CN214703308U - System for reducing temperature drift and improving detection precision of water pollution factors - Google Patents
System for reducing temperature drift and improving detection precision of water pollution factors Download PDFInfo
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- CN214703308U CN214703308U CN202121057241.1U CN202121057241U CN214703308U CN 214703308 U CN214703308 U CN 214703308U CN 202121057241 U CN202121057241 U CN 202121057241U CN 214703308 U CN214703308 U CN 214703308U
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Abstract
The utility model discloses a system for reduce temperature drift, improve water pollution factor and detect precision, should include color comparison pond, LED light source and transmission end photoelectric detector, emit end photoelectric detector, transmission end photoelectric detector converts the luminous intensity of transmitted light into detection end voltage signal, emits end photoelectric detector with the luminous intensity of the light that emits of LED light source converts reference end voltage signal; the correction unit corrects the voltage signal at the detection end to obtain a corrected voltage signal; the analysis unit is used for obtaining the pollution factor value in the sample by utilizing the corrected voltage signal. The utility model discloses, utilize the luminous intensity that the light source jetted out the end to rectify the luminous intensity of transmitted light, owing to adopt the same photoelectric detector, consequently, can get rid of noise signal's influence, improved the detection precision, reduced the temperature drift, data error, accuracy and repeatability all obtain very big promotion.
Description
Technical Field
The utility model relates to a water pollution factor detection technology field such as pollution sources and surface water, concretely relates to reduce the temperature and float, improve the system that water pollution factor detected the precision, especially a water pollution factor detecting system.
Background
At present, the assessment factors (detection indexes) of the pollution source and the surface water in China mainly comprise chemical oxygen demand (CODcr), ammonia nitrogen (NH3-N), Total Phosphorus (TP), Total Nitrogen (TN) and permanganate index (CODmn), and the national standard method is mainly a chemical method of laboratory analysis, is complex and long in time-consuming to operate, cannot be monitored in real time, and cannot meet the development requirement of modern environmental monitoring.
Therefore, the chinese utility model CN 102680462B discloses a method and a monitoring device for on-line monitoring of the content of multiple heavy metals in a water body, which adopts a measuring light source capable of providing light sources with multiple wavelengths or continuous wavelengths; the control system samples, reacts and develops color, and specific wavelength light in a measuring light source is adopted to carry out absorbance measurement on the colorimetric solution by an optical detection device, wherein the optical detection device is an optical sensor or a spectrometer; after the control system measures the content of heavy metal pollutants corresponding to light with a specific wavelength in a water sample to be measured, the measurement of the content of heavy metal corresponding to the light with the wavelength is finished; and (5) circulating the chromogenic measurement until the content of all heavy metal pollutants is determined to be finished. The scheme adopts a spectrometer with a light splitting function, and the content of heavy metal substances in various different water is determined by detecting transmitted light of a contrast color cell. Although the monitoring efficiency is improved, because the receiving signals of the photodetectors in the spectrometer are generally very weak, and the signals output by the photodetectors are often deeply buried in noise, the detection result is greatly influenced by the noise and the temperature drift, the detection precision is low, and the repeatability is poor.
In view of the above, there is a need for improvement of the existing water pollution factor detection method and system to reduce the temperature drift and improve the detection accuracy of the water pollution factor.
SUMMERY OF THE UTILITY MODEL
To the above defect, the utility model aims to solve the technical problem that a system for reduce the temperature and float, improve water pollution factor and detect the precision is provided to it is lower to solve prior art detection precision, the relatively poor problem of repeatability.
For this reason, the utility model provides a system for reduce temperature drift, improve water pollution factor and detect precision, including being used for making the sample produce the color comparison pond of digesting the reaction, and be used for to the color comparison pond provides the LED light source of incident light, and is used for detecting the warp the transmission end photoelectric detector of the transmitted light of color comparison pond, transmission end photoelectric detector converts the luminous intensity of transmitted light into sense terminal voltage signal ADmea, still includes:
the emitting end photoelectric detector is the same as the transmission end photoelectric detector, is arranged at the emitting end of the LED light source, and is used for detecting the light intensity of the emitted light of the LED light source and converting the light intensity into a reference end voltage signal ADref;
a correction unit, configured to correct the detection terminal voltage signal ADmea by using a formula ADxz ═ ADmea/ADref, so as to obtain a corrected voltage signal ADxz;
and the analysis unit is used for analyzing the corrected voltage signal ADxz by utilizing the linear relation between the pollution factor value and the light intensity voltage signal of the transmitted light to obtain the pollution factor value in the sample.
In the above system, preferably, the LED light source is driven by a constant current source type photo-emission circuit, and the constant current source type photo-emission circuit includes:
and a CS pin of the constant current driver is connected with a GND pin through an external resistor, and the wavelength of the LED light source is changed by adjusting the external resistor.
In the above system, preferably, the emitting-end photodetector and the transmitting-end photodetector each include a pre-amplification circuit, a main amplification circuit, and a filter circuit, light emitted from the LED light source is converted into a reference-end voltage signal ADref sequentially through the pre-amplification circuit, the main amplification circuit, and the filter circuit of the emitting-end photodetector, and the transmitted light is converted into a detection-end voltage signal ADmea sequentially through the pre-amplification circuit, the main amplification circuit, and the filter circuit of the transmitting-end photodetector.
According to the above technical scheme, the utility model provides a system that reduction temperature is floated, is improved water pollution factor and is detected precision has solved prior art and has detected the precision lower, the relatively poor problem of repeatability. Compared with the prior art, the utility model discloses following beneficial effect has:
adopt the photoelectric detector the same with the detection end, gather the luminous intensity of light source outgoing end to rectify the luminous intensity of transmitted light, can get rid of noise signal's influence, improve and detect the precision, reduce the temperature drift, data error, accuracy and repeatability all obtain very big promotion.
Drawings
In order to clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments of the present invention or the prior art will be briefly described and explained below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a flow chart of a method for reducing temperature drift and improving detection accuracy of water pollution factors provided by the present invention;
FIG. 2 is a schematic view of a system for reducing temperature drift and improving detection accuracy of water pollution factors provided by the present invention;
fig. 3 is a schematic circuit diagram of a medium constant current source type photoemission circuit according to the present invention;
fig. 4 is a schematic diagram of a middle transmission end photodetector according to the present invention;
fig. 5 is a circuit diagram of the main amplifier circuit of the present invention;
fig. 6 is a circuit diagram of the filter circuit of the present invention;
fig. 7 shows the data of the detection result of the present invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiment of the present invention, under the premise that the person skilled in the art does not make creative work, all other embodiments obtained belong to the protection scope of the present invention.
The utility model discloses an implementation principle is:
simultaneously detecting the light intensity of the light source emitting end and the light intensity of the transmitted light which is emitted out of the cuvette by using the same photoelectric detector, converting the light intensity of the light source emitting end into a reference end voltage signal ADref, and converting the light intensity of the transmitted light into a detection end voltage signal ADmea;
correcting the detection end voltage signal ADmea by using a formula ADxz ═ ADmea/ADref to obtain a corrected voltage signal ADxz;
and analyzing the corrected voltage signal ADxz by utilizing the linear relation between the pollution factor value and the light intensity voltage signal of the transmitted light to obtain the pollution factor value in the sample.
The utility model provides a scheme utilizes the luminous intensity that the light source jetted out the end to rectify the luminous intensity of transmitted light, owing to adopt the same photoelectric detector, consequently, can get rid of among the photoelectric detector noise signal's influence, improved the detection precision, reduced the temperature drift, data error, accuracy and repeatability all obtain very big promotion.
In order to explain and explain the technical solution and implementation of the present invention more clearly, several preferred embodiments for implementing the technical solution of the present invention are introduced below.
It should be noted that the terms of orientation such as "inside, outside", "front, back" and "left and right" are used herein as reference objects, and it is obvious that the use of the corresponding terms of orientation does not limit the scope of protection of the present invention.
Referring to fig. 1, fig. 1 is a flow chart of a method for reducing temperature drift and improving detection accuracy of water pollution factors according to the present invention.
As shown in fig. 1, the method comprises the steps of:
and step 110, putting the sample into the colorimetric pool, and carrying out digestion reaction with the reagent in the colorimetric pool.
Step 120, adjusting the wavelength of the LED light source according to the contamination factor in the sample to be detected.
Step 130, using the same photodetector to simultaneously detect the light intensity of the light source emitting end and the light intensity of the transmitted light emitted from the cuvette, converting the light intensity of the light source emitting end into a reference terminal voltage signal ADref, and converting the light intensity of the transmitted light into a detection terminal voltage signal ADmea;
step 140, correcting the detection terminal voltage signal ADmea by using a formula ADxz ═ ADmea/ADref, so as to obtain a corrected voltage signal ADxz;
and 150, analyzing the corrected voltage signal ADxz by utilizing the linear relation between the pollution factor value and the light intensity voltage signal of the transmitted light to obtain the pollution factor value in the sample.
The system is provided with a linear relation between the value of the pollution factor and the light intensity voltage signal of the transmitted light, which is obtained by calibrating for a plurality of times in advance as in the prior art, and of course, a standard curve in the prior art can be adopted, and the test process is completely the same as that of the standard curve, for example: the same test conditions such as reagents and test temperature are adopted.
The utility model discloses the scheme is got the correction transmitted light value of the light detection absorbance of color comparison pond, comes the theoretical concentration of original particular material of reduction to get rid of the influence that temperature, circuit noise caused.
In the above steps, a method for detecting a specific contamination factor in a sample is described, for example, any one of chemical oxygen demand (CODcr), ammonia nitrogen (NH3-N), Total Phosphorus (TP), Total Nitrogen (TN), and permanganate index (CODmn), which is to be detected, the wavelength of the light emitted from the LED light source, and corresponding reagents and test conditions need to be changed according to the contamination factor, and the result is compared with a preset corresponding curve.
Therefore, various pollution factor values in the sample are obtained through multiple times of detection and analysis.
The first embodiment is described in detail.
Please refer to fig. 2, fig. 2 is a schematic diagram of a system for reducing temperature drift and improving detection precision of water pollution factors according to an embodiment of the present invention, that is, a water pollution factor detection system capable of reducing temperature drift and improving detection precision of water pollution factors.
As shown in FIG. 2, the system comprises an LED light source 10, an exit side photodetector 20, a digestion reaction cuvette 30, a transmission side photodetector 40, a calibration unit 50, and an analysis unit 60.
And the LED light source 10 is used for generating a beam of parallel monochromatic light and vertically passes through the digestion reaction colorimetric pool 30 along the longitudinal direction. The LED light source 10 may be a monochromatic LED light source, or the emitted light from the LED light source 10 may be filtered into monochromatic light.
The outgoing-side photodetector 20 and the transmission-side photodetector 30 adopt the same structure (parameters).
The emitting end photoelectric detector 20 is disposed at an emitting end of the LED light source, and is configured to detect light intensity of light emitted from the LED light source 10, convert the light intensity into a reference end voltage signal ADref, output the reference end voltage signal ADref to the calibration unit 50, equally divide light emitted from the LED light source into two parts by a spectroscope, one part emits into the digestion reaction colorimetric pool 30, and the other part emits light intensity detected by the wind object emitting end photoelectric detector 20.
The digestion reaction colorimetric pool 30 is used for inputting pollution factors and generating digestion reaction with detection reagents therein, and the digestion reaction colorimetric pool 30 adopts the prior art and can adjust the temperature to correspond to different detection factors.
The transmission-side photodetector 40 is configured to detect the transmitted light emitted from the digestion reaction cuvette 30, convert the light intensity of the transmitted light into a detection-side voltage signal ADmea, and output the detection-side voltage signal ADmea to the calibration unit 50.
The correction unit 50 corrects the detection terminal voltage signal ADmea using the following formula ADxz ═ ADmea/ADref, and obtains a corrected voltage signal ADxz.
The analyzing unit 60 is configured to analyze the corrected voltage signal ADxz by using a linear relationship between the contamination factor value and the light intensity voltage signal of the transmitted light, so as to obtain the contamination factor value in the sample.
In specific embodiment 2, the LED light source 10 is driven by a constant current source type photo-emission circuit, the circuit adopts QX7136(U3) to construct a low quiescent current and low voltage difference LED constant current driver, and the interior of the QX7136 has soft start, overheat protection and low voltage protection.
The specific circuit is shown in fig. 3, wherein a VDD pin of the constant current driving chip QX7136 is connected to an anode of the LED light source, and the LED pin is connected to a cathode of the LED light source; the CS pin is connected with an external resistor R14, the output current for driving the LED light source is adjusted by adjusting an external resistor R14, the wavelength of the LED light source is changed, and the DRV pin is arranged in a suspension mode. The VDD pin and the GND pin are connected through a capacitor C4 to play a role of protection.
In specific embodiment 2, the output current is adjusted in the range of 10mA to 400mA by adjusting the external resistor R14 with a low temperature drift, and the external resistor R14 is selected to be 2.7 Ω to 5.3 Ω because the current IF is 10 to 20 mA.
The external resistor R14 is a multi-shift resistor, and each shift corresponds to an output wavelength.
The corresponding relationship between the pollution factor and the wavelength of the LED light source is as follows:
| serial number | Contamination factor | Detection method | Wavelength of LED |
| 1 | CODcr | Colorimetric method of potassium dichromate | 610nm, exocarpium Citri rubrum |
| 2 | NH3-N | Salicylic acid colorimetric method | 700nm, red |
| 3 | TP | Ammonium molybdate colorimetry | 700nm, red |
| 4 | TN | Colorimetric method of resorcin | 365nm, pink violet |
| 5 | CODmn | Oxidation colorimetric method of potassium permanganate | 525nm, emerald green |
Signals received by the photodetector are generally very weak, and signals output by the photodetector are often buried in noise, so that preprocessing is performed to process such weak signals, so as to filter most of the noise, and amplify the weak signals to a voltage amplitude required by a subsequent processor.
The outgoing-side photodetector 20 and the transmitting-side photodetector 30 have the same structure, and the transmitting-side photodetector 30 is taken as an example to illustrate a specific circuit thereof.
As shown in fig. 4, the transmission-side photodetector 40 includes a pre-amplification circuit 41, a main amplification circuit 42, and a filter circuit 43.
The preamplification circuit 41 is a photodiode preamplification circuit, and is used for converting a detected light intensity signal into a voltage signal, which belongs to the prior art and is not described herein again.
The circuit of the main amplification circuit 42 may employ an example as shown in fig. 5 for amplifying the voltage signal output from the pre-amplification circuit 41.
The circuit of the filter circuit 43 may employ an example as shown in fig. 6, employing a first order low pass filter circuit to remove noise outside the useful signal band, including ambient noise and noise introduced by the preamplifier.
The first-order low-pass filter circuit comprises active devices such as an integrated operational amplifier and the like, and the operational amplifier has high input impedance, low output impedance, high open-loop gain and good stability, and is simple in structure and excellent in performance.
Use the utility model discloses a concrete implementation is as follows, and the testing result of a lot of is as the picture shows, and the testing result of luminousness is very stable, and data error, accuracy and repeatability all obtain very big promotion, can get rid of noise interference's influence, improve and detect the precision, have reduced the temperature and have floated.
The principle about the utility model excluding the influence of noise signals is explained as follows:
ADxz＝ADmea/ADref；
wherein, ADref is the voltage of the light detection reference end, ADmea light detection quantity end, and ADxz is the corrected light transmission value obtained through correction calculation.
Because the same optical detection circuit is used at the optical detection reference end and the optical detection quantity end, and the optical detection reference end and the optical detection quantity end are in the same temperature and humidity environment, the light source detection noise signals caused by the temperature, the circuit noise and the like of the two ends have an equal ratio relation, namely:
△ADref＝ADref×Nref；
△ADmea＝ADmea×Nmea；
nref is the rate of change of the reference side signal, e.g., 5% or 10%; nmea is the measurement side signal rate of change.
1. The error analysis of the algorithm in the prior art comprises the following steps:
ADmea1＝(ADmea0+△ADmea0)＝(ADmea0+ADmea0×Nmea)＝ADmea0×(1+Nmea)；
therefore, ADmea1/ADmea0 is (1+ Nmea).
It can be seen from the calculation result that the noise signal Δ ADmea has a great influence on the actual value error, accuracy and repeatability of the measurement result, and because this noise signal inevitably exists and is difficult to avoid, in the actual detection, even if noise shielding, circuit improvement and thermostatic control are carried out by hundreds of thousands of meters, the influence of Nmea can only be possibly reduced, but cannot be eradicated.
2. Adopt the utility model discloses correction algorithm's error analysis:
ADxz＝ADmea/ADref＝(ADmea+△ADmea)/(ADref+△ADref)
＝(ADmea+ADmea×Nmea)/(ADref+ADref×Nref)
＝ADmea×(Nmea+1)/ADref×(Nref+1)；
because Nmea is Nref, ADxz is ADmea/ADref.
The calculation result shows that the influence of noise signals delta ADref and delta ADmea is fundamentally eliminated through the corrected calculation result, and the numerical error, the accuracy and the repeatability of data are greatly improved.
Synthesize the description of above concrete embodiment, the utility model provides a reduce the temperature and float, improve the system of water pollution factor detection precision compares with prior art, has following advantage:
firstly, the photoelectric detector which is the same as the detection end is adopted to collect the light intensity of the emitting end of the light source and correct the light intensity of the transmitted light, so that the influence of noise signals can be eliminated, the detection precision is improved, the temperature drift is reduced, and the data error, the accuracy and the repeatability are greatly improved.
Secondly, by changing the wavelength of the LED light source and replacing the detection reagent, various pollution factor values in the sample can be obtained, and the efficiency is further improved.
And thirdly, the photoelectric detector consists of a preamplifier circuit, a main amplifier circuit and a filter circuit, wherein the filter circuit adopts a first-order low-pass filter circuit to remove noise outside a useful signal frequency band, including environmental noise and noise introduced by the preamplifier.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The present invention is not limited to the above-mentioned best mode, and any person should learn the structural change made under the teaching of the present invention, all with the present invention has the same or similar technical solution, all fall into the protection scope of the present invention.
Claims (3)
1. A detection system for reducing temperature drift and improving water body pollution factors comprises a colorimetric pool for enabling a sample to generate digestion reaction, an LED light source for providing incident light for the colorimetric pool, and a transmission end photoelectric detector for detecting transmitted light transmitted by the colorimetric pool, wherein the transmission end photoelectric detector converts the light intensity of the transmitted light into a detection end voltage signal ADmea, and is characterized by further comprising:
the emitting end photoelectric detector is the same as the transmission end photoelectric detector, is arranged at the emitting end of the LED light source, and is used for detecting the light intensity of the emitted light of the LED light source and converting the light intensity into a reference end voltage signal ADref;
a correction unit, configured to correct the detection terminal voltage signal ADmea by using a formula ADxz ═ ADmea/ADref, so as to obtain a corrected voltage signal ADxz;
and the analysis unit is used for analyzing the corrected voltage signal ADxz by utilizing the linear relation between the pollution factor value and the light intensity voltage signal of the transmitted light to obtain the pollution factor value in the sample.
2. The detection system for reducing the temperature drift and improving the water body pollution factor according to claim 1, wherein the LED light source is driven by a constant current source type photoelectric emission circuit, and the constant current source type photoelectric emission circuit comprises:
and a CS pin of the constant current driver is connected with a GND pin through an external resistor, and the wavelength of the LED light source is changed by adjusting the external resistor.
3. The detection system for reducing the temperature drift and improving the water body pollution factor according to claim 1, wherein the outgoing-side photodetector and the transmission-side photodetector each comprise a pre-amplifying circuit, a main amplifying circuit and a filter circuit, the outgoing light from the LED light source is converted into a reference-side voltage signal ADref through the pre-amplifying circuit, the main amplifying circuit and the filter circuit of the outgoing-side photodetector in sequence, and the transmission light is converted into a detection-side voltage signal ADmea through the pre-amplifying circuit, the main amplifying circuit and the filter circuit of the transmission-side photodetector in sequence.
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