JP2018128323A - Optical gas sensor and gas detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical gas sensor capable of miniaturizing an optical gas sensor in which a plurality of light sources are arranged in a housing while ensuring a large optical path length so as to detect a gas to be detected. To do. An optical gas sensor 1 is a non-dispersive infrared absorption type sensor, in which an LED 11a that emits infrared light having a first wavelength and a red having a second wavelength different from the first wavelength are used. The LED 11b that emits external light, one photodiode 12 that receives the infrared light emitted from the LED 11a and the LED 11b, and the reflection that guides the infrared light emitted from the LED 11a to the photodiode 12 by reflecting the infrared light. The portions 13a to 13d and the housing portion 10 in which the LEDs 11a and 11b, the photodiode 12, and the reflecting portions 13a to 13d are arranged on the inner surface 101a side are provided. [Selection diagram] Fig. 6

Description

  The present invention relates to an optical gas sensor and a gas detector, and more particularly to an optical gas sensor and a gas detector including a light source and a light receiving unit.

  Conventionally, an optical gas sensor including a light source and a light receiving unit is known (see, for example, Patent Document 1).

  Patent Document 1 discloses a non-dispersive infrared absorption system including a gas cell (casing unit), two light sources, two light receiving units that receive infrared light emitted from the two light sources, and a reflecting unit. An optical gas sensor is disclosed. The reflection unit is configured to guide the light to each of the two light receiving units by reflecting infrared light emitted from the two light sources. The two light sources and the two light receiving units are disposed in the gas cell.

Japanese Patent No. 6010702

  In a non-dispersive infrared absorption type sensor, it is preferable to ensure a relatively large optical path length of infrared light in order to sufficiently absorb infrared light in a gas to be detected and increase detection sensitivity. Further, in the field of optical gas sensors, there is a conventional problem of downsizing the apparatus. In this regard, in the optical gas sensor in which the two light sources and the two light receiving units described in Patent Document 1 are disposed in the gas cell, an optical path length that is large enough to detect the gas to be detected is secured. There is a problem that it is necessary to achieve further downsizing of the apparatus.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to detect a detection target gas in an optical gas sensor in which a plurality of light sources are arranged in a casing. An optical gas sensor capable of reducing the size of the apparatus while ensuring a sufficiently large optical path length, and a gas detector including the optical gas sensor are provided.

  An optical gas sensor according to a first aspect of the present invention is a non-dispersive infrared absorption sensor, and a first light source that emits infrared light having a first wavelength is different from a first wavelength. A second light source that emits infrared light having a wavelength of 1, a first light source that receives infrared light emitted from the first light source and the second light source, and an infrared light that is emitted from the first light source. By this, the reflection part guided to a light-receiving part, and the housing | casing part by which a 1st light source, a 2nd light source, a light-receiving part, and a reflection part are arrange | positioned at an inner surface side are provided. Here, a non-dispersive infrared absorption sensor is a property in which gas molecules absorb infrared light in a spectral region where the wavelength of infrared light passing through the gas matches the level of internal energy of the gas molecules. It is a sensor that detects a specific gas by utilizing (the property that infrared light having a wavelength specific to gas attenuates at a rate corresponding to the gas concentration).

  In the optical gas sensor according to the first aspect of the present invention, as described above, the first light source, the second light source, the light receiving unit, and the infrared light emitted from the first light source are reflected to guide the light receiving unit. A housing part in which a reflecting part that emits light is disposed on the inner surface side is provided. Thereby, compared with the structure which arrange | positions two light sources and two light-receiving parts in the conventional gas cell (casing part), since the number of the light-receiving parts in a housing | casing part can be reduced by one, apparatus structure Can be simplified and the apparatus can be miniaturized. In addition, the number of light receiving parts can be reduced by one, and the infrared light emitted from the first light source can be reflected by the reflecting part in the housing part, so that a wider space is secured in the housing part. Thus, a larger optical path length can be secured. As a result, the detection target gas can be detected with higher accuracy. As described above, the apparatus can be miniaturized while ensuring a sufficiently long optical path length to detect the detection target gas.

  In the optical gas sensor according to the first aspect, preferably, the first light source is a light source for detection for detecting a gas to be detected, and the second light source is a light source for reference. If comprised in this way, by providing the 2nd light source for a reference from which the wavelength differs from the 1st light source for a detection, by the fall of the detection strength by the dirt inside a housing | casing part, and absorption of the gas of detection object It can be discriminated from a decrease in detection intensity. Specifically, when both the detection intensity of the infrared light from the light source for detection and the infrared light from the reference light source are decreased by the light receiving unit, it can be determined that the inside of the housing is dirty. it can. Further, when the detection intensity of the infrared light receiving unit from the reference light source does not decrease (is small), it can be determined that the inside of the casing is not substantially dirty. As a result, it is possible to appropriately determine the maintenance timing of the optical gas sensor.

  In the optical gas sensor according to the first aspect, preferably, a plurality of reflecting portions are provided, and the infrared light emitted from the first light source is reflected by the plurality of reflecting portions to be guided to the light receiving portion. Is done. If comprised in this way, in the inner surface side of a housing | casing part, since the infrared light radiate | emitted from the 1st light source can be multiply-reflected by several reflection parts, the optical path length of infrared light is ensured more largely. can do. As a result, the detection target gas can be detected with higher accuracy.

  In the optical gas sensor according to the first aspect, preferably, the reflecting portion reflects a large amount of infrared light emitted from the first light source at a side intersecting the inflow direction rather than the inflow direction of the detection target gas. It is configured as follows. If comprised in this way, compared with the case where more infrared light radiate | emitted from the 1st light source is reflected by the side which flows in the gas of detection object rather than the side which cross | intersects the inflow direction of gas of detection object. Since the ratio of the reflection part on the side where the gas to be detected flows in can be reduced, the ratio of the area into which the gas to be detected flows is increased correspondingly, and the gas to be detected is more effectively enclosed. Can flow into the body.

  In this case, preferably, the reflection part is configured to reflect the infrared light emitted from the first light source only on the side intersecting the inflow direction. If comprised in this way, since a reflection part can be provided only in the side which cross | intersects the inflow direction of the detection target gas, without providing a reflection part in the inflow direction of the detection target gas, While being able to make it easier to flow in, a housing | casing part (apparatus) can be reduced in size by the part in which the reflection part is not provided in the inflow direction of gas.

  In the optical gas sensor according to the first aspect described above, preferably, the casing includes a cylindrical side wall and a gas inflow part that is provided at one end of the side wall and allows a gas to be detected to flow in. The light source, the second light source, and the light receiving part are disposed on the inner surface of the side wall part. If comprised in this way, a 1st light source and a 2nd light source can be easily arrange | positioned by the cylindrical side wall part in the position where infrared light is received by the light-receiving part.

  In the optical gas sensor according to the first aspect, preferably, the reflecting portion, the first light source, the second light source, and the light receiving portion are arranged at substantially the same height. If comprised in this way, a housing | casing part (apparatus) can be reduced in size in a height direction.

  In the optical gas sensor according to the first aspect, preferably, the reflection unit is configured to guide the infrared light emitted from the second light source to the light receiving unit by reflecting the infrared light, and the first light source. The infrared light from the second light source and the infrared light from the second light source are provided so as to reflect each other a different number of times. If comprised in this way, since the infrared light radiate | emitted from the 2nd light source can be reflected by a reflection part, the optical path length of the infrared light radiate | emitted from the 2nd light source can be enlarged.

  In the optical gas sensor according to the first aspect, preferably, the reflection unit is configured to guide infrared light emitted from the first light source to the light receiving unit by a spiral optical path. If comprised in this way, infrared light can be delivered to a light-receiving part using the space in a housing | casing part efficiently by a helical optical path. As a result, a larger optical path length of infrared light can be ensured, so that the gas to be detected can be detected with higher accuracy.

  In the optical gas sensor according to the first aspect, preferably, the first light source and the second light source include a light emitting diode, and the light receiving unit includes a photodiode. If comprised in this way, compared with other light sources, such as an incandescent lamp and a fluorescent lamp, the light emitting diode will radiate | emit the infrared light of the comparatively narrow bandwidth centering on a 1st wavelength (peak). Energy efficiency can be improved. In addition, infrared light from the first light source and the second light source can be reliably received by the photodiode. In addition, compared with other light sources such as incandescent bulbs and photodetection elements that require about 0.2 seconds from the current flowing to the element until normal lighting, the response time is extremely short (about 50 to several hundred nsec). By using a diode and a photodiode, energy consumption at the time of rising can be reduced, and power consumption can be reduced because pulse driving can be performed at high speed.

  A gas detector according to a second aspect of the present invention includes the optical gas sensor according to the first aspect and a power source for supplying electric power to the optical gas sensor.

  In the gas detector according to the second aspect, the optical gas sensor according to the first aspect and a power source for supplying electric power to the optical gas sensor are provided. Thereby, compared with the structure which arrange | positions two light sources and two light-receiving parts in the conventional gas cell (casing part), since the number of the light-receiving parts in a housing | casing part can be reduced by one, apparatus structure Can be simplified and the apparatus can be miniaturized. In addition, the number of light receiving parts can be reduced by one, and the infrared light emitted from the first light source can be reflected by the reflecting part in the housing part, so that a wider space is secured in the housing part. Thus, a larger optical path length can be secured. As a result, the detection target gas can be detected with higher accuracy. As described above, the apparatus can be miniaturized while ensuring a sufficiently long optical path length to detect the detection target gas.

  According to the present invention, as described above, in the optical gas sensor in which a plurality of light sources are arranged in the housing unit while ensuring a long optical path length that allows detection of the gas to be detected, the apparatus can be miniaturized. Can do.

It is the block diagram which showed the whole structure of the gas detector by 1st Embodiment of this invention. 1 is a block diagram illustrating an overall configuration of an optical gas sensor according to a first embodiment of the present invention. It is the perspective view which showed the optical gas sensor by 1st Embodiment of this invention, and compatibility. It is the side view which showed the optical gas sensor by 1st Embodiment of this invention, and compatibility. It is typical sectional drawing which showed the inside of the housing | casing part of the optical gas sensor by 1st Embodiment of this invention. It is a perspective view for demonstrating reflection of the infrared light from the 1st light source for a detection by 1st Embodiment of this invention. It is a perspective view for demonstrating reflection of the infrared light from the 2nd light source for reference by 1st Embodiment of this invention. It is a perspective view for demonstrating reflection of the infrared light from the 1st light source for a detection by the 2nd Embodiment of this invention, and the 2nd light source for a reference. It is typical sectional drawing which showed the inside of the housing | casing part of the optical gas sensor by 3rd Embodiment of this invention. It is a perspective view for demonstrating reflection of the infrared light from the 1st light source for a detection by the 3rd Embodiment of this invention, and the 2nd light source for a reference.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

[First Embodiment]
With reference to FIGS. 1-7, the structure of the gas detector 100 by 1st Embodiment of this invention is demonstrated.

  The gas detector 100 according to the first embodiment shown in FIG. 1 is configured to detect a gas to be detected and notify the presence of the gas to be detected. For example, the gas detector 100 is configured to notify that the detection target gas has been detected when the detection concentration of the detection target gas is higher than a predetermined concentration. In addition, the gas detector 100 may include a detector that notifies (displays) the concentration value of the detection target gas (in addition to the notification (display), it may be a detector that warns at a predetermined concentration).

(Schematic configuration of gas detector)
The gas detector 100 includes an optical gas sensor 1, a notification unit 2, and a battery 3. The battery 3 is an example of the “power source” in the claims.

  The optical gas sensor 1 is a non-dispersive infrared absorption (NDIR) type sensor. A non-dispersive infrared absorption sensor is a property in which gas molecules absorb infrared light in a spectral region where the wavelength of infrared light passing through the gas matches the level of internal energy of gas molecules (specific to gases). This is a sensor that detects a specific gas by utilizing the property that infrared rays of a wavelength are attenuated at a rate corresponding to the gas concentration. A non-dispersive infrared absorption sensor can easily detect a detection target gas without separating it from other gases.

  The notification unit 2 is configured to perform a predetermined notification to the user when the detection target gas is detected by the optical gas sensor 1. For example, the notification unit 2 may include a light emitting unit (not shown), and may be configured to cause the light emitting unit to emit light when a gas to be detected is detected by the optical gas sensor 1. In addition, the notification unit 2 may be configured to emit a sound when gas is detected. The notification unit 2 may simply notify the user of gas detection or may warn the user that gas has been detected. Further, the notification unit 2 may be configured to notify the user when a gas exceeding a predetermined concentration value is detected, for example, by outputting it as a sound (displaying as an image). Further, the notification unit 2 may be configured to notify the user by outputting the density value as sound (displaying as an image) or the like without exceeding a predetermined density value.

  The battery 3 is a supply source of electric power supplied to each part of the gas detector 100 such as the optical gas sensor 1 and the notification unit 2. Since the gas detector 100 is battery-driven, it can be configured compactly and can be easily carried.

(Configuration of optical gas sensor)
Next, a detailed configuration of the optical gas sensor 1 will be described with reference to FIGS.

  As shown in FIG. 2, the optical gas sensor 1 includes a housing unit 10, an LED (light emitting diode) 11 a, an LED 11 b, a photodiode 12, reflection units 13 a to 13 e (see FIG. 6), temperature and humidity. A sensor 14, an atmospheric pressure sensor 15, a light source substrate 16 a (see FIG. 6), a light receiving unit substrate 16 b (see FIG. 6), a sensor substrate 16 c (see FIG. 6), and a microcomputer 17 are provided. The LED 11a is an example of the “first light source” in the claims. The LED 11b is an example of the “second light source” in the claims. The photodiode 12 is an example of the “light receiving unit” in the claims.

  The optical gas sensor 1 has so-called two light sources 1 having two infrared light sources (LEDs 11a and 11b) and one light receiving unit (photodiode 12) that receives each infrared light emitted from the two infrared light sources. This is a light receiving unit type sensor. One photodiode 12 is provided.

  As shown in FIGS. 3 and 4, the optical gas sensor 1 is provided with a compatible 1 a for attaching the optical gas sensor 1 to the gas detector 100 (see FIG. 1). The compatible 1a is formed in a cylindrical shape with one end opened. The compatible 1a is configured such that the optical gas sensor 1 can be attached to the inner side by accommodating the optical gas sensor 1 on the inner side from the opened one end.

  The compatible 1a has terminals 1b and 1c. The terminal 1c is provided outside the compatible 1a, and is configured to be electrically connected to the main body of the optical gas sensor 1 while being attached to the main body (not shown) of the optical gas sensor 1. Has been. Further, the terminal 1c is a versatile terminal. The terminal 1b is provided inside the compatible 1a. The terminal 1b is configured to be electrically connected to the optical gas sensor 1 in a state where the optical gas sensor 1 is attached (a state where a terminal 102a of the optical gas sensor 1 described later is in contact with the terminal 1b). . The compatible 1a includes a converter (not shown).

  The casing 10 includes a side wall 101, one wall 102, and the other wall 103. Hereinafter, the direction in which the one wall portion 102, the side wall portion 101, and the other wall portion 103 are arranged (the direction in which the side wall portion 101 extends) will be described as the A direction. Further, a direction orthogonal to the A direction will be described as a B direction (in FIG. 3 to FIG. 10, one of the B directions is shown as a representative). The other wall portion 103 is an example of the “gas inflow portion” in the claims.

  As shown in FIG. 3, the side wall 101 is formed in a cylindrical shape. On the other hand, the wall portion 102 is formed in a disc shape, and is provided at an end portion on one side (A2 direction side) of the side wall portion 101. Moreover, the one wall part 102 has the terminal 102a electrically connected to the terminal 1c of the compatible 1a on the outer surface of the A2 direction side. The other wall portion 103 is formed in a disc shape, and is provided at an end portion on the other side (A1 direction side) of the side wall portion 101. The other wall 103 has a plurality (three) of through holes 103a penetrating the other wall 103 in the A direction. The optical gas sensor 1 is configured to allow a gas to be detected to flow into the housing portion 10 through the through hole 103a. The through hole 103a is formed in an elongated oval shape. Further, the plurality of through holes 103a are arranged in parallel to each other. The plurality of through holes 103 a are provided over the entire other wall portion 103.

  As shown in FIGS. 5 to 7, LEDs 11 a and 11 b, a photodiode 12, and reflecting portions 13 a to 13 e are arranged on the inner surface side of the housing unit 10. Further, the LEDs 11 a and 11 b and the photodiode 12 are arranged on the inner surface 101 a of the side wall portion 101.

  The casing 10 is integrally formed with the reflecting portions 13a to 13e using a material such as aluminum or resin. In detail, the housing | casing part 10 is shape | molded integrally with the reflection parts 13a-13e with the metal mold | die using materials, such as aluminum and resin, and is formed by plating gold | metal | money etc. on the surface. .

  The LED 11a includes an LED chip 110a and a reflector 110b attached to the LED chip 110a. The LED chip 110a is installed on a flat plate-like light source substrate 16a extending in the A direction. The LED chip 110a is disposed on the inner side (center O (see FIG. 5) side) of the housing 10 than the light source substrate 16a. The LED chip 110a is generally arranged so as to emit infrared light toward the center of the housing 10 in a plan view (viewed from the direction A). The reflector 110b has a function of narrowing infrared light emitted from the LED chip 110a and spreading toward the center of the housing 10 to a predetermined angle range. The reflector 110b is fixedly attached to the LED chip 110a with an adhesive or the like.

  The LED 11a is a light source for detection for detecting a gas to be detected. That is, the LED 11a is a light source that emits infrared light having a first wavelength that is easily absorbed by the gas to be detected. Specifically, the LED 11a is a light source that emits infrared light having a relatively narrow bandwidth centered at the first wavelength that is easily absorbed by the detection target gas. For example, when the gas to be detected is methane gas, the first wavelength is generally set to 3.3 μm.

  As for the optical path length of the infrared light emitted from the LED 11a, the amount absorbed by the gas to be detected increases or decreases according to the size of the optical path length. Specifically, as the optical path length of infrared light increases, the amount absorbed by the detection target gas increases, and as the optical path length of infrared light decreases, the amount absorbed by the detection target gas decreases. For this reason, the optical gas sensor 1 can detect the gas to be detected more accurately as the optical path length of the infrared light emitted from the LED 11a becomes longer. Therefore, the optical gas sensor 1 according to the first embodiment includes a plurality of reflecting portions 13a to 13d in order to secure the size of the optical path length of infrared light in a limited space (the space in the housing portion 10). The infrared light emitted from the LED 11a is reflected.

  The LED 11b includes an LED chip 111a and a reflector 111b attached to the LED chip 111a. The LED chip 111a is installed on the light source substrate 16a. The LED chip 111a is disposed on the inner side (center side) of the housing unit 10 than the light source substrate 16a. The LED chip 111a is arranged on the A2 direction side of the LED chip 110a so as to be aligned with the LED chip 110a in the A direction. The LED chip 111a is generally arranged so as to emit infrared light toward the center of the housing 10 in a plan view (viewed from the direction A).

  The reflector 111b has a function of narrowing infrared light emitted from the LED chip 111a and spreading toward the center of the housing 10 to a predetermined angle range. The reflector 111b is fixedly attached to the LED chip 111a with an adhesive or the like.

  The LED 11b is not a light source for detection for detecting a gas to be detected, but a light source for reference. That is, the LED 11b is a light source that emits infrared light having a second wavelength different from the first wavelength that is easily absorbed by the gas to be detected. Specifically, the LED 11b is a light source that emits infrared light having a relatively narrow bandwidth centered on the second wavelength. For example, when the detection target gas is methane gas, the second wavelength is set to 3.9 μm, which is different from the first wavelength of 3.3 μm.

  The light source for reference is used to detect dirt inside the housing unit 10. Here, in a normal use mode, the optical gas sensor 1 includes the inside of the housing portion 10 (the surface of the housing portion 10, the reflecting portions 13 a to 13 e, the photodiode 12, and the LEDs 11 a and 11 b) by use over time. ), Dirt such as dust adheres, and the detection intensity of the photodiode 12 gradually decreases. In this case, if the optical gas sensor 1 has only one light source that emits infrared light (only the light source for detection), is the decrease in the detection intensity caused by dirt inside the housing portion 10? It becomes impossible to determine whether the detection target gas is absorbed. Therefore, the optical gas sensor 1 includes a reference light source that does not absorb the gas to be detected in addition to the light source for detection so that the dirt inside the housing unit 10 can be determined. It is configured.

  Specifically, when the optical gas sensor 1 is used over time, the detection intensity of the infrared light from the light source for detection and the infrared light from the reference light source by the photodiode 12 are both reduced. It can be determined that the inside of the casing 10 is dirty. As a result, it is possible to determine the maintenance timing of the optical gas sensor 1 using the reference light source. Further, when the optical gas sensor 1 is used over time, when the detection intensity of the infrared light from the reference light source by the photodiode 12 does not decrease (is small), the inside of the housing portion 10 is substantially dirty. It can be judged that there is not.

  Note that the reference light source (LED 11b) directly confirms contamination in the reflecting portions 13e and 13b that directly reflect the infrared light from the LED 11b, but the reflecting portions 13e and 13b are reflected by the reference light source. When it can be determined that it is dirty, it can be determined that dirt such as dust is also attached to the other components (the reflecting portions 13a, 13c, 13d, etc.) in the housing unit 10.

  Further, the reference light source (LED 11b) is also used to suppress detection value drift (variation) by the photodiode 12 of the detection light source (LED 11a).

  One photodiode 12 is provided. The photodiode 12 is installed on a flat plate-shaped light receiving unit substrate 16b extending in the A direction. The photodiode 12 is disposed so as to face the center side of the casing unit 10 so that infrared light from the center O (see FIG. 5) side of the casing unit 10 can be received.

  The photodiode 12 is disposed at a position substantially corresponding to the LED 11b in the A direction. The photodiode 12 is generally disposed at a position facing the LED 11b in the B direction orthogonal to the A direction. Further, the photodiode 12 is arranged on the A2 direction side with respect to the LED 11a in the A direction.

  The photodiode 12 is irradiated with infrared light from the LEDs 11a and 11b. Specifically, the infrared light from the LEDs 11a and 11b is alternately and repeatedly irradiated onto the photodiode 12 at different timings.

  The reflection units 13a to 13d are configured to guide the light to the photodiode 12 by reflecting the infrared light emitted from the LED 11a that is a light source for detection. In detail, the reflection part 13a is comprised so that the infrared light which passes along the optical path L1 radiate | emitted from LED11a may be reflected. The reflecting portion 13b is configured to reflect infrared light passing through the optical path L2 reflected by the reflecting portion 13a. The reflecting portion 13c is configured to reflect infrared light passing through the optical path L3 reflected by the reflecting portion 13b. The reflecting portion 13d is configured to guide the light to the photodiode 12 through the optical path L5 by reflecting the infrared light passing through the optical path L4 reflected by the reflecting portion 13c. Therefore, the infrared light emitted from the LED 11a is reflected four times by the reflecting portions 13a to 13d and then guided to the photodiode 12.

  The optical paths L1 to L5 are shown as straight lines in FIGS. 5 and 6, but this indicates the center position in the emission direction (traveling direction) of the infrared light, indicating the shape of the infrared light. It is not. The same applies to the other optical path diagrams.

  The reflection part 13b is arrange | positioned so that infrared light may be reflected in the A2 direction side rather than the reflection part 13a. Moreover, the reflection part 13c is arrange | positioned so that infrared light may be reflected in the A2 direction side rather than the reflection part 13b. Further, the reflecting portion 13d is arranged so as to reflect infrared light on the A2 direction side with respect to the reflecting portion 13c. That is, the infrared light emitted from the LED 11a is reflected by the reflecting portions 13a to 13d so as to travel in the A2 direction.

  The reflection parts 13e and 13b are configured to guide the light to the photodiode 12 by reflecting infrared light emitted from the LED 11b which is a light source for reference. Specifically, the reflecting portion 13e is configured to reflect infrared light passing through the optical path L1a emitted from the LED 11b. The reflecting portion 13b is configured to guide the light to the photodiode 12 through the optical path L3a by reflecting the infrared light passing through the optical path L2a reflected by the reflecting portion 13e. Therefore, the infrared light emitted from the LED 11b is reflected twice by the reflecting portions 13e and 13b and then guided to the photodiode 12. As a result, the reflecting portions 13a to 13e are provided so as to reflect the infrared light from the LED 11a and the infrared light from the LED 11b a different number of times.

  The LED 11b, the reflectors 13e and 13b, and the photodiode 12 are arranged at substantially the same height in the A direction so that the optical paths L1a, L2a, and L3a are substantially at the same position.

  Each of the reflecting portions 13a, 13c, and 13e has a spherical reflecting surface that is recessed from the inside to the outside of the housing portion 10 (a shape obtained by cutting a part of a spherical surface). The reflecting portions 13a, 13c, and 13e have a function of narrowing infrared light in the optical path direction after reflection by a spherical reflecting surface.

  Each of the reflecting portions 13b and 13d has a flat reflecting surface. The reflecting portions 13a to 13e are configured to guide the infrared light emitted from the LED 11a (11b) to the photodiode 12 by alternately reflecting the spherical light by the spherical reflecting surface and the flat reflecting surface. ing.

  The reflection units 13a to 13d reflect more infrared light emitted from the LED 11a on the side (B direction) intersecting the gas inflow direction than the gas inflow direction (A direction) of the detection target. It is configured. Specifically, the reflecting portions 13 a to 13 d are not provided on the one wall portion 102 on the A2 direction side and the other wall portion 103 on the A1 direction side of the housing portion 10, and B on the housing portion 10. It is provided only on the direction side, and is configured to reflect infrared light emitted from the LED 11a only on the side (B direction) intersecting the inflow direction (A direction) of the detection target gas.

  The temperature / humidity sensor 14 and the atmospheric pressure sensor 15 are disposed inside the housing unit 10. The temperature / humidity sensor 14 and the atmospheric pressure sensor 15 are installed on a sensor substrate 16c extending in the B direction. The sensor substrate 16c is a substrate that connects the light source substrate 16a and the light receiving unit substrate 16b, both extending in the A direction.

  The temperature / humidity sensor 14 is a sensor capable of measuring the temperature and humidity of the gas in the housing unit 10. The atmospheric pressure sensor 15 is a sensor that can measure the atmospheric pressure of the gas in the housing unit 10. Here, the detection intensity of the infrared light by the photodiode 12 varies according to the temperature, humidity, and atmospheric pressure of the space where the gas is placed (the space in the housing unit 10). For this reason, an error occurs in the detection intensity of the photodiode 12 for detecting the detection target gas. Therefore, the optical gas sensor 1 is configured to correct an error in the detection intensity of the photodiode 12 based on the measured values by the temperature / humidity sensor 14 and the atmospheric pressure sensor 15 under the control of the microcomputer 17.

  The microcomputer 17 is configured to control driving of each part of the optical gas sensor 1. As a specific example, the microcomputer 17 is configured to continuously turn on the LEDs 11a and the LEDs 11b alternately for 200 μsec. At this time, the microcomputer 17 is configured so that the LED 11a and the LED 11b are lit once every 0.5 seconds. In addition, the microcomputer 17 generally turns off the power of the analog circuit in the optical gas sensor 1 and puts the microcomputer 17 in the sleep mode at the timing when the LED 11a and the LED 11b are turned off (during the non-detection operation). It is configured to realize low power consumption.

[Effect of the first embodiment]
In the first embodiment, the following effects can be obtained.

  In the first embodiment, as described above, the LED 11a, the LED 11b, the photodiode 12, and the reflecting portions 13a to 13d that guide the photodiode 12 by reflecting the infrared light emitted from the LED 11a have the inner surface 101a. The housing part 10 arranged on the side is provided. Thereby, compared with the structure which arrange | positions two light sources and two photodiodes 12 in the conventional gas cell (housing | casing part), the number of the photodiodes 12 in the housing | casing part 10 can be reduced by one. Therefore, the apparatus configuration can be simplified and the apparatus can be miniaturized. In addition, the number of photodiodes 12 can be reduced by one, and the infrared light emitted from the LED 11a can be reflected by the reflecting portions 13a to 13d in the housing portion 10, so that the inside of the housing portion 10 can be reflected. Therefore, a larger space can be secured and a larger optical path length can be secured. As a result, the detection target gas can be detected with higher accuracy. As described above, the apparatus can be miniaturized while ensuring a sufficiently long optical path length to detect the detection target gas.

  In the first embodiment, as described above, the LED 11a is a light source for detection for detecting the gas to be detected, and the LED 11b is a light source for reference. Thus, by providing a reference LED 11b having a wavelength different from that of the detection LED 11a, it is possible to discriminate between a decrease in detection intensity due to dirt inside the casing 10 and a decrease in detection intensity due to absorption of gas to be detected. can do. Specifically, when both the detection intensity of the infrared light from the detection LED 11a and the infrared light from the reference LED 11b by the photodiode 12 are reduced, it is determined that the inside of the housing portion 10 is dirty. be able to. Further, when the detection intensity of the infrared light from the reference LED 11b by the photodiode 12 does not decrease (is small), it can be determined that the inside of the housing 10 is not substantially dirty. As a result, the maintenance timing of the optical gas sensor 1 can be appropriately determined.

  In the first embodiment, as described above, a plurality of reflecting portions 13a to 13d are provided, and the infrared light emitted from the LED 11a is reflected by the plurality of reflecting portions 13a to 13d, so that the photodiode 12 is reflected. Light guide. Thereby, since the infrared light emitted from the LED 11a can be multiple-reflected by the plurality of reflecting portions 13a to 13d on the inner surface side of the housing portion 10, it is possible to ensure a larger optical path length of the infrared light. Can do. As a result, the detection target gas can be detected with higher accuracy.

  In the first embodiment, as described above, the reflecting portions 13a to 13d reflect a large amount of infrared light emitted from the LED 11a on the side intersecting the inflow direction rather than the inflow direction of the detection target gas. To be configured. Thereby, compared with the case where more infrared light emitted from the LED 11a is reflected on the side where the detection target gas flows in than the side intersecting the inflow direction of the detection target gas, the detection target gas is reduced. Since the ratio of the reflecting portions 13a to 13d on the inflow side can be reduced, the ratio of the region into which the detection target gas flows is increased, and the detection target gas flows more effectively into the housing. Can be made.

  Moreover, in 1st this embodiment, as above-mentioned, reflection part 13a-13d is comprised so that the infrared light radiate | emitted from LED11a may be reflected only in the side which cross | intersects an inflow direction. As a result, the reflecting portions 13a to 13d can be provided only on the side intersecting the inflow direction of the detection target gas without providing the reflection portions 13a to 13d in the inflow direction of the detection target gas. The gas can be made to flow more easily, and the casing 10 (device) can be reduced in size because the reflecting portions 13a to 13d are not provided in the gas inflow direction.

  In the first embodiment, as described above, the casing 10 includes the cylindrical side wall 101 and the other wall 103 that is disposed at one end of the side wall 101 and into which the detection target gas flows. The LED 11 a, the LED 11 b, and the photodiode 12 are disposed on the inner surface 101 a of the side wall portion 101. Thereby, the LED 11 a and the LED 11 b can be easily arranged at a position where the infrared light is received by the photodiode 12 by the cylindrical side wall portion 101.

  In the first embodiment, as described above, the reflecting portion 13e is also configured to be guided to the photodiode 12 by reflecting the infrared light emitted from the LED 11b, and the infrared light from the LED 11a. The optical gas sensor 1 is configured to reflect infrared light from the LED 11b a different number of times. Thereby, since the infrared light radiate | emitted from LED11b can be reflected by the reflection part 13e, the optical path length of the infrared light radiate | emitted from LED11b can be enlarged.

  In the first embodiment, as described above, the LED 11a and the LED 11b are used as the light source, and the photodiode 12 is used as the light receiving unit. Thereby, by the light emitting diode (LED), compared with other light sources such as an incandescent bulb and a fluorescent lamp, infrared light having a relatively narrow bandwidth centered (peak) at the first wavelength and the second wavelength. Can be emitted, so that energy efficiency can be improved. Moreover, the infrared light from LED11a and LED11b can be reliably received with a photodiode. In addition, the LED 11a, which has a very short response time (50 to several hundreds of nanoseconds) compared to other light sources such as an incandescent light bulb and a light detection element that require about 0.2 seconds from when an electric current flows to the element until normal lighting. By using 11b and the photodiode 12, energy consumption at the time of rising can be reduced, and power consumption can be reduced because pulse driving can be performed at high speed.

[Second Embodiment]
Next, the configuration of the gas detector 200 including the optical gas sensor 201 according to the second embodiment will be described with reference to FIGS. 1, 2, and 8. The optical gas sensor 201 according to the second embodiment includes the optical gas sensor 1 according to the first embodiment in which the reflecting portions 13a to 13e, the LEDs 11a and 11b, and the photodiode 12 are arranged at different height positions (positions in the A direction). Unlike the above, the reflecting portions 213a to 213d, the LEDs 11a and 11b, and the photodiode 12 are arranged at the same height position. In addition, about the structure same as the said 1st Embodiment, the same code | symbol is attached | subjected and shown in the figure, and the description is abbreviate | omitted.

(Configuration of optical gas sensor)
A gas detector 200 according to the second embodiment of the present invention includes an optical gas sensor 201 as shown in FIG. As shown in FIG. 8, the optical gas sensor 201 includes reflecting portions 213a to 213d.

  Each reflection part 213a-213d, LED11a, 11b, and the photodiode 12 are arrange | positioned in the same height position in A direction, as shown in FIG.

  On the inner surface 101a side of the housing portion 10, the LED 11a and the photodiode 12 are arranged adjacent to each other. Further, on the inner surface 101a side of the housing part 10, a reflecting part 213b and a reflecting part 213d are arranged between the LED 11a and the LED 11b. Further, on the inner surface 101a side of the housing part 10, a reflecting part 213c and a reflecting part 213a are arranged between the photodiode 12 and the LED 11b. The reflecting portions 213a to 213d, the LEDs 11a and 11b, and the photodiodes 12 are generally equally arranged in the circumferential direction of the housing portion 10 in a plan view (as viewed from the direction A).

  The reflecting portions 213a to 213d are configured to guide the light to the photodiode 12 by reflecting infrared light emitted from the LED 11a that is a light source for detection. Specifically, the reflection unit 213a is configured to reflect infrared light that passes through the optical path L1c emitted from the LED 11a. Moreover, the reflection part 213b is comprised so that the infrared light which passes along the optical path L2c reflected by the reflection part 213a may be reflected. Moreover, the reflection part 213c is comprised so that the infrared light which passes along the optical path L3c reflected by the reflection part 213b may be reflected. Further, the reflecting portion 213d is configured to be guided to the photodiode 12 through the optical path L5c by reflecting infrared light passing through the optical path L4c reflected by the reflecting portion 213c. Therefore, the infrared light emitted from the LED 11a is reflected four times by the reflecting portions 213a to 213d and then guided to the photodiode 12.

  The reflecting portions 213c and 213d are configured to guide the light to the photodiode 12 by reflecting infrared light emitted from the LED 11b which is a reference light source. Specifically, the reflection unit 213c is configured to reflect infrared light passing through the optical path L1d emitted from the LED 11b. In addition, the reflecting portion 213d is configured to be guided to the photodiode 12 through the optical path L3d by reflecting the infrared light passing through the optical path L2d reflected by the reflecting portion 213c. Therefore, the infrared light emitted from the LED 11b is reflected twice by the reflecting portions 213c and 213d and then guided to the photodiode 12.

  Here, as described above, the reflecting portions 213a to 213d, the LEDs 11a and 11b, and the photodiode 12 are arranged at the same height position in the A direction, so that the optical paths L1c to L4c, L1d, and L2d are also in the A direction. They are arranged at approximately the same height.

  Each of the reflecting portions 213a to 213d has a spherical reflecting surface that is recessed from the inside to the outside of the housing portion 10 (a shape obtained by cutting off the end of the spherical surface). The reflecting portions 213a to 213d have a function of narrowing infrared light in the optical path direction after reflection by a spherical reflecting surface.

  The photodiode 12 is provided with a condenser lens 12a that condenses the received infrared light. The condensing lens 12 a has a hemispherical shape that protrudes to the inside of the housing unit 10.

[Effects of Second Embodiment]
In the second embodiment, the following effects can be obtained.

  In the second embodiment, as in the first embodiment, the LED 11a, the LED 11b, the photodiode 12, and the reflection portions 213a to 213a that guide the infrared light emitted from the LED 11a to the photodiode 12 are reflected. 213d is provided with the housing | casing part 10 arrange | positioned at the inner surface 101a side. Thereby, the device configuration can be simplified and the device can be miniaturized.

  In the second embodiment, as described above, the reflectors 213a to 213d, the LED 11a, the LED 11b, and the photodiode 12 are arranged at substantially the same height. Thereby, the housing | casing part 10 (apparatus) can be reduced in size in a height direction.

  Other effects of the second embodiment are the same as those of the first embodiment.

[Third embodiment]
Next, the configuration of the gas detector 300 including the optical gas sensor 301 of the third embodiment will be described with reference to FIGS. 1, 2, 9, and 10. Unlike the optical gas sensor 1 according to the first embodiment, the optical gas sensor 301 according to the third embodiment is different from the optical gas sensor 1 according to the first embodiment in which the reflective portions 13 a to 13 e are arranged only on the inner surface 101 a of the side wall portion 101 of the housing unit 10. Are arranged on the inner surface 101 a of the side wall portion 101 of the housing portion 10, the inner surface of the one wall portion 102, and the inner surface of the other wall portion 103. In addition, about the structure same as the said 1st Embodiment, the same code | symbol is attached | subjected and shown in the figure, and the description is abbreviate | omitted.

(Configuration of optical gas sensor)
A gas detector 300 according to the third embodiment of the present invention includes an optical gas sensor 301 as shown in FIG. As shown in FIG. 9, the optical gas sensor 301 includes reflecting portions 313a to 313i.

  On the inner surface 101a side of the housing portion 10, the LEDs 11a and 11b and the photodiode 12 are arranged on the same plane on the one wall portion 102 (A2 direction) side. The reflecting portions 313a, 313h, and 313i are all disposed on the inner surface of the other wall portion 103. The reflection portion 313b is disposed on the inner surface of the one wall portion 102. Further, the reflecting portions 313 c to 313 g (other reflecting portions) are disposed on the inner surface 101 a of the side wall portion 101.

  The reflecting portions 313a to 313h are configured to guide the light to the photodiode 12 by reflecting the infrared light emitted from the LED 11a. Specifically, the reflecting portion 313a is configured to reflect infrared light passing through the optical path L1e emitted from the LED 11a. Moreover, the reflection part 313b is comprised so that the infrared light which passes along the optical path L2e reflected by the reflection part 313a may be reflected. Moreover, the reflection part 313c is comprised so that the infrared light which passes along the optical path L3e reflected by the reflection part 313b may be reflected. Further, the reflecting portion 313d is configured to reflect infrared light passing through the optical path L4e reflected by the reflecting portion 313c. Further, the reflecting portion 313e is configured to reflect infrared light passing through the optical path L5e reflected by the reflecting portion 313d. The reflecting portion 313f is configured to reflect infrared light that passes through the optical path L6e reflected by the reflecting portion 313e. The reflecting portion 313g is configured to reflect infrared light that passes through the optical path L7e reflected by the reflecting portion 313f. In addition, the reflecting portion 313h is configured to be guided to the photodiode 12 through the optical path L9e by reflecting the infrared light passing through the optical path L8e reflected by the reflecting portion 313g. Therefore, the infrared light emitted from the LED 11a is reflected eight times by the reflecting portions 213a to 213d and then guided to the photodiode 12.

  The reflecting portions 313a to 313h are configured to guide the infrared light emitted from the LED 11a to the photodiode 12 so as to rotate in the clockwise direction when viewed from the A1 direction. Here, the reflecting portions 313a and 313b are configured to move the infrared light passing through the optical paths L2e and L3e (see FIG. 10) in the A2 direction. The reflecting portions 313c to 313f are configured to move the infrared light passing through the optical paths L3e to L7e (see FIG. 10) in the A1 direction. The reflection units 313g and 313h are configured to move the infrared light passing through the optical paths L8e and L9e (see FIG. 10) in the A2 direction.

  Further, in the third embodiment, in the A direction, infrared light that is emitted from the LED 11a to the A1 direction side and has not been reflected is once reflected to the A2 direction side (LED 11a side). Thereby, the optical gas sensor 301 can earn the optical path length of infrared light. At the same time, in the A direction, a configuration that reflects infrared light toward the photodiode 12 is arranged at a position facing the photodiode 12 so that the incident angle to the photodiode 12 is zero (the infrared light of the photodiode 12 Since the angle between the light receiving surface and the infrared light can be close to 90 degrees), a wide light receiving surface can be secured with respect to the size of the infrared light (the light receiving area of the photodiode 12). For this reason, infrared light can be easily received by the photodiode 12.

  The reflecting portion 313i is configured to guide the infrared light emitted from the LED 11b to the photodiode 12 by reflecting the infrared light. Specifically, the reflecting portion 313i is configured to guide the light to the photodiode 12 through the optical path L2f by reflecting infrared light passing through the optical path L1f emitted from the LED 11b. Therefore, the infrared light emitted from the LED 11b is reflected once by the reflecting portion 313i and then guided to the photodiode 12.

[Effect of the third embodiment]
In the third embodiment, the following effects can be obtained.

  In the third embodiment, as in the first embodiment, the LED 11a, the LED 11b, the photodiode 12, and the reflecting portions 313a to 315a that guide the infrared light emitted from the LED 11a to the photodiode 12 are reflected. 313h is provided with the housing portion 10 disposed on the inner surface 101a side. Thereby, the device configuration can be simplified and the device can be miniaturized.

  In the third embodiment, as described above, the reflecting portions 313a to 313h are configured to guide the infrared light emitted from the LED 11a to the photodiode 12 through the spiral optical path. Thereby, infrared light can be delivered to the photodiode 12 by efficiently using the space in the housing portion 10 by the spiral optical path. As a result, a larger optical path length of infrared light can be ensured, so that the gas to be detected can be detected with higher accuracy.

  Other effects of the third embodiment are the same as those of the first embodiment.

(Modification)
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of claims for patent, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first to third embodiments, an example in which a plurality of reflecting portions are provided has been described, but the present invention is not limited to this. In the present invention, only one reflecting portion may be provided.

  Moreover, although the example which provided the reflection part fixed to the housing | casing part was shown in the said 1st-3rd embodiment, this invention is not limited to this. In the present invention, for example, the reflection unit may be configured by a MEMS mirror or the like so as to be capable of vibrating with respect to the housing unit.

  Moreover, although the said 1st-3rd embodiment showed the example which comprised the 1st light source and 2nd light source of this invention by LED, this invention is not limited to this. In the present invention, the first light source and the second light source may be constituted by a light source other than an LED such as an incandescent lamp.

  Moreover, although the said 1st-3rd embodiment showed the example which comprised the light-receiving part of this invention with the photodiode, this invention is not limited to this. In the present invention, the light receiving part may be constituted by a light receiving part other than a photodiode such as a thermocouple.

  In the first to third embodiments, the example in which the number of reflections of the infrared light from the first light source and the infrared light from the second light source is different is shown. Not limited to. In this invention, you may comprise so that the frequency | count of reflection of the infrared light from a 1st light source and the infrared light from a 2nd light source may become the same.

  Moreover, although the example which used the power supply of this invention as the battery was shown in the said 1st-3rd embodiment, this invention is not limited to this. In the present invention, for example, the power source of the present invention may be an outlet portion that can be connected to a commercial power source.

  In the first to third embodiments, the example in which the first light source is the gas detection light source and the second light source is the reference light source is shown. However, the present invention is not limited to this. In the present invention, both the first light source and the second light source may be used as light sources for detecting different types of gases.

  Moreover, although the said 1st-3rd embodiment showed the example comprised so that an optical gas sensor and a gas detector (main part of a gas detector) may be electrically connected through compatibility, this invention was shown. Is not limited to this. In this invention, you may comprise so that an optical gas sensor and a gas detector can be directly electrically connected, without passing through compatibility.

  Moreover, although the example which formed the reflection part integrally with the housing | casing part was shown in the said 1st-3rd embodiment, this invention is not limited to this. In the present invention, the reflection portion may be formed separately from the housing portion.

  Moreover, in the said 1st-3rd embodiment, although the example which formed the housing | casing part with the metal mold | die was shown, this invention is not limited to this. In this invention, you may form a housing | casing part by methods other than metal mold | die, such as metal processing.

  The present invention is not limited to the number of infrared light reflections described in the first to third embodiments.

  Moreover, although the said 1st-3rd embodiment showed the example which used the 2nd light source as a light source for a reference, using the light source of the wavelength which does not have gas absorptivity as a 2nd light source of this invention, The invention is not limited to this. In the present invention, a gas light-absorbing wavelength light source may be used as the second light source, and the second light source may be used as both a reference light source and a detection light source.

  In the first to third embodiments, the example in which the first light source is the gas detection light source and the second light source is the reference light source is shown, but the present invention is not limited to this. In the present invention, both the first light source and the second light source may be gas detection light sources. As a specific example, the first light source and the second light source may have different bandwidth wavelengths, and the detection accuracy of one gas may be increased.

  In the first embodiment, an example in which the optical gas sensor includes three substrates for mounting a light source, a light receiving unit, and the like has been described. However, the present invention is not limited to this. In the present invention, the optical gas sensor may include only one substrate for mounting a light source, a light receiving unit, and the like. In this case, the substrate may be a flexible wiring substrate.

  In the first to third embodiments, the example in which the substrate, the reflection unit, the light receiving unit, and the like are arranged inside one housing unit is shown, but the present invention is not limited to this. In the present invention, another casing portion is arranged inside one casing portion, and holes are provided in the inner casing portion for installing a substrate, a reflection portion, a light receiving portion, and the like, respectively. You may install so that a board | substrate, a reflection part, and a light-receiving part may be inserted in this. In this case, the inner casing portion has a cylindrical shape, and may be configured such that the optical axis is adjusted by inserting each component.

  Moreover, in the said 1st-3rd embodiment, although the example provided with a temperature / humidity sensor and an atmospheric | air pressure sensor was shown, this invention is not limited to this. In the present invention, both the temperature / humidity sensor and the atmospheric pressure sensor may not be provided, and only one of them may be provided.

  In the said 1st-3rd embodiment, although the example which combined the spherical reflective surface and the flat reflective surface was shown as a reflection part, this invention is not limited to this. In the present invention, only one of a spherical reflecting surface and a flat reflecting surface may be provided. The shape of the reflecting surface may be any shape, and may be an ellipse or an aspherical surface (a curved surface that is neither a plane nor a sphere).

1, 201, 301 Optical gas sensor 3 Battery (power supply)
10 Housing 11a LED (first light source)
11b LED (second light source)
12 Photodiode (light receiving part)
13a, 13b, 13c, 13d, 13e, 213a, 213b, 213c, 213d, 313a, 313b, 313c, 313d, 313e, 313f, 313g, 313h Reflector 100, 200, 300 Gas detector 101 Side wall 101a Inner surface 103 Other Wall (gas inlet)

Claims (11)

A non-dispersive infrared absorption sensor,
A first light source that emits infrared light of a first wavelength;
A second light source that emits infrared light having a second wavelength different from the first wavelength;
One light receiving unit for receiving infrared light emitted from the first light source and the second light source;
A reflecting part for guiding the light to the light receiving part by reflecting infrared light emitted from the first light source;
An optical gas sensor comprising: the first light source, the second light source, the light receiving unit, and a housing unit on which the reflection unit is disposed on an inner surface side. The first light source is a light source for detection for detecting a gas to be detected,
The optical gas sensor according to claim 1, wherein the second light source is a reference light source. A plurality of the reflection portions are provided,
3. The optical gas sensor according to claim 1, wherein infrared light emitted from the first light source is guided to the light receiving unit by being reflected a plurality of times by the plurality of reflecting units.   The said reflection part is comprised so that more infrared rays radiate | emitted from the said 1st light source may be reflected in the side which cross | intersects the said inflow direction rather than the inflow direction of the gas of detection object. 4. The optical gas sensor according to any one of 3 above.   The optical gas sensor according to claim 4, wherein the reflection unit is configured to reflect infrared light emitted from the first light source only at a side intersecting the inflow direction. The housing portion includes a cylindrical side surface portion and a gas inflow portion that is provided at one end of the side surface portion and allows a gas to be detected to flow in,
The optical gas sensor according to claim 1, wherein the first light source, the second light source, and the light receiving unit are disposed on an inner surface of the side surface part.   The optical gas sensor according to claim 1, wherein the reflection unit, the first light source, the second light source, and the light receiving unit are disposed at substantially the same height position.   The reflection unit is configured to guide the infrared light emitted from the second light source to the light receiving unit by reflecting the infrared light, and the infrared light from the first light source and the second light source. The optical gas sensor according to claim 1, wherein the optical gas sensor is provided so as to reflect infrared light from a light source a different number of times.   The said reflection part is comprised so that the infrared light radiate | emitted from the said 1st light source may be guide | induced to the said light-receiving part by a helical optical path, The any one of Claims 1-8. Optical gas sensor. The first light source and the second light source include a light emitting diode,
The optical gas sensor according to claim 1, wherein the light receiving unit includes a photodiode. The optical gas sensor according to any one of claims 1 to 10,
A gas detector comprising: a power source that supplies electric power to the optical gas sensor.

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