CN106645036B - Liquid turbidity measuring device and its measurement method - Google Patents
Liquid turbidity measuring device and its measurement method Download PDFInfo
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- CN106645036B CN106645036B CN201710035404.8A CN201710035404A CN106645036B CN 106645036 B CN106645036 B CN 106645036B CN 201710035404 A CN201710035404 A CN 201710035404A CN 106645036 B CN106645036 B CN 106645036B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
- G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
- G01N21/532—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke with measurement of scattering and transmission
Abstract
The invention discloses a kind of liquid turbidity measuring device and its measurement methods, and liquid turbidity measurement method includes: step 1: accordingly driving two light source luminescents according to two sinusoidal current signals；Step 2: acquiring and convert transmitted light and scattering light acquisition two ways of digital signals that each light source is issued；Step 3: according to the transmitted intensity parameter and scattered light intensity parameter for obtaining each light source per the digital signal described all the way；Step 4: according to the transmitted intensity parameter of each light source and the scattered light intensity gain of parameter liquid turbidity.
Description
Technical field
The present invention relates to water quality measurement instrument fields, especially suitable in production ocean, rivers, lake, drainage pipeline
Online water turbidity degree monitor sensor, belong to liquid parameter field of measuring technique.
Background technique
The turbidity of liquid is the impurity pair such as different shapes and sizes in liquid, the suspended matter of specific gravity, microorganism and colloidal substance
A kind of reflection of absorption and the scattering process of light is a kind of optical property of liquid-like.With increasingly mentioning for people's living standard
Height, and to the growing interest of life and health, natural environment, the monitoring of water turbidity is increasingly valued by people.
Turbidity be not only measure liquid matter good degree one of important indicator, and be also investigate liquid handling effect it is important according to
According to.
Currently, turbidimetry instrument generally uses scattering type turbidimetry, pass through a pair of of light source and photoreceptor, measurement
90 degree scattered light intensities of the light in water sample, to calculate the turbidity in water.Since scattered light intensity is not only related to turbidity, also with
The parameters such as the intensity of light source and the coloration of liquid are related, and this measurement method is easy by light source ages, pollution and liquid
The factors such as coloration influence, and measurement is inaccurate.Some turbidimetry instruments use transmitted light-scattering light comparative measurement method, adopt
Measure the 90 degree of scattering light and projection light of a light source respectively with two photoreceptors, and according to turbid in their ratio calculation water
Degree, the influence this method eliminates the coloration of light source ages, pollution and liquid to measurement, but be easy since device is old
Change or pollution causes the gain of two photoreceptors inconsistent, causes measurement error.It is in 90 degree of angles that some nephelometers, which use,
Two pairs of light sources and photoreceptor, calculate separately the transmitted light and scattering light of two light sources in a manner of alternately measuring, and are compared
The measurement of turbidity is carried out more afterwards.Although this method can eliminate the influence of aging or the pollution of light source and photoreceptor, by
Measurement error is still resulted in when water body quickly flows or turbidity quickly changes in the Time Inconsistency of two groups of measurements.
Transmitted light I according to langbobier law, in liquidTWith incident light I0Luminous intensity have following relationship:
IT=I0e-τL [1]
Wherein, τ is attenuation coefficient relevant to optical wavelength and liquid coloration, and L is the light path of transmitted light.
According to Rayleigh scattering and Mie scattering principle, 90 degree of scattering light ISWith incident light I0Relational expression are as follows:
IS=α NI0e-τl [2]
Wherein α is scattering proportionality coefficient relevant to lambda1-wavelength, and N is the turbidity of liquid, and l is the light path for scattering light.
Therefore, the ratio of both transmitted light IT and 90 degree of scattering light IS luminous intensity are as follows:
This is one unrelated with luminous intensity, only physical quantity relevant to turbidity, coloration, light path and wavelength, with incident light
Intensity it is unrelated.If enabling incident light in sensor design and scattering the equivalent optical path of light, is i.e. L=l then has
Therefore, I at this timeSWith I0Ratio it is only related to turbidity and wavelength, and wavelength is a fixed value, we can be using calibration
Mode measures scattering Proportional coefficient K (from the principle, K=1/ α), to calculate the turbidity of liquid with following formula:
Can be seen that in transmitted light-scattering light comparison technique turbidimetry principle from above-mentioned derivation, if transmitted light and
The light path of scattering light is consistent, and the turbidity measured using this principle not will receive incident intensity drift and liquid color
The influence of the factors such as degree.However, in the measurement process of saturating coloured light and scattering light luminous intensity, due to photosensitive part aging or dirty
Measurement gain drift, the zero point as caused by measuring circuit aging and gain drift and ambient enviroment caused by dye object blocks
Influence of the light to measurement still can not be eliminated.
Therefore it is eager to develop a kind of liquid turbidity measuring device and its measurement method for overcoming drawbacks described above.
Summary of the invention
Technical problem to be solved by the present invention lies in providing a kind of liquid turbidity measurement method comprising:
Step 1: accordingly driving two light source luminescents according to two sinusoidal current signals；
Step 2: acquiring and convert transmitted light and scattering light acquisition two ways of digital signals that each light source is issued；
Step 3: according to the transmitted intensity parameter and scattering light for obtaining each light source per the digital signal described all the way
Intensive parameter；
Step 4: according to the transmitted intensity parameter of each light source and the scattered light intensity gain of parameter liquid
Body turbidity.
Above-mentioned liquid turbidity measurement method, wherein the step 1 includes:
Step 11: output sine wave signal of the two-way with direct current biasing；
Step 12: the two-way sine wave signal is accordingly converted into two-way sine wave analog voltage signal；
Step 13: the two-way sine wave analog voltage signal is accordingly converted into two sinusoidal current signals,
And drive two light source luminescents.
Above-mentioned liquid turbidity measurement method, wherein the step 2 includes:
Step 21: what the transmitted light and another light source that respectively correspondingly one light source of acquisition is issued issued
The scattering light；
Step 22: amplifying the transmitted light and the scattering light that each light source of acquisition is issued；
Step 23: described in the transmitted light and another light source that amplified one light source is issued issue
Scattering light is converted to the digital signal all the way, while the transmitted light and one that amplified another light source is issued
The scattering light that the light source issues is converted to digital signal described in another way.
Above-mentioned liquid turbidity measurement method, wherein also include 0 step: two sines are exported according to control signal
Current signal.
Above-mentioned liquid turbidity measurement method, wherein it is turbid to obtain the liquid in Yu Suoshu step 4 according to the following formula
Degree:
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is obtained by experimental calibration；R42、R53Respectively two
The transmitted intensity parameter of light source；R43、R52The scattered light intensity parameter of respectively two light sources.
The present invention also provides a kind of liquid turbidity measuring device comprising:
Two light sources；
Driving unit exports two sinusoidal current signals and accordingly drives two light source luminescents；
Two photosensitive units accordingly acquire and convert transmitted light and scattering light acquisition two that each light source is issued
Railway digital signal；
Light intensity parameter obtaining unit, according to the transmitted intensity for obtaining each light source per the digital signal described all the way
Parameter and scattered light intensity parameter；
Processing unit is controlled, according to the transmitted intensity parameter and the scattered light intensity parameter of each light source
Obtain liquid turbidity.
Above-mentioned liquid turbidity measuring device, wherein the driving unit includes:
Digital signal generator exports sine wave signal of the two-way with direct current biasing；
Two-digit analog converter is electrically connected at the digital signal generator, two digital-to-analogue conversions
Device exports after the two-way sine wave signal is accordingly converted to two-way sine wave analog voltage signal respectively；
Two voltage/current conversion modules, are electrically connected at two digital analog converters correspondingly, and two
The two-way sine wave analog voltage signal is accordingly converted to two sines respectively by the voltage/current conversion module
After current signal, accordingly export to two light sources to drive two light source luminescents.
Above-mentioned liquid turbidity measuring device, wherein each photosensitive unit includes:
Photoreceptor, the transmitted light and another light source that accordingly one light source of acquisition is issued issue described
Scatter light；
Gain amplifier, is electrically connected at the photoreceptor, and the gain amplifier respectively correspondingly amplifies the one of acquisition
The scattering light that the transmitted light and another light source that the light source is issued issue；
Analog-digital converter, is electrically connected at the gain amplifier, and the analog-digital converter respectively will amplification
Scattering light described in the transmitted light that the light source of one afterwards is issued and another light source is converted to the number letter all the way
Number.
Above-mentioned liquid turbidity measuring device, wherein it is single that the control processing unit outputs control signals to the driving
Member, the driving unit obtain two sinusoidal current signals according to the control signal.
Above-mentioned liquid turbidity measuring device, wherein the control processing unit obtains the liquid according to the following formula
Turbidity:
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is obtained by experimental calibration；R42、R53Respectively two
The transmitted intensity parameter of light source；R43、R52The scattered light intensity parameter of respectively two light sources.
Switching device of the invention is directed to the prior art its effect and is:
1, it using the sensor design method of double light sources, eliminates pollutant and blocks and measurement result caused by component aging
Drift.
2, using the measuring circuit of orthogonal modulation, the environment light pair such as circuit null offset and natural light, artificial light is eliminated
The influence of measurement result.
3, using the measuring circuit of orthogonal modulation, work measurement while realizing double light sources is eliminated and uses work measurement side
Measurement error caused by formula is mutated as turbidity.
Detailed description of the invention
Fig. 1 is the flow chart of fluid present invention turbidimetry method；
Fig. 2 is the flow chart step by step of step 1 in Fig. 1；
Fig. 3 is the flow chart step by step of step 2 in Fig. 1；
Fig. 4 is the electrical block diagram of fluid present invention turbidity meter；
Fig. 5 is the mounting structure schematic diagram of fluid present invention turbidity meter.
Specific embodiment
Hereby detailed content and technology for the present invention explanation is now described further with a preferred embodiment, but not
It should be interpreted the limitation that the present invention is implemented.
Referring to Figure 1-3, Fig. 1 is the flow chart of fluid present invention turbidimetry method；Fig. 2 is the substep of step 1 in Fig. 1
Rapid flow chart；Fig. 3 is the flow chart step by step of step 2 in Fig. 1.As shown in Figure 1-3, liquid turbidity measurement method of the invention,
Include:
Step 1: accordingly driving two light source luminescents according to two sinusoidal current signals；
Step 2: acquiring and convert transmitted light and scattering light acquisition two ways of digital signals that each light source is issued；
Step 3: the transmitted intensity parameter and scattered light intensity parameter of each light source are obtained according to each railway digital signal；
Step 4: according to the transmitted intensity parameter of each light source and scattered light intensity gain of parameter liquid turbidity.
Further, the step 1 includes:
Step 11: output sine wave signal of the two-way with direct current biasing；
Step 12: two-way sine wave signal is accordingly converted into two-way sine wave analog voltage signal；
Step 13: two-way sine wave analog voltage signal being accordingly converted into two sinusoidal current signals, and is driven
Move two light source luminescents.
Still further, the step 2 includes:
Step 21: respectively correspondingly acquiring the transmitted light that a light source is issued and the scattering light that another light source issues；
Step 22: amplifying the transmitted light and scattering light that each light source of acquisition is issued；
Step 23: the transmitted light that an amplified light source is issued and the scattering light that another light source issues are converted to all the way
Digital signal, while the transmitted light that amplified another light source is issued and the scattering light that a light source issues are converted into another way
Digital signal.
Further, liquid turbidity measurement method of the invention also includes 0 step: exporting two just according to control signal
String current signal.
Wherein, the liquid turbidity is obtained according to the following formula in Yu Suoshu step 4:
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is obtained by experimental calibration；R42、R53Respectively two
The transmitted intensity parameter of light source；R43、R52The scattered light intensity parameter of respectively two light sources.
Refer to the electrical block diagram that Fig. 4 is fluid present invention turbidity meter；Fig. 5 is fluid present invention turbidity
The mounting structure schematic diagram of measuring device.As illustrated in figures 4-5, liquid turbidity measuring device of the invention includes: two light sources
L41, L42, driving unit, two photosensitive units 43, light intensity parameter obtaining unit 44 and control processing unit 45；Driving unit
42 two sinusoidal current signals of output accordingly drive described two light sources L41, L42 to shine；Two photosensitive units 43 are accordingly
It acquires and converts transmitted light and scattering light acquisition two ways of digital signals that each light source 41 is issued；Light intensity parameter obtains
Unit 44 is according to the transmitted intensity parameter and scattered light intensity for obtaining each described light source L41, L42 per the digital signal described all the way
Spend parameter；Control the transmitted intensity parameter and the scattering light of the processing unit 45 according to each described light source L41, L42
Intensive parameter obtains liquid turbidity.Wherein in the present embodiment, light intensity parameter obtaining unit 44 is DSP module, but of the invention
It is not limited thereto.
Further, the driving unit includes: digital signal generator 421, two-digit analog converter 422 and two
A voltage/current conversion module 423；Digital signal generator 421 exports sine wave signal of the two-way with direct current biasing；Two numbers
Word analog converter 422 is electrically connected at the digital signal generator 421, and two digital analog converters 422 are distinguished
It is exported after the two-way sine wave signal is accordingly converted to two-way sine wave analog voltage signal；Two voltage/currents turn
Mold changing block 423 is electrically connected at two digital analog converters 422, two voltage/current conversions correspondingly
It is right after the two-way sine wave analog voltage signal is accordingly converted to two sinusoidal current signals respectively by module 423
It exports with answering to described two light sources L41, L42 to drive described two light sources L41, L42 to shine.Wherein in the present embodiment,
Driving unit 42 also includes two resistance 424, and each resistance 424 is connected to digital analog converter 422 and voltage/current conversion
Between module 423.
Still further, each photosensitive unit 43 includes: photoreceptor 431, gain amplifier 432 and simulation numeral
Converter 433；Photoreceptor 431 accordingly acquires the transmitted light that a light source L41 is issued and another light source L42
The scattering light issued；Gain amplifier 432 is electrically connected at photoreceptor 431, and gain amplifier 432 accordingly amplifies acquisition
The transmitted light that is issued of a light source L41 and the scattering light that issues of another light source L42；Simulation numeral turns
Parallel operation 433 is electrically connected at gain amplifier 432, and the analog-digital converter 433 is respectively by amplified one light source
Scattering light described in the transmitted light that L41 is issued and another light source L42 is converted to the digital signal all the way.
It is worth noting that, the principle of two photosensitive units 43 and structure are all the same, the difference is that the mould of a photosensitive unit
Intend digital quantizer 433 respectively by the amplified one light source L41 transmitted light issued and another light source L42
The scattering light is converted to the digital signal all the way, and the analog-digital converter 433 of another photosensitive unit respectively will amplification
Scattering light described in the transmitted light that the light source L42 of one afterwards is issued and another light source L41 is converted to another way institute
State digital signal.
Still further, the control processing unit 45 outputs control signals to the digital signal hair of the driving unit 42
The digital signal generator 421 of raw device 421, the driving unit 42 exports two sinusoidal currents according to the control signal
Signal；Control processing unit 45 obtains the liquid turbidity according to the following formula:
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is obtained by experimental calibration；R42、R53Respectively two
The transmitted intensity parameter of light source；R43、R52The scattered light intensity parameter of respectively two light sources.
The course of work of fluid present invention turbidity meter is illustrated below in conjunction with Fig. 4-5.
The purpose of the present invention is for current turbidity transducer vulnerable to fouling product attachment, generate device aging and cause turbidity
Measurement generates drift and is easy to be influenced the shortcomings that causing measurement error by bias light, and particular for rivers, storm sewer,
Or the fast-changing environment of the turbidity such as sewage conduct, propose one kind can antipollution and aging drift, anti-surrounding environment light is dry
It disturbs, and being capable of fast synchronized response turbidity transducer design method.
In order to eliminate the factor of above-mentioned influence turbidimetry precision, the invention proposes a kind of liquid based on Orthogonal Double light source
Body turbidimetry method and measuring device.
Wherein, measuring device is as shown in Figure 5: including circular cylindrical cavity 5, light source L41, light source L42, two photoreceptors 431；
Wherein, light source L41 and light source L42 is in 90 degree of angles, and wavelength is identical, and photoreceptor 431 faces two light sources respectively.For
For the photoreceptor 431 of face light source L41, the light that light source L41 is issued is transmitted light, and the light that light source L42 is issued is 90 degree of scatterings
Light；For the photoreceptor 431 of face light source L42, the light that light source L42 is issued is transmitted light, and the light that light source L41 is issued is 90
Degree scattering light.
By in figure it is found that transmitted light light path, the light source L42 to face of the photoreceptor 431 of light source L41 to face light source L41
The transmitted light light path of the photoreceptor 431 of light source L42, the photoreceptor 431 of light source L41 to face light source L42 scattering light light path, with
And the scattering light light path of the photoreceptor 431 of light source L42 to face light source L41 be all it is equal, be equal to the interior straight of cylindrical cavity 5
Diameter D.And since light source L41 is identical with the wavelength of light source L42, their scattering Proportional coefficient K is also identical.Therefore basis
Formula [4] above-mentioned is available:
Wherein IS2For the scattered light intensity of the photoreceptor 431 of light source L41 to face light source L42；IT2It is light source L41 to just
To the transmitted intensity of the photoreceptor 431 of light source L41；IS3For the scattering light of the photoreceptor 431 of light source L42 to face light source L41
Intensity；IT3For the transmitted intensity of the photoreceptor 431 of light source L42 to face light source L42.
We use I2And I3The intensity of light source of light source L41 and light source L42 are respectively indicated, A4 and A5 respectively indicate face light source
The integration gain of the photoreceptor 431 of L41 and the photoreceptor 431 of face light source L42 and its measuring circuit.It is then above-mentioned according to formula
[1] and [2], the transmitted intensity reading R of the light source L41 measured on the photoreceptor 431 of face light source L4142Are as follows:
R42=A4I2e-τD [6]
The scattered light intensity of the light source L42 measured on the photoreceptor 431 of face light source L41 reads R43Are as follows:
R42=A4αNI7e-τD [7]
The transmitted intensity of the light source L42 measured on the photoreceptor 431 of face light source L42 reads R53Are as follows:
R53=A5I3e-τD [8]
The scattered light intensity of the light source L41 measured on the photoreceptor 431 of face light source L42 reads R52Are as follows:
R52=A5αNI2e-τD [9]
By above-mentioned formula, we are available:
That is,One directly proportional to turbidity, and with luminous intensity I2、I3And photoreceptor and its
Circuit gain A4 and A5 all unrelated physical quantity.UsingTo characterize the ratio of scattering light and transmitted light:
And turbidity is calculated with following formula, light source, photoreceptor and measuring circuit can be completely eliminated due to aging
Or turbidimetry error caused by pollution:
Wherein K=1/ α is turbidity conversion coefficient, can be obtained by calibration experiment.
We can eliminate light source, photoreceptor and measuring circuit the turbidimetry error as caused by aging or pollution.
And in actual measurement, it would be desirable to eliminate as much as the zero point of influence and measuring circuit of the surrounding environment light to measurement
Drift.Meanwhile in order to cope with the fast-changing use environment of the turbidity such as rainwater, sewage conduct, the sensor of above-mentioned double light sources must
Must two-way scattering light measured simultaneously with two-way projection light, come prevent using alternately measurement method when, as turbidity be mutated caused by
Measurement error.
Measuring device of the invention is first by digital signal generator 421 with frequency fSGenerate two-way with direct current biasing just
String wave signal V2And V3:
Wherein A2、A3It is the alternating component amplitude of signal, T2、T3It is the alternating component period of two paths of signals, φ2、φ3It is to hand over
The phase of ingredient is flowed, n is the sequence of values of AC signal.B2、B3It is the flip-flop of signal, needs respectively greater than or be equal to A2
And A3, guarantee V2And V3Greater than 0.Wherein,WithThis two-way sine wave AC signal
It must be orthogonal, it can a sequence length N is found, so that the result of their mutual inner products is 0.According to sine wave
Characteristic, the sine wave of two same periods, if phase phase difference be 90 degree, they are on the sequence length of complete cycle in this way
It is orthogonal when progress inner product；If the period of two sine waves is different, as long as their period, there are common multiples, with them
Period common multiple be sequence length carry out inner product when, they are also orthogonal.We can adopt and design two with the aforedescribed process
The orthogonal sine wave signal in road.
Then, this two-way sine wave digital signal is generated sine of the two-way with direct current biasing by digital analog converter by us
Wave simulation voltage signal, and two light sources are respectively driven in a manner of current excitation by voltage/current conversion module 423
L41,L42.Since the luminous intensity and exciting current of light source are proportional, light source L41 and light source L42 luminous intensity can retouch
It states are as follows:
Wherein, k2And k3The respectively conversion proportionality coefficient of light source L41 and light source L42 from digital signal to luminous intensity.
Luminous intensity that photoreceptor 431 receives is by amplification, then with same sample rate fSAfter carrying out analog-to-digital conversion (ADC)
Obtain two ways of digital signals V4And V5.Wherein V4Contain the transmitted light of light source L41 and the scattering light of light source L42, V5Contain light
The transmitted light of source L42 and the scattering light of light source L41
According to formula [1] and [2], we are known:
V4(n)=A4e-τlI2(n)+A4αNe-τlI3(n) [17]
V5(n)=A5e-τlI3(n)+A5αNe-τlI2(n) [18]
[15] [16] are substituted into obtain:
We are in DSP module respectively to V4And V5Taking length is the sequence of N, orthogonal on light source L41 and light source L42
AC signalWithDemodulation calculating is carried out in the form of inner product respectively, obtains two senses
Respective reading R42, R43, R52 and the R53 of light device to two light signals:
Formula [19] are substituted into [21], it is known that:
Since N is T2And T3Common multiple, by the first item inner product factor in formula known to trigonometric function characteristicIt is equal toThe Section 2 inner product factor and due to orthogonality, in formulaEqual to 0.The Section 3 inner product factorIt is SIN function
0 is as a result also equal to equal to the summation of itself complete cycle with the inner product of direct current signal.Therefore, known to us:
R42=k2A2A4e-τD [26]
This be one only with light source L41 AC modulation amplitude A2Relevant value, the flip-flop B with light source L412, Yi Jiguang
The modulated signal of source L42 is unrelated.That is, we can receive from the photoreceptor 431 of face light source L41 according to formula [21]
To signal in, the response amplitude generated by the excitation of light source L41 alternating component is individually demodulated and is extracted, not by light source L42
Influence.
Equally, we can analyze to obtain
R43=α NK3A3A4e-τD [27]
R52=α Nk2A2A5e-τD [28]
R52=k3A3A5e-τD [29]
In this way, we from two photoreceptors 431 while can demodulate in the case where light source L41 and L42 are worked at the same time
Each photoreceptor is extracted to 4 AC signal amplitude responses of each light source, so that formula [12] can be set up, and
The calculating of turbidity can be carried out using the formula.
In foregoing circuit measurement process, the null offset of measuring circuit will be in demodulating process with the shape of flip-flop
Formula participates in demodulation.Since direct current signal is orthogonal with sine wave signal, the result after null offset demodulation is 0, will not be to survey
Amount has an impact.For ambient light interference, environment light be broadly divided into sunlight isocandela degree be flip-flop natural light,
And the artificial light that incandescent lamp, fluorescent lamp etc. are driven with 50Hz alternating current.And artificial light had not only included flip-flop, but also included
The 50Hz fundamental component, and 100Hz, 150Hz, 200Hz as caused by non-linear factor etc. generated due to 50Hz alternating current
Frequency multiplication ingredient.It is influenced to eliminate ambient light interference, we can select suitable sources frequency and time of measuring sequence length (example
Such as the signal of 40Hz and 1 second length of time series) so that our light signal and direct current and 50Hz, 100Hz,
The AC signals such as 150Hz, 200Hz are all orthogonal, and in this way when carrying out turbidimetry, measurement result would not be by ambient light interference
Factor affects.
Wherein, in the present embodiment,
1, it using the LED of two 940nm as light source, is installed in the cylindrical cavity body that diameter is 2.5cm；
2, in circuit as shown in Figure 4, using 10kHz as sample rate, DAC is controlled by digital signal generator and generates two
Road exchange rate is 1V, and direct current biasing amplitude is 1V, and frequency 25Hz, sequence length is 1000 (i.e. 100ms), and phase is respectively
0 degree and 90 degree of quadrature voltage signal；
3, two-way quadrature voltage signal is converted into electric current between 0~2mA by the resistance for being respectively 1k Ω with two resistance values
The alternately current signal of sinusoidal variations drives as the electric current of light source L41 and light source L42；
4, two photoreceptors 431 are adopted respectively with the sample rate of 10kHz by the signal that gain amplifier acquisition comes
Sample, the time point of sampling and digital signal generator generate the speed sync of orthogonal signalling；
5, this four readings of R42, R43, R52 and R53, formula are calculated using formula [21]-[24] in DSP module
It is 400, φ, 2 value is 0 degree that middle N value, which is 1000, T value, and 3 value of φ is 90 degree.
6, according to formulaThe ratio of 90 degree of scattering light and transmitted intensity is calculated, and according to formula [12]
Conversion obtains turbidity actual value.Wherein the Proportional coefficient K in formula [12] can be obtained by calibration.
The above specific embodiment is only application case of the invention, and in actual use, related personnel can be at this
It carry out various modifications and changes within the scope of the technical idea of invention, for example, in the case where not changing light source and photoreceptor position
Cavity is changed to rectangular, cross, modification time of measuring, excitation signal strength, period, frequency, phase etc..
In conclusion the present invention can rise using vertically pair light sources, and using the method that Orthogonal Double light source measures simultaneously
To measuring simultaneously, measurement error caused by turbidity suddenly change when avoiding alternately measuring, and eliminate 50Hz alternating current and its drive
The function of the surrounding environment lights such as dynamic lamp influence caused by measurement.
Above are only presently preferred embodiments of the present invention, not be used to limit the scope of implementation of the present invention, without departing substantially from
In the case where spirit of that invention and its essence, those skilled in the art make in accordance with the present invention various to be changed accordingly
Become and deform, but these corresponding changes and modifications all should fall within the scope of protection of the appended claims of the present invention.
Claims (10)
1. a kind of liquid turbidity measuring device, characterized by comprising:
Two light sources have an angle between two light sources and wavelength are identical；
Driving unit exports two sinusoidal current signals accordingly while driving two light source luminescents, wherein described two
Sinusoidal current signal is orthogonal；
Two photosensitive units accordingly acquire simultaneously and convert transmitted light and scattering light acquisition two that each light source is issued
Railway digital signal, wherein the light path of the transmitted light and the scattering light is identical；
Light intensity parameter obtaining unit, according to the transmitted intensity parameter for obtaining each light source per the digital signal described all the way
And scattered light intensity parameter；
Processing unit is controlled, according to the transmitted intensity parameter of each light source and the scattered light intensity gain of parameter
Liquid turbidity.
2. liquid turbidity measuring device as described in claim 1, which is characterized in that the driving unit includes:
Digital signal generator exports sine wave signal of the two-way with direct current biasing；
Two-digit analog converter is electrically connected at the digital signal generator, two digital analog converters point
It is exported after the two-way sine wave signal is not converted to two-way sine wave analog voltage signal accordingly；
Two voltage/current conversion modules are electrically connected at two digital analog converters, described in two correspondingly
The two-way sine wave analog voltage signal is accordingly converted to two sinusoidal currents respectively by voltage/current conversion module
After signal, accordingly export to two light sources to drive two light source luminescents.
3. liquid turbidity measuring device as described in claim 1, which is characterized in that each photosensitive unit includes:
Photoreceptor, the transmitted light and another light source that respectively correspondingly one light source of acquisition is issued issue described
Scatter light；
Gain amplifier, is electrically connected at the photoreceptor, and the gain amplifier respectively correspondingly amplifies described in the one of acquisition
The scattering light that the transmitted light and another light source that light source is issued issue；
Analog-digital converter, is electrically connected at the gain amplifier, and the analog-digital converter respectively will be amplified
Scattering light described in the transmitted light that one light source is issued and another light source is converted to the digital signal all the way.
4. liquid turbidity measuring device as described in claim 1, which is characterized in that the control processing unit output control letter
Number to the driving unit, the driving unit is according to control signal output two sinusoidal current signals.
5. liquid turbidity measuring device as described in claim 1, which is characterized in that the control processing unit is according to following public
Formula obtains the liquid turbidity:
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is obtained by experimental calibration；R42、R53Respectively two light sources
Transmitted intensity parameter；R43、R52The scattered light intensity parameter of respectively two light sources.
6. a kind of liquid turbidity measurement method, which is characterized in that applied to liquid described in any one of the claims 1-5
Turbidity meter, liquid turbidity measurement method includes:
Step 1: accordingly driving two light source luminescents according to two sinusoidal current signals；
Step 2: acquiring and convert transmitted light and scattering light acquisition two ways of digital signals that each light source is issued；
Step 3: according to the transmitted intensity parameter and scattered light intensity for obtaining each light source per the digital signal described all the way
Parameter；
Step 4: turbid according to the transmitted intensity parameter of each light source and the scattered light intensity gain of parameter liquid
Degree.
7. liquid turbidity measurement method as claimed in claim 6, which is characterized in that the step 1 includes:
Step 11: output sine wave signal of the two-way with direct current biasing；
Step 12: the two-way sine wave signal is accordingly converted into two-way sine wave analog voltage signal；
Step 13: the two-way sine wave analog voltage signal being accordingly converted into two sinusoidal current signals, and is driven
Move two light source luminescents.
8. liquid turbidity measurement method as claimed in claim 6, which is characterized in that the step 2 includes:
Step 21: the transmitted light and another light source that respectively correspondingly one light source of acquisition is issued issue described
Scatter light；
Step 22: amplifying the transmitted light and the scattering light that each light source of acquisition is issued；
Step 23: the scattering that the transmitted light and another light source that amplified one light source is issued issue
Light is converted to the digital signal all the way, while described in the transmitted light and one that amplified another light source is issued
The scattering light that light source issues is converted to digital signal described in another way.
9. liquid turbidity measurement method as claimed in claim 6, which is characterized in that also include 0 step: defeated according to control signal
Two sinusoidal current signals out.
10. liquid turbidity measurement method as claimed in claim 6, which is characterized in that in Yu Suoshu step 4 according to the following formula
Obtain the liquid turbidity:
Wherein, N is liquid turbidity；K is conversion coefficient, and K is obtained by experimental calibration；R42、R53Respectively two light sources it is saturating
Penetrate light intensity parameter；R43、R52The scattered light intensity parameter of respectively two light sources.
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| CN107664627B (en) * | 2017-09-19 | 2020-04-21 | 杭州遥测物联网技术有限公司 | Method for measuring low turbidity value by adopting laser amplitude modulation type light source |
| JP7056612B2 (en) * | 2019-02-28 | 2022-04-19 | 横河電機株式会社 | Turbidity measurement method and turbidity meter |
| CN110726698B (en) * | 2019-11-28 | 2022-02-22 | 浙江农林大学 | Turbidity monitoring method for urban river ecological intelligent monitoring parent station |
| CN113155743B (en) * | 2021-04-23 | 2022-06-07 | 中国科学院大学 | Turbidity measuring method and system based on quadrature signal modulation |
| CN116879120A (en) * | 2023-09-06 | 2023-10-13 | 中国华能集团清洁能源技术研究院有限公司 | Smoke detection device |
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