Gas detection device

Abstract

The present invention provides a gas detection device capable of outputting a detection signal with high stability. The gas detection device (1) comprises: a light emitting unit (10) which emits light of a wavelength band including a wavelength absorbed by a gas to be detected; a light receiving unit (20) which is sensitive to the wavelength band; a package (40) which houses the light emitting unit (10) and the light receiving unit (20); a light guiding unit (50) which guides light to the light receiving unit (20); a joint (60) which joins the package (40) and the light guiding unit (50); and a heat insulating unit (70) which is provided in a gap between the package (40) and the light guiding unit (50), wherein a portion of a surface of the package (40) facing the light guiding unit (50) has a proximity region (D) in which the distance between the package (40) and the light guiding unit (50) is less than 500 μm, and at least a portion of the heat insulating unit (70) and at least a portion of the joint (60) are provided adjacent to a portion of the proximity region (D).

Description

Technical Field

[0001] The invention relates to a gas detection device. Background Art

[0002] Gas detection devices have been used in a variety of fields. For example, a gas detection device is known in which a light-emitting unit that emits infrared light and a detector that detects infrared light of a specific wavelength are arranged inside a housing having an ellipsoidal reflector to detect a target gas (e.g., see Patent Document 1).

[0003] In recent years, demand for gas detection devices to be installed in portable devices such as smartphones has increased, leading to a trend towards smaller and thinner devices (see, for example, Patent Document 2). Electronic components installed in portable devices are densely packed, resulting in a high heat density. Furthermore, to ensure waterproofing, the device housing must be airtight, making it prone to heat accumulation. Furthermore, heat flux generated by heat sources such as power supplies, cameras, and computing devices installed in portable devices primarily diffuses through the substrate.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent Application Publication No. 2018 / 0348121

[0007] Patent Document 2: U.S. Patent No. 9,955,244 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] For example, Figure 4 As shown, in a conventional gas detection device 1B, the package 40B and the light guide 50B are directly joined without a joint or the like. Consequently, there is no thermal insulation between the package 40B, which has a smaller heat capacity, and the light guide 50B, which has a larger heat capacity. Consequently, the heat generated by the heat source flows more toward the light guide 50B via the substrate 100B than toward the package 40B, making it difficult to achieve uniform temperature within the package 40B.

[0010] As a result, the temperatures of the light emitting unit 10B, light receiving unit 20B, and control unit 30B built into the package 40B become uneven, causing an instability in the output signal of the gas detection device 1B. This problem becomes more pronounced as the gas detection device 1B becomes smaller.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas detection device capable of outputting a highly stable detection signal.

[0012] Solutions for solving problems

[0013] A gas detection device in one embodiment comprises: a light-emitting portion that emits light in a wavelength band including wavelengths absorbed by a detected gas; a light-receiving portion that is sensitive to the wavelength band; a package that incorporates the light-emitting portion and the light-receiving portion; a light-guiding portion that guides the light toward the light-receiving portion; a joining portion that joins the package and the light-guiding portion; and a thermal insulation portion that is arranged in a gap between the package and the light-guiding portion, wherein a portion of a surface of the package opposite to the light-guiding portion has a proximity region in which the distance between the package and the light-guiding portion is less than 500 μm, and at least a portion of the heat-insulating portion and at least a portion of the joining portion are adjacently arranged in a portion of the proximity region.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to provide a gas detection device capable of outputting a highly stable detection signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic cross-sectional view showing an example of the structure of a gas detection device according to one embodiment of the present invention.

[0017] Figure 2A It is a perspective view showing an example of the structure of a gas detection device according to one embodiment of the present invention.

[0018] Figure 2B It is a plan view showing an example of the structure of a gas detection device according to one embodiment of the present invention.

[0019] Figure 3 It is a schematic cross-sectional view showing an example of the structure of a gas detection device according to a modified example.

[0020] Figure 4 This is a schematic cross-sectional view showing an example of the structure of a conventional gas detection device.

[0021] Description of Reference Numerals

[0022] 1. Gas detection device; 1A. Gas detection device; 1B. Gas detection device; 10. Light-emitting portion; 10B. Light-emitting portion; 20. Light-receiving portion; 20B. Light-receiving portion; 30. Control portion; 30B. Control portion; 40. Package; 40B. Package; 41. Metal wire; 42. Lead frame; 50. Light-guiding portion; 50B. Light-guiding portion; 51. Gas port; 52. Dust filter; 60. Joint; 70. Thermal insulation portion; 70a. Thermal insulation portion; 70b. Thermal insulation portion; 100. Substrate; 101. Metal wiring. DETAILED DESCRIPTION

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, in principle, the same reference numerals are used for the same structural elements, and repeated descriptions are omitted. In each figure, for ease of explanation, the ratio of the vertical and horizontal dimensions of each structure is exaggerated relative to the actual ratio.

[0024] In addition, for the sake of convenience, "upper" refers to the light guide side depicted in the drawings, and "lower" refers to the substrate side depicted in the drawings. However, "upper" and "lower" are defined for convenience only and are not to be construed as limiting.

[0025] <Gas Detection Device>

[0026] Reference Figure 1 、 Figure 2A as well as Figure 2B , an example of the structure of the gas detection device 1 according to this embodiment will be described.

[0027] Gas detection device 1 is mounted on substrate 100 and uses NDIR (Non-Dispersive InfraRed) technology to detect the concentration of a target gas based on the absorption of infrared light by the introduced target gas. Gas detection device 1 is a compact device, measuring, for example, 7 mm in length, 5 mm in width, and 3 mm in height. Examples of target gases include carbon dioxide, methane, water vapor, propane, formaldehyde, carbon monoxide, nitric oxide, ammonia, sulfur dioxide, and alcohols.

[0028] The gas detection device 1 includes a light emitting unit 10 , a light receiving unit 20 , a control unit 30 , a package 40 , a light guiding unit 50 , a bonding unit 60 , and a heat insulating unit 70 .

[0029] 〔Luminous part〕

[0030] The light emitting unit 10 emits light in a wavelength band including wavelengths absorbed by the target gas based on a driving current or a driving voltage supplied from the control unit 30. For example, the light emitting unit 10 emits light in a wavelength band of 2.0 μm to 12.0 μm.

[0031] The light emitting unit 10 is, for example, an LED (Light Emitting Diode), a lamp, a laser (light amplification by stimulated emission of radiation), an organic light emitting element, a MEMS (Micro Electro Mechanical Systems) heater, or a VCSEL (Vertical Cavity Surface Emitting Laser).

[0032] The light-emitting unit 10 is embedded in the package 40. In the gas detection device 1, a thermal insulation portion 70a is provided in the gap S1 between the package 40 and the light-guiding unit 50, thereby enhancing thermal insulation between the package 40 and the light-guiding unit 50. Therefore, even if heat flows into the gas detection device 1, it is difficult for the heat to flow toward the light-guiding unit 50. As a result, the temperature inside the package 40 quickly becomes uniform, and the temperature of the light-emitting unit 10 embedded in the package 40 also quickly stabilizes.

[0033] The upper surface of the light emitting portion 10 may be in contact with the heat insulating portion 70b. Providing the heat insulating portion 70b on the upper surface of the light emitting portion 10 can further stabilize the temperature of the light emitting portion 10.

[0034] The light emitting unit 10 is preferably built into the package 40 , but may be provided outside the package 40 if it can maintain a temperature substantially equal to that of the light receiving unit 20 and the control unit 30 (with an error of approximately ±0.1° C.).

[0035] The light emitting unit 10 may further include an optical filter having a function of selectively transmitting light of a certain wavelength band.

[0036] 〔Light Receiving Department〕

[0037] The light receiving unit 20 is sensitive to wavelengths that include wavelengths absorbed by the target gas and receives light transmitted through the target gas. For example, the light receiving unit 20 receives light in a wavelength band between 2.0 μm and 12.0 μm. Based on the amount of light received, the light receiving unit 20 outputs a detection signal indicating the concentration of the target gas to the control unit 30. The higher the concentration of the target gas, the smaller the amount of light received by the light receiving unit 20. The lower the concentration of the target gas, the larger the amount of light received by the light receiving unit 20.

[0038] The light receiving unit 20 is, for example, a photodiode, a phototransistor, a thermopile, a pyroelectric sensor, a bolometer, a photoacoustic detector, or the like.

[0039] The light receiving unit 20 is embedded in the package 40. In the gas detection device 1, a thermal insulation portion 70a is provided in the gap S1 between the package 40 and the light guide 50, thereby enhancing the thermal insulation between the package 40 and the light guide 50. Therefore, even if heat flows into the gas detection device 1, it is difficult for the heat to flow toward the light guide 50. As a result, the temperature inside the package 40 quickly becomes uniform, and the temperature of the light receiving unit 20 embedded in the package 40 also quickly stabilizes.

[0040] The upper surface of the light receiving unit 20 may be in contact with the heat insulating portion 70b. Providing the heat insulating portion 70b on the upper surface of the light receiving unit 20 can further stabilize the temperature of the light receiving unit 20.

[0041] The light receiving unit 20 is preferably built into the package 40 , but may be provided outside the package 40 if it can maintain a temperature substantially equal to that of the light emitting unit 10 and the control unit 30 (with an error of approximately ±0.1° C.).

[0042] The light receiving unit 20 may further include an optical filter having a function of selectively transmitting light of a certain wavelength band.

[0043] [Control Department]

[0044] The control unit 30 may include at least one of a general-purpose processor that executes functions corresponding to the read program and a dedicated processor dedicated to specific processing. The dedicated processor may include an application-specific integrated circuit (ASIC) or a nonvolatile / volatile memory.

[0045] The control unit 30 controls the light emitting unit 10 and the light receiving unit 20. For example, if the light receiving unit 20 is not used in the gas detection device 1, the control unit 30 can also control only the light emitting unit 10. For example, if the light emitting unit 10 is not used in the gas detection device 1, the control unit 30 can also control only the light receiving unit 20.

[0046] The control unit 30 is built into the package 40. In the gas detection device 1, a thermal insulation portion 70a is provided in the gap S1 between the package 40 and the light guide 50, thereby enhancing thermal insulation between the package 40 and the light guide 50. Therefore, even if heat flows into the gas detection device 1, it is less likely to flow toward the light guide 50. As a result, the temperature inside the package 40 quickly becomes uniform, and the temperature of the control unit 30 built into the package 40 also quickly stabilizes.

[0047] The control unit 30 is preferably built into the package 40 , but may be provided outside the package 40 or outside the gas detection device 1 .

[0048] [Package]

[0049] The package 40 is bonded to the light guide portion 50 via the bonding portion 60. When the package 40 and the light guide portion 50 are bonded via the bonding portion 60, a gap S1 is formed between the package 40 and the light guide portion 50.

[0050] The package 40 houses the light-emitting unit 10, the light-receiving unit 20, and the control unit 30. In the gas detection device 1, a heat-insulating unit 70a is provided in the gap S1 between the package 40 and the light-guiding unit 50, thereby increasing the heat insulation between the package 40 and the light-guiding unit 50. Therefore, even if heat flows into the gas detection device 1, it is difficult for the heat to flow into the light-guiding unit 50, so that the temperature inside the package 40 quickly becomes uniform (temperature uniformity effect). Moreover, a heat-insulating unit 70b in contact with the upper surface of the light-emitting unit 10 and the upper surface of the light-receiving unit 20 is provided in the detection space S2 between the package 40 and the light-guiding unit 50, thereby preventing the problem of uneven temperature inside the package 40 caused by structural unevenness of the light-guiding unit 50. As a result, the light-emitting unit 10, the light-receiving unit 20, and the control unit 30 built into the package 40 can quickly make their respective temperatures uniform and maintain a stable temperature state.

[0051] In addition to the light emitting unit 10 , the light receiving unit 20 , and the control unit 30 , the package 40 incorporates metal members such as metal wires 41 for electrically connecting these elements and a lead frame 42 for electrically connecting these elements to the outside.

[0052] The package 40 has a protrusion X that contacts the light guide 50. This protrusion X allows the package 40 to form a gap S1 between the package 40 and the light guide 50, even if the thickness of the joint 60 becomes excessively thin during mass production. This allows the distance between the package 40 and the light guide 50 to be maintained at a certain level (e.g., approximately 2 μm to 5 μm). Therefore, providing the thermal insulation portion 70 a in this gap S1 improves the thermal insulation between the package 40 and the light guide 50.

[0053] The projection X may be intentionally formed or may be, for example, an unintentionally formed protrusion of the lead frame 42. Using a protrusion as the projection X allows the gap S1 to be easily formed between the package 40 and the light guide 50 without requiring a special manufacturing process for forming the projection X.

[0054] The metal component content of package 40 is preferably 25% or greater, more preferably 33% or greater. The higher the metal component content of package 40, the lower the thermal resistance. Therefore, by ensuring that the metal component content falls within this range, heat can be rapidly diffused within package 40, allowing the temperature within package 40 to be quickly uniformized.

[0055] The temperature of the package 40 is not particularly limited as long as the temperature inside is uniform, as long as the temperature errors of the light emitting unit 10 , the light receiving unit 20 , and the control unit 30 can be suppressed to approximately ±0.1°C.

[0056] The package 40 is preferably formed of a material having insulating properties. Examples of such a material include thermosetting resins such as epoxy resins, and thermosetting resins obtained by mixing silica fillers into these resins.

[0057] The metal wire 41 is preferably formed of a good conductor, such as a metal like gold, an alloy, or aluminum. The lead frame 42 is preferably formed of a good conductor, such as a metal like copper, an alloy, or carbon. When the lead frame 42 is formed of copper, which has a high thermal conductivity (thermal conductivity: 398 W / m·K), heat can flow quickly to the package 40, further improving temperature uniformity.

[0058] 〔Light guide section〕

[0059] The light guide 50 reflects the light emitted by the light emitting unit 10 once or multiple times in the detection space S2 and guides the light to the light receiving unit 20. The light emitting unit 10 and the light receiving unit 20 are optically connected via the light guide 50.

[0060] The light guide portion 50 is bonded to the package 40 via the bonding portion 60. When the package 40 and the light guide portion 50 are bonded via the bonding portion 60, a gap S1 is formed between the package 40 and the light guide portion 50.

[0061] The light guide unit 50 includes an ellipsoidal reflector whose inner surface serves as a reflector. The light guide unit 50 may further include optical elements such as a plane reflector, a concave reflector, a convex reflector, a lens, and a diffraction grating.

[0062] The reflective mirror is formed of, for example, metal, glass, ceramics, stainless steel, or the like.

[0063] From the perspective of improving sensitivity, the reflector is preferably formed of a material with a low light absorption coefficient and a high reflectivity. Examples of such materials include alloys containing aluminum, gold, and silver, dielectrics, or resin housings coated with a laminate thereof. Examples of materials for the resin housing include LCP (liquid crystal polymer), PP (polypropylene), PEEK (polyetheretherketone), PA (polyamide), PPE (polyphenylene ether), PC (polycarbonate), PPS (polyphenylene sulfide), PMMA (polymethyl methacrylate resin), or hard resins obtained by mixing two or more of these.

[0064] From the viewpoint of improving reliability and suppressing degradation over time, the reflector is preferably formed by a resin shell coated with gold or an alloy layer containing gold. Furthermore, in order to improve reflectivity, a dielectric laminate film is preferably formed on the surface of the metal layer. In the case where the inner surface of the light guide portion 50 is formed by vapor deposition or plating on the resin shell, productivity can be improved and lightweighting can be achieved. In addition, in the case where the inner surface of the light guide portion 50 is formed by vapor deposition or plating on the resin shell, the difference in thermal expansion coefficient between the package 40 and the light guide portion 50 is reduced, thereby suppressing thermal deformation and suppressing changes in sensitivity.

[0065] The manufacturing process of the light guide portion 50 is not particularly limited, and the light guide portion 50 may be formed by, for example, cutting. Alternatively, the light guide portion 50 may be formed by injection molding in consideration of productivity.

[0066] The light guide 50 further includes a gas port 51 and a dust filter 52. The gas port 51 is used to introduce the gas to be detected into the detection space S2 or to remove the gas to be detected from the detection space S2. The dust filter 52 is a filter attached to the gas port 51 to remove dust and dirt present in the detection space S2.

[0067] The gas port 51 is preferably provided at the upper portion of the light guide portion 50. By providing the gas port 51 at the upper portion of the light guide portion 50, it is easy to install the dust filter 52 on the gas port 51, and the manufacturing process of the light guide portion 50 is simplified. In addition, the gas port 51 may be provided at the side of the light guide portion 50. In the case where the gas port 51 is provided at the side of the light guide portion 50, the position of the gas port 51 may be adjusted in such a manner that at least the gas port 51 does not contact the joint 60 and the thermal insulation portion 70. In addition, the gas to be detected may not be introduced into the detection space S2 from a portion other than the gas port 51.

[0068] 〔Joint〕

[0069] The joint 60 joins the package 40 and the light guide portion 50. At least a portion of the joint 60 is provided adjacent to the thermal insulation portion 70 in a part of the proximity region D described later. The joint 60 and the thermal insulation portion 70 may also be provided with other components therebetween, but are preferably provided in direct contact. The thickness of the joint 60 is preferably not less than 2 μm and not more than 500 μm. By having the thickness of the joint 60 satisfy this range, even in the case where the package 40 does not have the convex portion X, a gap S1 can be formed between the package 40 and the light guide portion 50, and the distance between the package 40 and the light guide portion 50 can be maintained to a certain extent.

[0070] The joint 60 is preferably formed of a thermosetting material. For example, the joint 60 is preferably formed of a thermosetting resin such as epoxy resin, a resin with a ceramic material added to a thermosetting resin, or a metal paste. Furthermore, the joint 60 may contain beads, fillers, or the like in these materials. By incorporating beads, fillers, or the like into the joint 60, the thickness of the joint 60 is prevented from becoming excessively thin during mass production.

[0071] The manufacturing process of the bonding portion 60 is not particularly limited, and the bonding portion 60 may be formed by, for example, applying a resin material to the package 40 , placing the light guide 50 on the package 40 , and then subjecting the applied resin material to a temperature-raising and curing step.

[0072] Furthermore, although heat flows slightly toward the light guide 50 via the joint 60 , the speed is very slow. This avoids the problem of the conventional gas detection device 1B where the heat flows more toward the light guide 50B than toward the package 40B, causing the temperature inside the package 40B to become uneven.

[0073] [Thermal insulation part]

[0074] The thermal insulation portion 70 is provided in the space between the package 40 and the light guide 50, and has the function of improving thermal insulation between the package 40 and the light guide 50. For example, the thermal insulation portion 70a is provided in the gap S1 between the package 40 and the light guide 50. For example, the thermal insulation portion 70b is provided in the detection space S2 between the package 40 and the light guide 50.

[0075] Providing the thermal insulation portion 70a in the gap S1 between the package 40 and the light guide 50 improves thermal insulation between the package 40 and the light guide 50. Consequently, even if heat flows into the gas detection device 1, it is difficult for the heat to flow toward the light guide 50, resulting in a rapid uniformization of the temperature within the package 40. This temperature uniformity also rapidly uniformizes the temperatures of the light-emitting unit 10, light-receiving unit 20, and control unit 30 within the package 40. Consequently, the gas detection device 1 can output a highly stable detection signal.

[0076] Furthermore, by providing the thermal insulation portion 70b in the detection space S2 between the package 40 and the light guide 50, the temperatures of the light-emitting unit 10 and the light-receiving unit 20 can be stabilized. Furthermore, the temperature unevenness within the package 40 caused by structural non-uniformity of the light guide 50 is less likely to occur. Consequently, the temperatures of the light-emitting unit 10, light-receiving unit 20, and control unit 30 within the package 40 quickly become uniform, maintaining a stable temperature state. Consequently, the gas detection device 1 can output a highly stable detection signal.

[0077] The heat insulating portion 70 is preferably formed of a material having high heat insulation properties and a large amount of gas or space built therein relative to the material volume. Examples of such materials include air, porous materials, zeolite materials, foamed resins, fibrous materials such as glass wool or ceramic fibers.

[0078] The thermal conductivity of the heat insulating portion 70 is preferably 0.1 W / m·K or less. The lower the thermal conductivity of the heat insulating portion 70, the greater the thermal resistance, and the more the temperature uniformity effect can be improved. For example, the thermal conductivity of air is extremely low at 0.0257 W / m·K at 20°C. In other words, air is a material with low thermal conductivity, is cheap, and can be easily used. Therefore, it is most preferred to use air as the heat insulating portion 70. In addition, from the viewpoint of further improving thermal insulation, the thermal conductivity of the heat insulating portion 70 is preferably lower than the thermal conductivity of the joint 60.

[0079] The thickness of the thermal insulation portion 70 is preferably between 2 μm and 500 μm. The thicker the thermal insulation portion 70, the greater the thermal resistance, which improves the temperature uniformity. However, if the thermal insulation portion 70 is too thick, foreign matter such as dust can easily enter, reducing its effectiveness. Therefore, by ensuring that the thickness of the thermal insulation portion 70 falls within this range, the temperature uniformity can be improved while preventing the ingress of foreign matter.

[0080] For example, the thermal conductivity of epoxy resin is 0.3 W / m·K, while the thermal conductivity of air is 0.0257 W / m·K. The thermal conductivity of epoxy resin is one digit greater than that of air. Therefore, when epoxy resin is used for thermal insulation 70, the thickness of thermal insulation 70 can be reduced by one digit compared to when air is used for thermal insulation 70.

[0081] As described above, it is preferable that the thermal conductivity, thickness, etc. of the heat insulating portion 70 be appropriately adjusted according to the material used. This can enhance the temperature uniformity effect.

[0082] At least a portion of the heat insulating portion 70 is provided in a portion close to the region D. The coverage of at least a portion of the heat insulating portion 70 is preferably 30% or more, and preferably 50% or more and 90% or less. Figure 2A and Figure 2BAs shown, proximity region D refers to the area of ​​the package 40 surface facing the light guide 50, and is the area where the distance between the package 40 and the light guide 50 is 500 μm or less. The coverage ratio is the ratio of the area of ​​the thermal insulation portion 70 covering proximity region D to the area of ​​the proximity region D.

[0083] The greater the coverage of the thermal insulation part 70, the greater the thermal resistance, and the more the temperature uniformity effect can be improved. On the other hand, the smaller the coverage of the thermal insulation part 70, the less the thermal resistance, but the ratio of the area of ​​the joint 60 covering the close area D relative to the area of ​​the close area D can be increased, thereby improving the bonding strength between the package 40 and the light guide part 50. Therefore, considering the balance between the temperature uniformity effect and the bonding strength, it is preferable to specify the coverage. By ensuring that the coverage of the thermal insulation part 70 satisfies this range, the temperature uniformity effect can be improved, and the bonding strength between the package 40 and the light guide part 50 can be appropriately maintained.

[0084] As described above, by providing the heat insulating portion 70 in the space between the package 40 and the light guide 50, it is possible to improve the thermal insulation between the package 40 and the light guide 50. Thus, even if heat flows into the gas detection device 1, it is possible to effectively prevent the heat from flowing into the light guide 50, thereby quickly making the temperature inside the package 40 uniform.

[0085] [Substrate]

[0086] The gas detection device 1 is mounted and fixed on the substrate 100. The substrate 100 is, for example, a printed circuit board, a flexible printed circuit board, or a rigid-flexible substrate.

[0087] The substrate 100 includes metal wiring 101 , a base material, resin, etc. The substrate 100 is electrically connected to the light emitting unit 10 , the light receiving unit 20 , the control unit 30 , etc., which are built into the package 40 , via a lead frame 42 .

[0088] Examples of the substrate include paper, glass cloth, polyimide film, PET film, and ceramics. Examples of the resin include phenolic resin, epoxy resin, polyimide resin, bismaleimide triazine resin, fluororesin, and polyphenylene ether resin.

[0089] The gas detection device 1 of this embodiment utilizes the joint 60 or the protrusion X to form a gap S1 between the light guide 50 and the package 40. A thermal insulation portion 70a is provided in this gap S1. This improves the thermal insulation between the package 40 and the light guide 50, thereby preventing heat flowing into the gas detection device 1 from flowing toward the light guide 50 and rapidly achieving uniform temperature within the package 40B. As a result, the gas detection device 1 can output a highly stable detection signal even in a compact form.

[0090] <Modification>

[0091] Reference Figure 3 , an example of the structure of a gas detection device 1A according to a modified example will be described.

[0092] The gas detection device 1A of Modified Example 1 differs from the gas detection device 1 of the present embodiment in that the gas detection device 1 of the present embodiment has the protrusion X on the side of the package 40, while the gas detection device 1A of Modified Example 1 has the protrusion Y on the side of the light guide 50. The remaining structures are the same as those of the gas detection device 1 of the present embodiment, and therefore, repeated descriptions are omitted.

[0093] The light guide 50 has a protrusion Y that contacts the package 40. This contact allows the light guide 50 to form a gap S1 between the package 40 and the light guide 50, even if the thickness of the joint 60 becomes too thin during mass production. This allows the distance between the package 40 and the light guide 50 to be maintained at a certain level (e.g., approximately 2 μm to 5 μm). Therefore, providing the thermal insulation portion 70 a in this gap S1 improves the thermal insulation between the package 40 and the light guide 50.

[0094] The projections Y may be intentionally formed or may be burrs formed unintentionally. Using burrs as the projections Y eliminates the need for a special manufacturing process for forming the projections Y, and allows the gap S1 to be easily formed between the package 40 and the light guide 50 .

[0095] In the modified example, the gas detection device 1A utilizes the joint 60 or the protrusion Y to form a gap S1 between the light guide 50 and the package 40. A thermal insulation portion 70a is provided in this gap S1. This improves the thermal insulation between the package 40 and the light guide 50, thereby preventing heat flowing into the gas detection device 1 from flowing toward the light guide 50 and rapidly achieving uniform temperature within the package 40B. As a result, the gas detection device 1A can output a highly stable detection signal even in a compact form.

[0096] The above embodiments are described as representative examples, but it is obvious to those skilled in the art that various modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the above embodiments, but rather can be variously modified and altered without departing from the scope of the claims.

Claims

1. A gas detection device, wherein: The gas detection device has: a light emitting unit that emits light in a wavelength band including a wavelength absorbed by a gas to be detected; a light receiving portion having sensitivity to the wavelength band; a package body, which houses the light emitting unit and the light receiving unit; a light guiding portion for guiding the light toward the light receiving portion; a joining portion for joining the package body and the light guide portion; as well as a heat insulating portion provided in a gap between the packaging body and the light guiding portion; A portion of the surface of the package facing the light guide portion has a proximity region where the distance between the package and the light guide portion is 500 μm or less. At least a portion of the heat insulating portion and at least a portion of the joint portion are provided in a local portion of the proximity region. The ratio of the area of ​​the heat insulating portion covering the proximity region to the area of ​​the proximity region, that is, the coverage ratio, is 30% or more and 90% or less.

2. The gas detection device according to claim 1, wherein: The thermal conductivity of the thermal insulation part is 0.1 W / m · Below K.

3. The gas detection device according to claim 1 or 2, wherein: The thermal insulation portion has a thickness of 2 μm or more and 500 μm or less.

4. The gas detection device according to claim 1 or 2, wherein: The content of the metal member in the package is 25% or more.

5. The gas detection device according to claim 1 or 2, wherein: The package body has a convex portion in contact with the light guide portion.

6. The gas detection device according to claim 1 or 2, wherein: The light guide portion has a convex portion that contacts the package body.

7. The gas detection device according to claim 1 or 2, wherein: The thermal insulation is a gas.

8. The gas detection device according to claim 1 or 2, wherein: The gas detection device further includes a control unit that controls the light emitting unit and the light receiving unit, and the package incorporates the control unit.

9. The gas detection device according to claim 1 or 2, wherein: The thermal conductivity of the heat insulating portion is lower than the thermal conductivity of the joining portion.

10. The gas detection device according to claim 1 or 2, wherein: The light guide portion has a gas port for introducing a gas to be detected.

11. The gas detection device according to claim 1 or 2, wherein: At least a portion of the thermal insulation portion and at least a portion of the joining portion are disposed adjacent to each other.

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