CN101349642A - Infrared gas sensor based on optical reading technique - Google Patents
Infrared gas sensor based on optical reading technique Download PDFInfo
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- CN101349642A CN101349642A CN 200810058805 CN200810058805A CN101349642A CN 101349642 A CN101349642 A CN 101349642A CN 200810058805 CN200810058805 CN 200810058805 CN 200810058805 A CN200810058805 A CN 200810058805A CN 101349642 A CN101349642 A CN 101349642A
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Abstract
The invention relates to an infrared gas sensor on the base of the optical readout technique, which comprises an upper cover, a lower cover, a deflected film, a reference deflected film, a light-guiding block, a data processing circuit, a filter, a reference filter, a heat insulation block, a white LED light source, a RGB color digital sensor and a constant temperature ring, wherein the deflected film is fixed by a suspension arm, two surfaces of the film are respectively a visible light reflecting surface and an infrared heat-absorbing surface, wherein the visible light reflecting surface of the film is provided with a convex and concave reflection-type grid structure, and the infrared heat-absorbing surface of the film is formed by materials which have great difference with the thermal elasticity coefficients of materials for producing the visible light reflecting surface. The infrared gas sensor adopts an optical readout technique, which changes the variation of gas concentration into the variation of the wavelength of visible light, and the variation of the wavelengths of visible light is output in digital signals through the RGB color digital sensor. The infrared gas sensor removes a signal processing circuit which is magnified by weak signals, avoids an easily-disturbed step, improves the reliability, the stability and the measurement precision of the infrared gas sensor, and lowers the production cost.
Description
Technical field:
The invention belongs to the device that gas concentration is converted to numeral output, be specifically related to a kind of infrared gas sensor.
Technical background:
Gas sensor is to adopt the element that the gas that is detected is had a sensitivity characteristic concentration of gas to be converted into the device of corresponding electric signal.According to the difference of the gas detecting element that is adopted, gas sensor has different types such as semiconductor gas sensor, electrochemical gas sensor, solid-state electrolyte gas sensor, carrier catalysis combustion type gas sensor, optical type gas sensor, macromolecule gas sensor.
In these sensors of various types, the infrared gas sensor in the optical type gas sensor is a purposes gas sensor extensive, the most with the fastest developing speed.
Advantages such as response speed is fast, measuring accuracy is high, the life-span is long although infrared gas sensor has, the calibrate cycle is long have very important weakness equally.It is very faint to the absorption of infrared spectrum mainly to show as all gases, and concentration is low more, and the variable quantity of infrared signal is more little.With regard to methane gas sensor, the voltage of exporting during corresponding to 1% concentration change based on the sensor of carrier catalysis principle of work reaches the millivolt level, and the output during corresponding to 1% concentration change only can reach the microvolt level based on the sensor of infrared-gas principle of absorption work, both compare, the latter is low three orders of magnitude, greatly improved the designing requirement of sensor front end and follow up amplifier, be difficult to realize that high sensitivity, high-precision gas concentration detect cheaply.
How could effectively improve the sensitivity and the resolution of infrared gas sensor, reduce the designing requirement and the manufacturing cost of sensor front end and follow up amplifier, be improve sensor stability and reliability and make it must solution with lower cost replacement vector catalytic sensor institute major issue.
Technology contents:
The object of the present invention is to provide a kind ofly can significantly improve infrared gas sensor sensitivity and resolution, and can guarantee when reducing manufacturing cost that sensor is stable, the new infrared gas sensor of reliably working.
The present invention adopts optical reading technique, faint gas concentration is changed converting the wavelength of visible light variation to, and with RGB colorful digital sensor the wavelength of visible light variation is showed with digital signal.
The present invention adopts following technical scheme to constitute infrared gas sensor based on optical reading technique.
A kind of infrared gas sensor based on optical reading technique, by loam cake, lower cover, tested gas deflection film, reference deflection film, the leaded light piece, the data processing circuit plate, tested gas optical filter, the reference optical filter, heat insulation, tested gas White LED light source, the reference gas White LED light source, tested gas RGB colorful digital sensor, reference RGB colorful digital sensor, the constant temperature ring is formed, it is characterized in that: a surface of described deflection film is the visible light reflecting surface with the alternate reflection-type grating structure of convex-concave, another surface is the infrared heat-absorbent surface that has the material than big difference to constitute by the hot coefficient of dilatation with visible light reflecting surface composition material, and described deflection film cantilever is fixed.
White LED light source adopts known paster encapsulation white light-emitting diode, optical filter adopts known product, G20, G5 optical filter as perkinelme company, RGB colorful digital sensor adopts known patch-type encapsulating products, as the ADJD-S371-QR999 colorful digital sensor of AVGO company.
The wide spectrum infrared light that is sent by infrared light supply passes the optical filter that the air chamber that contains tested gas arrives sensor, obtains the infrared light of specific wavelength after optical filter filters; The infrared radiation of this specific wavelength is to the heat-absorbent surface of deflection film, because the heat effect of Infrared, make the film curved deflector, the size of deflection angle has reflected the power that shines infrared light on the film, infrared light is weak more, the film deflection angle is more little, shows that the concentration of tested gas is high more, and is many more by the infrared light of gas absorption.The incident angle that shines the compound white light on the thin film grating reflecting surface with fixed angle changes because of the deflection of film, the diffraction light wavelength that thereupon produces on specific direction also changes, thus, finish tested gas concentration and changed the variation that converts the different wave length of diffraction light on specific direction to.Subsequently, RGB colorful digital sensor converts the diffraction light of different wave length on the specific direction to high-resolution digital signal output that three AD converter quantification numerical digit width are 10bit.
Compared with prior art, the present invention has the following advantages.
The sensitivity of sensor, resolution, measuring accuracy, stability, reliability all are improved, and simultaneously, have reduced the cost of sensor.
The infrared heat responsiveness of existing rpyroelectric infrared methane gas sensor is usually less than 600V/W, the power of infrared light supply is lower than 500mW, after light source omnidirectional disperses, shine useful power on the sensor along with the increase of irradiation distance becomes the relation decay of 2 powers, the change in voltage on the pyroelectric sensor that concentration change caused of methane gas 1% is about 10 microvolts.Because the change in voltage on gas concentration variation and the sensor is proportionate, under 0.01% gas concentration change condition, change in voltage on the sensor approximately is 0.1 microvolt, detect this faint change in voltage, and amplifier gain at least will be up to more than the 140DB.In fact, the highest detection precision that existing infrared methane sensor can be realized can only reach 0.1% concentration change, and the change in voltage of 1 microvolt is suitable approximately and on the sensor.Because the change in voltage of sensor output is minimum, signal is submerged in the noise under a lot of situations, because the amplifier full gain is high, any small noise or voltage fluctuation, temperature variation all can be amplified noise, cause the measuring accuracy of sensor and lean on property decline.
In the infrared sensor based on optical reading technique of patent disclosure of the present invention, the deflection film is formed through indeformable micro unit serial connection by a plurality of distortion micro units.The distortion micro unit is made up of the material that two kinds of thermal expansivity differ greatly, and indeformable unit is made up of homogenous material, the fixing cantilever design that forms of an end of film.The deflection of film cantilever free end is got by the stack of each distortion micro unit deflection on the whole film tape.For example, the length sum (also being the raster pitch cycle) of distortion micro unit and indeformable micro unit is when being 750 nanometers, 2666 distortion micro units are arranged on 2000 microns long film tapes approximately, and average little deflection that the deflection that obtains at the film cantilever free end is equivalent to each distortion micro unit has amplified 2666 times! Be equivalent in sensor, be provided with a front-end amplifier that does not efficiently have the electrical equipment noise, effectively improved the response sensitivity of sensor the faint variation of gas concentration.
Improving sensor to gas concentration in the faint variation response sensitivity, the present invention also utilizes the color separation principle of diffraction grating, the measurement yardstick that detects the deformation of thin membrane amount has been narrowed down to the nanoscale of different colours wavelength of light distribution range.For example, RGB that the present invention selects for use numeral output color sensor is 645 nanometers to the peak value of response wavelength of red light, is 542 nanometers to the peak value of response wavelength of green light, is 460 nanometers to the peak value of response wavelength of blue coloured light.Be subjected to the gas concentration variable effect, when gas concentration strengthens gradually, it is to taper to green light (542 nanometer) by red (645 nanometer) light that film deflection causes the process of diffraction light wavelength variations, change the process of blue coloured light (460 nanometer) again into, in whole visible light variation range, wavelength difference is 185 nanometers, and each primary colours AD converter of RGB colorful digital sensor the position long be 10bit, the color-resolution that is obtained by three AD converter is combined as 2
30=1073741824,185 nanometers are again by 2
30Segmentation, as seen, very faint film changes and can both be measured comes out, and has greatly improved the resolution of the little deflection of detection film.
With the infrared gas sensor of prior art is that concentration change with gas shows different with faint change in voltage, infrared gas sensor of the present invention is the wavelength variations of brightness and the sufficiently high diffraction light of color saturation with the change transitions of gas concentration, the wavelength signals of diffraction light is by RGB colorful digital sensor sample, amplify, be converted into the output of RGB three primary colours digital signal, removed feeble signal amplifying signal modulate circuit, avoid the link that is subject to disturb, effectively improved sensor reliability, reduced the sensor cost in the time of stability and measuring accuracy.
Description of drawings:
Fig. 1 is front view, sectional view, the shaft side figure of infrared gas sensor.
Fig. 2 is the sectional view of deflection film.
Fig. 3 is a RGB colorful digital principle of sensors block diagram.
Fig. 4 is the fundamental diagram of infrared gas detector.
Specific embodiments:
Referring to Fig. 1, a kind of infrared gas sensor of reading based on optics is made up of loam cake 1, lower cover 2, tested gas deflection film 3, reference deflection film 4, leaded light piece 5, data processing circuit 6, tested gas optical filter 7, reference optical filter 8, heat insulation 9, tested gas White LED light source 10, reference gas White LED light source 11, tested gas RGB colorful digital sensor 12, reference RGB colorful digital sensor 13, constant temperature ring 14.
The infrared light wavelength that penetrates tested gas optical filter 7 be special setting can and have the wavelength of maximum absorption peak by tested gas absorption, for methane, this wavelength is 3.30 microns.The wavelength that penetrates the Infrared of reference filter plate 8 is near tested gas maximum absorption wavelength, and can not be by tested gas absorption, and simultaneously also not by the wavelength of other gas absorption, reference wavelength is chosen as 3.95 microns.
When containing tested gas in the air chamber, the Infrared that penetrates reference filter plate 8 is not absorbed, and the infrared light intensity that is radiated on the reference deflection film 4 is eager to excel than penetrating the light intensity that tested gas optical filter 7 shines on the tested gas deflection film 3.Because light intensity difference, it is also different to be radiated two heats on the film, cause the deflection angle difference of two films, the diffraction light wavelength is also different on specific direction, each component that the rgb light that tested gas RGB colorful digital sensor 12 and reference RGB color data sensor 13 collect is strong is also inequality, and each value of RGB of two RGB colorful digital sensor outputs is also inequality.After 6 couples of two-way RGB of digital processing unit circuit data are handled, can obtain getting rid of environmental interference, only by the wavelength variable quantity due to the gas absorption.According to the correlationship of visible wavelength variable quantity and tested gas concentration, can calculate the concentration of tested gas.
Fig. 2 has provided the part sectioned view of deflection film 3.Optical grating reflection face (22) is deposited on the thermal absorption face (21) by the mode of plated film, the structure that the indeformable district serial connection that the distorted area that the formation double layer material is formed is formed by single material links to each other.After each distorted area and the indeformable district serial connection, form a distortion micro unit.The length of each distortion micro unit also is the pitch cycle of grating simultaneously.Little distortion of each micro unit is transmitted through accumulation, becomes the moderate finite deformation of film cantilever free end.
Fig. 3 is the principle of work synoptic diagram of known RGB color data product sensor ADJD-S371-QR999.The white composite line that is sent by White LED light emitting diode 31 is under the guiding of the light pilot hole of leaded light piece 5 shown in Figure 1, shine on tested gas deflection film 3, the reference deflection film 4 with fixing incident angle, be reflected on R red sensor 32 shown in Figure 3, the green sensor 33 of G and the blue look sensor 34 of B at the diffraction light that produces on the film, sampling module 36 is sent in the output of RGB sensor, data after the sampling enter AD converter 37, form the RGB data output of three groups of long 10bit of being respectively in position.
Fig. 4 utilizes sensor of the present invention to form the principle of work synoptic diagram of an infrared gas detector.
Above embodiment only is a specific embodiment of the present invention, and this embodiment does not produce restriction to basic essential elements of the present invention.
Claims (1)
1, a kind of infrared gas sensor based on optical reading technique, by loam cake, lower cover, tested gas deflection film, reference deflection film, the leaded light piece, the data processing circuit plate, tested gas optical filter, the reference optical filter, heat insulation, tested gas White LED light source, the reference gas White LED light source, tested gas RGB colorful digital sensor, reference RGB colorful digital sensor, the constant temperature ring is formed, it is characterized in that: a surface of described deflection film is the visible light reflecting surface with the alternate reflection-type grating structure of convex-concave, another surface is the infrared heat-absorbent surface that has the material than big difference to constitute by the hot coefficient of dilatation with visible light reflecting surface composition material, and described deflection film cantilever is fixed.
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| CN 200810058805 CN101349642A (en) | 2008-08-11 | 2008-08-11 | Infrared gas sensor based on optical reading technique |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102466522A (en) * | 2010-11-09 | 2012-05-23 | 南阳森霸光电有限公司 | Pyroelectric infrared sensor |
| CN102803936A (en) * | 2010-04-02 | 2012-11-28 | 3M创新有限公司 | Filter systems including patterned optical analyte sensors and optical readers |
| CN109211823A (en) * | 2017-06-29 | 2019-01-15 | 韩国交通大学校产学合作团 | The non-dispersive infrared carbon dioxide gas sensor of hydrophobic film with deposition |
-
2008
- 2008-08-11 CN CN 200810058805 patent/CN101349642A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102803936A (en) * | 2010-04-02 | 2012-11-28 | 3M创新有限公司 | Filter systems including patterned optical analyte sensors and optical readers |
| US8858692B2 (en) | 2010-04-02 | 2014-10-14 | 3M Innovative Properties Company | Filter systems including patterned optical analyte sensors and optical readers |
| CN102803936B (en) * | 2010-04-02 | 2016-03-23 | 3M创新有限公司 | Comprise the filter system of patterned optical analyte sensor and optical reader |
| US9440176B2 (en) | 2010-04-02 | 2016-09-13 | 3M Innovative Properties Company | Filter systems including patterned optical analyte sensors and optical readers |
| CN102466522A (en) * | 2010-11-09 | 2012-05-23 | 南阳森霸光电有限公司 | Pyroelectric infrared sensor |
| CN102466522B (en) * | 2010-11-09 | 2013-04-24 | 南阳森霸光电有限公司 | Pyroelectric infrared sensor |
| CN109211823A (en) * | 2017-06-29 | 2019-01-15 | 韩国交通大学校产学合作团 | The non-dispersive infrared carbon dioxide gas sensor of hydrophobic film with deposition |
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Open date: 20090121 |