Gas detection device

Abstract

To provide a gas detection device that can obtain good optical properties. [Solution] The gas detection device 1 comprises a substrate 2, a light-emitting unit 3, a light-receiving unit 4, a light-guiding unit 5, and a fixing unit that fixes the light-guiding unit 5 and the substrate 2. The light-guiding unit 5 has at least two legs 54, and the substrate 2 has at least two position reference units 63 that contact the legs 54. The position reference units 63 determine the position of the light-guiding unit 5 in a direction perpendicular to the substrate 2, and the fixing unit is configured independently of the position reference units 63 and the legs 54.

Description

Technical Field

[0001] The present disclosure relates to a gas detection device.

Background Art

[0002] Conventionally, a gas detection device 105 including a substrate 100, a light emitting portion 101 and a light receiving portion 102 provided on the substrate 100, and a light guiding portion 104 provided on the substrate 100 via an adhesive 103 has been known (see FIG. 6).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional gas detection device, due to manufacturing variations such as differences in the thickness of the adhesive, the positions of the light emitting portion, the light receiving portion, and the light guiding portion with respect to the substrate, particularly in the vertical direction, were not determined. As a result, there was a problem that displacement of the light guiding portion with respect to the light emitting portion or the light receiving portion occurred, and the optical characteristics of the gas detection device deteriorated. And, the closer the distance between the light emitting portion or the light receiving portion and the light guiding portion, the greater the relative displacement amount with respect to the distance between the two when the light guiding portion is displaced by a certain amount. Therefore, this problem has become more prominent as the gas detection device is miniaturized or made lower-profile.

[0005] In view of this point, an object of the present disclosure is to provide a gas detection device capable of obtaining good optical characteristics.

Means for Solving the Problems

[0006] A gas detection device according to one embodiment of the present disclosure comprises a substrate, a light-emitting unit provided on the substrate, a light-receiving unit provided on the substrate, a light-guiding unit provided on the substrate that guides the light emitted by the light-emitting unit to the light-receiving unit, and a fixing unit that fixes the light-guiding unit and the substrate, wherein the light-guiding unit has at least two legs, the substrate has at least two position reference units that contact the legs, the position of the light-guiding unit in a direction perpendicular to the substrate is determined by the position reference units, and the fixing unit is configured independently of the position reference units and the legs. [Effects of the Invention]

[0007] According to one embodiment of this disclosure, a gas detection device that can obtain good optical properties can be provided. [Brief explanation of the drawing]

[0008] [Figure 1A] This is a schematic cross-sectional view showing an example of the configuration of a gas detection device according to one embodiment of the present disclosure. [Figure 1B] This is a schematic top view showing an example of the configuration of a gas detection device according to one embodiment of the present disclosure. [Figure 2] This is a schematic bottom view showing an example of the configuration of the light guide section in a gas detection device according to one embodiment of the present disclosure. [Figure 3] This is a cross-sectional photograph showing an example of the configuration of the light guide section in a gas detection device according to one embodiment of the present disclosure. [Figure 4] These are schematic cross-sectional and schematic bottom views showing an example of the configuration of a gas detection device according to a modified example. [Figure 5] This is a schematic cross-sectional view showing an example of the configuration of a gas detection device according to a modified example. [Figure 6] This is a schematic cross-sectional view showing an example of the configuration of a conventional gas detection device. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. In principle, identical components will be given the same reference numeral, and redundant descriptions will be omitted. In each drawing, for the sake of clarity, the aspect ratios of each component are shown exaggerated from their actual proportions.

[0010] Furthermore, for the sake of clarity in this specification, "upper" refers to the light guide side as depicted in the drawings, and "lower" refers to the substrate side as depicted in the drawings. However, "upper" and "lower" are merely terms defined for convenience and should not be interpreted restrictively.

[0011] Furthermore, in this specification, "approximately zero" refers to a numerical range that is substantially close to zero, and includes a slight range of numerical values ​​that are between zero and zero.

[0012] Furthermore, in this specification, "fixed" means reducing the degree of freedom of movement in all three orthogonal directions.

[0013] <Gas detection device> An example of the configuration of the gas detection device 1 according to this embodiment will be described with reference to Figures 1A, 1B, and 2.

[0014] Figure 1(A) is a schematic cross-sectional view showing an example of the configuration of the gas detection device 1 along line AA shown in Figure 1(B). In Figures 1(A) and 1(B), the Cartesian coordinates are set such that the X or Y direction is horizontal to the substrate 2, and the Z direction is perpendicular to the substrate 2. The gas detection device 1 is a small device, for example, with a length of 10 mm to 25 mm in the X direction, 15 mm to 35 mm in the Y direction, and 4 mm to 12 mm in the Z direction.

[0015] The gas detection device 1 includes a substrate 2, a light emitting unit 3, a light receiving unit 4, a light guiding unit 5, and a position reference unit 6. The position reference unit 6 includes a first position reference unit 61, a second position reference unit 62, and a third position reference unit 63 (the position reference unit that contacts the leg portion 54). The gas detection device 1 is, for example, an NDIR (Non Dispersive InfraRed) type device that detects the concentration of a detected gas based on the amount of infrared absorption by the introduced detected gas. The detected gas is, for example, carbon dioxide, methane, water vapor, propane , formaldehyde, carbon monoxide, hydrogen sulfide, nitric oxide, nitrous oxide, ammonia, sulfur dioxide, alcohol (such as methanol, ethanol, etc.), refrigerant gas (such as R32, R1234yf, etc.), MCH (methylcyclohexane), or a mixed gas thereof, etc.

[0016] According to the configuration of the gas detection device in the present embodiment, it can be applied as a light emitting and receiving device for uses other than gas detection. That is, the disclosed content derived by replacing the above-described "gas detection device" with "optical concentration measurement device", "optical physical quantity measurement device", "light emitting and receiving device", "optical device", etc. is included in the scope of the present disclosure. For example, it becomes possible to detect the state of the optical path space (as an example other than gas, the presence or concentration of a specific component of a fluid, etc.). For example, it can be used for a component detection device or a component concentration measurement device of a substance (such as water or body fluid) existing in the optical path space between the light emitting unit and the light receiving unit. For example, when the substance existing in the optical path space is blood, the component detection device or the component concentration measurement device can be used for measuring the glucose concentration in the blood.

[0017] A component detection device or a component concentration measurement device can measure the glucose concentration in blood glucose by measuring the absorption of light with wavelengths of 1 to 10 μm. In measuring the glucose concentration in blood glucose, it is preferable to measure the absorption of light at 1.6 μm, 2.0 to 2.3 μm, and 9.6 μm. A small, highly accurate, and highly reliable non-invasive glucose concentration measuring instrument can be realized. With such a glucose concentration measuring instrument, for example, a diabetic patient can accurately measure their blood glucose level without causing damage to the skin as in an invasive method. Also, based on the measured blood glucose level, more accurate medication (e.g., insulin) management can be realized.

[0018] 〔Substrate〕 On the main surface side of the substrate 2, a light emitting portion 3, a light receiving portion 4, a control portion, etc. are mounted. Also, the substrate 2 is provided with a first position reference portion 61, a second position reference portion 62, and a third position reference portion 63 on the main surface side. The light emitting portion 3 is provided in the first position reference portion 61. The light receiving portion 4 is provided in the second position reference portion 62. The light guiding portion 5 is provided in the third position reference portion 63. Note that the main surface is the surface on which the light guiding portion 5 is provided among the surfaces of the substrate 2 having the largest area.

[0019] By providing the light emitting portion 3 in the first position reference portion 61 on the substrate 2, the position of the light emitting portion 3 in the direction perpendicular to the main surface of the substrate 2 is determined. By providing the light receiving portion 4 in the second position reference portion 62 on the substrate 2, the position of the light receiving portion 4 in the direction perpendicular to the main surface of the substrate 2 is determined. By providing the light guiding portion 5 in the third position reference portion 63 on the substrate 2, the position of the light guiding portion 5 in the direction perpendicular to the main surface of the substrate 2 is determined.

[0020] That is, by determining the positions of the light emitting portion 3, the light receiving portion 4, and the light guiding portion 5 in the direction perpendicular to the main surface of the substrate 2, respectively, the position of the light guiding portion 5 with respect to the light emitting portion 3 or the light receiving portion 4 is also determined. Thereby, the variation in the relative distance (about several tens of μm) between the light emitting portion 3 or the light receiving portion 4 and the light guiding portion 5 can be suppressed, and the deterioration of the optical characteristics of the gas detection device 1 can be suppressed.

[0021] Substrate 2 is, for example, a printed circuit board, a flexible printed circuit board, a rigid-flexible circuit board, or a ceramic circuit board. Substrate 2 comprises metal wiring, a base material, a resin, etc. The base material is, for example, paper, glass cloth, polyimide film, PET film, ceramics, etc. The resin is, for example, phenolic resin, epoxy resin, polyimide resin, bismaleimide triazine resin, fluororesin, polyphenylene oxide resin, etc.

[0022] [Light-emitting part] The light-emitting unit 3 emits light in a wavelength band that includes wavelengths absorbed by the detected gas, in accordance with the drive current or drive voltage supplied from the control unit. For example, the light-emitting unit 3 emits light in a wavelength band of 2.0 μm or more and 12.0 μm or less. The configuration of the light-emitting unit 3 is not particularly limited, and it is sufficient that it emits light in a wavelength band that includes wavelengths absorbed by the detected gas. The light-emitting unit 3 may further include an optical filter that has the function of selectively transmitting light in a certain wavelength band.

[0023] The light-emitting unit 3 may be, for example, an LED (Light Emitting Diode), a lamp, a laser (light amplification by stimulated emission of radiation), an organic light-emitting unit, a MEMS (Micro Electro Mechanical Systems) heater, a VCSEL (Vertical Cavity Surface Emitting Laser), or a PCSEL (Photonic Crystal Surface Emitting). The light-emitting unit 3 may also include an auxiliary optical unit having a light-gathering function or a wavelength-selective function. The auxiliary optical unit may be, for example, a lens, a wavelength-selective filter, or a diffraction grating.

[0024] The light-emitting unit 3 is mounted on the substrate 2. The light-emitting unit 3 is positioned at a first position by the first position reference unit 61 and fixed to the substrate 2, for example, via solder. The solder is provided in the area facing the light-emitting unit 3 and the first position reference unit 61 and around it, and is spread over the surface of the first position reference unit 61. The light-emitting unit 3 is electrically connected to each electronic component via wiring including the first position reference unit 61. The solder is very thin and does not affect the positional misalignment of the light guide unit 5 relative to the light-emitting unit 3.

[0025] The first position is an ideal position where the propagation efficiency and light collection efficiency of the light transmitted from the light-emitting unit to the light-receiving unit via the light-guiding unit are well balanced. It is the position perpendicular to the main surface of the substrate 2 where the deviation of the light-guiding unit 5 from the ideal position relative to the light-emitting unit 3 is minimized, i.e., the position where the variation in the relative distance between the light-emitting unit 3 and the light-guiding unit 5 is approximately zero. By positioning the light-emitting unit 3 at the first position by the first position reference unit 61, the deterioration of optical characteristics (light propagation efficiency or light collection efficiency) in the gas detection device 1 can be suppressed, and the deterioration of the gas detection function can be prevented.

[0026] The relative distance between the light-emitting section 3 and the light-guiding section 5 is preferably about 1 to 20 times the diagonal distance of the light-emitting section 3, more preferably 15 times or less, and even more preferably 10 times or less. Specifically, the relative distance between the light-emitting section 3 and the light-guiding section 5 may be about 2 mm. Here, the relative distance between the light-emitting section 3 and the light-guiding section 5 may be the distance between the light-emitting center of the light-emitting section 3 and the center of the optical functional surface of the light-guiding section 5 that directly receives the light emitted from the light-emitting section. For example, if the light-guiding section 5 has a quadratic curved mirror that collimates the light emitted from the light-emitting section 3, the distance between the center of the quadratic curved mirror and the light-emitting center of the light-emitting section 3 may be taken as the relative distance between the light-emitting section 3 and the light-guiding section 5. The diagonal distance of the light-emitting section 3 may be the diagonal distance of the region in the light-emitting section 3 that has a light-emitting function, i.e., the light-emitting surface. For example, if the light-emitting section 3 is an LED encapsulated in resin, the diagonal distance of the light-emitting surface of the LED may be taken as the diagonal distance of the light-emitting section 3. Thus, even if the gas detection device 1 is miniaturized or made lower in height, the positions of the light-emitting unit 3 and the light-guiding unit 5 in the direction perpendicular to the substrate 2 are fixed, so variations in the relative distance between the light-emitting unit 3 and the light-guiding unit 5 are suppressed, and the gas detection device 1 can maintain good optical characteristics.

[0027] The light-emitting unit 3 is preferably a surface light source. Even if the light-emitting unit 3 is a surface light source, the variation in the relative distance between the light-emitting unit 3 and the light guide unit 5 is suppressed, so the gas detection device 1 can maintain good optical characteristics. Furthermore, while surface light sources such as LEDs and MEMS heaters emit light only on the light-emitting surface side, point light sources such as light bulbs emit light in all three-dimensional angles. Therefore, if the light-emitting unit 3 is a surface light source, light can be efficiently propagated from the light-emitting unit to the light-receiving unit, and stray light can be suppressed, thereby reducing the deterioration of the gas detection function due to stray light.

[0028] [Light receiving section] The light-receiving unit 4 is sensitive to wavelengths that include wavelengths absorbed by the gas to be detected, and receives light that has passed through the gas to be detected. For example, the light-receiving unit 4 receives light in the wavelength range of 2.0 μm to 12.0 μm. The light-receiving unit 4 outputs a detection signal indicating the concentration of the gas to be detected to the control unit according to the amount of light it receives. The higher the concentration of the gas to be detected, the smaller the amount of light received by the light-receiving unit 4, and the lower the concentration of the gas to be detected, the larger the amount of light received by the light-receiving unit 4. The light-receiving unit 4 may be equipped with an auxiliary optical unit that has a light-gathering function or a wavelength-selective function. An auxiliary optical unit is, for example, a lens, a wavelength-selective filter, or a diffraction grating.

[0029] The light-receiving unit 4 may be, for example, a photodiode, phototransistor, thermopile, pyroelectric sensor, bolometer, or photoacoustic detector.

[0030] The light-receiving unit 4 is mounted on the substrate 2. The light-receiving unit 4 is positioned at a second position by the second position reference unit 62 and fixed to the substrate 2, for example, via solder. The solder is provided in the area facing the light-receiving unit 4 and the second position reference unit 62 and around it, and spreads wetly over the surface of the second position reference unit 62. The light-receiving unit 4 is electrically connected to each electronic component via wiring including the second position reference unit 62. The solder is very thin and does not affect the positional misalignment of the light guide unit 5 relative to the light-receiving unit 4.

[0031] The second position is an ideal position where the propagation efficiency and collection efficiency of light transmitted from the light-emitting section to the light-receiving section via the light-guiding section are well balanced. It is the position perpendicular to the main surface of the substrate 2 where the deviation of the light-guiding section 5 from the ideal position relative to the light-receiving section 4 is minimized, i.e., the position where the variation in the relative distance between the light-receiving section 4 and the light-guiding section 5 is approximately zero. By positioning the light-receiving section 4 at the second position by the second position reference section 62, the deterioration of optical characteristics and the deterioration of the gas detection function can be suppressed in the gas detection device 1.

[0032] The relative distance between the light-receiving unit 4 and the light-guiding unit 5 is preferably about 1 to 20 times the diagonal distance of the light-receiving unit 4, and more preferably 15 times or less. Specifically, the relative distance between the light-receiving unit 4 and the light-guiding unit 5 may be about 2 mm. Here, the relative distance between the light-receiving unit 4 and the light-guiding unit 5 may be the distance between the light-receiving center of the light-receiving unit 4 and the center of the optical functional surface of the light-guiding unit 5 that directly propagates light to the light-receiving unit 4. For example, if the light-guiding unit 5 has a quadratic curved mirror that focuses light to the light-receiving unit 4, the distance between the center of the quadratic curved mirror and the light-receiving center of the light-receiving unit 4 may be taken as the relative distance between the light-receiving unit 4 and the light-guiding unit 5. The diagonal distance of the light-receiving unit 4 may be the diagonal distance of the region in the light-receiving unit 4 that has a light-receiving function, that is, the diagonal distance of the light-receiving surface. For example, if the light-receiving unit 4 is a photodiode sealed in resin, the diagonal distance of the light-receiving surface of the photodiode may be taken as the diagonal distance of the light-receiving unit 4. Thus, even if the gas detection device 1 is miniaturized or made lower in height, the positions of the light-receiving unit 4 and the light-guiding unit 5 in the direction perpendicular to the main surface of the substrate 2 are fixed. As a result, variations in the relative distance between the light-receiving unit 4 and the light-guiding unit 5 are suppressed, and the gas detection device 1 can maintain good optical characteristics.

[0033] When the light guide unit 5 is an imaging optical system, it is preferable that the area of ​​the light receiving surface of the light receiving unit 4 is greater than or equal to the size of the image formed on the light receiving surface of the light receiving unit 4 than that of the light guide unit 5. Specifically, it is preferable that the area of ​​the light receiving surface of the light receiving unit 4 is 1.5 times or more the area of ​​the image, and more preferably 2 times or more. As a result, even if the light guide unit 5 deforms due to environmental fluctuations such as temperature and humidity or deterioration over time, and the position of the image formed on the light receiving surface of the light receiving unit 4 changes slightly, the image will remain within the light receiving surface, and the amount of light propagated from the light emitting unit 3 to the light receiving unit 4 will not change, thus reducing the deterioration of the gas detection performance of the gas detection device 1. Here, the image may be an area within the light receiving surface that has an illuminance of 10% or more of the peak illuminance. On the other hand, if the area of ​​the light-receiving surface is too large relative to the area of ​​the image, the average illuminance of the light received by the light-receiving unit 4 decreases, and the detection signal output by the light-receiving unit 4 decreases. Therefore, it is preferable that the area of ​​the light-receiving surface of the light-receiving unit 4 is 16 times or less the area of ​​the image.

[0034] [Light guide section] The light guide unit 5 guides the light emitted by the light-emitting unit 3 to the light-receiving unit 4 by reflecting it once or multiple times in the detection space S. The light guide unit 5 optically connects the light-emitting unit 3 and the light-receiving unit 4. The light guide unit 5 may be, for example, an imaging optical system combining multiple quadratic curved mirrors.

[0035] The light guide unit 5 is positioned at the third position by the third position reference unit 63 and mounted on the substrate 2, for example, by fitting.

[0036] The third position is an ideal position where the propagation efficiency and collection efficiency of light transmitted from the light-emitting unit to the light-receiving unit via the light-guiding unit are well balanced. It is the position perpendicular to the main surface of the substrate 2 where the deviation of the light-guiding unit 5 from the ideal position relative to the light-emitting unit 3 or light-receiving unit 4 is minimized, i.e., the position where the variation in the relative distance between the light-emitting unit 3 or light-receiving unit 4 and the light-guiding unit 5 is approximately zero. By positioning the light-guiding unit 5 at the third position by the third position reference unit 63, the deterioration of optical characteristics and the deterioration of the gas detection function can be suppressed in the gas detection device 1.

[0037] The light guide unit 5 comprises a resin housing, a reflective section, and the like. Examples of materials for the resin housing include LCP (liquid crystal polymer), PP (polypropylene), PEEK (polyether ether ketone), PA (polyamide), PPE (polyphenylene ether), PC (polycarbonate), PPS (polyphenylene sulfide), PMMA (polymethyl methacrylate resin), or a hard resin made by mixing two or more of these. Examples of materials for the reflective section include metal, glass, ceramics, and stainless steel. From the viewpoint of improving detection sensitivity, it is preferable that the reflective section be formed from a material with a low light absorption coefficient and high reflectivity. Examples of such materials include aluminum, alloys containing gold and silver, dielectrics, and laminates thereof. Furthermore, from the viewpoint of reliability and changes over time, the reflective section may be formed from gold or a gold-containing alloy layer. The light guide unit 5 may also contain beads, fillers, and the like in these materials.

[0038] Preferably, a dielectric laminated film is formed on the surface of the metal layer on the inner surface of the light guide section 5. This increases the reflectivity. Furthermore, preferably, vapor deposition, sputtering, or plating is applied to the resin housing on the inner surface of the light guide section 5. This improves the productivity of the gas detection device 1 and reduces its weight. In addition, since the difference in thermal expansion coefficients between the substrate 2 and the light guide section 5 can be reduced, thermal deformation of the gas detection device 1 can be suppressed and fluctuations in detection sensitivity can be reduced.

[0039] The manufacturing process for the light guide section 5 is not particularly limited, but it may be formed by cutting, pressing, etc. Alternatively, the light guide section 5 may be formed by injection molding, taking productivity into consideration. If the light guide section 5 has multiple reflective sections, the multiple reflective sections may be molded as a single unit. By molding them as a single unit, the assembly process can be simplified and productivity can be increased. Furthermore, by molding the light guide section 5 as a single unit, deterioration of optical performance due to assembly errors can be suppressed. In addition, if the light guide section 5 is composed of multiple components, the joints connecting each component may shift position due to aging or environmental changes (temperature changes, humidity changes), potentially causing deterioration of optical performance. By molding the light guide section 5 as a single unit, such joint-related deterioration can be suppressed, and the reliability of the gas detection device 1 can be increased.

[0040] The light guide unit 5 may include various optical elements such as ellipsoidal mirrors, plane mirrors, concave mirrors, convex mirrors, lenses, and diffraction gratings.

[0041] The light guide unit 5 may further include a gas port, a dust filter, and the like. The gas port introduces the gas to be detected into the detection space S, or discharges the gas to be detected from the detection space S. The gas port is preferably provided on the top of the light guide unit 5, but it may also be provided on the side of the light guide unit 5. Providing the gas port on the top of the light guide unit 5 makes it easier to attach a dust filter to the gas port and simplifies the manufacturing process of the light guide unit 5. The dust filter is attached to the gas port to prevent dust, dirt, and other particles from entering the detection space S. The dust filter may be, for example, a nonwoven fabric or a PTFE film.

[0042] As shown in Figure 2, the light guide portion 5 is fixed to the substrate 2 in region Y by a fixing portion. The fixing portion is, for example, an adhesive. The adhesive is preferably 50 μm or more and 1 mm or less in thickness. When the substrate 2 is a printed circuit board and the light guide portion 5 is fixed to the substrate 2 with an adhesive, it is preferable that the area on the substrate 2 to which the adhesive is applied has exposed prepreg, and it is preferable that the area on the light guide portion 5 to which the adhesive is applied has been roughened or textured. Prepreg has higher adhesive strength with the adhesive than copper patterns or solder resist, and roughening or textured surfaces make it easier to create an anchoring effect, so the light guide portion 5 and the substrate 2 can be fixed more securely. The light guide portion 5 may also be fixed to the substrate 2 in region Y by, for example, crimping, fitting, pins, screws, claws, grommets, welding, etc. In addition, the light guide portion 5 is in contact with the third position reference portion 63 and its legs 54 provided on the substrate 2 in region X.

[0043] The robustness of the gas detection device 1 can be enhanced by fixing the light guide unit 5 to the substrate 2 by the fixing unit in region Y. Furthermore, because the light guide unit 5 is fixed to the substrate 2 by the fixing unit in region Y, it is not necessary to provide adhesive in region X to fix the light guide unit 5 to the substrate 2 as in conventional designs. This suppresses deviation of the light guide unit 5 from its ideal position due to variations in adhesive thickness. In addition, the light guide unit 5 has legs 54, and the legs 54 contact the third position reference unit 63 of the substrate 2 to determine its position perpendicular to the substrate 2. By fixing it to the substrate 2 by the fixing unit in region Y, the light guide unit 5 can be fixed to a desired position on the substrate 2 while suppressing positional deviation of the light guide unit 5 relative to the light-emitting unit 3 or light-receiving unit 4 caused by manufacturing variations. In other words, by separating and independently configuring the fixing part that secures the light guide part 5 to the substrate 2 and the third position reference part 63 and leg part 54 that determine the position of the light guide part 5 perpendicular to the substrate 2, it is possible to eliminate the misalignment of the light guide part 5 that occurs when the adhesive is responsible for both fixing the light guide part 5 to the substrate 2 and positioning the light guide part 5 perpendicular to the substrate 2. There are multiple legs 54, and if the contact area of ​​each leg 54 with the substrate 2 is sufficiently smaller than the area of ​​the main surface of the substrate 2, and can be considered a point, then a plane is defined, and therefore the number of legs 54 may be three or more, preferably three. Here, "sufficiently small area" means that the contact area of ​​each leg 54 with the substrate 2 may be one-tenth or less of the area of ​​the main surface of the substrate 2. Also, if the contact area of ​​each leg 54 with the substrate 2 is too small, the leg 54 may not be able to obtain sufficient mechanical strength, so the contact area of ​​each leg 54 with the substrate 2 may be 1 / 1500th or more of the area of ​​the main surface of the substrate 2, and the contact area of ​​each leg 54 with the substrate 2 may be 0.2 mm 2The above is sufficient. Furthermore, if the maximum length of the contact surface of at least one leg 54 with the substrate 2 is not small compared to the maximum length of the main surface of the substrate 2, the contact surface of the leg 54 with the substrate 2 can be considered as a line segment relative to the leg 54, and if there are two or more legs 54, a plane is defined, so the number of legs 54 can be two or more. Here, the maximum length may be the maximum length connecting any two points in the plane, and not small means that the maximum length of the contact surface of at least one leg 54 with the substrate 2 may be one-tenth or more of the maximum length of the main surface of the substrate 2. Also, the upper limit of the maximum length of the contact surface of one leg 54 with the substrate 2 is 90% of the maximum length of the main surface of the substrate 2. Furthermore, when using adhesive for the fixing portion, an appropriate gap may be provided between the light guide portion 5 and the substrate 2, taking into account the thickness of the adhesive. Specifically, the dimension of the region Y of the light guide portion 5 in the Z direction may be reduced by the thickness of the adhesive. This ensures that the light guide portion 5 directly contacts the substrate only in the region X facing the third position reference portion 63, and that an appropriate adhesive thickness is secured, thereby allowing the Z-direction positions of the light guide portion 5 and the substrate 2 to be precisely determined while being securely fixed together.

[0044] Even if adhesive is used in the fixing part, the light-emitting part 3 is positioned in the first position by the first position reference part 61, the light-receiving part 4 is positioned in the second position by the second position reference part 62, and the light-guiding part 5 is positioned in the third position by the third position reference part 63. Since the positions of the light-emitting part 3, the light-receiving part 4, and the light-guiding part 5 are determined in a direction perpendicular to the main surface of the substrate 2, positional displacement of the light-guiding part 5 relative to the light-emitting part 3 or the light-receiving part 4 is suppressed.

[0045] [Position reference part] The position reference unit 6 comprises a first position reference unit 61, a second position reference unit 62, and a third position reference unit 63. The first position reference unit 61, the second position reference unit 62, and the third position reference unit 63 are each provided on the substrate 2. The first position reference unit 61 determines the position of the light-emitting unit 3 in a direction perpendicular to the main surface of the substrate 2. The second position reference unit 62 determines the position of the light-receiving unit 4 in a direction perpendicular to the main surface of the substrate 2. The third position reference unit 63 determines the position of the light-guiding unit 5 in a direction perpendicular to the main surface of the substrate 2.

[0046] The first position reference portion 61 is, for example, a land (surface pad) on the substrate 2. The first position reference portion 61 is formed of a conductive material such as copper. The first position reference portion 61 positions the light-emitting portion 3 to a first position and is electrically connected to the light-emitting portion 3, for example, via solder. The shape of the first position reference portion 61 is not particularly limited, but it may be, for example, rectangular. If the light-emitting portion 3 has multiple electrical terminals, there may be multiple first position reference portions 61. If the first position reference portion 61 is a land, gold plating may be applied to the land surface to prevent deterioration due to oxidation or corrosion. Also, if the first position reference portion 61 is a land, it is preferable that there is no resist on the entire land surface, because if there is resist on the surface, the position of the light-emitting portion 3 cannot be precisely determined. Also, if the first position reference portion 61 is a land, there may be through holes or non-through holes in the plane.

[0047] The second position reference portion 62 is, for example, a land (surface pad) on the substrate 2. The second position reference portion 62 is formed of a conductive material such as copper. The second position reference portion 62 positions the light receiving portion 4 to the second position and is electrically connected to the light receiving portion 4, for example, via solder. The shape of the second position reference portion 62 is not particularly limited, but it may be, for example, rectangular. If the light receiving portion 4 has multiple electrical terminals, there may be multiple first position reference portions 61. If the second position reference portion 62 is a land, gold plating may be applied to the land surface to prevent deterioration due to oxidation or corrosion. Also, if the second position reference portion 62 is a land, it is preferable that there is no resist on the entire land surface, because if there is resist on the surface, the position of the light receiving portion 4 cannot be precisely determined. Also, if the second position reference portion 62 is a land, there may be through holes or non-through holes in the plane.

[0048] The third position reference portion 63 is, for example, a land (surface pad) on the substrate 2. The third position reference portion 63 is formed of a conductive material such as copper. The third position reference portion 63 positions the light guide portion 5 to the third position and joins it with the light guide portion 5, for example, by fitting. If the third position reference portion 63 is a land, gold plating may be applied to the land surface to prevent deterioration due to oxidation or corrosion. Also, if the third position reference portion 63 is a land, it is preferable that there is no resist on the entire land surface, as the position of the light guide portion 5 cannot be precisely determined if there is resist on the surface. Also, if the third position reference portion 63 is a land, there may be through holes or non-through holes in the plane. The shape of the third position reference portion 63 is not particularly limited and may be, for example, circular. Even if the light guide portion 5 is slightly misaligned with respect to the substrate 2 in a direction parallel to the main surface of the substrate, it is preferable that the area of ​​the third position reference portion 63 when viewed from above the main surface of the substrate is larger than the area of ​​the contact portion of the light guide portion that is in contact with the third position reference portion 63, so that it can be precisely positioned in the direction perpendicular to the main surface of the substrate. There are multiple third position reference portions 63, and if the area of ​​each third position reference portion 63 is sufficiently smaller than the area of ​​the main surface of the substrate 2 and can be considered as a point relatively, a plane is defined, so the number of third position reference portions 63 may be three or more, and preferably three. Here, "sufficiently small area" means that the area of ​​each third position reference portion 63 may be one-tenth or less of the area of ​​the main surface of the substrate 2. Furthermore, if the area of ​​the third position reference portion 63 is too small, sufficient mechanical strength cannot be obtained. Therefore, the area of ​​each third position reference portion 63 may be 1 / 1500 or more of the area of ​​the main surface of the substrate 2, and the area of ​​each third position reference portion 63 may be 0.2 mm². 2The above is sufficient. Furthermore, if the maximum length of at least one third position reference portion 63 is not small relative to the maximum length of the main surface of the substrate 2, the relevant third position reference portion 63 can be considered as a line segment, and if there are two or more third position reference portions 63, a plane is defined, so the number of third position reference portions 63 may be two or more. Here, the maximum length may be the maximum length connecting any two points in the plane, and not small means that the maximum length of at least one third position reference portion 63 may be one-tenth or more of the maximum length of the main surface of the substrate 2. Also, the upper limit of the maximum length of the third position reference portion 63 is 90% of the maximum length of the main surface of the substrate 2. When there are multiple third position reference portions 63, the bonding between the substrate 2 and the light guide portion 5 is stable, so it is preferable that at least two or more third position reference portions 63 are located near the edge of the substrate when viewed from above the main surface of the substrate. For example, the vicinity of the edge of the substrate may be a distance of 1 / 3 or less of the longitudinal distance on the main surface of the substrate. The vicinity of the edge of the substrate is preferably at a distance of 1 / 4 or less of the longitudinal distance on the main surface of the substrate. Furthermore, if the third position reference portion 63 is too close to the edge of the substrate, the processing accuracy of the third position reference portion 63 deteriorates, so it is preferable that the third position reference portion 63 is at least 0.2 mm away from the edge of the substrate when viewed from above the main surface of the substrate. Also, if there are multiple third position reference portions 63, in order to stabilize the bonding between the substrate 2 and the light guide portion 5, it is preferable that any two third position reference portions 63 are at least 1 / 2 of the longitudinal distance on the main surface of the substrate when viewed from above the main surface of the substrate. Furthermore, the maximum distance between any two third position reference portions 63 is 90% of the maximum length of the main surface of the substrate 2.

[0049] The first position reference section 61, the second position reference section 62, and the third position reference section 63 are formed by a similar process, for example, by a known printed circuit board manufacturing process. The thickness of each of the first position reference section 61, the second position reference section 62, and the third position reference section 63 is very thin compared to the thickness of the gas detection device 1 (approximately 5 mm), ranging from approximately 10 μm to approximately 80 μm. By forming the first position reference section 61, the second position reference section 62, and the third position reference section 63 by a similar process, their respective thicknesses can be made uniform. Furthermore, by forming the first position reference section 61, the second position reference section 62, and the third position reference section 63 from the same material, positioning accuracy can be improved, thereby realizing a gas detection device 1 with good optical characteristics. In addition, by arranging the first position reference section 61, the second position reference section 62, and the third position reference section 63 in close proximity, the influence of land thickness variations that occur during the manufacturing process can be reduced, and their respective thicknesses can be made more precisely uniform. For example, by placing at least one third position reference section 63 on the perpendicular bisector of the line segment connecting any first position reference section 61 and second position reference section 62 in an overhead view of the main surface of the substrate, the thickness of each section can be aligned more precisely. Here, any line connecting the light-emitting section 3 and the light-receiving section 4 in an overhead view of the main surface of the substrate may be used as the line segment connecting any first position reference section 61 and second position reference section 62.

[0050] Furthermore, the third position reference section 63 may be provided in region Rt, for example, as shown in Figure 22 of Japanese Patent Application Publication No. 2021-144027. In this case, because the first position reference section 61, the second position reference section 62, and the third position reference section 63 are clustered in relatively close areas on the substrate 2, the influence of uneven land thickness that occurs during the manufacturing process can be reduced, and the thickness of each can be more precisely aligned. In Figure 22 of Japanese Patent Application Publication No. 2021-144027, the straight line Lp is the perpendicular bisector of the line segment connecting the center of the light-emitting section 3 and the center of the light-receiving section 4. The straight line Le is a straight line passing through the light-emitting section 3 parallel to the straight line Lp. The straight line Ld is a straight line passing through the light-receiving section 4 parallel to the straight line Lp. Region Rt is the largest region within the main plane of the substrate sandwiched between the straight lines Le and Ld.

[0051] As described above, the gas detection device 1 is equipped with a position reference unit 6 on the substrate 2 that determines the position of the light-emitting unit 3, the light-receiving unit 4, and the light-guiding unit 5 in at least the perpendicular direction to the substrate 2. This solves the conventional problem of misalignment of the light-guiding unit 5 relative to the light-emitting unit 3 or light-receiving unit 4 due to manufacturing variations such as differences in adhesive thickness. As a result, variations in the relative distance between the light-emitting unit 3 or light-receiving unit 4 and the light-guiding unit 5 can be suppressed, thus preventing deterioration of optical characteristics in the gas detection device 1, such as blurred images and reduced light propagation to the light-receiving unit 4. Furthermore, even if the gas detection device 1 is miniaturized or made low-profile (for example, even if the relative distance between the light-emitting unit 3 or light-receiving unit 4 and the light-guiding unit 5 is shortened from approximately 10 mm to approximately 5 mm), a gas detection device 1 with good optical characteristics can be realized.

[0052] [Control Unit] The control unit may include at least one general-purpose processor that performs functions according to the program to be loaded, and a dedicated processor specialized for specific processing. The general-purpose processor may be, for example, a microcontroller unit (MCU). The processor is, for example, an Application Specific Integrated Circuit (ASIC). The control unit may include an Analog Front End (AFE), an Analog to Digital Converter (ADC), or non-volatile / volatile memory.

[0053] The control unit controls the light-emitting unit 3 and the light-receiving unit 4. For example, the control unit calculates the concentration of the detected gas based on the detection signal output from the light-receiving unit 4. The control unit can also control only the light-emitting unit 3 independently if the light-receiving unit 4 is not used in the gas detection device 1, or control only the light-receiving unit 4 independently if the light-emitting unit 3 is not used in the gas detection device 1. The control unit may be located inside the gas detection device 1 or outside the gas detection device 1.

[0054] In this embodiment, the gas detection device 1 has a position reference unit 6 provided on the main surface of the substrate 2 that determines the position of the light-emitting unit 3, the light-receiving unit 4, and the light-guiding unit 5 in at least a direction perpendicular to the main surface of the substrate 2. This makes it possible to realize a gas detection device 1 that can obtain good optical characteristics even if the gas detection device 1 is miniaturized or reduced in height.

[0055] <Variation> Next, an example of the configuration of the gas detection device 1A according to a modified example will be described.

[0056] The differences between the modified gas detection device 1A and the gas detection device 1 according to this embodiment are that the modified gas detection device 1A further includes a fourth position reference section in addition to the first position reference section 61, the second position reference section 62, and the third position reference section 63, and that the light guide section 5A further includes a second fixing section in the region facing the fourth position reference section. The other configurations are the same as those of the gas detection device 1 according to this embodiment, so a redundant explanation will be omitted.

[0057] The fourth position reference section is provided on the substrate 2. The fourth position reference section determines the position of the light guide section 5A in the horizontal direction with respect to the main surface of the substrate 2. The direction in which the position is determined may be only one direction, or it may have a degree of freedom in a certain direction. There may be multiple fourth position reference sections.

[0058] As shown in Figure 4, the fourth position reference part is, for example, a through hole 21 on the substrate 2. By inserting the pin 51 formed in the light guide part 5A into the through hole 21 in the substrate 2, the position of the light guide part 5A in the horizontal direction can be determined. The through hole 21 may be a circular hole 21A, or it may be an elongated hole 21B formed by extending a circle in one direction. For example, if the pin 51 is cylindrical, and the through hole 21 is a circular hole 21A, the horizontal position of the light guide part 5A can be completely determined, while if the through hole 21 is an elongated hole 21B, the horizontal position of the light guide part 5A can be determined in only one direction. Also, as shown in Figure 5, a through hole 52 with an outer shape similar to the through hole 21 on the substrate 2 is provided in the light guide part 5A, and by passing the pin 53 through the two through holes 21 and the through hole 52, the position of the light guide part 5A in the horizontal direction can be determined. The aforementioned pin 53 determines the position of the light guide 5A in the horizontal direction, and after fixing the light guide 5A to the substrate 2 with the fixing part, the pin 53 may be removed from the two through holes 21 and 52.

[0059] The fourth position is the ideal position where the propagation efficiency and collection efficiency of light transmitted from the light-emitting unit to the light-receiving unit via the light-guiding unit are well balanced. It is the position in the horizontal direction with respect to the substrate 2 where the deviation of the light-guiding unit 5A from the ideal position relative to the light-emitting unit 3 or light-receiving unit 4 is minimized, i.e., the position where the variation in the relative distance between the light-emitting unit 3 or light-receiving unit 4 and the light-guiding unit 5A is approximately zero. By positioning the light-guiding unit 5A at the fourth position by the fourth position reference unit, the deterioration of optical characteristics and the deterioration of the gas detection function can be suppressed in the gas detection device 1.

[0060] The fourth position reference section is preferably provided near the light-emitting section 3 and the light-receiving section 4 on the substrate 2. For example, it may be provided on the perpendicular bisector of the line segment connecting the centers of the light-emitting section 3 and the light-receiving section 4. This makes it possible to further reduce the horizontal positional misalignment between the light-emitting section 3 and the light-receiving section 4 on the substrate 2 and the light-guide section 5A, even if the light guide section 5A rotates around the fourth position reference section as the center of rotation.

[0061] The light guide portion 5A further includes a second fixing portion in the region facing the fourth position reference portion. The light guide portion 5A is fixed on the substrate 2 by the second fixing portion. The second fixing portion is, for example, a pin with a locking function. The light guide portion 5A is fixed on the substrate 2 and its position in the horizontal direction relative to the substrate 2 is determined, for example, when the pin is inserted into the fourth position reference portion.

[0062] Preferably, the light guide portion 5A has been subjected to a special surface treatment, such as priming, coating, or plating. As shown in Figure 3, it is preferable that the filler content of the interior D of the light guide portion 5A is greater than that of the surface F. This improves the smoothness of the reflective portion R that is in contact with the surface F. Furthermore, for example, when a pin is inserted into the fourth position reference portion, rattle of the light guide portion 5A relative to the substrate 2 is suppressed, and the light guide portion 5A can be stably positioned on the substrate 2. Also, for example, when a pin contacts the third position reference portion 63, rattle of the light guide portion 5A relative to the substrate 2 is suppressed, and the light guide portion 5A can be stably positioned on the substrate 2. As a result, the position of the light guide portion 5A can be precisely determined, further improving the optical characteristics of the gas detection device 1.

[0063] The second fixing portion is preferably formed from a thermosetting material. The second fixing portion may be formed from, for example, a thermosetting resin such as epoxy resin, a resin to which a ceramic material has been added to a thermosetting resin, or a metal paste.

[0064] The modified gas detection device 1A has a first position reference section 61, a second position reference section 62, and a third position reference section 63 provided on the substrate 2 that determine the position of the light-emitting section 3, the light-receiving section 4, and the light-guiding section 5A in a direction perpendicular to the substrate 2, and a fourth position reference section provided on the substrate 2 that determines the position of the light-guiding section 5A in a direction horizontal to the substrate 2. As a result, even if the gas detection device 1A is miniaturized or reduced in height, a gas detection device 1A that can obtain good optical characteristics can be realized.

[0065] Although the embodiments described above are representative examples, it will be apparent to those skilled in the art that many modifications and substitutions are possible within the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited by the embodiments described above, and various modifications and changes are possible without departing from the scope of the claims. [Explanation of Symbols]

[0066] 1. Gas detection device 1A Gas detection device 2 circuit boards 3. Light-emitting part 4 Light receiving section 5. Light guide section 5A light guide 6 Position reference part 21 Through holes 21A through hole 21B Through hole 51 pins 52 Through holes 53 pins 54 Legs 61 1st position reference part 62 2nd position reference part 63 3rd position reference part 100 circuit boards 101 Light-emitting part 102 Light receiving part 103 Adhesive 104 Light guide section 105 Gas detection device

Claims

1. circuit board and A light-emitting part provided on the substrate, A light-receiving unit provided on the substrate, A light guide unit provided on the substrate, which guides the light emitted by the light-emitting unit to the light-receiving unit, A fixing part that fixes the light guide part and the substrate, Equipped with, The light guide unit has at least two legs, The substrate comprises at least two position reference portions that contact the legs, The position of the light guide portion in the direction perpendicular to the substrate is determined by the position reference portion. The aforementioned fixing part is configured independently of the position reference part and the leg part, in the gas detection device.

2. circuit board and A light-emitting part provided on the substrate, A light-receiving unit provided on the substrate, A light guide unit provided on the substrate, which guides the light emitted by the light-emitting unit to the light-receiving unit, A fixing part that fixes the light guide part and the substrate, Equipped with, The light guide unit has at least three legs, The substrate comprises at least three position reference portions that contact the legs, The position of the light guide portion in the direction perpendicular to the substrate is determined by the position reference portion. The aforementioned fixing part is configured independently of the position reference part and the leg part, in the gas detection device.

3. The light guide unit has three legs, The substrate comprises three of the position reference sections. The gas detection device according to claim 1.

4. The substrate further comprises a first position reference section and a second position reference section. The light-emitting part is provided on the first position reference part, The light receiving unit is provided on the second position reference unit, The first position reference unit determines the position of the light-emitting unit in a direction perpendicular to the substrate, The second position reference unit determines the position of the light receiving unit in a direction perpendicular to the substrate, The first position reference portion, the second position reference portion, and the position reference portion that contacts the leg portion are formed of the same material. The gas detection device according to claim 1 or 2.

5. The light-emitting part is fixed to the substrate via solder, The light-receiving unit is fixed to the substrate via solder. The gas detection device according to claim 1 or 2.

6. The first position reference portion, the second position reference portion, and the position reference portion that contacts the leg portion are lands on the substrate. The gas detection device according to claim 4.

7. The aforementioned fixing part is an adhesive. The gas detection device according to claim 1 or 2.

8. The substrate further comprises a horizontal position reference section that determines the position of the light guide section in the horizontal direction relative to the substrate. The gas detection device according to claim 1 or 2.

9. The relative distance between the light-emitting portion or the light-receiving portion and the light-guiding portion is 10 times or less the diagonal distance of the light-receiving portion. The gas detection device according to claim 1 or 2.

10. The light guide portion has a larger internal filler content compared to the surface. The gas detection device according to claim 1 or 2.

11. The light-receiving unit has a light-receiving area that is greater than or equal to the size of the image. The gas detection device according to claim 1 or 2.

12. The light-emitting part is a surface light source. The gas detection device according to claim 1 or 2.

13. At least one of the position reference sections is provided on the perpendicular bisector of the line segment connecting the light-emitting section and the light-receiving section. The gas detection device according to claim 1 or 2.

14. At least two of the position reference portions are provided near the edge of the substrate. The gas detection device according to claim 1 or 2.

15. Any two locations of the position reference section are separated by a distance of 1 / 2 or more of the longitudinal distance on the main surface of the substrate. The gas detection device according to claim 1 or 2.

16. At least one of the position reference portions is provided in the largest area within the main surface of the substrate, sandwiched between a straight line passing through the light-emitting portion and parallel to the perpendicular bisector of the line segment connecting the center of the light-emitting portion and the center of the light-receiving portion, and a straight line passing through the light-receiving portion and parallel to the perpendicular bisector. The gas detection device according to claim 1 or 2.

Images