CN212207094U - NDIR gas detection module based on pyroelectric infrared detector - Google Patents
NDIR gas detection module based on pyroelectric infrared detector Download PDFInfo
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- CN212207094U CN212207094U CN202020766025.3U CN202020766025U CN212207094U CN 212207094 U CN212207094 U CN 212207094U CN 202020766025 U CN202020766025 U CN 202020766025U CN 212207094 U CN212207094 U CN 212207094U
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Abstract
The utility model discloses a NDIR gas detection module based on pyroelectric infrared detector, including overcoat casing and optical cavity, the overcoat casing is fixed on the circuit board, be provided with the detection air chamber in the overcoat casing, the ventilative window that link up with the detection air chamber still has been seted up on the overcoat casing, optical cavity sets up in detecting the air chamber, be provided with through type optical channel in the optical cavity, the bleeder vent has been seted up on optical cavity's the chamber wall, follows be provided with infrared source and pyroelectric infrared detector in the optical cavity at optical channel axial both ends respectively, infrared source and pyroelectric infrared detector are connected with the circuit board electricity. The utility model discloses simple structure can effectively promote the comprehensive properties of gaseous module, enlarges its application in the gaseous detection area of high accuracy.
Description
Technical Field
The utility model relates to a sensor technical field, concretely relates to gaseous module that detects of NDIR based on pyroelectric infrared detector.
Background
The existing gas detection module can be divided into non-dispersive infrared, catalytic combustion, electrochemistry, semiconductor gas-sensitive, ultrasonic and the like according to the working principle. The gas detection module based on the non-dispersive infrared (NDIR) principle has the advantages of high precision and sensitivity, good stability and reliability, high reaction speed, strong anti-interference capability, wide range, long service life and the like, is widely applied to the fields of industrial pollutants, indoor environment monitoring and the like, and has very large market prospect.
The NDIR gas detection module generally comprises an infrared light source, a gas chamber, an infrared detector, a processing circuit, a software algorithm and the like. The working principle of the detection module is that different kinds of gas molecules are utilized to show different absorption peaks due to chemical bond vibration under the action of infrared radiation, each gas can have strong absorption to the infrared radiation with specific wavelength, and the absorption capacity can be increased along with the increase of concentration, namely the Lambert beer absorption law, the formula of which is as follows:
I＝I0·e-klc
i is the infrared radiation intensity proportional to the output signal of the infrared detector of the detection channel, I0The infrared radiation intensity is in direct proportion to the output signal of the reference channel infrared detector, k is the absorption coefficient of the target gas, c is the concentration of the target gas, and l is the optical path length from the infrared light source to the infrared detector. Knowing the intensity of the infrared radiation after passing through the target gas, the target gas concentration value can be converted by this formula. The infrared detector is used as the core component of the gas detection module, has the functions of detecting the change of infrared irradiation intensity after passing through the target gas in a non-contact mode, converting the change into a voltage signal, amplifying the voltage signal and outputting the amplified voltage signal to a signal receiverThe signal processing circuit performs analysis.
According to the working principle of the NDIR gas detection module, the signal-to-noise ratio of the infrared detector can directly influence the final performance index of the gas detection module. At present, most infrared detectors for NDIR gas detection modules are in a thermopile type, the amplitude of output signals is weak, and the signal-to-noise ratio is not high. Therefore, the reflectivity of infrared irradiation is improved by polishing the inside of the air chamber or adding a metal coating, the inside of the air chamber is designed into a complex optical focusing curved surface or the power of an infrared light source is increased to improve the infrared irradiation intensity, the technical indexes such as the resolution ratio, the linear error and the like of the gas detection module are improved by adopting the technical means such as the operational amplifier chip with low noise and low offset voltage, and the gas concentration detection precision is improved.
However, the above technical means also causes the problems of complex module structure, increased manufacturing cost, increased power consumption, poor system stability, and the like. At present, many NDIR gas detection modules based on thermopile infrared detectors are on the market, the nominal measurement range is 400-5000 ppm, the resolution ratio is 50-100 ppm and is different, due to the limitation of the performance of the thermopile detectors, the performance index of the gas detection module is further improved on the premise of controlling the manufacturing cost and the volume size, and the application of the NDIR gas detection module in some fields with high-precision detection requirements is limited.
Disclosure of Invention
The to-be-solved technical problem of the utility model is to provide a gaseous module that detects of NDIR based on pyroelectric infrared detector, simple structure can effectively promote the comprehensive properties of gaseous module, enlarges its application in the gaseous detection area of high accuracy.
In order to solve the technical problem, the utility model provides a gaseous module that detects of NDIR based on heat release electric infrared detector, including overcoat casing and optical cavity, the overcoat casing is fixed on the circuit board, be provided with the detection air chamber in the overcoat casing, still set up on the overcoat casing and detect the ventilative window that the air chamber link up, optical cavity sets up in detecting the air chamber, be provided with through type optical channel in the optical cavity, the bleeder vent has been seted up on optical cavity's the chamber wall, follows be provided with infrared source and heat release electric infrared detector in the optical cavity at optical channel axial both ends respectively, infrared source and heat release electric infrared detector are connected with the circuit board electricity, still be provided with the light source light filter in the optical channel of infrared source's illuminating part front end.
Further, a waterproof breathable film is arranged on the breathable window.
Furthermore, an opening is formed in the bottom of the outer casing, the outer casing is sleeved on the optical cavity through the opening, an elastic sealing rubber ring is further arranged between the bottom of the outer casing and the circuit board, and the outer casing is locked on the circuit board through screws.
Furthermore, the pins of the infrared light source and the pins of the pyroelectric infrared detector are connected with the corresponding adapter plates in a welding mode, and the adapter plates are connected with the circuit board in a welding mode.
Furthermore, the pyroelectric infrared detector is of a dual-channel structure and comprises a detection channel and a reference channel, the detection channel and the reference channel are mutually independent, and the detection channel and the reference channel both comprise pyroelectric chips and narrow-band filters which are arranged in a matched mode.
Further, the wavelength range of the infrared light emitted by the infrared light source is 1-16 μm.
Furthermore, the optical cavity is of a hollow cylindrical structure, the air holes are of a circular structure, and the number of the air holes is multiple and the air holes are arranged at equal intervals along the outer surface of the optical cavity.
Furthermore, an infrared mounting hole and a detector mounting hole are respectively formed in two ends of the optical cavity, and the inner cavity of the optical cavity, the infrared mounting hole and the detector mounting hole are coaxially arranged.
Further, the infrared light source and the pyroelectric infrared detector are both packaged in a TO39 mode.
Furthermore, the outer casing is made of polycarbonate, the optical cavity is made of aluminum alloy, and concave-convex matching positioning parts are arranged between the infrared mounting hole and the infrared light source and between the detector mounting hole and the pyroelectric infrared detector.
The utility model has the advantages that:
(1) through using the pyroelectric infrared detector of high performance, simplified optical cavity structural design by a wide margin, adopt simple workable straight-through cylindricality structure, be equipped with infrared light source and pyroelectric infrared detector at optical cavity both ends, not only guaranteed that infrared light distributes evenly in the operating temperature scope to convenient assembling is favorable to reducing the module cost.
(2) Through arranging the optical cavity in the detection air chamber in the outer shell, and adopting the high-performance double-channel pyroelectric detector, the interference of fluctuation of external environmental factors such as temperature, atmospheric pressure, airflow and the like on target gas concentration detection is obviously inhibited, the sensitivity and the stability of the gas module are improved, and the requirement in the field of high-precision gas concentration detection is met.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention;
fig. 2 is an exploded view of the present invention;
fig. 3 is a schematic cross-sectional structure of the present invention.
The numbers in the figures illustrate the following: 1. a jacket shell; 2. an optical cavity; 3. a circuit board; 4. detecting the air chamber; 5. a ventilation window; 6. air holes are formed; 7. an infrared light source; 8. a pyroelectric infrared detector; 9. a light source filter; 10. a waterproof breathable film; 11. an elastic sealing rubber ring; 12. a screw; 13. an adapter plate; 14. the concave-convex matching limiting part.
Detailed Description
The present invention is further described with reference to the following drawings and specific embodiments so that those skilled in the art can better understand the present invention and can implement the present invention, but the embodiments are not to be construed as limiting the present invention.
Referring to fig. 1 to3, an embodiment of the NDIR gas detection module based on pyroelectric infrared detector of the present invention includes an outer casing 1 and an optical cavity 2, the outer casing is fixed on a circuit board 3, a detection air chamber 4 is provided in the outer casing, and the outer casingStill set up on the body with detect ventilation window 5 that the air chamber link up, be provided with waterproof ventilated membrane 10 on the ventilation window, in gas gets into through ventilation window and detects the air chamber, waterproof ventilated membrane plays the effect of separation moisture, form convection diffusion formula structure, and the optics cavity sets up in detecting the air chamber, bleeder vent 6 has been seted up on the chamber wall of optics cavity, the gas that gets into in detecting the air chamber gets into through optical channel that sets up in the optics cavity through the bleeder vent again, be detected by infrared light source 7 and the cooperation of pyroelectric infrared detector 8 that set up respectively in the optical cavity along optical channel axial both ends afterwards, infrared light source and pyroelectric infrared detector are connected with the circuit board electricity. A light source filter 9 made of B is arranged in the optical channel at the front end of the infrared light source luminous partaF2The infrared ray can be effectively filtered, the infrared ray from 2.5 mu m to 12 mu m can be transmitted, and the transmittance at the position of 12 mu m can reach 80%. The circuit board is welded with a chip for signal control, acquisition, processing and storage and a PCB connector, and the PCB connector can be a KF2ED-3.81mm plug-in PCB wiring terminal.
The bottom of the outer casing is provided with an opening, the outer casing is sleeved on the optical cavity through the opening, an elastic sealing rubber ring 11 is further arranged between the bottom of the outer casing and the circuit board, the outer casing is locked on the circuit board through a screw 12, the opening is formed in the bottom of the outer casing, the difficulty of preparing a detection air chamber can be reduced, the outer casing can be matched with the surface of the circuit board to form the bottom-sealed detection air chamber after being fixed with the circuit board through the elastic sealing rubber ring, and the fixing effect of the screw locking is stable and reliable.
The optical cavity is of a hollow cylindrical structure, so that infrared light rays can be conveniently irradiated, the air holes are of a circular structure, the number of the air holes is multiple, and the air holes are arranged at equal intervals along the outer surface of the optical cavity, so that gas can be uniformly diffused into the optical cavity, the consistency of the concentration inside the optical cavity is ensured, and the assembly is convenient. The outer casing is made of polycarbonate and has a cuboid structure, so that the outer casing has the advantages of low preparation cost, light weight, good weather resistance, high strength and effective flame retardance; the preparation material of optics cavity is the aluminum alloy, be convenient for process the hole, it is concrete, infrared mounting hole and detector mounting hole have been processed respectively on optics cavity both ends, the inner chamber of optics cavity, infrared mounting hole and the coaxial setting of detector mounting hole, guarantee that infrared light of infrared light source penetrates directly on pyroelectric infrared detector's detection face, all be provided with unsmooth cooperation location portion 14 between infrared mounting hole and the infrared light source and between detector mounting hole and the pyroelectric infrared detector, guarantee pyroelectric infrared detector and infrared light source installation angle's unity, improve product assembly uniformity.
The signal-to-noise ratio of the pyroelectric infrared detector is one order of magnitude higher than that of a thermopile infrared detector; the overall design effectively promotes the comprehensive properties of the gas module, and the application of the gas module in the high-precision gas detection field is enlarged. Pyroelectric infrared detector is TO39 encapsulation and is the binary channels structure, contains sense passage and reference channel respectively, and sense passage and reference channel mutually independent set up, all contain the pyroelectric chip and the narrowband optical filter that the cooperation set up in sense passage and the reference channel, and the pyroelectric chip of each passageway is 2mm2The JFET tube is integrated in the lithium tantalate slice to form a voltage amplification mode, so that the signal-to-noise ratio is high. The light transmission range of the narrow-band filter of the detection channel is set according to the characteristic absorption peaks of different target gases or according to different characteristic absorption peaks of the same target gas, such as NBPF 4.26 μm-90nm, NBPF 10.56 μm-370 nm. The transmission range of the reference channel narrowband filter is set to be NBPF 3.95um-90 nm.
The infrared light source is made by adopting an MEMS (micro-electromechanical systems) process and can emit infrared light with the wavelength range of 1-16 microns, the infrared light source is packaged by TO39, and when the modulation frequency is 100Hz, the intensity of the infrared light can reach one sixth of that of 1 Hz.
And the pin of infrared source and the pin of pyroelectric infrared detector all with the keysets 13 welded connection that corresponds, keysets and circuit board welded connection, the form of switching can satisfy connection structure's stability when can guaranteeing power supply and signal transmission, can also play the effect that infrared source and pyroelectric infrared detector stably installed. The optical cavity can be fixed on the circuit board through epoxy glue, also can be unsettled to set up in detecting the gas chamber, and during unsettled, optical cavity and infrared light source and pyroelectric infrared detector fixed connection consequently can be with fixed and built on stilts setting of optical cavity through infrared light source, pyroelectric infrared detector and two keysets, form a body coupling structure.
When the pyroelectric infrared detector is used, the infrared light source is modulated to a certain fixed frequency, such as 1Hz, by the MCU circuit on the main circuit board, and emitted infrared light rays are converged through an optical channel in the optical cavity and then reach a detection surface of the pyroelectric infrared detector. Target gas freely diffuses into the detection gas chamber through the waterproof breathable film and then freely diffuses into the optical channel in the optical cavity through the breathable hole again, interference of fluctuation of external environmental factors such as temperature, atmospheric pressure, airflow and the like on target gas concentration detection can be remarkably inhibited through twice diffusion, infrared light rays can be absorbed after passing through the target gas in the optical channel to weaken infrared optical signals, the central wavelength of the optical filter used by the reference channel is 3.95 microns, the infrared light rays with the wavelength are not absorbed by the target gas, the infrared light rays received by the reference channel and the detection channel are inconsistent in intensity, weak electric signals generated by the reference channel and the detection channel are also different, the weak electric signals are amplified and filtered by the analog amplification circuit and then input to an AD interface of the MCU on the circuit board, the AD converted signals are converted into digital signals, and the MCU performs a series of processing on the signals, The table lookup operation (conventional processing method, not detailed) is performed to calculate the gas concentration. The double-channel pyroelectric detector has the advantages that the reference channel signal is only related to the attenuation of the light source and the pollution of the inner wall of the cavity and is unrelated to the change of the gas concentration, and the interference can be eliminated by the reference of the reference channel signal and the reference channel signal, so that a numerical value only for the change of the concentration information is obtained.
This detection module adopts the form that the double-cavity body cover was established for when target gas diffusion got into the second cavity, the interference that external environment factor fluctuation such as temperature, atmospheric pressure, air current detected target gas concentration can be ignored basically, and the use of binary channels pyroelectric infrared detector in addition effectively improves the sensitivity and the stability of gaseous module, thereby satisfies the demand in high accuracy gas concentration detection area.
The above embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. Equivalent substitutes or changes made by the technical personnel in the technical field on the basis of the utility model are all within the protection scope of the utility model. The protection scope of the present invention is subject to the claims.
Claims (10)
1. The NDIR gas detection module based on the pyroelectric infrared detector is characterized by comprising an outer sleeve shell and an optical cavity, wherein the outer sleeve shell is fixed on a circuit board, a detection air chamber is arranged in the outer sleeve shell, a ventilation window communicated with the detection air chamber is further formed in the outer sleeve shell, the optical cavity is arranged in the detection air chamber, a straight-through optical channel is arranged in the optical cavity, air holes are formed in the wall of the optical cavity, an infrared light source and a pyroelectric infrared detector are arranged in the optical cavity along the axial direction of the optical channel, and the infrared light source and the pyroelectric infrared detector are electrically connected with the circuit board.
2. The pyroelectric infrared detector-based NDIR gas detection module as claimed in claim 1, wherein the gas permeable window is provided with a waterproof gas permeable membrane.
3. The NDIR gas detection module based on pyroelectric infrared detector as claimed in claim 1, wherein the bottom of the outer casing is provided with an opening, the outer casing is sleeved on the optical cavity through the opening, an elastic sealing rubber ring is further arranged between the bottom of the outer casing and the circuit board, and the outer casing is locked on the circuit board through screws.
4. The NDIR gas detection module based on pyroelectric infrared detector as claimed in claim 1, wherein the pins of the infrared light source and the pins of the pyroelectric infrared detector are welded with the corresponding adapter plate, and the adapter plate is welded with the circuit board.
5. The NDIR gas detection module based on pyroelectric infrared detector as claimed in claim 1, wherein the pyroelectric infrared detector is a dual-channel structure, and comprises a detection channel and a reference channel respectively, the detection channel and the reference channel are arranged independently, and the detection channel and the reference channel both comprise pyroelectric chips and narrow band filters which are arranged in a matching manner.
6. The NDIR gas detection module based on pyroelectric infrared detector as claimed in claim 1, wherein the wavelength range of the infrared light emitted from the infrared light source is 1 μm-16 μm.
7. The pyroelectric infrared detector-based NDIR gas detection module as claimed in claim 1, wherein a light source filter is further disposed in the optical channel in front of the light emitting part of the infrared light source.
8. The NDIR gas detection module based on pyroelectric infrared detector as claimed in claim 1, wherein the optical cavity is a hollow cylinder structure, the air holes are circular structure, and the number of the air holes is multiple and arranged at equal intervals along the outer surface of the optical cavity.
9. The pyroelectric infrared detector-based NDIR gas detection module as claimed in claim 8, wherein the optical cavity is provided with an infrared mounting hole and a detector mounting hole at two ends, respectively, and the inner cavity of the optical cavity, the infrared mounting hole and the detector mounting hole are coaxially arranged.
10. The NDIR gas detection module based on pyroelectric infrared detector as claimed in claim 9, wherein the infrared light source and pyroelectric infrared detector are both TO39 package, the outer casing is made of polycarbonate, the optical cavity is made of aluminum alloy, and the concave-convex matching positioning parts are arranged between the infrared mounting hole and the infrared light source and between the detector mounting hole and the pyroelectric infrared detector.
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| CN202020766025.3U CN212207094U (en) | 2020-05-11 | 2020-05-11 | NDIR gas detection module based on pyroelectric infrared detector |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113049634A (en) * | 2021-03-19 | 2021-06-29 | 青岛芯笙微纳电子科技有限公司 | Miniature gas sensor based on heat effect |
| WO2023131334A1 (en) * | 2022-01-10 | 2023-07-13 | 杭州三花研究院有限公司 | Gas detection device |
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2020
- 2020-05-11 CN CN202020766025.3U patent/CN212207094U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113049634A (en) * | 2021-03-19 | 2021-06-29 | 青岛芯笙微纳电子科技有限公司 | Miniature gas sensor based on heat effect |
| CN113049634B (en) * | 2021-03-19 | 2022-08-23 | 青岛芯笙微纳电子科技有限公司 | Miniature gas sensor based on heat effect |
| WO2023131334A1 (en) * | 2022-01-10 | 2023-07-13 | 杭州三花研究院有限公司 | Gas detection device |
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Effective date of registration: 20220216 Address after: 215000 room 306, building B, science and technology entrepreneurship Park, Zhangjiagang Free Trade Zone, Suzhou, Jiangsu Patentee after: Suzhou Purong Sensing Technology Co.,Ltd. Address before: No.1 Xihu Road, economic and Technological Development Zone, Qinhuangdao City, Hebei Province Patentee before: INTRINIC CRYSTAL TECHNOLOGY CO.,LTD. |