JP6810625B2 - Optical gas sensor and gas detector - Google Patents

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).

The above-mentioned Patent Document 1 describes a non-dispersive infrared absorption method including a gas cell (housing portion), two light sources, two light receiving portions that receive infrared light emitted from the two light sources, and a reflecting portion. Optical gas sensor is disclosed. The reflecting unit is configured to guide 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 arranged in the gas cell.

Japanese Patent No. 6010702

In a non-dispersive infrared absorption type sensor, it is preferable that a relatively large optical path length of infrared light is secured in order to sufficiently absorb infrared light into the gas to be detected to increase the detection sensitivity. Further, in the field of optical gas sensors, miniaturization of the device has been a conventional issue. Regarding this point, in the optical gas sensor in which the two light sources and the two light receiving portions described in Patent Document 1 are arranged in the gas cell, an optical path length large enough to detect the gas to be detected is secured. There is a problem that it is necessary to achieve further miniaturization of the device.

The present invention has been made to solve the above problems, and one object of the present invention is to be able to detect a gas to be detected by an optical gas sensor in which a plurality of light sources are arranged in a housing portion. It is an object of the present invention to provide an optical gas sensor capable of miniaturizing an apparatus while ensuring a sufficiently large optical path length, and a gas detector provided with the optical gas sensor.

The optical gas sensor according to the first aspect of the present invention is a non-dispersive infrared absorption type sensor, and has a first light source that emits infrared light of a first wavelength and a second light source that is different from the first wavelength. A second light source that emits infrared light of the same wavelength, one light receiving unit that receives infrared light emitted from the first light source and the second light source, and an infrared light emitted from the first light source are reflected. As a result, it is provided with a reflecting unit that guides the light receiving portion to the light receiving portion, and a housing portion in which the first light source, the second light source, the light receiving portion, and the reflecting portion are arranged on the inner surface side, and the first light source detects the gas to be detected. It is a light source for detection for detection, the second light source is a light source for reference, and the optical path length of infrared light of the first light source is larger than the optical path length of infrared light of the second light source . Here, the non-dispersive infrared absorption type sensor has a property that gas molecules absorb infrared light in a spectral region in which the wavelength of infrared light passing through the gas matches the level of the internal energy of the gas molecules. It is a sensor that detects a specific gas by utilizing (the property that infrared rays with a wavelength peculiar to gas are attenuated at a rate corresponding to the gas concentration).
The optical gas sensor according to the second aspect of the present invention is a non-dispersive infrared absorption type sensor, and has a first light source that emits infrared light of a first wavelength and a second light source that is different from the first wavelength. A second light source that emits infrared light of the same wavelength, one light receiving unit that receives infrared light emitted from the first light source and the second light source, and an infrared light emitted from the first light source are reflected. As a result, it is provided with a reflecting portion that guides the light receiving portion to the light receiving portion, and a housing portion in which the first light source, the second light source, the light receiving portion, and the reflecting portion are arranged on the inner surface side, and the reflecting portion is emitted from the second light source. It is configured to guide the infrared light to the light receiving part by reflecting the infrared light, so that the infrared light from the first light source and the infrared light from the second light source are reflected different times from each other. It is provided in.
The optical gas sensor according to the third aspect of the present invention is a non-dispersive infrared absorption type sensor, and has a first light source that emits infrared light of a first wavelength and a second light source that is different from the first wavelength. A second light source that emits infrared light of the same wavelength, one light receiving unit that receives infrared light emitted from the first light source and the second light source, and an infrared light emitted from the first light source are reflected. As a result, a reflecting unit that guides light to the light receiving unit and a housing portion in which the first light source, the second light source, the light receiving unit, and the reflecting unit are arranged on the inner surface side are provided, and the reflecting unit is provided with a spiral optical path. It is configured to guide the infrared light emitted from the first light source to the light receiving unit.

In the optical gas sensor according to the first to third aspects of the present invention, as described above, the light is received by reflecting the infrared light emitted from the first light source, the second light source, the light receiving unit, and the first light source. A housing portion in which a reflecting portion for guiding light is arranged on the inner surface side is provided on the portion. As a result, the number of light receiving parts in the housing can be reduced by one as compared with the conventional configuration in which two light sources and two light receiving parts are arranged in the gas cell (housing part). Can be simplified and the device can be miniaturized. In addition, the number of light receiving portions can be reduced by one, and the infrared light emitted from the first light source can be reflected by the reflecting portion in the housing portion, so that a wider space can be secured in the housing portion. Therefore, a larger optical path length can be secured. As a result, the gas to be detected can be detected more accurately. As described above, the device can be miniaturized while ensuring an optical path length large enough to detect the gas to be detected.
Further, in the optical sensor according to the first aspect, the first light source is a detection light source for detecting the gas to be detected, and the second light source is a reference light source. With this configuration, by providing a second light source for reference whose wavelength is different from that of the first light source for detection, the detection intensity is lowered due to dirt inside the housing portion, and the gas to be detected is absorbed. It can be determined that the detection intensity is reduced. Specifically, when the detection intensity of the infrared light from the detection light source and the infrared light from the reference light source are both reduced, it can be determined that the inside of the housing is dirty. it can. Further, if there is no decrease (small) in the detection intensity due to the infrared light receiving portion from the reference light source, it can be determined that the inside of the housing portion is not substantially dirty. As a result, the maintenance time of the optical gas sensor can be appropriately determined.
Further, in the optical sensor according to the second aspect, the reflecting portion is configured to guide the light receiving portion by reflecting infrared light emitted from the second light source, and is configured to guide the light receiving portion from the first light source. The infrared light of the above and the infrared light from the second light source are reflected so as to be reflected different times from each other. With this configuration, the infrared light emitted from the second light source can be reflected by the reflecting unit, so that the optical path length of the infrared light emitted from the second light source can be increased.
Further, in the optical sensor according to the third aspect, the reflecting portion is configured to guide infrared light emitted from the first light source to the receiving portion by a spiral optical path. With this configuration, the spiral optical path makes it possible to efficiently utilize the space inside the housing portion to deliver infrared light to the light receiving portion. As a result, a larger optical path length of infrared light can be secured, so that the gas to be detected can be detected more accurately.

In the optical gas sensor according to the first to third aspects, 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 receive the light receiving portion. Guided to. With this configuration, the infrared light emitted from the first light source can be multiple-reflected by the plurality of reflecting portions on the inner surface side of the housing portion, so that the optical path length of the infrared light can be further secured. can do. As a result, the gas to be detected can be detected more accurately.

In the optical gas sensor according to the first to third aspects, preferably, the reflecting portion emits infrared light emitted from the first light source on the side intersecting the inflow direction of the gas to be detected. It is configured to reflect a lot. With this configuration, compared to the case where more infrared light emitted from the first light source is reflected on the side where the gas to be detected flows in than on the side intersecting the inflow direction of the gas to be detected. Since the ratio of the reflective portion on the side where the gas to be detected flows can be reduced, the ratio of the region where the gas to be detected flows can be increased accordingly to more effectively package the gas to be detected. It can be made to flow into the body.

In this case, preferably, the reflecting portion is configured to reflect the infrared light emitted from the first light source only on the side intersecting the inflow direction. With this configuration, it is possible to provide the reflecting portion only on the side intersecting the inflow direction of the gas to be detected without providing the reflecting portion in the inflow direction of the gas to be detected. In addition to making it easier to flow in, the housing portion (device) can be miniaturized because the reflecting portion is not provided in the inflow direction of the gas.

In the optical gas sensor according to the first to third aspects, the housing portion preferably includes a tubular side wall portion and a gas inflow portion provided at one end of the side wall portion to allow the gas to be detected to flow in. , The first light source, the second light source, and the light receiving portion are arranged on the inner surface of the side wall portion. With this configuration, the tubular side wall portion allows the first light source and the second light source to be easily arranged at positions where infrared light is received by the light receiving portion.

In the optical gas sensor according to the first to third aspects, preferably, the reflecting unit, the first light source, the second light source, and the light receiving unit are arranged at substantially the same height position. With this configuration, the housing portion (device) can be miniaturized in the height direction.

In the optical gas sensor according to the first to third aspects, preferably, the first light source and the second light source include a light emitting diode, and the light receiving unit includes a photodiode. With this configuration, the light emitting diode emits infrared light having a relatively narrow bandwidth centered on the first wavelength (peak) as compared with other light sources such as incandescent lamps and fluorescent lamps. Therefore, energy efficiency can be improved. In addition, the photodiode can reliably receive infrared light from the first light source and the second light source. In addition, the response time is extremely short (about 50 to several hundred nsec) compared to other light sources such as incandescent lamps and light detection elements, which normally take about 0.2 seconds from the flow of current through the element to lighting. By using the diode and the photodiode, the energy consumption at the time of rising can be reduced, and the power consumption can be reduced because the pulse drive can be performed at high speed.

The gas detector according to the fourth aspect of the present invention includes an optical gas sensor according to any one of the first to third aspects , and a power source for supplying electric power to the optical gas sensor.

In the gas detector according to the fourth aspect, an optical gas sensor according to any one of the first to third aspects and a power source for supplying electric power to the optical gas sensor are provided. As a result, the number of light receiving parts in the housing can be reduced by one as compared with the conventional configuration in which two light sources and two light receiving parts are arranged in the gas cell (housing part). Can be simplified and the device can be miniaturized. In addition, the number of light receiving portions can be reduced by one, and the infrared light emitted from the first light source can be reflected by the reflecting portion in the housing portion, so that a wider space can be secured in the housing portion. Therefore, a larger optical path length can be secured. As a result, the gas to be detected can be detected more accurately. As described above, the device can be miniaturized while ensuring an optical path length large enough to detect the gas to be detected.

According to the present invention, as described above, in an optical gas sensor in which a plurality of light sources are arranged in a housing while ensuring a large optical path length so that the gas to be detected can be detected, the device can be miniaturized. Can be done.

It is a block diagram which showed the whole structure of the gas detector by 1st Embodiment of this invention. It is a block diagram which showed the whole structure of the optical gas sensor by 1st Embodiment of this invention. It is a perspective view which showed the optical gas sensor and compatibility by 1st Embodiment of this invention. It is a side view which showed the optical gas sensor and compatibility by 1st Embodiment of this invention. It is a schematic cross-sectional view which showed the inside of the housing part of the optical gas sensor by 1st Embodiment of this invention. It is a perspective view for demonstrating the reflection of infrared light from the 1st light source for detection by 1st Embodiment of this invention. It is a perspective view for demonstrating the reflection of infrared light from the 2nd light source for reference by 1st Embodiment of this invention. It is a perspective view for demonstrating the reflection of infrared light from the 1st light source for detection and the 2nd light source for reference according to 2nd Embodiment of this invention. It is a schematic cross-sectional view which showed the inside of the housing part of the optical gas sensor according to the 3rd Embodiment of this invention. It is a perspective view for demonstrating the reflection of infrared light from the 1st light source for detection and the 2nd light source for reference according to 3rd Embodiment of this invention.

Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[First Embodiment]
The configuration of the gas detector 100 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 7.

The gas detector 100 according to the first embodiment shown in FIG. 1 is configured to detect the 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 gas to be detected (in addition to the notification (display), a detector that warns at a predetermined concentration may be used).

(Outline 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 a "power source" within the scope of the claims.

The optical gas sensor 1 is a non-dispersive infrared absorption (NDIR, non-dispersive infrared) type sensor. A non-dispersive infrared absorption sensor has the property that 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 (specific to gas). It is a sensor that detects a specific gas by utilizing (the property that infrared rays of wavelength are attenuated at a rate corresponding to the gas concentration). The non-dispersive infrared absorption sensor can easily detect the gas to be detected without separating it from other gases.

The notification unit 2 is configured to give a predetermined notification to the user when the gas to be detected is detected by the optical gas sensor 1. For example, the notification unit 2 may have a light emitting unit (not shown) and may be configured to emit light when the gas to be detected is detected by the optical gas sensor 1. In addition, the notification unit 2 may be configured to emit a voice when gas is detected. The notification unit 2 may simply notify the user of the detection of gas, or may warn the user that the 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 by outputting (displaying as an image) as a voice to that effect. Further, the notification unit 2 may be configured to notify the user by outputting (displaying as an image) the density value as voice even if the density value does not exceed a predetermined density value.

The battery 3 is a power supply source of electric power supplied to each part of the gas detector 100 such as the optical gas sensor 1 and the notification part 2. Since the gas detector 100 is battery-powered, 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. 2 to 7.

As shown in FIG. 2, the optical gas sensor 1 includes a housing portion 10, an LED (light emitting diode) 11a, an LED 11b, a photodiode 12, a reflecting portion 13a to 13e (see FIG. 6), and temperature and humidity. It includes a sensor 14, a pressure sensor 15, a light source substrate 16a (see FIG. 6), a light receiving portion substrate 16b (see FIG. 6), a sensor substrate 16c (see FIG. 6), and a microcomputer 17. The LED 11a is an example of the "first light source" in the claims. Further, the LED 11b is an example of the "second light source" in the claims. Further, the photodiode 12 is an example of the "light receiving portion" in the claims.

The optical gas sensor 1 is a so-called two light source 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. It is a light source type sensor. One photodiode 12 is provided.

As shown in FIGS. 3 and 4, the optical gas sensor 1 is provided with a compatible 1a 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 open. The compatible 1a is configured so that the optical gas sensor 1 can be mounted inside by accommodating the optical gas sensor 1 inside from one open end.

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

The housing portion 10 includes a side wall portion 101, one wall portion 102, and the other wall portion 103. Hereinafter, the direction in which the one wall portion 102, the side wall portion 101, and the other wall portion 103 are lined up (the direction in which the side wall portion 101 extends) will be described as the A direction. Further, the direction orthogonal to the A direction will be described as the B direction (in FIGS. 3 to 10, one of the B directions is represented as a representative). The other wall portion 103 is an example of a "gas inflow portion" within the scope of the claims.

As shown in FIG. 3, the side wall portion 101 is formed in a cylindrical shape. On the other hand, the wall portion 102 is formed in a disk shape, and is provided at one end (A2 direction side) of the side wall portion 101. On the other hand, the wall portion 102 has a terminal 102a electrically connected to the terminal 1c of the compatible 1a on the outer surface on the A2 direction side. The other wall portion 103 is formed in a disk shape, and is provided at an end portion on the other side (A1 direction side) of the side wall portion 101. The other wall portion 103 has a plurality (three) through holes 103a penetrating the other wall portion 103 in the A direction. The optical gas sensor 1 is configured so that the gas to be detected can 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 so as to be arranged in parallel with each other. Further, the plurality of through holes 103a are provided over the entire other wall portion 103.

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

The housing portion 10 is integrally formed with the reflective portions 13a to 13e by a material such as aluminum or resin. Specifically, the housing portion 10 is integrally molded with the reflective portions 13a to 13e by a mold using a material such as aluminum or resin, and is formed by plating the surface with gold or the like. ..

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-shaped light source substrate 16a extending in the A direction. The LED chip 110a is arranged inside the housing portion 10 (on the center O (see FIG. 5) side) of the light source substrate 16a. The LED chip 110a is generally arranged so as to emit infrared light toward the center of the housing portion 10 in a plan view (viewed from the A direction). The reflector 110b has a function of narrowing the infrared light emitted from the LED chip 110a and spreading toward the center of the housing portion 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 detection light source for detecting the 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 on a first wavelength that is easily absorbed by the gas to be detected. For example, when the gas to be detected is methane gas, the first wavelength is set to approximately 3.3 μm.

The amount of infrared light emitted from the LED 11a absorbed by the gas to be detected increases or decreases depending on 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 infrared light path length decreases, the amount absorbed by the detection target gas decreases. Therefore, 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, in the optical gas sensor 1 of the first embodiment, in order to secure the size of the optical path length of infrared light in a limited space (space in the housing portion 10), a plurality of reflecting portions 13a to 13d are used. , Is configured to reflect infrared light emitted from the LED 11a.

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 arranged inside (center side) of the housing portion 10 with respect to 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 portion 10 in a plan view (viewed from the A direction).

The reflector 111b has a function of narrowing the infrared light emitted from the LED chip 111a and spreading toward the center of the housing portion 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 the 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 a second wavelength. For example, when the gas to be detected is methane gas, the second wavelength is set to 3.9 μm, which is different from the first wavelength of 3.3 μm.

The reference light source is used to detect dirt inside the housing portion 10. Here, in a normal usage mode, the optical gas sensor 1 includes the inside of the housing portion 10 (the surface of the housing portion 10, the reflecting portions 13a to 13e, the photodiode 12, the LEDs 11a, and 11b) due to use over time. ) Is attached with dirt such as dust, 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 (if it is only a light source for detection), is the decrease in detection intensity due to dirt inside the housing portion 10? , It becomes impossible to determine whether it is due to the absorption of the gas to be detected. Therefore, the optical gas sensor 1 is provided with a light source for reference that does not absorb the gas to be detected in addition to the light source for detection so that the dirt inside the housing portion 10 can be determined. It is configured.

Specifically, when the detection intensity of the infrared light from the detection light source and the infrared light from the reference light source by the photodiode 12 decreases due to the use of the optical gas sensor 1 over time, It can be determined that the inside of the housing portion 10 is dirty. As a result, the reference light source makes it possible to determine the maintenance time of the optical gas sensor 1. Further, if the detection intensity of the infrared light from the reference light source is not reduced (small) by the photodiode 12 due to the use of the optical gas sensor 1 over time, the inside of the housing portion 10 is substantially dirty. It can be judged that there is no such thing.

It should be noted that the reference light source (LED11b) is directly confirmed to be dirty in the reflection portions 13e and 13b that directly reflect the infrared light from the LED 11b, but the reflection portions 13e and 13b are confirmed by the reference light source. When it can be determined that the housing portion 10 is dirty, it can be determined that the other configurations (reflection portions 13a, 13c, 13d, etc.) in the housing portion 10 are also contaminated with dirt such as dust.

The reference light source (LED11b) is also used to suppress drift (fluctuation) of the detection value of the detection light source (LED11a) by the photodiode 12.

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

The photodiode 12 is arranged at a position substantially corresponding to the LED 11b in the A direction. Further, the photodiode 12 is generally arranged at a position facing the LED 11b in the B direction orthogonal to the A direction. Further, the photodiode 12 is arranged in the A2 direction 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 photodiode 12 is repeatedly and alternately irradiated with infrared light from the LEDs 11a and 11b at different timings.

The reflecting units 13a to 13d are configured to guide the photodiode 12 by reflecting infrared light emitted from the LED 11a, which is a light source for detection. Specifically, the reflecting unit 13a is configured to reflect infrared light passing through the optical path L1 emitted from the LED 11a. Further, the reflecting unit 13b is configured to reflect infrared light passing through the optical path L2 reflected by the reflecting unit 13a. Further, the reflecting unit 13c is configured to reflect infrared light passing through the optical path L3 reflected by the reflecting unit 13b. Further, the reflecting unit 13d is configured to guide infrared light through the optical path L4 reflected by the reflecting unit 13c to the photodiode 12 by the optical path L5. Therefore, the infrared light emitted from the LED 11a is reflected by the reflecting units 13a to 13d four times and then guided to the photodiode 12.

The optical paths L1 to L5 are shown in a straight line in FIGS. 5 and 6, which indicate the central position of the infrared light emission direction (traveling direction) and indicate the shape of the infrared light. I'm not. Hereinafter, the same applies to the diagrams of other optical paths.

The reflecting portion 13b is arranged so as to reflect infrared light on the A2 direction side of the reflecting portion 13a. Further, the reflecting portion 13c is arranged so as to reflect infrared light on the A2 direction side of the reflecting portion 13b. Further, the reflecting portion 13d is arranged so as to reflect infrared light on the A2 direction side of 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 reflecting units 13e and 13b are configured to guide the photodiode 12 by reflecting infrared light emitted from the LED 11b, which is a reference light source. Specifically, the reflecting unit 13e is configured to reflect infrared light that passes through the optical path L1a emitted from the LED 11b. Further, the reflecting unit 13b is configured to guide infrared light through the optical path L2a reflected by the reflecting unit 13e to the photodiode 12 by the optical path L3a. 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 reflecting portions 13e, 13b, and the photodiode 12 are arranged at substantially the same height position with respect to each other so that the optical paths L1a, L2a, and L3a are at substantially the same position in the A direction.

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

The reflecting portions 13b and 13d each have a flat reflecting surface. The reflecting units 13a to 13e are configured to guide infrared light emitted from the LEDs 11a (11b) to the photodiode 12 by alternately reflecting the infrared light emitted from the spherical reflecting surface and the flat reflecting surface. ing.

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

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

The temperature / humidity sensor 14 is a sensor capable of measuring the temperature and humidity of the gas in the housing 10. Further, the atmospheric pressure sensor 15 is a sensor capable of measuring the atmospheric pressure of the gas in the housing portion 10. Here, the detection intensity of infrared light by the photodiode 12 varies depending on the temperature, humidity, and atmospheric pressure of the space in which the gas is placed (the space inside the housing portion 10). Therefore, an error occurs in the detection intensity of the photodiode 12 for detecting the gas to be detected. 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 barometric pressure sensor 15 under the control of the microcomputer 17.

The microcomputer 17 is configured to control the drive of each part of the optical gas sensor 1. As a specific example, the microcomputer 17 is configured to alternately light the LEDs 11a and the LEDs 11b for 200 μsec continuously. At this time, the microcomputer 17 is configured such that the LED 11a and the LED 11b are turned on once every 0.5 seconds. Further, the microcomputer 17 generally turns off the power of the analog circuit in the optical gas sensor 1 at the timing when the LEDs 11a and 11b are turned off (during non-detection operation), and puts the microcomputer 17 in the sleep mode. , It is configured to achieve 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 light to the photodiode 12 by reflecting the infrared light emitted from the LED 11a are inner surfaces 101a. A housing portion 10 arranged on the side is provided. As a result, the number of photodiodes 12 in the housing 10 can be reduced by one as compared with the conventional configuration in which the two light sources and the two photodiodes 12 are arranged in the gas cell (housing portion). Therefore, the device configuration can be simplified and the device can be miniaturized. Further, 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. It is possible to secure a wider space and a larger optical path length. As a result, the gas to be detected can be detected more accurately. As described above, the device can be miniaturized while ensuring an optical path length large enough to detect the gas to be detected.

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

Further, 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 on the photodiode 12. Guide light. As a result, 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, so that the optical path length of the infrared light can be secured larger. Can be done. As a result, the gas to be detected can be detected more accurately.

Further, 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 with respect to the inflow direction of the gas to be detected. Configure to do. As a result, the gas to be detected can be detected as compared with the case where more infrared light emitted from the LED 11a is reflected on the side where the gas to be detected flows in than the side intersecting the inflow direction of the gas to be detected. Since the ratio of the reflecting portions 13a to 13d on the inflow side can be reduced, the ratio of the region where the detection target gas flows in can be increased accordingly, and the detection target gas flows into the housing more effectively. Can be made to.

Further, in the first embodiment, as described above, the reflecting portions 13a to 13d are configured to reflect the infrared light emitted from the LED 11a only on the side intersecting the inflow direction. As a result, the reflecting portions 13a to 13d can be provided only on the side intersecting the inflow direction of the gas to be detected without providing the reflecting portions 13a to 13d in the inflow direction of the gas to be detected. The gas can be made easier to flow in, and the housing portion 10 (device) can be miniaturized because the reflecting portions 13a to 13d are not provided in the gas inflow direction.

Further, in the first embodiment, as described above, the housing portion 10 is provided with the tubular side wall portion 101 and the other wall portion 103 arranged at one end of the side wall portion 101 to allow the gas to be detected to flow in. The LED 11a, the LED 11b and the photodiode 12 are provided and arranged on the inner surface 101a of the side wall portion 101. As a result, the tubular side wall 101 allows the LEDs 11a and 11b to be easily arranged at positions where infrared light is received by the photodiode 12.

Further, in the first embodiment, as described above, the reflecting portion 13e is configured to guide the infrared light emitted from the LED 11b to the photodiode 12 by also 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 the infrared light from the LED 11b and the infrared light from the LED 11b a different number of times. As a result, the infrared light emitted from the LED 11b can be reflected by the reflecting unit 13e, so that the optical path length of the infrared light emitted from the LED 11b can be increased.

Further, 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. As a result, the light emitting diode (LED) enables infrared light having a relatively narrow bandwidth centered (peak) at the first wavelength and the second wavelength as compared with other light sources such as incandescent lamps and fluorescent lamps. Can be emitted, so that energy efficiency can be improved. In addition, the photodiode can reliably receive infrared light from the LEDs 11a and 11b. In addition, the response time is extremely short (50 to several hundred nseconds) compared to other light sources such as incandescent lamps and photodetection elements, which normally take about 0.2 seconds from the flow of current through the element to normal lighting. By using the 11b and the photodiode 12, the energy consumption at the time of rising can be reduced, and the power consumption can be reduced because the pulse drive can be performed at high speed.

[Second Embodiment]
Next, the configuration of the gas detector 200 including the optical gas sensor 201 of the second embodiment will be described with reference to FIGS. 1, 2 and 8. The optical gas sensor 201 according to the second embodiment is the same as the optical gas sensor 1 according to the first embodiment in which the reflecting portions 13a to 13e, the LEDs 11a, 11b and the photodiode 12 are arranged at different height positions (positions in the A direction). However, the reflecting portions 213a to 213d, the LEDs 11a and 11b, and the photodiode 12 are arranged at the same height position. The same configuration as that of the first embodiment is shown with the same reference numerals in the drawings, and the description thereof will be omitted.

(Configuration of optical gas sensor)
As shown in FIG. 1, the gas detector 200 according to the second embodiment of the present invention includes an optical gas sensor 201. As shown in FIG. 8, the optical gas sensor 201 includes reflection portions 213a to 213d.

As shown in FIG. 8, 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.

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

The reflecting units 213a to 213d are configured to guide the photodiode 12 by reflecting the infrared light emitted from the LED 11a, which is a light source for detection. Specifically, the reflecting unit 213a is configured to reflect infrared light passing through the optical path L1c emitted from the LED 11a. Further, the reflecting unit 213b is configured to reflect infrared light passing through the optical path L2c reflected by the reflecting unit 213a. Further, the reflecting unit 213c is configured to reflect infrared light passing through the optical path L3c reflected by the reflecting unit 213b. Further, the reflecting unit 213d is configured to guide the photodiode 12 by the optical path L5c by reflecting infrared light passing through the optical path L4c reflected by the reflecting unit 213c. Therefore, the infrared light emitted from the LED 11a is reflected by the reflecting units 213a to 213d four times and then guided to the photodiode 12.

The reflecting units 213c and 213d are configured to guide the photodiode 12 by reflecting infrared light emitted from the LED 11b, which is a light source for reference. Specifically, the reflecting unit 213c is configured to reflect infrared light passing through the optical path L1d emitted from the LED 11b. Further, the reflecting unit 213d is configured to guide infrared light through the optical path L2d reflected by the reflecting unit 213c to the photodiode 12 by the optical path L3d. 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, since the reflecting portions 213a to 213d, the LEDs 11a, 11b, and the photodiode 12 are arranged at the same height position in the A direction, the optical paths L1c to L4c, L1d, and L2d are also arranged in the A direction. They are located at approximately the same height.

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

The photodiode 12 is provided with a condenser lens 12a that collects the received infrared light. The condenser lens 12a has a hemispherical shape protruding inward of the housing portion 10.

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

In the second embodiment, similarly to the first embodiment, the LED 11a, the LED 11b, the photodiode 12, and the reflecting portions 213a to guide the infrared light emitted from the LED 11a to the photodiode 12 by reflecting the infrared light. A housing portion 10 in which the 213d is arranged on the inner surface 101a side is provided. As a result, the device configuration can be simplified and the device can be miniaturized.

Further, in the second embodiment, as described above, the reflecting portions 213a to 213d, the LEDs 11a, the LEDs 11b, and the photodiode 12 are arranged at substantially the same height position. As a result, the housing portion 10 (device) can be miniaturized in the 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. 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 reflection portions 13a to 13e are arranged only on the inner surface 101a of the side wall portion 101 of the housing portion 10, and the reflection portions 313a to 313i Are arranged on the inner surface 101a of the side wall portion 101 of the housing portion 10, the inner surface of one wall portion 102, and the inner surface of the other wall portion 103. The same configuration as that of the first embodiment is shown with the same reference numerals in the drawings, and the description thereof will be omitted.

(Configuration of optical gas sensor)
As shown in FIG. 1, the gas detector 300 according to the third embodiment of the present invention includes an optical gas sensor 301. As shown in FIG. 9, the optical gas sensor 301 includes reflection portions 313a to 313i.

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

The reflecting units 313a to 313h are configured to guide the photodiode 12 by reflecting the infrared light emitted from the LED 11a. Specifically, the reflecting unit 313a is configured to reflect infrared light passing through the optical path L1e emitted from the LED 11a. Further, the reflecting unit 313b is configured to reflect infrared light passing through the optical path L2e reflected by the reflecting unit 313a. Further, the reflecting unit 313c is configured to reflect infrared light passing through the optical path L3e reflected by the reflecting unit 313b. Further, the reflecting unit 313d is configured to reflect infrared light passing through the optical path L4e reflected by the reflecting unit 313c. Further, the reflecting unit 313e is configured to reflect infrared light passing through the optical path L5e reflected by the reflecting unit 313d. Further, the reflecting unit 313f is configured to reflect infrared light passing through the optical path L6e reflected by the reflecting unit 313e. Further, the reflecting unit 313g is configured to reflect infrared light passing through the optical path L7e reflected by the reflecting unit 313f. Further, the reflecting unit 313h is configured to guide the photodiode 12 by the optical path L9e by reflecting infrared light passing through the optical path L8e reflected by the reflecting unit 313g. Therefore, the infrared light emitted from the LED 11a is reflected by the reflecting units 213a to 213d eight times and then guided to the photodiode 12.

The reflecting units 313a to 313h are configured to guide the infrared light emitted from the LED 11a to the photodiode 12 by turning the infrared light emitted from the LED 11a 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 units 313c to 313f are configured to move infrared light passing through the optical paths L3e to L7e (see FIG. 10) in the A1 direction. The reflecting portions 313g and 313h are configured to move 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, the infrared light emitted from the LED 11a toward the A1 direction and not yet reflected is once reflected toward the A2 direction side (LED11a side). As a result, the optical gas sensor 301 can obtain 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 angle of incidence on the photodiode 12 is zero (infrared light of the photodiode 12). Since the angle between the light receiving surface and the infrared light can be made close to 90 degrees), the light receiving surface can be secured widely with respect to the magnitude of the infrared light (the light receiving area of the photodiode 12). Therefore, the photodiode 12 can easily receive infrared light.

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

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

In the third embodiment, similarly to the first embodiment, the LED 11a, the LED 11b, the photodiode 12, and the reflecting portions 313a to guide the infrared light emitted from the LED 11a to the photodiode 12 by reflecting the infrared light. A housing portion 10 in which the 313h is arranged on the inner surface 101a side is provided. As a result, the device configuration can be simplified and the device can be miniaturized.

Further, 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 by a spiral optical path. As a result, infrared light can be delivered to the photodiode 12 by efficiently utilizing the space in the housing portion 10 by the spiral optical path. As a result, it is possible to secure an optical path length of larger infrared light, so that the gas to be detected can be detected more accurately.

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

(Modification example)
It should be noted that the embodiments disclosed this time are exemplary in all respects and are not considered to be restrictive. The scope of the present invention is shown by the scope of claims rather than the description of the above-described embodiment, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims.

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

Further, in the first to third embodiments, an example in which the reflecting portion is fixedly provided in the housing portion is shown, but the present invention is not limited to this. In the present invention, for example, the reflective portion may be configured by a MEMS mirror or the like so as to be vibrable with respect to the housing portion.

Further, in the first to third embodiments, an example in which the first light source and the second light source of the present invention are configured by LEDs is shown, but the present invention is not limited to this. In the present invention, the first light source and the second light source may be configured by a light source other than the LED such as an incandescent light bulb.

Further, in the first to third embodiments, an example in which the light receiving portion of the present invention is configured by a photodiode is shown, but the present invention is not limited to this. In the present invention, the light receiving portion may be configured by a light receiving portion other than a photodiode such as a thermocouple.

Further, in the first to third embodiments, an example is shown in which the infrared light from the first light source and the infrared light from the second light source are reflected differently in the number of times of reflection. Not limited to. In the present invention, the infrared light from the first light source and the infrared light from the second light source may be reflected at the same number of times.

Further, in the first to third embodiments, an example in which the power source of the present invention is a battery is shown, but the present invention is not limited to this. In the present invention, for example, the power supply of the present invention may be an outlet portion that can be connected to a commercial power supply.

Further, in the first to third embodiments, an example is shown in which the first light source is a light source for gas detection and the second light source is a light source for reference, 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 used as light sources for detecting different types of gas.

Further, in the first to third embodiments, an example in which the optical gas sensor and the gas detector (main body of the gas detector) are electrically connected via a compatible is shown. Is not limited to this. In the present invention, the optical gas sensor and the gas detector may be configured to be directly electrically connectable without interposing a compatible.

Further, in the first to third embodiments, an example in which the reflective portion is integrally formed with the housing portion is shown, but the present invention is not limited to this. In the present invention, the reflective portion may be formed separately from the housing portion.

Further, in the first to third embodiments, an example in which the housing portion is formed by a mold is shown, but the present invention is not limited to this. In the present invention, the housing portion may be formed by a method other than the mold such as metal processing.

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

Further, in the first to third embodiments, an example is shown in which a light source having a wavelength having no gas absorption is used as the second light source of the present invention and the second light source is used as a reference light source. The invention is not limited to this. In the present invention, a gas-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 first light source is used as a light source for gas detection and the second light source is used as a reference light source, 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 used as a light source for gas detection. As a specific example, the first light source and the second light source may have wavelengths having different bandwidths to improve the detection accuracy of one gas.

Further, in the first embodiment, an example is shown in which the optical gas sensor includes three substrates for mounting a light source, a light receiving unit, and the like, but 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 board may be a flexible wiring board.

In the first to third embodiments, an example in which a substrate, a reflecting portion, a light receiving portion, and the like are arranged inside one housing portion is shown, but the present invention is not limited to this. In the present invention, another housing portion is arranged inside one housing portion, and a hole portion for installing a substrate, a reflection portion, a light receiving portion, etc. is provided in the inner housing portion, and the hole portion is provided. The substrate, the reflecting portion, and the light receiving portion may be inserted into the substrate. In this case, the inner housing portion has a cylindrical shape, and may be configured so that the optical axis is adjusted by inserting each component.

Further, in the first to third embodiments, an example including a temperature / humidity sensor and a barometric pressure sensor has been shown, but the present invention is not limited to this. In the present invention, both the temperature / humidity sensor and the barometric pressure sensor may not be provided, or only one of them may be provided.

In the first to third embodiments, an example in which a spherical reflecting surface and a flat reflecting surface are combined as a reflecting portion is shown, but the present 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. Further, the shape of the reflecting surface may be any shape, and may be an elliptical shape or an aspherical shape (a curved surface that is neither a flat surface nor a spherical surface).

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 inflow)

Claims (10)

It is a non-dispersive infrared absorption type sensor.
A first light source that emits infrared light of the first wavelength,
A second light source that emits infrared light of a second wavelength different from the first wavelength,
A light receiving unit that receives infrared light emitted from the first light source and the second light source, and
A reflecting unit that guides the light receiving unit by reflecting infrared light emitted from the first light source,
A housing portion in which the first light source, the second light source, the light receiving portion, and the reflecting portion are arranged on the inner surface side is provided .
The first light source is a detection light source for detecting the gas to be detected.
The second light source is a reference light source.
An optical gas sensor in which the optical path length of infrared light of the first light source is larger than the optical path length of infrared light of the second light source . It is a non-dispersive infrared absorption type sensor.
A first light source that emits infrared light of the first wavelength,
A second light source that emits infrared light of a second wavelength different from the first wavelength,
A light receiving unit that receives infrared light emitted from the first light source and the second light source, and
A reflecting unit that guides the light receiving unit by reflecting infrared light emitted from the first light source,
A housing portion in which the first light source, the second light source, the light receiving portion, and the reflecting portion are arranged on the inner surface side is provided.
The reflecting unit is configured to guide the light receiving unit by reflecting infrared light emitted from the second light source, and the infrared light from the first light source and the second light source. An optical gas sensor provided to reflect infrared light from a light source a different number of times. It is a non-dispersive infrared absorption type sensor.
A first light source that emits infrared light of the first wavelength,
A second light source that emits infrared light of a second wavelength different from the first wavelength,
A light receiving unit that receives infrared light emitted from the first light source and the second light source, and
A reflecting unit that guides the light receiving unit by reflecting infrared light emitted from the first light source,
A housing portion in which the first light source, the second light source, the light receiving portion, and the reflecting portion are arranged on the inner surface side is provided.
The reflecting portion is an optical gas sensor configured to guide infrared light emitted from the first light source to the light receiving portion by a spiral optical path. A plurality of the reflecting portions are provided.
The optics according to any one of claims 1 to 3 , wherein the infrared light emitted from the first light source is guided to the light receiving portion by being reflected a plurality of times by the plurality of reflecting portions. Type gas sensor. The reflecting portion is configured to reflect more infrared light emitted from the first light source on the side intersecting the inflow direction than the inflow direction of the gas to be detected. The optical gas sensor according to any one of 4 . The optical gas sensor according to claim 5 , wherein the reflecting portion is configured to reflect infrared light emitted from the first light source only on the side intersecting the inflow direction. The housing portion includes a tubular side surface portion and a gas inflow portion provided at one end of the side surface portion to allow gas to be detected to flow in.
The optical gas sensor according to any one of claims 1 to 6 , wherein the first light source, the second light source, and the light receiving portion are arranged on the inner surface of the side surface portion. The optical gas sensor according to any one of claims 1 to 7 , wherein the reflecting unit, the first light source, the second light source, and the light receiving unit are arranged at substantially the same height position. The first light source and the second light source include a light emitting diode.
The optical gas sensor according to any one of claims 1 to 8 , wherein the light receiving unit includes a photodiode. The optical gas sensor according to any one of claims 1 to 9 ,
A gas detector including a power source that supplies electric power to the optical gas sensor.

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