relative to the substrate 2. A low degree of bonding indicates that the light guide member 5 is weakly bonded to the substrate 2, or is bonded with a gap, or the side 7as and side 2s are partially in contact but have little friction and are therefore easy to move relative to the substrate 2.

As described above, the light guide member 5 may rotate relative to the substrate 2 with the first joint member 6 as the axis of rotation. The second joint member 7 suppresses free rotation with the z-axis as the axis of rotation, but allows slight rotation by having a gap between the second joint member 7 and the hole 25. Here, the permitted slight rotation can be determined by the size of the gap. As described above, as long as the first reflecting portion 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 the same as before the rotation. Therefore, the gap between the second joint 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 relative to the substrate 2. In addition, when the mounting tolerances of the second joint member 7 and the first joint member 6 are the same, the greater the distance between the two joint members, the less the angular deviation of the optical member, which is good from the viewpoint of mass production yield. In particular, it is preferable that the distance between the centers of the vertical projection images of the first and second bonding members onto the main surface 20 of the substrate 2 is longer than half the maximum distance on the substrate 2. Here, since the difference in thermal expansion coefficient between different resin materials is about 100 ppm, and the maximum temperature difference in the general use environment of electronic devices is about 150°C, the amount of distortion due to thermal expansion is estimated to be 1.5% of the maximum length of the light-guiding member 5 from the product of these. Therefore, the gap should be designed to be 1.5% or more of the maximum length of the light-guiding member 5.

As shown in FIG. 5, the hole 25 of the substrate 2 has a step that contacts the head of the screw, which is the fastener 7b. The fastener 7b is screwed into the insertion portion 7a connected to the light-guiding member 5, so that the substrate 2 and the light-guiding member 5 are strongly joined in the z-axis direction. Therefore, the movement of the light-guiding member 5 in the z-axis direction relative to the substrate 2 is further restricted, and the translational degree of freedom in the z direction is lost. In addition, with regard to the degree of freedom of rotation about the axis connecting the two constraint points, the first joint member 6 and the substrate are in surface contact, so that the rotation is suppressed and the degree of freedom of rotation is lost. In other words, the light-guiding member 5 does not have the degree of freedom of rotation about the axis connecting the contact points between the first joint member 6, the second joint member 7, and the substrate 2.

The first joining member 6 also restricts the degree of freedom of the light guide member 5 in the translation direction with respect to each of the x-axis, y-axis, and z-axis with respect to the substrate 2. On the other hand, the second joining member 7, as described above, 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 in the direction in which the gap exists is not restricted. As shown in FIG. 13, over-constraint generally occurs when an object is constrained at two or more constraint points and with respect to the same degree of freedom. When an object is deformed due to thermal expansion or the like, distortion can occur along the line segment connecting the constraint points. In the case of over-constraint, the distortion cannot be freely extended by the constraint points, so the distortion deviates in a direction different from the direction connecting the constraint points, resulting in deformation other than the overall homothetic contraction (expansion).

Therefore, as shown in FIG. 11, the hole 25 is an elongated hole, and is therefore not overly constrained. Therefore, the second bonding member 7 can move freely in the direction of the elongated hole, and distortion due to thermal expansion is reduced. In particular, when the hole 25 is elongated in the direction connecting the centers of the vertical projection images of the first bonding member and the second bonding member onto the main surface 20 of the substrate 2, the gas detection device 1 can suppress deterioration of optical performance due to expansion. This is because, although distortion may occur between the constrained points, when there is no constraint in the direction connecting the constrained points, the distortion can be completely eliminated by moving freely, and no deformation other than homothetic contraction (expansion) due to temperature change is caused.

As described above, in the gas detection device 1 according to this embodiment, due to the above configuration, even if distortion occurs in the substrate 2 due to thermal expansion, the light-guiding member 5 is not affected by the deformation. Furthermore, even if the light-guiding member 5 moves to its maximum relative to the substrate 2 as described above, the second bonding member 7 properly maintains the optical path. Therefore, the gas detection device 1 is capable of suppressing deterioration of optical performance due to deformation other than homothetic contraction (expansion).

In addition, the gas detection device 1 is arranged so that the vertical projection image 6i onto the main surface 20 of the substrate 2 is on the perpendicular bisector of the line segment connecting the center of the first region 21 and the center of the second region 22, so that the illuminance distribution on the image plane (light-receiving surface) does not change and fluctuations in gas detection sensitivity are suppressed. As shown in FIG. 12, the intensity distribution on the object plane (light-emitting surface) and the illuminance distribution on the image plane (light-receiving surface) are distributed point-symmetrically with respect to the rotation axis, and when the substrate 2 is deformed due to thermal expansion, deformation occurs symmetrically with respect to the perpendicular bisector. This is because the movement of the illuminance distribution on the light-receiving surface created by the light-emitting surface matches the movement of the light-receiving surface in both direction and amount.

Also, as shown in FIG. 15, if the vertical projection images of the first and second bonding members 6 and 7 onto the main surface of the substrate are located in region Rt, when the substrate 2 is deformed due to thermal expansion, the illuminance distribution on the image surface (light receiving surface) is less likely to change for the same reason, and fluctuations in gas detection sensitivity are suppressed. Here, line Lp is the perpendicular bisector 23 of the line segment connecting the center of the first region 21 and the center of the second region 22. Line Le is a line passing through the first region 21 parallel to line Lp. Line Ld is a line passing through the second region 22 parallel to line Lp. Region Rt is the largest region within the main surface of the substrate sandwiched between lines Le and Ld.

Second Embodiment
6 is a diagram showing an example of a cross section of a gas detection device 1 according to another embodiment of the present disclosure. The gas detection device 1 according to this embodiment differs from the gas detection device 1 according to the above-described first embodiment in the configuration of the first bonding member 6. The 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 this embodiment is shown in FIG. 1, as in the first embodiment. Moreover, the same components as those of the gas detection device 1 according to the first embodiment are denoted by the same reference numerals as in FIGS. 1 to 4, and detailed description thereof will be omitted.

As shown in FIG. 6, in this embodiment, the first joining member 6 is not a column. 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, and a joining portion 63 that joins the first portion 6a, the second portion 6b, and the third mirror 512. By joining the third mirror 512 to the first joining member 6, the relative position of the first reflecting portion 51 to the second reflecting portion 52 is more firmly fixed.

Figure 7 is a diagram showing an example of the arrangement and shape of the first bonding member 6 in this embodiment. In Figure 7, the main surface 20 of the substrate 2 viewed in the negative direction of the z axis is shown. In this embodiment, the vertical projection image 6i onto the main surface 20 of the substrate 2 is arch-shaped. The first bonding member 6 is arranged so that the vertical projection image 6i onto 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. As described above, by bringing the vertical projection image 6i of the first bonding member 6 closer 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, which contributes to keeping the deviation from the optical path parameters small.

As described above, the gas detection device 1 according to this embodiment has the same effect as the first embodiment due to the above-mentioned configuration. Furthermore, the gas detection device 1 according to this embodiment includes a first joining member 6 having a joining portion 63 to which the third mirror 512 is also joined, so that the relative position of the first reflecting portion 51 to the second reflecting portion 52 can be fixed even more firmly.

(Modification)
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.

For example, the vertical projection image 6i of the first joining member 6 may be a polygonal shape. As a variation, as shown in FIG. 8, the vertical projection image 6i may be a square, and the first joining member 6 may be a square prism.

For example, in the above embodiment, the first joining member 6 is described as being composed of one part. The first joining member 6 may be composed of multiple parts. Here, the multiple parts are spaced apart from each other, but are arranged to a certain degree in close proximity so that they collectively form a rotation axis when an external force is applied to the light-guiding member 5 in a direction parallel to the main surface 20 of the substrate 2. As one modified example, as shown in FIG. 9, the vertical projection image 6i may be multiple solid circles. In this case, the first joining member 6 can more firmly join the substrate 2 and the light-guiding member 5.

For example, in the above embodiment, it has been described that the relative position of the first reflecting portion 51 with respect to the second reflecting portion 52 is fixed by integral formation or adhesive or the like. As one modified example, as shown in FIG. 10, the second reflecting portion 52 may be strongly joined together with the first reflecting portion 51 to the second bottom surface portion 62 of the first joining member 6 by adhesive, screws, tabs, fitting, grommets, welding or the like. In this case, the second reflecting portion 52 may be formed integrally with the second mirror 521 and the fourth mirror 522, and may include an extension portion 523 that extends to the first reflecting portion 51.

For example, in the above embodiment, the first joint member 6 has a shape with a long side in the z-axis direction, but may have a shape with a long side in a direction other than the z-axis. For example, as shown in FIG. 14, the first joint member 6 may be a column with a long side in the x-axis direction. The first joint member 6 may be connected to one side of the main surface 20 of the substrate 2 parallel to the x-axis and to 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-guiding member 5 may move in the positive direction of the z-axis with respect to the substrate 2, with the first joint member 6 as the rotation axis. However, if the substrate 2 and the light-guiding member 5 are strongly joined in the z-axis direction by the fastener 7b, the movement of the light-guiding 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 degree of bonding, and the second reflecting portion 52 is joined to the substrate 2 by the second joining member 7 having a low degree of bonding. Here, the combination of the first joining member 6 and the second joining member 7 with 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. Also, for example, the first joining member 6 and the second joining member 7 may join a desired reflecting portion of the first reflecting portion 51 or the second reflecting portion 52 to the substrate 2.

Looking at the above-described embodiment from another perspective, the gas detection device of this embodiment includes a substrate, a light-emitting element 3 that is provided on the main surface 20 of the substrate and emits light, a light-receiving element 4 that is provided on the main surface 20 of the substrate and receives the light, a light-guiding 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, and the first joining member connects the substrate and the light-guiding member to a first constrained degree in a first direction parallel to the plane of the substrate, a second constrained degree in a second direction parallel to the plane of the substrate and perpendicular to the first direction, and the first bonding member constrains the substrate and the light guide member in the translational direction by a fourth degree of constraint in the first direction, a fifth degree of constraint in the second direction, and a sixth degree of constraint in the third direction, and at least one of the degrees of constraint is zero, one of the first degree of constraint and the fourth degree of constraint is not zero, one of the second degree of constraint and the fifth degree of constraint is not zero, and one of the third degree of constraint and the sixth degree of constraint is not zero.

The degree of constraint here is an index that indicates whether an object can move freely in translation in a certain direction, and a degree of constraint of zero means that the object can move freely in that direction. A specific method for measuring the degree of constraint is to displace a point on the object a specified amount X, and then measure the average displacement amount Y of the entire object. In this case, the degree of constraint is the absolute value of (X-Y)/X. However, if the degree of constraint is 0.01 or less, it is considered to be zero.

At least one of the first to sixth degrees of constraint is zero, allowing at least one of the first and second joining members to move freely in one of the first to third directions.

In addition, by having either the first or fourth degree of constraint not be zero, either the second or fifth degree of constraint not be zero, and either the third or sixth degree of constraint not be zero, the entire light-guiding member is prevented from coming off the substrate.

In other words, the light-guiding member and the substrate are fixed as a whole, and can move freely in either the first to third directions when an external force is applied to the light-guiding member or when distortion occurs due to thermal expansion, making it possible to suppress distortion of the optical path while maintaining the reliability of the device.

There are no particular limitations on the method for making each degree of constraint zero, but as shown in the above-mentioned embodiment, examples include a method of removing the fastener when inserting the insertion portion of the joining member into the hole (which can make the third and sixth degrees of constraint zero), and a method of making the insertion portion not in contact with the side of the hole (which can make the first, second, fourth, and fifth degrees of constraint zero).

To suppress distortion of the optical path due to external forces and stresses in the planar direction of the substrate, the fourth and/or fifth constraint degrees can be set to zero (in this case, the second bonding member side is free to move in at least one direction in the planar direction parallel to the substrate). Alternatively, the first and/or second constraint degrees can be set to zero (in this case, the first bonding member side is free to move in at least one direction in the planar direction parallel to the substrate).

To suppress distortion of the optical path due to external forces and stresses in the direction perpendicular to the substrate, the sixth degree of constraint can be set to zero (in this case, the second bonding member side is free to move in the direction perpendicular to the substrate). Alternatively, the third degree of constraint can be set to zero (in this case, the first bonding member side is free to move in the direction perpendicular to the substrate).

From the standpoint of reliability and ease of assembly, it may be preferable for the first to third constraint degrees to be non-zero.

LIST OF SYMBOLS 1 Gas detection device 2 Substrate 2s Side of hole 3 Light emitting element 4 Light receiving element 5 Light guide member 6 First joint member 6a First portion 6b Second portion 6i Vertical projection image 7 Second joint member 7a Insertion portion 7as Side of insertion portion 7b Fastener 20 Main surface 21 First region 21c Center of first region 22 Second region 22c Center of second region 23 Perpendicular bisector 24 Midpoint 25 Hole 51 First reflecting portion 52 Second reflecting portion 53 Vent 54 Cell 61 First bottom portion 62 Second bottom portion 63 Joint portion 511 First mirror 512 Third mirror 513 Fifth mirror 521 Second mirror 522 Fourth mirror 523 Extension portion

Claims (19)

A substrate;
A light emitting element that is provided on a main surface of the substrate and emits light;
a light receiving element provided on a main surface of the substrate and receiving the light;
a light guiding member that guides the light emitted by the light emitting element to the light receiving element;
A first bonding member;
A second joining member,
the first bonding member bonds the substrate and the light guiding member and suppresses movement of the light guiding member in a direction parallel to and/or perpendicular to a main surface of the substrate when an external force is applied to the light guiding member;
the second bonding member bonds the substrate and the light guiding member, and when an external force is applied to the light guiding member or when distortion occurs due to thermal expansion, suppresses movement of the light guiding member in a direction parallel to a main surface of the substrate and/or suppresses movement within a plane perpendicular to the main surface of the substrate;
At least one of a first bonding member and a second bonding member is movable in a direction parallel to a main surface of the substrate or in a plane perpendicular to the main surface of the substrate ,
Except for the case where the first bonding member and the second bonding member suppress the movement of the substrate in the directions parallel and perpendicular to the main surface of the substrate, respectively,
a perpendicular bisector of a line segment connecting the center of the light receiving element and the center of the light emitting element is defined as a straight line Lp, a 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 the light emitting element and parallel to the straight line Lp is defined as a straight line Le, the largest area within the main surface of the substrate sandwiched between the straight line Ld and the straight line Le is defined as a region Rt, and a vertical projection image of the first bonding member onto the main surface of the substrate exists in the region Rt. The gas detection device according to claim 1, wherein the first joint member fixes the substrate and becomes a rotation axis when an external force is applied to the light guide section in a direction parallel to the main surface of the substrate and perpendicular to a line connecting the starting point and the first joint member, with the first joint member being the starting point and the point on the surface of the light guide member farthest from the first joint member as the starting point. the substrate has a hole;
The gas detection device according to claim 1 , wherein the second joint member is connected to the light guide member and includes an insertion portion, at least a portion of which is inserted into the hole. the hole penetrates the substrate;
4. The gas detection device according to claim 3, wherein the second bonding member includes a fastener that is inserted from the hole in a bottom surface that is the surface opposite to the main surface of the substrate and fastens the inserted portion. The gas detection device according to claim 4, wherein the fastener screws the insert. The gas detection device according to any one of claims 3 to 5, wherein at least a portion of the side of the portion of the insertion part inserted into the hole does not contact the side of the hole. The gas detection device according to claim 6, wherein the portion of the first joining member that is joined to the substrate does not have a space between the portion and the substrate. The gas detection device according to any one of claims 3 to 7, wherein the hole is an elongated hole. The gas detection device according to claim 8, wherein the elongated hole is a hole extending in a direction connecting the centers of the vertical projection images of the first and second bonding members onto the main surface of the substrate. The gas detection device according to any one of claims 1 to 9, wherein the second bonding member suppresses movement in any direction other than a direction connecting the centers of the vertical projection images of the first bonding member and the second bonding member onto the main surface of the substrate when distortion occurs due to thermal expansion. The gas detection device according to any one of claims 1 to 10, wherein the light guide member comprises a first reflecting portion and a second reflecting portion. The gas detection device according to claim 11, wherein the first reflecting portion is fixed in position relative to the second reflecting portion. the first reflecting portion is bonded to the substrate by the first bonding member,
The gas detection device according to claim 11 , 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 multiple parts. The gas detection device according to any one of claims 1 to 13, wherein the first joining member is composed of a single part. The gas detection device according to claim 15, wherein the first bonding member has a vertical projection image on the main surface of the substrate that is a solid circle, a hollow circle, an arch, or a polygon. 2 . The gas detection device according to claim 1 , wherein the first bonding member is disposed such that a vertical projection image of the first bonding member onto the main surface of the substrate is on the straight line Lp. 18. The gas detection device according to claim 1 , wherein a distance between the centers of vertical projection images of the first bonding member and the second bonding member onto the main surface of the substrate is longer than half a maximum distance on the substrate. 19. The gas detection device according to claim 1, wherein a bonding degree of the second bonding member is smaller than a bonding degree of the first bonding member.

Images