Gas detector

Abstract

To provide a gas detector which can detect more sensitively or can detect more than one gas component at one time, and also can remove influence of remaining gas when detecting gas components continuously.SOLUTION: The present invention includes: a first detection room 13A and a second detection room 13B having a predetermined capacity; light-emitting means 15A, 15B arranged in at least one of the first detection room and the second detection room, the light-emitting means emitting light at a predetermined frequency; a resonance passage 16 for fluidly connecting the first detection room and the second detection room; a measurement room 18 fluidly connected to the resonance passage; a microphone 17 arranged in the measurement room, the microphone measuring the intensity of an acoustic wave; and air intake and exhaust mechanisms 21A, 21B for forcibly exhausting gas remaining in the first detection room and in the second detection room and taking a new measurement gas into the first detection room and in the second detection room.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas detection device that detects gas components that cause odors and the like, and more particularly to a gas detection device that detects gas components using a photoacoustic sensor. [Background technology]

[0002] At manufacturing sites for fermented products such as miso and soy sauce, cosmetics, and food storage warehouses, there is a quality control item for odor (also called fragrance), but it is difficult to implement digital transformation (DX).For this reason, odor identification relies on the experience and senses of on-site workers, leading to increased management costs and training costs.

[0003] Recently, attempts have been made to improve the efficiency of quality control through digitalization by quantifying odors (type of gas, concentration, etc.) using odor sensors. Quantifying odors requires gas sensors that detect gas components and odor components according to the purpose. As a sensor for detecting gas components and odor components, for example, a photoacoustic sensor using the photoacoustic effect as described in JP 2020-78418 A (Patent Document 1) has been proposed.

[0004] The photoacoustic effect is a phenomenon in which, when light of a specific wavelength (such as laser light) is intermittently (pulsed) irradiated onto molecules of a specific component that composes a gas, the molecules that absorb the light undergo thermal expansion and contraction, generating acoustic waves. Photoacoustic sensors are small and capable of detecting gas components with high sensitivity, so their application in various manufacturing sites is being promoted. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-26652 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, the photoacoustic sensor is based on the principle of detecting acoustic waves generated by thermal expansion and contraction of molecules that absorb light using a microphone. It is required to improve the detection sensitivity and detect multiple gas components simultaneously. However, the photoacoustic sensor described in Patent Document 1 has only one detection cell, so it is difficult to meet the demand for improving the detection sensitivity and detecting multiple gas components simultaneously. In addition, when measuring gas components continuously, it is also necessary to forcibly discharge the residual gas in the detection cell to eliminate the influence of the residual gas components.

[0007] An object of the present invention is to provide a novel gas detection device that can solve at least one of the above-mentioned problems. [Means for solving the problem]

[0008] The present invention is characterized in that the gas detection device comprises a first detection chamber and a second detection chamber each having a predetermined volume, a light emitting means arranged in either or both of the first detection chamber and the second detection chamber and emitting light at a predetermined frequency, a resonance passage fluidly connecting the first detection chamber and the second detection chamber, a measurement chamber fluidly connected to the resonance passage, a microphone arranged in the measurement chamber and measuring the intensity of an acoustic wave, and an intake and exhaust mechanism which forcibly exhausts gas remaining in the first detection chamber and the second detection chamber and draws new measurement gas into the first detection chamber and the second detection chamber. Effect of the Invention

[0009] According to the present invention, it is possible to improve detection sensitivity, detect multiple gas components simultaneously, and eliminate the influence of residual gas components when measuring gas components continuously. [Brief description of the drawings]

[0010] [Figure 1] 1 is a configuration diagram showing the configuration of a gas detection device according to a first embodiment of the present invention. [Diagram 2]FIG. 4 is a configuration diagram showing the configuration of a gas detection device according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a configuration diagram showing the configuration of a model that models the second embodiment. [Figure 4A] FIG. 4 is an explanatory diagram showing a simulation result of a model in the first embodiment. [Figure 4B] FIG. 11 is an explanatory diagram showing a simulation result of a model in the second embodiment. [Diagram 5] FIG. 11 is a configuration diagram showing the configuration of a gas detection device according to a third embodiment of the present invention. [Figure 6] FIG. 11 is a configuration diagram showing the configuration of a gas detection device according to a fourth embodiment of the present invention. [Figure 7] FIG. 11 is a configuration diagram showing the configuration of a gas detection device according to a fifth embodiment of the present invention. [Figure 8] FIG. 11 is a configuration diagram showing the configuration of a gas detection device according to a sixth embodiment of the present invention. [Figure 9] FIG. 13 is a configuration diagram showing the configuration of a gas detection device according to a seventh embodiment of the present invention. [Figure 10] FIG. 13 is a flow chart illustrating the operation flow of the gas detection device according to the eighth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and application examples within the technical concept of the present invention are also included within its scope. EXAMPLES

[0012] In Fig. 1, the gas detection device OD includes at least a photoacoustic cell 10 and an intake and exhaust mechanism 21. In this embodiment, the intake and exhaust mechanism 21 is made up of a first intake and exhaust mechanism 21A and a second intake and exhaust mechanism 21B. The first intake and exhaust mechanism 21A and the second intake and exhaust mechanism 21B are made up of propeller fans of the same specifications, but fans of other types can also be used. The intake and exhaust mechanism can also be a single intake and exhaust mechanism without being divided.

[0013] The photoacoustic cell 10 is disposed on one surface (hereinafter referred to as the front surface) of a flat substrate (e.g., a resin substrate, etc.) 11, and the intake and exhaust mechanisms 21A and 21B are disposed on the other surface (hereinafter referred to as the back surface) of the substrate 11. In particular, the photoacoustic cell 10 is provided on the front surface of the substrate 11 on which a control circuit and the like are mounted. In this manner, the substrate 11, the photoacoustic cell 10, and the intake and exhaust mechanism 21 are integrated as a whole into an assembly. Therefore, this assembly can be incorporated into a box made of synthetic resin or the like to be assembled as a gas detection device.

[0014] The control circuit of the substrate 11 has a function of controlling the emission frequency and light intensity of the light emitting means described later, and a function of measuring acoustic waves from a microphone described later. For this reason, by disposing the photoacoustic cell 10 on the surface of the substrate 11 on which the control circuit is provided, connection wiring and the like is made easy.

[0015] The photoacoustic sensor 10 includes a housing 12 made of a metal material or a resin material, and a first detection chamber 13A and a second detection chamber 13B having a predetermined volume are formed inside the housing 12. The first detection chamber 13A and the second detection chamber 13B are hollow spaces and are formed to have substantially the same shape and the same spatial volume. For example, the spatial shape of the first detection chamber 13A and the second detection chamber 13B can be formed to be a cylindrical shape or a rectangular parallelepiped shape. In this embodiment, the spatial shape is determined to be a cylindrical shape.

[0016] A first suction hole 14A that fluidly connects the first detection chamber 13A to the outside is formed in a wall surface 12W of the housing 12 on the opposite side of the first detection chamber 13A from the substrate 11. Similarly, a second suction hole 14B that fluidly connects the second detection chamber 13B to the outside is formed in a wall surface 12W of the housing 12 on the opposite side of the second detection chamber 13B from the substrate 11.

[0017] The number of suction holes 14A and 14B may be one or more, as long as they have a suction area that allows the necessary amount of measurement gas to be smoothly introduced into the detection chambers 13A and 13B. The suction holes 14A and 14B have the same suction area.

[0018] Here, the outside refers to a space in which the gas to be measured exists, and corresponds to the manufacturing site or storage warehouse as described above. Therefore, the measurement gas existing in the manufacturing site or storage warehouse is drawn into the first detection chamber 13A and the second detection chamber 13B from the first suction through hole 14A and the second suction through hole 14B.

[0019] A first LED element 15A, which is a first light emitting means, is disposed in the first detection chamber 13A, and the first LED element 15A emits light in a pulsed manner at a predetermined frequency to thermally excite a specific component of the measurement gas Gas in the first detection chamber 13A. The first LED element 15A is provided on the front surface side of the substrate 11, and is controlled and driven by a control circuit (not shown).

[0020] Similarly, a second LED element 15B, which is a second light emitting means, is disposed in the second detection chamber 13B, and the second LED element 15B emits light in a pulsed manner at a predetermined frequency to thermally excite a specific component of the measurement gas Gas in the second detection chamber 13B. The second LED element 15B is also provided on the front surface side of the substrate 11, and is controlled and driven by a control circuit (not shown).

[0021] Here, the first detection chamber 13A and the second detection chamber 13B may detect the same gas component or different gas components. In this case, the light emission frequency of each of the LED elements 15A and 15B may be determined according to the gas component to be detected. In this way, by providing two detection chambers 13A and 13B, it is possible to detect the same gas component or different gas components. Note that instead of LED elements, a semiconductor laser or the like may be used as the light emitting means. Furthermore, it is also possible to provide a light emitting means (LED or laser) in only one of the detection chambers and use the other detection chamber as a resonance chamber.

[0022] The first detection chamber 13A and the second detection chamber 13B are fluidly connected by a straight resonance passage 16 formed inside the housing 12. This resonance passage 16 has a circular cross section perpendicular to the axis of the resonance passage 16, and has a function of resonating and amplifying minute photoacoustic waves generated in the first detection chamber 13A and the second detection chamber 13B. This makes it easy to measure the photoacoustic waves by a microphone, which will be described later.

[0023] Furthermore, a measurement chamber 18 that houses a microphone 17 that measures photoacoustic waves is formed on the side of the housing 12 that contacts the substrate 11. The measurement chamber 18 is fluidly connected to the resonance passage 16 via a connection passage 19. The connection point between the resonance passage 16 and the connection passage 19 corresponds to the midpoint of the resonance passage 16 that is connected to the first detection chamber 13A and the second detection chamber 13B, and ensures the geometric symmetry of the first detection chamber 13A, the second detection chamber 13B, and the resonance passage 16. In other words, the first detection chamber 13A, the second detection chamber 13B, and the resonance passage 16 are shaped line-symmetrically on the paper with the axis of the connection passage 19 as the boundary.

[0024] A microphone 17 for measuring the intensity of the photoacoustic wave is disposed in the measurement chamber 18. The microphone 17 is provided on the front surface side of the substrate 11, and is controlled and driven by a control circuit (not shown). In this manner, the photoacoustic wave generated by the light emission of the LED elements 15A and 15B is measured by the microphone 17, and the intensity of the photoacoustic wave measured by the microphone 17 is converted into an electrical signal. These processes are carried out by a control circuit such as that shown in Patent Document 1, for example.

[0025] In addition, a first exhaust hole 20A is formed in the substrate 11 on which the first detection chamber 13A is located, fluidically connecting the first detection chamber 13A and the first intake and exhaust mechanism 21A. Similarly, a second exhaust hole 20B is formed in the substrate 11 on which the second detection chamber 13B is located, fluidically connecting the second detection chamber 13B and the second intake and exhaust mechanism 21B. The intake holes 14A, 14B and the exhaust holes 20A, 20B are formed in positions facing each other, and are in a positional relationship that allows the measurement gas to easily flow.

[0026] The number of exhaust holes 20A and 20B may be one or more, but what is important is that they have an exhaust area that allows the necessary amount of measurement gas to be smoothly exhausted from the detection chambers 13A and 13B. Moreover, the exhaust holes 20A and 20B have the same exhaust area.

[0027] The intake and exhaust mechanisms 21A and 21B are the same type of propeller fan and have the same intake and exhaust performance. The intake and exhaust mechanisms 21A and 21B are driven intermittently at predetermined time intervals to forcibly exhaust the measured measurement gas in the detection chambers 13A and 13B from the exhaust holes 20A and 20B of the detection chambers 13A and 13B, and at the same time introduce new measurement gas to be used for the next measurement into the detection chambers 13A and 13B from the intake holes 14A and 14B. This eliminates residual gas in the detection chambers 13A and 13B, making it possible to eliminate the adverse effects of residual gas.

[0028] Thus, this embodiment includes a first detection chamber and a second detection chamber, a resonant passage fluidly connecting the first detection chamber and the second detection chamber, a microphone for detecting acoustic waves, and an intake and exhaust mechanism for forcibly discharging gas remaining in the first detection chamber and the second detection chamber and drawing new measurement gas into the first detection chamber and the second detection chamber.

[0029] Therefore, it is possible to improve the detection sensitivity and detect multiple gas components simultaneously, and when measuring gas components continuously, it is possible to eliminate the influence of residual gas components in each detection chamber. EXAMPLES

[0030] Next, the second embodiment will be described. In the first embodiment, when a specific gas component of a measurement gas is detected in the first detection chamber 13A and the second detection chamber 13B, the same measurement gas is also present in the resonance passage 16. Therefore, when the measurement of a specific gas component is completed and the measured measurement gas is discharged, there is a risk that the measurement gas present in the resonance passage 16 will remain because the performance of the first intake and exhaust mechanism 21A and the second intake and exhaust mechanism 21B are the same.

[0031] In other words, new measurement gas sucked in through the intake holes 14A, 14B of the first detection chamber 13A and the second detection chamber 13B, and measured measurement gas exhausted through the exhaust holes 20A, 20B of the first detection chamber 13A and the second detection chamber 13B flow through the space between the first detection chamber 13A and the second detection chamber 13B, so that the measurement gas in the resonance passage 16 is not exhausted and becomes residual measurement gas.

[0032] For this reason, when a new measurement gas is measured, the residual measurement gas that has already been measured and exists in the resonance passage 16 may affect the new measurement gas, making it possible to make an accurate measurement impossible. In other words, if the concentration or gas components of the residual measurement gas differ from those of the new measurement gas, it may become impossible to perform an accurate analysis of the gas components.

[0033] Therefore, in the second embodiment, a gas detection device is proposed that can smoothly discharge the residual measurement gas that has been measured and is present in the resonance passage 16. Here, the same reference numbers as those in the gas detection device shown in Fig. 1 indicate the same parts and components, and therefore a repeated explanation will be omitted. However, explanations may be given as necessary.

[0034] 2, first intake and exhaust mechanism 22A is a propeller fan with high gas exhaust performance, and second intake and exhaust mechanism 22B is a propeller fan with low gas exhaust performance compared to first intake and exhaust mechanism 22A. In other words, first intake and exhaust mechanism 22A is a propeller fan with high static pressure (blows a lot of air), and second intake and exhaust mechanism 22B is a propeller fan with low static pressure (blows a little air).

[0035] As a result, the pressure in the first detection chamber 13A becomes lower than the pressure in the second detection chamber 13B, and this pressure difference generates a new flow of measurement gas in the resonance passage 16. The first intake and exhaust mechanism 22A and the second intake and exhaust mechanism 22B function as a "pressure difference generating mechanism" that generates a flow of measurement gas in the resonance passage 16 that connects the first detection chamber 13A and the second detection chamber 13B.

[0036] In addition, because the first intake and exhaust mechanism 22A causes an excess of the measurement gas to flow from the second detection chamber 13B through the resonance passage 16 into the first detection chamber 13A, the area of ​​the first exhaust hole 20A is made larger than the area of ​​the second exhaust hole 20B to allow the measurement gas to be discharged smoothly.

[0037] Here, the measurement gas discharged is a mixture of the measurement gas that has already been measured and the new measurement gas, and the exchange of the measurement gas is completed by driving the intake and exhaust mechanisms 22A and 22B for a predetermined period of time.

[0038] Fig. 3 shows a model for simulating the flow of the measurement gas in the first detection chamber 13A, the second detection chamber 13B, and the resonance passage 16 shown in Fig. 2. Using this model, the flow of the measurement gas when the exhaust performance of the intake and exhaust mechanisms 22A and 22B is changed is simulated, and the results are shown in Fig. 4A and Fig. 4B.

[0039] 4A shows a case where the exhaust performance of the first intake and exhaust mechanism 22A and the second intake and exhaust mechanism 22B are the same as that of the first intake and exhaust mechanism 22A and the second intake and exhaust mechanism 22B, as shown in FIG. 1. Here, the exhaust performance is shown by the air flow speed, and both are set to a flow speed of 1.0 m / s. As can be seen from FIG. 4A, no flow of the measurement gas was observed in the resonance passage 16.

[0040] On the other hand, Fig. 4B shows a case where the first intake and exhaust mechanism 22A has a higher exhaust performance than the second intake and exhaust mechanism 22B, as shown in Fig. 2. Here, the exhaust performance is shown by the air flow speed, and the flow speed of the first intake and exhaust mechanism 22A is set to 1.0 m / s, and the flow speed of the second intake and exhaust mechanism 22B is set to 0.2 m / s. As can be seen from Fig. 4B, the flow of the measurement gas in the resonance passage 16 was confirmed.

[0041] In this embodiment, after detecting a specific gas component in the measurement gas in the first detection chamber 13A and the second detection chamber 13B with the intake and exhaust mechanisms 22A and 22B stopped, when it is desired to detect a specific gas component in the next measurement gas, the intake and exhaust mechanisms 22A and 22B are driven to exhaust the measured measurement gas.

[0042] At this time, because the exhaust performance of the first intake and exhaust mechanism 22A is high, a pressure difference occurs between the first detection chamber 13A and the second detection chamber 13B, and new measurement gas flows from the second detection chamber 13B through the resonance passage 16 to the first detection chamber 13 and is exhausted, so that there is no residual measurement gas in the resonance passage 16. In this state, the intake and exhaust mechanisms 22A and 22B are stopped, and the gas components of the new measurement gas in the first detection chamber 13A and the second detection chamber 13B are detected.

[0043] In this manner, in this embodiment, when a new measurement gas is measured, there is no residual measurement gas that has already been measured in the resonance passage, so that the new measurement gas can be accurately detected without adversely affecting it. EXAMPLES

[0044] Next, a third embodiment will be described. In the third embodiment, a configuration for discharging the residual measurement gas present in the resonance passage 16 is also shown. Here, the same reference numbers as those in the gas detection device shown in Fig. 1 indicate the same parts and components, so a repeated explanation will be omitted. However, explanations may be given as necessary.

[0045] In FIG. 5, the first detection chamber 13A does not have a first exhaust through hole 20A, and is closed by the substrate. On the other hand, the second detection chamber 13B has a second exhaust through hole 20B. Therefore, the first intake and exhaust mechanism 1A is not provided, and only the second intake and exhaust mechanism 21B is provided at the second exhaust through hole 20B. Also, the second detection chamber 13B does not have a second intake through hole 14B, and is closed by the wall surface 12W of the housing 12. On the other hand, the first detection chamber 13A has a first intake through hole 14A.

[0046] This intake / exhaust mechanism 21B, the blocked first exhaust hole 20A of the first detection chamber 13A, and the blocked second intake hole 14B of the second detection chamber 13B function as a "pressure difference generating mechanism" that generates a flow of measurement gas in the resonance passage 16 connecting the first detection chamber 13A and the second detection chamber 13B.

[0047] Therefore, when the second intake and exhaust mechanism 21B is driven to exchange the measurement gas, new measurement gas flows in through the first intake hole 14A, flows into the resonance passage 16 together with the measured measurement gas in the first detection chamber 13A, and is further discharged from the exhaust hole 19B together with the measured measurement gas in the second detection chamber 13B. In this way, the new measurement gas flows in the order of the first intake hole 14A → first detection chamber 13A → resonance passage 16 → second detection chamber 13B → exhaust hole 19B, so that the remaining measurement gas in the first detection chamber 13A, the second detection chamber 13B, and the resonance passage 16 can be discharged.

[0048] In this manner, also in this embodiment, when a new measurement gas is measured, the residual measurement gas that has already been measured and is present in the resonance passage is no longer present, so that the new measurement gas is not adversely affected and the measurement gas can be accurately detected. In addition, the number of intake and exhaust mechanisms can be reduced, so that the overall manufacturing cost can be reduced and power consumption during use can be reduced. EXAMPLES

[0049] Next, a fourth embodiment will be described. In the fourth embodiment, a configuration for discharging the residual measurement gas present in the resonance passage 16 is also shown. Here, the same reference numbers as those in the gas detection device shown in Fig. 1 indicate the same parts and components, and therefore a repeated explanation will be omitted. However, explanations may be given as necessary.

[0050] The embodiment shown in Fig. 6 is a modified example of the embodiment shown in Fig. 5, and differs in that a second suction hole 14B is provided in the second detection chamber 13B. With this configuration, when replacing with new measurement gas, the new measurement gas is also introduced from the second suction hole 14B, so that the measurement gas that has already been measured can be efficiently discharged.

[0051] In this embodiment as well, the intake and exhaust mechanism 21B and the blocked first exhaust hole 20A of the first detection chamber 13A function as a "pressure difference generating mechanism" that generates a flow of measurement gas in the resonance passage 16 connecting the first detection chamber 13A and the second detection chamber 13B.

[0052] In this manner, also in this embodiment, when a new measurement gas is measured, the residual measurement gas that has already been measured and is present in the resonance passage is no longer present, so that the new measurement gas is not adversely affected and the measurement gas can be accurately detected. In addition, the number of intake and exhaust mechanisms can be reduced, so that the overall manufacturing cost can be reduced and power consumption during use can be reduced. EXAMPLES

[0053] Next, a fifth embodiment will be described. The fifth embodiment also shows a configuration for discharging the residual measurement gas present in the resonance passage 16. Here, the same reference numbers as those in the gas detection device shown in Fig. 1 indicate the same parts and components, and therefore a repeated explanation will be omitted. However, explanations may be given as necessary.

[0054] 7, intake and exhaust mechanism 23 is equipped with one large propeller fan. This propeller fan includes rotating shaft 24 and fan 25 fixed thereto. Here, center CR of rotating shaft 24 is disposed at a position eccentric to the axis CA of connecting passage 19 by ΔC toward second detection chamber 13B.

[0055] Here, the amount of eccentricity ΔC is determined so that the second exhaust hole 20B coincides with the area where the fan 25 is most efficient at exhausting gas. On the other hand, the first exhaust hole 20A is positioned out of alignment with the area where the fan 25 is most efficient at exhausting gas due to the eccentricity of the rotation shaft 24.

[0056] In this embodiment, the eccentrically disposed intake and exhaust mechanism 23 functions as a “pressure difference generating mechanism” that generates a flow of the measurement gas in the resonance passage 16 connecting the first detection chamber 13A and the second detection chamber 13B.

[0057] In this embodiment, when a specific gas component of the measurement gas in the first detection chamber 13A and the second detection chamber 13B is detected while the intake and exhaust mechanism 23 is stopped, if a specific gas component of the next measurement gas is to be detected, the intake and exhaust mechanism 23 is driven to exhaust the measured measurement gas.

[0058] At this time, because the second exhaust hole 20B has a greater exhaust performance, a pressure difference occurs between the first detection chamber 13A and the second detection chamber 13B, and new measurement gas flows from the first detection chamber 13A through the resonance passage 16 to the second detection chamber 13B and is exhausted, so that there is no residual measurement gas in the resonance passage 16. In this state, the intake and exhaust mechanism 23 is stopped, and the gas components of the new measurement gas in the first detection chamber 13A and the second detection chamber 13B are detected.

[0059] In this manner, in the present embodiment, when a new measurement gas is measured, the residual measurement gas that has already been measured and is present in the resonance passage is no longer present, so that the new measurement gas is not adversely affected and the measurement gas can be accurately detected. In addition, the number of intake and exhaust mechanisms can be reduced, so that the overall manufacturing cost can be reduced and power consumption during use can be reduced. EXAMPLES

[0060] Next, a sixth embodiment will be described. The sixth embodiment also shows a configuration for discharging the residual measurement gas present in the resonance passage 16. Here, the same reference numbers as those in the gas detection device shown in Fig. 1 indicate the same parts and components, and therefore a repeated explanation will be omitted. However, explanations may be given as necessary.

[0061] 8, the intake and exhaust mechanism 23 is equipped with one large propeller fan. This propeller fan includes a rotating shaft 24 and a fan 25 fixed thereto. Here, the rotation center CR of the rotating shaft 24 is coaxial with the axis CA of the connecting passage 19. Therefore, the first exhaust through-hole 10A and the second exhaust through-hole 20B have the same exhaust performance.

[0062] On the other hand, the discharge area of ​​the second discharge hole 20B is larger than that of the first discharge hole 20A. Therefore, the measurement gas is discharged from the first discharge hole 20A and the second discharge hole 20B by the intake and exhaust mechanism 23, but the amount of discharged gas is larger from the second discharge hole 20B. Therefore, the pressure in the second detection chamber 13B becomes lower than the pressure in the first detection chamber 13A, and the measurement gas in the first detection chamber 13A flows into the second detection chamber 13B through the resonance passage 16 and is further discharged from the second discharge hole 20B.

[0063] In this embodiment as well, the intake and exhaust mechanism 23 and the second intake hole 14B formed in the second detection chamber 13B, which has a larger exhaust area than the first exhaust hole 20A formed in the first detection chamber 13A, function as a "pressure difference generating mechanism" that generates a flow of measurement gas in the resonance passage 16 connecting the first detection chamber 13A and the second detection chamber 13B.

[0064] In this manner, in the present embodiment, when a new measurement gas is measured, the residual measurement gas that has already been measured and is present in the resonance passage is no longer present, so that the new measurement gas is not adversely affected and the measurement gas can be accurately detected. In addition, the number of intake and exhaust mechanisms can be reduced, so that the overall manufacturing cost can be reduced and power consumption during use can be reduced. EXAMPLES

[0065] Next, a seventh embodiment will be described. The seventh embodiment also shows a configuration for discharging the residual measurement gas present in the resonance passage 16. Here, the same reference numbers as those in the gas detection device shown in Fig. 1 indicate the same parts and components, so a repeated explanation will be omitted. However, explanations may be given as necessary.

[0066] 9, intake and exhaust mechanism 23 is disposed on the wall surface of housing 12 opposite substrate 11, and is configured to supply measurement gas to first intake hole 14A of first detection chamber 13A and second intake hole 14B of second detection chamber 13B. Intake and exhaust mechanism 23 is equipped with one large propeller fan, and this propeller fan has rotating shaft 24 and fan 25 fixed thereto.

[0067] Here, the rotation center CR of the rotating shaft 24 is coaxial with the axis CA of the connecting passage 19. Therefore, the first suction hole 14A and the second suction hole 14B have the same discharge performance for pushing in the measurement gas.

[0068] On the other hand, the exhaust area of ​​the second exhaust hole 20B is larger than that of the first exhaust hole 20A. Therefore, the intake and exhaust mechanism 23 exhausts gas from the first exhaust hole 20A and the second exhaust hole 20B, but the amount of gas exhausted from the second exhaust hole 20B is greater.

[0069] As a result, the pressure in the first detection chamber 13A becomes higher than the pressure in the second detection chamber 13B, and the measurement gas in the first detection chamber 13A flows through the resonance passage 16 to the second detection chamber 13B and is further discharged from the second exhaust hole 20B.

[0070] In this embodiment as well, the intake and exhaust mechanism 23 and the second intake hole 14B formed in the second detection chamber 13B, which has a larger exhaust area than the first exhaust hole 20A formed in the first detection chamber 13A, function as a "pressure difference generating mechanism" that generates a flow of measurement gas in the resonance passage 16 connecting the first detection chamber 13A and the second detection chamber 13B.

[0071] In this manner, in the present embodiment, when a new measurement gas is measured, the residual measurement gas that has already been measured and is present in the resonance passage is no longer present, so that the new measurement gas is not adversely affected and the measurement gas can be accurately detected. In addition, the number of intake and exhaust mechanisms can be reduced, so that the overall manufacturing cost can be reduced and power consumption during use can be reduced. EXAMPLES

[0072] The above-described embodiments are related to the configuration of the gas detection device, and the operation of the gas detection device (exchange of measurement gas) will now be briefly described. A control circuit for controlling the operation of the LED element, microphone, and intake and exhaust mechanism is mounted on the board, and the control circuit operates the LED elements 15A, 15B, and microphone 17 to measure the measurement gas, and then operates the intake and exhaust mechanism for a predetermined time to exhaust the measured measurement gas from the first detection chamber 13A, the resonance passage 16, and the second detection chamber 13B.

[0073] In step S10 in Fig. 10, the intake and exhaust mechanism is driven to exhaust the measured measurement gas remaining in the first and second detection chambers. At this time, new measurement gas is introduced into the first and second detection chambers, and new measurement gas is also introduced into the resonance passage at the same time.

[0074] Next, in step S11, the introduction of new measurement gas is continued for a predetermined time, and the intake and exhaust mechanism is driven until the first detection chamber and the second detection chamber are filled with the new measurement gas.

[0075] Next, in step S12, the LED element is caused to emit light at a predetermined frequency, and the intensity of the photoacoustic wave at this time is measured by a microphone. At this time, the control circuit executes necessary processing.

[0076] Next, in order to exhaust the measured measurement gas and introduce new measurement gas, the intake and exhaust mechanism is driven in step S13. Furthermore, in step S14, the introduction of new measurement gas is continued for a predetermined time, and the intake and exhaust mechanism is driven until the first detection chamber and the second detection chamber are filled with new measurement gas. By repeating these steps, the measurement gas can be measured intermittently and continuously.

[0077] By performing such a measurement operation, residual gas in the resonance passage is discharged, and furthermore, the operation of the intake and exhaust mechanism during the measurement is stopped, thereby preventing the microphone from picking up the operating sounds of the intake and exhaust mechanism (e.g., a propeller fan), making it possible to measure the time-series changes in odor with high accuracy.

[0078] As described above, the present invention is characterized in that the gas detection device comprises a first detection chamber and a second detection chamber each having a predetermined volume, a light emitting means that is arranged in either or both of the first detection chamber and the second detection chamber and emits light at a predetermined frequency, a resonance passage that fluidly connects the first detection chamber and the second detection chamber, a measurement chamber that is fluidly connected to the resonance passage, a microphone that is arranged in the measurement chamber and measures the intensity of the acoustic wave, and an intake and exhaust mechanism that forcibly expels gas remaining in the first detection chamber and the second detection chamber and draws new measurement gas into the first detection chamber and the second detection chamber.

[0079] This makes it possible to improve detection sensitivity and detect multiple gas components simultaneously, and also makes it possible to eliminate the influence of residual gas components when measuring gas components continuously.

[0080] The present invention is not limited to the above-mentioned embodiments, but includes various modified examples. The above-mentioned embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment. [Explanation of symbols]

[0081] Reference Signs List 10...photoacoustic sensor, 11...substrate, 12...housing, 13A...first detection chamber, 13B...second detection chamber, 14A...first intake hole, 14B...second intake hole, 15A...first LED element, 15B...second LED element, 16...resonance passage, 17...microphone, 18...measurement chamber, 19...connection passage, 20A...first exhaust hole, 20B...second exhaust hole, 21A...first intake and exhaust mechanism, 21B...second intake and exhaust mechanism, 22A...first intake and exhaust mechanism, 22A...second intake and exhaust mechanism.

Claims

1. a first detection chamber and a second detection chamber each having a predetermined volume; A light emitting means that emits light at a predetermined frequency and is disposed in either or both of the first detection chamber and the second detection chamber; a resonant passage fluidly connecting the first detection chamber and the second detection chamber; a measurement chamber fluidly connected to the resonant passage; A microphone disposed in the measurement chamber for measuring the intensity of the photoacoustic wave; an intake and exhaust mechanism that forcibly exhausts the measured measurement gas remaining in the first detection chamber and the second detection chamber and draws new measurement gas into the first detection chamber and the second detection chamber; A gas detection device comprising:

2. 2. The gas detection device according to claim 1, the first detection chamber, the second detection chamber, the light emitting means, the resonant passage, the measurement chamber, and the microphone are disposed on one surface of a substrate; The intake and exhaust mechanism is disposed on the other surface of the substrate. A gas detection device comprising:

3. 3. The gas detection device according to claim 2, The intake and exhaust mechanism is provided individually for the first detection chamber and the second detection chamber, or is provided in common for the first detection chamber and the second detection chamber. A gas detection device comprising:

4. 4. The gas detection device according to claim 3, the first detection chamber is provided with a first intake hole through which the new measurement gas is introduced and a first exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; The second detection chamber is provided with a second intake hole through which the new measurement gas is introduced and a second exhaust hole through which the measured measurement gas flows to the intake and exhaust mechanism. A gas detection device comprising:

5. a first detection chamber and a second detection chamber each having a predetermined volume; A light emitting means that emits light at a predetermined frequency and is disposed in either or both of the first detection chamber and the second detection chamber; a resonant passage fluidly connecting the first detection chamber and the second detection chamber; a measurement chamber fluidly connected to the resonant passage; A microphone disposed in the measurement chamber for measuring the intensity of the photoacoustic wave; an intake and exhaust mechanism that forcibly exhausts the measured measurement gas remaining in the first detection chamber and the second detection chamber and draws new measurement gas into the first detection chamber and the second detection chamber; a pressure difference generating mechanism that generates a pressure difference between the first detection chamber and the second detection chamber when the intake and exhaust mechanism is operated, to exhaust the measured measurement gas remaining in the resonance passage; A gas detection device comprising:

6. 6. The gas detection device according to claim 5, the first detection chamber, the second detection chamber, the light emitting means, the resonant passage, the measurement chamber, and the microphone are disposed on one surface of a substrate; The intake and exhaust mechanism is disposed on the other surface of the substrate. A gas detection device comprising:

7. 7. The gas detection device according to claim 6, the first detection chamber is provided with a first intake hole through which the new measurement gas is introduced and a first exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the second detection chamber is provided with a second intake hole through which the new measurement gas is introduced and a second exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the intake and exhaust mechanism includes a first intake and exhaust mechanism connected to the first exhaust through-hole and a second intake and exhaust mechanism connected to the second exhaust through-hole, The pressure difference generating mechanism generates a pressure difference between the first detection chamber and the second detection chamber by determining that one of the first intake and exhaust mechanism and the second intake and exhaust mechanism has a larger exhaust amount of the measured measurement gas than the other. A gas detection device comprising:

8. 7. The gas detection device according to claim 6, The first detection chamber has an intake hole through which the new measurement gas is introduced, the second detection chamber is provided with an exhaust hole through which the measured gas flows to the intake and exhaust mechanism; The pressure difference generating mechanism generates a pressure difference between the first detection chamber and the second detection chamber by connecting the intake and exhaust mechanism to the exhaust hole, and causes the new measurement gas to flow through the intake hole, the first detection chamber, the resonance passage, the second detection chamber, and the exhaust hole in this order. A gas detection device comprising:

9. 9. The gas detection device according to claim 8, The second detection chamber is provided with a second intake hole through which the new measurement gas is introduced. A gas detection device comprising:

10. 7. The gas detection device according to claim 6, the first detection chamber is provided with a first intake hole through which the new measurement gas is introduced and a first exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the second detection chamber is provided with a second intake hole through which the new measurement gas is introduced and a second exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the intake and exhaust mechanism is a propeller fan connected to the first exhaust hole and the second exhaust hole, The pressure difference generating mechanism generates a pressure difference between the first detection chamber and the second detection chamber by disposing the axis of the rotating shaft of the propeller fan eccentrically toward the first exhaust through hole or the second exhaust through hole. A gas detection device comprising:

11. 7. The gas detection device according to claim 6, the first detection chamber is provided with a first intake hole through which the new measurement gas is introduced and a first exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the second detection chamber is provided with a second intake hole through which the new measurement gas is introduced and a second exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the intake and exhaust mechanism is a single intake and exhaust mechanism connected to the first exhaust through-hole and the second exhaust through-hole, The pressure difference generating mechanism generates a pressure difference between the first detection chamber and the second detection chamber by making the discharge area of ​​one of the first discharge through hole and the second discharge through hole larger than the discharge area of ​​the other. A gas detection device comprising:

12. 7. The gas detection device according to claim 6, the first detection chamber is provided with a first intake hole through which the new measurement gas is introduced and a first exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the second detection chamber is provided with a second intake hole through which the new measurement gas is introduced and a second exhaust hole through which the measured measurement gas is allowed to flow to the intake and exhaust mechanism; the intake and exhaust mechanism is a single intake and exhaust mechanism connected to the first intake hole and the second intake hole, The pressure difference generating mechanism generates a pressure difference between the first detection chamber and the second detection chamber by making the discharge area of ​​one of the first discharge through hole and the second discharge through hole larger than the discharge area of ​​the other. A gas detection device comprising:

13. 6. The gas detection device according to claim 5, the first detection chamber, the second detection chamber, the light emitting means, the resonance passage, the measurement chamber, and the microphone are disposed on one surface of a substrate, and the intake and exhaust mechanism is disposed on the other surface of the substrate; a control means for controlling operations of the light emitting means, the microphone, and the intake and exhaust mechanism is mounted on the board; The control means operates the light emitting means and the microphone to measure the new measurement gas, and then operates the intake and exhaust mechanism for a predetermined time to exhaust the measured measurement gas from the first detection chamber, the resonance passage, and the second detection chamber. A gas detection device comprising:

14. a first detection chamber and a second detection chamber each having a predetermined volume; A light emitting means that emits light at a predetermined frequency and is disposed in either or both of the first detection chamber and the second detection chamber; a resonant passage fluidly connecting the first detection chamber and the second detection chamber; a measurement chamber fluidly connected to the resonant passage; A microphone is disposed in the measurement chamber and measures the intensity of the photoacoustic wave, At least one of the first detection chamber and the second detection chamber is provided with a passage hole through which the measurement gas passes on a surface on which the light emitting means is provided. A gas detection device comprising:

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