CN101105449B - Double light source double sensitive element infra-red multiple gas detection sensor - Google Patents
Double light source double sensitive element infra-red multiple gas detection sensor Download PDFInfo
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- CN101105449B CN101105449B CN2007101200698A CN200710120069A CN101105449B CN 101105449 B CN101105449 B CN 101105449B CN 2007101200698 A CN2007101200698 A CN 2007101200698A CN 200710120069 A CN200710120069 A CN 200710120069A CN 101105449 B CN101105449 B CN 101105449B
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Abstract
The invention relates to a birefringence source double sensitive component infrared multi-gas inspecting sensor, which comprises two infrared light emitting diodes, an infrared detector, an air chamber, a reflecting mirror and a metal strainer. The air chamber is a tube shape, and the bottom is a concave spherical surface and the middle part is a column surface. The metal strainer is connected with the top end nozzle of the air chamber, a reflecting mirror is equipped on the rear part of the metal strainer, and the inner surface of the reflecting mirror is a paraboloid. The infrared light emitting diodes and the infrared detector are in the same surface on the bottom of the air chamber, and the infrared light emitting diodes and the infrared detector are distributed symmetrically on the two sides of the center line of the air chamber. The infrared detector is composed of a tube-shaped casing, an infrared sensitive component, a light separating plate, a color absorber and a window. Composed with the prior infrared gas sensor, the invention is prominently characterized in that the non-isolated-type reflecting air chamber is designed and the detecting principle of the birefringence source double sensitive component is adopted, the mismatch of the prior infrared double detector gas sensor detecting component is solved, and the volume is reduced and the survey precision is greatly enhanced.
Description
Technical field
The present invention relates to gas concentration detecting sensor technical field, is a kind of double light source double sensitive element infra-red multiple gas detection sensor.
Background technology
A branch of infrared light intensity will reduce by a gas container time, and loss of strength is the function of active gas molecular amounts in the certain volume, and it is the function of expression gas concentration.The interaction of gas and infrared light only takes place at the specific wavelength of infrared light, with this true combination, can design the concentration that a kind of instrument is used for measuring specific gas.Infrared analyzer unit is a kind of physics formula analytical instrument of the infrared ray absorbing principle being made according to gas.Usually it seems, the continuous coverage of infrared analyzer unit energy, and measurement range is wide, the precision height, and highly sensitive, and good selectivity is arranged.Infrared gas analyzer volume in the past is big, and weight is big, and inconvenience is carried, and the price height.Early stage because the restriction of device, for example in order to reach higher precision, sensor itself needs big air chamber, can't realize miniaturization, present development along with the optical MEMS technology, the particularly appearance of novel semi-conductor device (infrared LED, infrared eye) and micro-optical device (MEMS grating, the infrared thermistor detector of MEMS), the miniaturization of infrared optics gas detecting system has become possibility.
" non-dispersive infrared gas analyser of multiple constituent concentration in the measurement gas sample simultaneously " patent (patent No.: ZL90109218.5) of Frankfurt, Germany Hartmann ﹠ Braun Aktiengesellschaft application, the sample cell that comprises two placed adjacent, they feed sample gas and reference gas respectively, and the radiant light that infrared origin sends passes through sample cell after modulation.Second identical gas radiation receiver of structure is set at the back of first radiation receiver, and fills second kind of composition of sample gas.Between first and second radiation receivers, a radiation filter is set, this wave filter can see through the radiant light of the more weak radiation absorption of second kind of composition in the sample gas.This instrument uses two to isolate sample cell, and volume is bigger.(patent No.: ZL02274241.7), adopted single light source double detector theory structure and reflective air chamber, two detectors are difficult to process just the samely utility model patent " double detector infrared gas analyzer ", have the problem of detector mismatch.Its air chamber is same isolates mutually, and volume is bigger.(patent No.: ZL94242250.3), use chopper to isolate light source, modulation is complicated, and volume is bigger for utility model patent " infrared light multiple gases analyser optical devices ".
Changzhou city section can Electrical Appliances Co., Ltd apply for a kind of infrared sulfur hexafluoride detector patent (application number 200620069040.2) in 2006.This instrument adopts electric adjustable infrared light supply and optics receiving element to be oppositely arranged on and detects the air chamber both sides, electric adjustable infrared light supply emission infrared light passes the detection air chamber and is received by the optics receiving element, temperature compensation unit is connected with the optics receiving element, the pulse regulation unit is connected with electric adjustable infrared light supply, the optics receiving element is connected with signal amplification unit, signal amplification unit is connected with filter unit, filter unit is connected with photoelectric conversion unit, photoelectric conversion unit is connected with the A/D converting unit, logic control CPU and pulse regulation unit, temperature compensation unit and A/D converting unit connect.
This instrument adopts the single channel technology, can't overcome the problem that the variation of infrared light supply output power, detector biasing etc. bring, and accuracy of detection is lower; In addition, this instrument because adopt electric adjustable infrared light supply and orthoscopic air chamber structure that the optics receiving element is oppositely arranged simultaneously again taking into account the certain air chamber length of reservation under the prerequisite of enough signal to noise ratio (S/N ratio)s, so sensor bulk is relatively large.
Summary of the invention
Problems such as it is low to the objective of the invention is to solve existing infrared gas sensor precision, and volume is big provide the high precision double light source double sensitive element infra-red multiple gas detection sensor of a kind of pair of light source, Lazer's sensing unit and open air chamber structure.
The present invention adopts following technical scheme to realize:
A kind of double light source double sensitive element infra-red multiple gas detection sensor, it comprises two infrarede emitting diodes, infrared eye, air chamber, catoptron, metal filter screen;
Described air chamber is a tubular, the bottom of this air chamber becomes concave spherical surface, the middle part of this air chamber is the face of cylinder, top ports place at air chamber is connected with metal filter screen, be provided with catoptron at the metal filter screen rear portion, it is parabolic that the inside surface of this catoptron is, and described infrarede emitting diode and infrared eye are positioned at same plane, air chamber bottom and are the rotational symmetry placement with the air chamber center line; Infrarede emitting diode places the focus place at the bottom of the concave spherical surface air chamber as far as possible, and effect is that infrared light reflection with scattering is to catoptron;
Above-mentioned infrared eye is by cylindrical case, infrared sensor, form every tabula rasa, optical filter and saturating window; Describedly be located at the infrared eye centerline of cylindrical case every tabula rasa, sensitive element is selected thermoelectric type, thermocouple type or photoconduction type infrared spectrum absorbing material for use according to the difference of gas response wave band.Two infrared sensors are symmetrically distributed in every the tabula rasa both sides, and place the bottom of cylindrical case 13, respectively as probe unit and reference unit, the front end of the cylindrical case of infrared eye is provided with the saturating window of sealing, pastes two transmission filters of corresponding gas characteristic wave band to be measured and non-characteristic wave bands wavelength respectively on saturating window inside surface detector center line both sides.
The object of the invention to solve the technical problems can also adopt following technical measures further to realize.
Outer end, bottom at air chamber is provided with the pin welding substrate, connects the modulation of source signal input pin pin that to have two infrarede emitting diodes, the power pins and the signal output pin of two infrared sensors on the pin welding substrate.
Catoptron and air chamber inner surface material adopt the gold-plated or steel chromium plating of brass, to increase ir scattering reflection of light ability.
The material of above-mentioned saturating window is lithium fluoride or calcium fluoride or sapphire single-crystal body, and the light wavelength that sees through is confined in the transmission range of two transmission filters.
According to the difference of the special response wave band of gas, above-mentioned infrared sensor is selected thermocouple type or the thermoelectric type or the photoconduction type infrared spectrum absorbing material of respective response wave band for use.
Metal filter screen makes things convenient for gaseous diffusion to enter air chamber, plays dust reduction capability simultaneously.
The present invention adopts time double light path and Space Double light path to mix detection mode, and described two infrarede emitting diodes are alternately luminous, and two infrared sensors obtain four road detection signals.
Index path of the present invention is Space Double light beam and time twin-beam mixing detection mode (seeing shown in Figure 1);
Major parameter in the index path: the light intensity of two LEDs 1, LED2 is respectively I
r, I
m, the responsiveness of two sensitive elements is respectively R
r, R
m, the projection of tested gas is than being τ
a, and the transmittance of air chamber is τ
0, the optical filter that is attached to reference unit 1 is the arrowband transmission filter of centre wavelength away from tested gas characteristic absorption peak, the optical filter that is attached on the probe unit 2 is the arrowband transmission filter of the corresponding tested gas characteristic absorption peak of centre wavelength.By the optical filter of the integrated corresponding gas with various characteristic absorption peak sensitive element material different, promptly can measure different types of gas with response wave band.
Infrarede emitting diode by foreign frequency 4Hz, amplitude is+the pulse square wave driven of 5V respectively.Two light emitting diodes replace fluorescent lifetime and are spaced apart 5ms, probe unit optical filter and reference unit optical filter have correspondingly become two light paths to optical system, so just realized that light path is Space Double light beam and time twin-beam mixing detection mode, promptly surveys light path and reference path.
The transmittance of supposing gas is τ
aThe transmittance of air chamber is τ
0, when LED 1 sent pulsed light, the output voltage of sensitive element 1 and sensitive element 2 was respectively
V
rr＝I
rR
r (1)
V
rm＝I
rR
mτ
aτ
0 (2)
When driven for emitting lights diode (LED) 2 sent pulsed light, the output voltage of sensitive element 1 and sensitive element 2 was respectively
V
mr＝I
mR
r (3)
V
mm＝I
mR
mτ
aτ
0 (4)
Then obtain the factor K relevant with gas concentration value
Sensitive element will produce one with responsiveness and emissive porwer irrelevant and and τ
a 2τ
0 2The signal that is directly proportional.With Lazer's sensing unit, two light source, can eliminate lumination of light emitting diode power (I like this
r, I
m) unsettled influence and sensitive element responsiveness (R
r, R
m) unsettled influence.Eliminated I, R influence back signal only with the transmittance τ of tested gas
aThe transmittance τ of air chamber
0(because attenuation that optical device and dust cause) is relevant.
Survey sensitive element and with reference to the signal of sensitive element by receiving with the subsequent detection circuit, directly the variable after offsetting is handled, it obtains the result of formula (5) by computed in software, can reduce the influence of drift and elimination dust and steam, reduce the source of error, improved the precision of measuring.It is reflective that light path design becomes, and the advantage of this design is that infrared energy passes tested gas for twice, has guaranteed suitable optical path distance in smaller size smaller, has also improved accuracy of detection.Because reference path and to measure light path be to work under same environment, the potential difference (PD) ratio of getting both compares, and has just avoided changing the drift that causes because of environmental change and sensitive element responsiveness.
The present invention compares with existing infrared gas sensor, its outstanding substantive distinguishing features is the detection principle that has designed non-isolated reflection air chamber and adopted two light source Lazer sensing unit, solved the disadvantage of existing infrared double detector gas sensor detecting element mismatch, reduced volume, when reducing volume, make detection accuracy improve one more than the order of magnitude, detection accuracy is improved greatly.
Description of drawings
Fig. 1 is a light path synoptic diagram of the present invention.
Fig. 2 is a main TV structure synoptic diagram of the present invention.
Fig. 3 is that air chamber is looked on Fig. 2 right side and infrared eye partly cuts open structural representation.
Fig. 4 is that infrared eye partly cuts open the structure for amplifying synoptic diagram.
Fig. 5 is Fig. 4 infrared eye left side TV structure synoptic diagram.
Fig. 6 is that Fig. 2 A-A is to structural representation.
Embodiment
Referring to Fig. 2～shown in Figure 6: a kind of double light source double sensitive element infra-red multiple gas detection sensor, it comprises two infrarede emitting diodes 1,2, infrared eye 3, air chamber 4, catoptron 5, metal filter screen 6;
Described air chamber 4 is a tubular, the bottom of this air chamber 4 becomes concave spherical surface 15, the middle part of this air chamber 4 is the face of cylinder, top ports place at air chamber is connected with metal filter screen 6, be provided with catoptron 5 at the metal filter screen rear portion, it is parabolic that the inside surface of this catoptron 5 is, and described infrarede emitting diode 1,2 and infrared eye 3 are positioned at same plane, air chamber bottom and are the rotational symmetry placement with the air chamber center line; Infrarede emitting diode places the focus place at the bottom of the concave spherical surface air chamber as far as possible, and effect is that infrared light reflection with scattering is to catoptron.
Described infrared eye 3 is by cylindrical case 13, infrared sensor 9, form every tabula rasa 10, optical filter 11 and saturating 12; The described infrared eye centerline of being located at cylindrical case every tabula rasa 10, two infrared sensors are symmetrically distributed in every the tabula rasa both sides, and place the bottom of cylindrical case 13, respectively as probe unit and reference unit, the front end of the cylindrical case 13 of infrared eye is provided with the saturating window 12 of sealing, pastes two transmission filters 11 of corresponding gas characteristic wave band to be measured and non-characteristic wave bands wavelength respectively on saturating window inside surface detector center line both sides.
Outer end, bottom at air chamber 4 is provided with pin welding substrate 7, connects the modulation of source signal input pin 16 that to have two infrarede emitting diodes 1,2, the power pins 14 and the signal output pin 8 of two infrared sensors on pin welding substrate 7.
Catoptron and air chamber inner surface material adopt the gold-plated or steel chromium plating of brass.
The material of described window is lithium fluoride or calcium fluoride or sapphire single-crystal body.
Described infrared sensor is thermocouple type or thermoelectric type or photoconduction type infrared spectrum absorbing material.
During use, gas diffuses into air chamber from metal filter screen; Can be directly welded in sensor on the circuit board or place special base.
This double light source double sensitive element infra-red multiple gas detection sensor has that volume is little, low in energy consumption, highly sensitive, good stability, the advantages such as easy batch production, by usage space dual-beam and time dual-beam mixing detection mode, solved the shortcomings such as the two detection infrared sensor detecting element mismatches of existing single light source, volume are big, made accuracy of detection improve one more than the order of magnitude. By the optical filter that the changes corresponding gas with various characteristic absorption peak sensing element material different with response wave band, namely can detect different types of gas.
Claims (6)
1. double light source double sensitive element infra-red multiple gas detection sensor, it is characterized in that: it comprises two infrarede emitting diodes (1,2), infrared eye (3), air chamber (4), catoptron (5), metal filter screen (6);
Described air chamber (4) is a tubular, the bottom of this air chamber (4) becomes concave spherical surface (15), the middle part of this air chamber (4) is the face of cylinder, be connected with metal filter screen (6) at the top ports place of air chamber, be provided with catoptron (5) at the metal filter screen rear portion, it is parabolic that the inside surface of this catoptron (5) is, and described two infrarede emitting diodes (1,2) are positioned at same plane, air chamber bottom with infrared eye (3) and are that rotational symmetry is placed with the air chamber center line;
Described infrared eye (3) is by cylindrical case (13), infrared sensor (9), form every tabula rasa (10), optical filter (11) and saturating window (12); The described infrared eye centerline of being located at cylindrical case every tabula rasa (10), two infrared sensors are symmetrically distributed in every the tabula rasa both sides, and place the bottom of cylindrical case (13), respectively as probe unit and reference unit, the front end of the cylindrical case of infrared eye (13) is provided with the saturating window (12) of sealing, pastes two transmission filters (11) of corresponding gas characteristic wave band to be measured and non-characteristic wave bands wavelength respectively on saturating window inside surface detector center line both sides.
2. double light source double sensitive element infra-red multiple gas detection sensor according to claim 1, it is characterized in that: be provided with pin welding substrate (7) in the outer end, bottom of air chamber (4), on pin welding substrate (7), connect the power pins (14) and the signal output pin (8) of the modulation of source signal input pin (16) that to have two infrarede emitting diodes (1,2), two infrared sensors.
3. double light source double sensitive element infra-red multiple gas detection sensor according to claim 1 and 2 is characterized in that: catoptron and air chamber inner surface material adopt the gold-plated or steel chromium plating of brass.
4. double light source double sensitive element infra-red multiple gas detection sensor according to claim 3 is characterized in that: the material of described window is lithium fluoride or calcium fluoride or sapphire single-crystal body.
5. double light source double sensitive element infra-red multiple gas detection sensor according to claim 4 is characterized in that: described infrared sensor is thermocouple type or thermoelectric type or photoconduction type infrared spectrum absorbing material.
6. double light source double sensitive element infra-red multiple gas detection sensor according to claim 5, it is characterized in that: adopt time double light path and Space Double light path to mix detection mode, described two infrarede emitting diodes are alternately luminous, and two infrared sensors obtain four road detection signals.
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| CN2007101200698A CN101105449B (en) | 2007-08-08 | 2007-08-08 | Double light source double sensitive element infra-red multiple gas detection sensor |
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| CN2007101200698A CN101105449B (en) | 2007-08-08 | 2007-08-08 | Double light source double sensitive element infra-red multiple gas detection sensor |
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| CN101105449B true CN101105449B (en) | 2010-09-15 |
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