CN106645036A - Liquid turbidity measuring device and measuring method thereof - Google Patents
Liquid turbidity measuring device and measuring method thereof Download PDFInfo
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- CN106645036A CN106645036A CN201710035404.8A CN201710035404A CN106645036A CN 106645036 A CN106645036 A CN 106645036A CN 201710035404 A CN201710035404 A CN 201710035404A CN 106645036 A CN106645036 A CN 106645036A
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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 liquid turbidity measuring device and a measuring method thereof. The liquid turbidity measuring method comprises: step 1 of correspondingly driving two light sources to give out light according to two sine-wave current signals; step 2 of collecting and converting transmission light and scattered light emitted by each light source to obtain two paths of digital signals; step 3 of obtaining a transmission light strength parameter and a scattered light strength parameter of each light source according to each path of digital signals; step 4 of obtaining the liquid turbidity according to the transmission light strength parameter and the scattered light strength of each light source.
Description
Technical field
The present invention relates to water quality measurement instrument field, is particularly well-suited to make in ocean, rivers, lake, drainage pipeline
Online water turbidity degree monitoring sensor, belong to liquid parameter field of measuring technique.
Background technology
The turbidity of liquid is the impurity pair such as different shapes and sizes in liquid, the suspension of proportion, 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 carrying for people's living standard
Height, and to life and health, the growing interest of natural environment, for the monitoring of water turbidity is increasingly subject to people's attention.
Turbidity is not only weighs one of important indicator of liquid matter good degree, and be also investigate liquid handling effect it is important according to
According to.
At present, turbidimetry instrument typically adopts scattering type turbidimetry, by a pair of light sources and photoreceptor, measurement
90 degree scattered light intensities of the light in water sample to calculate water in turbidity.Due to scattered light intensity it is not only related to turbidity, also with
The parameters such as the colourity of the intensity of light source and liquid are related, and this metering system is easily by light source ages, pollution and liquid
The factors such as colourity affect, and measurement is inaccurate.Some turbidimetry instruments employ transmitted light-scattered light comparative measurement method, adopt
90 degree of scattered lights and projection light of a light source are measured respectively with two photoreceptors, and it is turbid in their ratio calculation water
Degree, this method eliminates impact of the colourity of light source ages, pollution and liquid to measuring, but easily because device is old
Change or pollution causes the gain of two photoreceptors inconsistent, cause measure error.It is in 90 degree of angles that some nephelometers are adopted
Two pairs of light sources and photoreceptor, in the way of alternately measuring the transmitted light and scattered light of two light sources are calculated respectively, and are compared
The measurement of turbidity is carried out more afterwards.Although this method can eliminate aging or pollution the impact of light source and photoreceptor, by
In the Time Inconsistency of two groups of measurements, quickly flow in water body, or turbidity is when quickly changing, and still results in measure error.
According to langbobier law, transmitted light I in liquidTWith incident light I0Luminous intensity have following relation：
IT=I0e-τL [1]
Wherein, τ is the attenuation coefficient related to optical wavelength and liquid colourity, and L is the light path of transmitted light.
According to Rayleigh scattering and Mie scattering principle, 90 degree of scattered lights ISWith incident light I0Relational expression be：
IS=α NI0e-τl [2]
Wherein α is the scattering proportionality coefficient related to lambda1-wavelength, and N is the turbidity of liquid, and l is the light path of scattered light.
Therefore, transmitted light IT is with the ratio of 90 degree of both scattered lights IS luminous intensities：
This is unrelated with luminous intensity, only related to a turbidity, colourity, light path and wavelength physical quantity, with incident light
Intensity it is unrelated.If in Sensor Design, making the equivalent optical path of incident light and scattered light, i.e. L=l, then have
Therefore, now ISWith I0Ratio it is only related to turbidity and wavelength, and wavelength is a fixed value, and we can adopt what is demarcated
Mode, measures scattering Proportional coefficient K (from the principle, K=1/ α), so as to calculate the turbidity of liquid with formula below：
Can be seen that in the turbidimetry principle of transmitted light-scattering light comparison technique from above-mentioned derivation, if transmitted light and
The light path of scattered light is consistent, and the turbidity measured using this principle will not be subject to incident intensity drift and liquid color
The impact of the factors such as degree.However, in the measurement process of saturating coloured light and scattered light luminous intensity, due to photosensitive part it is aging or dirty
Dye thing blocks the measurement gain drift for causing, the zero point caused because measuring circuit is aging and gain drift and surrounding environment
Light still can not be eliminated to the impact for measuring.
Therefore it is eager to develop a kind of liquid turbidity measurement apparatus and its measuring method for overcoming drawbacks described above.
The content of the invention
The technical problem to be solved is to provide a kind of liquid turbidity measuring method, wherein, comprising：
Step 1：Two light source luminescents are accordingly driven according to two sinusoidal current signals；
Step 2：Gather and change transmitted light and scattered light acquisition two ways of digital signals that each light source is sent；
Step 3：According to transmitted intensity parameter and scattered light that each light source is obtained per the data signal all the way
Intensive parameter；
Step 4：According to the transmitted intensity parameter and the scattered light intensity gain of parameter liquid of each light source
Body turbidity.
Above-mentioned liquid turbidity measuring method, wherein, the step 1 is included：
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 measuring method, wherein, the step 2 is included：
Step 21：What the transmitted light and another light source that respectively correspondingly light source described in collection one is sent sent
The scattered light；
Step 22：Amplify the transmitted light and the scattered light that each described light source of collection is sent；
Step 23：Described in the transmitted light and another light source that light source described in after by amplification one is sent sends
Scattered light is converted to the data signal all the way, while the transmitted light and that another described light source after by amplification is sent
The scattered light that the light source sends is converted to data signal described in another road.
Above-mentioned liquid turbidity measuring method, wherein, also comprising 0 step：Two sines are exported according to control signal
Current signal.
Above-mentioned liquid turbidity measuring method, wherein, the liquid is obtained according to equation below in the step 4 turbid
Degree：
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is by experimental calibration acquisition；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 measurement apparatus, wherein, comprising：
Two light sources；
Driver element, two sinusoidal current signals of output accordingly drive two light source luminescents；
Two photosensitive units, accordingly gather and change transmitted light and scattered light acquisition two that each light source is sent
Railway digital signal；
Light intensity parameter obtaining unit, according to the transmitted intensity that each light source is obtained per the data signal all the way
Parameter and scattered light intensity parameter；
Control process unit, according to the transmitted intensity parameter and the scattered light intensity parameter of each light source
Obtain liquid turbidity.
Above-mentioned liquid turbidity measurement apparatus, wherein, the driver element is included：
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
The two-way sine wave signal is accordingly converted to exported after two-way sine wave analog voltage signal respectively by device；
Two voltage/current modular converters, are electrically connected at correspondingly two digital analog converters, two
The two-way sine wave analog voltage signal is accordingly converted to two sines by the voltage/current modular converter respectively
After current signal, accordingly export to two light sources to drive two light source luminescents.
Above-mentioned liquid turbidity measurement apparatus, wherein, each photosensitive unit is included：
Photoreceptor, it is described that the transmitted light and another light source that accordingly light source described in collection one is sent sends
Scattered light；
Gain amplifier, is electrically connected at the photoreceptor, and the gain amplifier respectively correspondingly amplifies the one of collection
The scattered light that the transmitted light and another light source that the light source is sent sends；
Analog-digital converter, is electrically connected at the gain amplifier, and the analog-digital converter will amplify respectively
The transmitted light and scattered light described in another light source that light source described in afterwards is sent is converted to the numeral letter all the way
Number.
Above-mentioned liquid turbidity measurement apparatus, wherein, it is single that the control process unit outputs control signals to the driving
Unit, the driver element obtains two sinusoidal current signals according to the control signal.
Above-mentioned liquid turbidity measurement apparatus, wherein, the control process unit obtains the liquid according to equation below
Turbidity：
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is by experimental calibration acquisition；R42、R53Respectively two
The transmitted intensity parameter of light source；R43、R52The scattered light intensity parameter of respectively two light sources.
The switching device of the present invention is directed to prior art its effect：
1st, using the Sensor Design method of double light sources, eliminate pollutant and block the measurement result caused with component aging
Drift.
2nd, using the measuring circuit of orthogonal modulation, circuit null offset, and the ambient light pair such as natural light, artificial light are eliminated
The impact of measurement result.
3rd, using the measuring circuit of orthogonal modulation, work measurement while double light sources is realized, eliminates and adopt work measurement side
The measure error that formula is caused due to turbidity mutation.
Description of the drawings
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 for the present invention and technology explanation, are now described further with a preferred embodiment, but not
The restriction of present invention enforcement should be interpreted.
Fig. 1-3 are referred to, 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 Figure 1-3, liquid turbidity measuring method of the invention,
Comprising：
Step 1：Two light source luminescents are accordingly driven according to two sinusoidal current signals；
Step 2：Gather and change transmitted light and scattered light acquisition two ways of digital signals that each light source is sent；
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 and scattered light intensity gain of parameter liquid turbidity of each light source.
Further, the step 1 is included：
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 is accordingly converted into two sinusoidal current signals, and is driven
Move two light source luminescents.
Yet further, the step 2 is included：
Step 21：Respectively correspondingly gather the transmitted light that a light source sent and the scattered light that another light source sends；
Step 22：Amplify transmitted light and scattered light that each light source of collection is sent；
Step 23：The scattered light that the transmitted light and another light source that a light source after by amplification is sent sends is converted to all the way
Data signal, while the scattered light that the transmitted light that sent of another light source after by amplification and a light source send is converted to another road
Data signal.
Further, liquid turbidity measuring method of the invention also includes 0 step：Two are being exported according to control signal just
String current signal.
Wherein, the liquid turbidity is obtained according to equation below in the step 4：
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is by experimental calibration acquisition；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 measurement apparatus.As illustrated in figures 4-5, liquid turbidity measurement apparatus of the invention, comprising：Two light sources
L41, L42, driver element, two photosensitive units 43, light intensity parameter obtaining unit 44 and control process units 45；Driver element
42 two sinusoidal current signals of output accordingly drive described two light sources L41, L42 to light；Two photosensitive units 43 are accordingly
Gather and change transmitted light and scattered light acquisition two ways of digital signals that each light source 41 is sent；Light intensity parameter is obtained
Unit 44 is according to the transmitted intensity parameter and scattered light intensity that each described light source L41, L42 are obtained per the data signal all the way
Degree parameter；The transmitted intensity parameter and the scattered light of the control process 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 be DSP module, but the present invention
It is not limited thereto.
Further, the driver element is included：Digital signal generator 421, two-digit analog converter 422 and two
Individual voltage/current modular converter 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
The two-way sine wave signal is accordingly converted to and export after two-way sine wave analog voltage signal；Two voltage/currents turn
Mold changing block 423 is electrically connected at correspondingly two digital analog converters 422, two voltage/current conversions
Module 423 is respectively accordingly converted to the two-way sine wave analog voltage signal after two sinusoidal current signals, right
Export with answering to described two light sources L41, L42 to drive described two light sources L41, L42 to light.Wherein in the present embodiment,
Driver element 42 also includes two resistance 424, and each resistance 424 is connected to digital analog converter 422 and voltage/current conversion
Between module 423.
Yet further, each photosensitive unit 43 is included：Photoreceptor 431, gain amplifier 432 and simulation numeral
Converter 433；Photoreceptor 431 accordingly gathers the transmitted light and another light source L42 that light source L41 described in is sent
The scattered light for sending；Gain amplifier 432 is electrically connected at photoreceptor 431, and gain amplifier 432 accordingly amplifies collection
One described in the scattered light that sends of the transmitted lights that sent of light source L41 and another light source L42；Simulation numeral turns
Parallel operation 433 is electrically connected at gain amplifier 432, the analog-digital converter 433 respectively by amplification after one described in light source
The transmitted light and scattered light described in another light source L42 that L41 is sent is converted to the data signal all the way.
It should be noted that the principle of two photosensitive units 43 and structure all same, the except for the difference that mould of a photosensitive unit
Intend digital quantizer 433 respectively by amplification after one described in the transmitted lights that sent of light source L41 and another light source L42
The scattered light is converted to the data signal all the way, and the analog-digital converter 433 of another photosensitive unit will amplify respectively
The transmitted light and scattered light described in another light source L41 that light source L42 described in afterwards is sent is converted to another road institute
State data signal.
Yet further, the control process unit 45 outputs control signals to the data signal of the driver element 42
Raw device 421, the digital signal generator 421 of the driver element 42 exports two sinusoidal currents according to the control signal
Signal；Control process unit 45 obtains the liquid turbidity according to equation below：
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is by experimental calibration acquisition；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 easily to be adhered to by fouling product, produce device aging for current turbidity transducer and cause turbidity
Measurement produces drift and easily by bias light is affected to cause the shortcoming of measure error, and particular for rivers, storm sewer,
Or the fast-changing environment of turbidity such as sewage conduct, propose one kind can antipollution and aging drift, anti-surrounding environment light does
Disturb, and being capable of fast synchronized response turbidity transducer method for designing.
In order to eliminate the factor of above-mentioned impact turbidimetry precision, the present invention proposes a kind of liquid based on Orthogonal Double light source
Body turbidimetry method and measurement apparatus.
Wherein, measurement apparatus are as shown in Figure 5：Comprising 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 respectively two light sources.For
Just for the photoreceptor 431 of light source L41, the just transmitted light that light source L41 sends, just 90 degree of scatterings that light source L42 sends
Light；For just for the photoreceptor 431 of light source L42, the just transmitted light that light source L42 sends, light source L41 send just 90
Degree scattered light.
From in figure, light source L41 to the transmitted light light path just to the photoreceptor 431 of light source L41, light source L42 are to just right
The transmitted light light path of the photoreceptor 431 of light source L42, light source L41 to the scattered light light path just to the photoreceptor 431 of light source L42, with
And light source L42 is to being equal just to the scattered light light path of the photoreceptor 431 of light source L41, the interior straight of cylindrical cavity 5 is equal to
Footpath D.And because light source L41 is identical with the wavelength of light source L42, their scattering Proportional coefficient K is also identical.Therefore basis
Aforesaid formula [4], can obtain：
Wherein IS2It is light source L41 to just to the scattered light intensity of the photoreceptor 431 of light source L42；IT2It is light source L41 to just
Transmitted intensity to the photoreceptor 431 of light source L41；IS3It is light source L42 to just to the scattered light of the photoreceptor 431 of light source L41
Intensity；IT3It is light source L42 to just to the transmitted intensity of the photoreceptor 431 of light source L42.
We use I2And I3The intensity of light source of light source L41 and light source L42 is represented respectively, and A4 and A5 is represented respectively just to light source
The photoreceptor 431 of L41 and just to the photoreceptor 431 and its integration gain of measuring circuit of light source L42.It is then aforesaid according to formula
[1] and [2], the just transmitted intensity reading R of the light source L41 to measuring on the photoreceptor 431 of light source L4142For：
R42=A4I2e-τD [6]
The scattered light intensity reading R of the light source L42 just to measuring on the photoreceptor 431 of light source L4143For：
R42=A4αNI7e-τD [7]
The transmitted intensity reading R of the light source L42 just to measuring on the photoreceptor 431 of light source L4253For：
R53=A5I3e-τD [8]
The scattered light intensity reading R of the light source L41 just to measuring on the photoreceptor 431 of light source L4252For：
R52=A5αNI2e-τD [9]
By above-mentioned formula, we can obtain：
That is,Be one to be directly proportional to turbidity, and with luminous intensity I2、I3, and photoreceptor and its
Circuit gain A4 and A5 all unrelated physical quantity.UsingTo characterize the ratio of scattered light and transmitted light：
And turbidity is calculated with equation below, light source, photoreceptor and measuring circuit can be completely eliminated due to aging
Or the turbidimetry error that pollution is caused：
Wherein K=1/ α, are turbidity conversion coefficients, can be obtained by calibration experiment.
We can eliminate the turbidimetry error that light source, photoreceptor and measuring circuit are caused due to aging or pollution.
And in actually measurement, it would be desirable to eliminate as much as impact of the surrounding environment light to measuring, and the zero point of measuring circuit
Drift.Meanwhile, in order to tackle the fast-changing use environment of the turbidity such as rainwater, sewage conduct, the sensor of above-mentioned pair of light source must
Palpus two-way scattered light is measured to prevent using measuring method is replaced with two-way projection light simultaneously when, caused due to turbidity mutation
Measure error.
The measurement apparatus of the present invention are first by digital signal generator 421 with frequency fSProduce two-way with direct current biasing just
String ripple signal V2And V3：
Wherein A2、A3It is the alternating component amplitude of signal, T2、T3It is the alternating component cycle of two paths of signals, φ2、φ3It is to hand over
The phase place of stream composition, n is the sequence of values of AC signal.B2、B3It is the flip-flop of signal, needs to be respectively greater than or equal to A2
And A3, it is ensured that V2And V3More than 0.Wherein,WithThis two-way sine wave AC signal must
Must be orthogonal, you can to find a sequence length N so that they each other inner product result be 0.According to sine wave
Characteristic, the sine wave of two same periods, if phase is 90 degree, so they are enterprising in the sequence length of complete cycle
It is orthogonal during row inner product；If the cycle of two sine waves is different, as long as there is common multiple in their cycle, then with they
When cycle common multiple carries out inner product for sequence length, they are also orthogonal.We can adopt and design two-way with the aforedescribed process
Orthogonal sine wave signal.
Then, this two-way sine wave data signal is produced sine of the two-way with direct current biasing by us by digital to analog converter
Wave simulation voltage signal, and by voltage/current modular converter 423, in the way of current excitation, two light sources are driven respectively
L41、L42.Due to the luminous intensity of light source it is proportional with exciting current, therefore, light source L41 and light source L42 luminous intensities can be retouched
State for：
Wherein, k2And k3The respectively conversion proportionality coefficient of light source L41 and light source L42 from data signal to luminous intensity.
Luminous intensity that photoreceptor 431 is received through amplifying, 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 scattered light of light source L42, V5Contain light
The transmitted light of source L42 and the scattered light of light source L41
According to formula [1] and [2], we understand：
V4(n)=A4e-τlI2(n)+A4αNe-τlI3(n) [17]
V5(n)=A5e-τlI3(n)+A5αNe-τlI2(n) [18]
Substitute into [15] [16] to obtain：
We are in DSP module respectively to V4And V5The sequence that length is N is taken, it is and orthogonal on light source L41 and light source L42
AC signalWithIt is demodulated calculating 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] is substituted into [21], it is known that：
Because N is T2And T3Common multiple, by trigonometric function characteristic understand formula in the Section 1 inner product factorIt is equal toAnd due to orthogonality, the Section 2 inner product factor in formula
Equal to 0.The Section 3 inner product factorIt is the inner product of SIN function and direct current signal, equal to itself complete cycle
Summation, be as a result also equal to 0.Therefore, we understand：
R42=k2A2A4e-τD [26]
This be one only with light source L41 AC modulation amplitude As2Related value, flip-flop B with light source L412, Yi Jiguang
The modulated signal of source L42 is unrelated.That is, we can be from just receiving to the photoreceptor 431 of light source L41 according to formula [21]
To signal in, the response amplitude for producing is encouraged by light source L41 alternating components, individually demodulation is extracted, not by light source L42
Impact.
Equally, we can analyze and obtain
R43=α NK3A3A4e-τD [27]
R52=α Nk2A2A5e-τD [28]
R52=k3A3A5e-τD [29]
So, we can simultaneously demodulate in the case where light source L41 and L42 works simultaneously from two photoreceptors 431
4 AC signal amplitude responses of each photoreceptor to each light source are extracted, so that formula [12] can be set up, and
The formula can be adopted to carry out the calculating of turbidity.
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.Due to direct current signal it is orthogonal with sine wave signal, therefore null offset demodulation after result be 0, will not to survey
Amount produces impact.For ambient light interference, ambient light be broadly divided into sunshine isocandela degree be flip-flop natural light,
And the artificial light that incandescent lamp, fluorescent lamp etc. are driven with 50Hz alternating currents.And artificial light had both included flip-flop, include again
Due to the 50Hz fundamental components that 50Hz alternating currents are produced, and 100Hz, 150Hz, the 200Hz caused due to non-linear factor etc.
Frequency multiplication composition.Affect to eliminate ambient light interference, we can select suitable sources frequency and time of measuring sequence length (example
Such as the signal and the length of time series of 1 second of 40Hz) so that our light signal and direct current and 50Hz, 100Hz,
The AC signals such as 150Hz, 200Hz are all orthogonal, and so when turbidimetry is carried out, measurement result would not be subject to ambient light interference
Factor have impact on.
Wherein, in the present embodiment,
1st, the LED with two 940nm is installed as light source in the cylindrical cavity body of a diameter of 2.5cm；
2nd, in circuit as shown in Figure 4, with 10kHz as sample rate, DAC is controlled by digital signal generator and generates two
Road AC-amplitudes are 1V, and direct current biasing amplitude is 1V, and frequency is 25Hz, and sequence length is 1000 (i.e. 100ms), and phase place is respectively
0 degree and 90 degree of quadrature voltage signal；
3rd, respectively with the resistance that two resistances are 1k Ω, two-way quadrature voltage signal is converted into electric current between 0～2mA
Alternately the current signal of sinusoidal variations, drives as the electric current of light source L41 and light source L42；
4th, two photoreceptors 431 are adopted respectively through the signal that gain amplifier collection comes with the sample rate of 10kHz
Sample, time point and the digital signal generator of sampling generate the speed sync of orthogonal signalling；
5th, R42, R43, R52 and R53 this four readings, formula are calculated using formula [21]-[24] in DSP module
It is that the values of 400, φ 2 are 0 degree that middle N values are 1000, T values, and the values of φ 3 are 90 degree.
6th, according to formulaThe ratio of 90 degree of scattered lights and transmitted intensity is calculated, and according to formula [12]
Conversion obtains turbidity actual value.Proportional coefficient K wherein in formula [12] can be obtained by demarcating.
Above specific embodiment is only the application case of the present invention, and in actual use, related personnel can be at this
Various modifications and changes are carried out in the range of the technological thought of invention, for example, in the case where light source and photoreceptor position is not changed
Cavity is changed into square, cross, modification time of measuring, excitation signal strength, cycle, frequency, phase place etc..
In sum, the present invention can be risen using vertical double light sources, and the method measured using Orthogonal Double light source simultaneously
To measurement simultaneously, it is to avoid the measure error that turbidity suddenly change is caused when alternately measuring, and eliminate 50Hz alternating currents and its drive
The function of the impact that the surrounding environment lights such as dynamic lamp are caused to measurement.
Above are only presently preferred embodiments of the present invention, not for limit the present invention enforcement scope, without departing substantially from
In the case of spirit of the invention and its essence, those of ordinary skill in the art various change accordingly when can be made according to the present invention
Become and deform, but these corresponding changes and deformation should all belong to the protection domain of appended claims of the invention.
Claims (10)
1. a kind of liquid turbidity measuring method, it is characterised in that include：
Step 1：Two light source luminescents are accordingly driven according to two sinusoidal current signals；
Step 2：Gather and change transmitted light and scattered light acquisition two ways of digital signals that each light source is sent；
Step 3：According to transmitted intensity parameter and scattered light intensity that each light source is obtained per the data signal all the way
Parameter；
Step 4：It is turbid according to the transmitted intensity parameter and the scattered light intensity gain of parameter liquid of each light source
Degree.
2. liquid turbidity measuring method as claimed in claim 1, it is characterised in that the step 1 is included：
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 is driven
Move two light source luminescents.
3. liquid turbidity measuring method as claimed in claim 1, it is characterised in that the step 2 is included：
Step 21：It is described that the transmitted light and another light source that respectively correspondingly light source described in collection one is sent sends
Scattered light；
Step 22：Amplify the transmitted light and the scattered light that each described light source of collection is sent；
Step 23：The scattering that the transmitted light and another light source that light source described in after by amplification one is sent sends
Light is converted to the data signal all the way, while described in the transmitted light and that sent of another described light source after by amplification
The scattered light that light source sends is converted to data signal described in another road.
4. liquid turbidity measuring method as claimed in claim 1, it is characterised in that also comprising 0 step：It is defeated according to control signal
Go out two sinusoidal current signals.
5. liquid turbidity measuring method as claimed in claim 1, it is characterised in that according to equation below in the step 4
Obtain the liquid turbidity：
Wherein, N is liquid turbidity；K is conversion coefficient, and K is by experimental calibration acquisition；R42、R53Respectively two light sources it is saturating
Penetrate light intensity parameter；R43、R52The scattered light intensity parameter of respectively two light sources.
6. a kind of liquid turbidity measurement apparatus, it is characterised in that include：
Two light sources；
Driver element, two sinusoidal current signals of output accordingly drive two light source luminescents；
Two photosensitive units, accordingly gather and change transmitted light and scattered light two ways of acquisition that each light source is sent
Word signal；
Light intensity parameter obtaining unit, according to the transmitted intensity parameter that each light source is obtained per the data signal all the way
And scattered light intensity parameter；
Control process unit, according to the transmitted intensity parameter and the scattered light intensity gain of parameter of each light source
Liquid turbidity.
7. liquid turbidity measurement apparatus as claimed in claim 6, it is characterised in that the driver element is included：
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
The two-way sine wave signal is not accordingly converted to and export after two-way sine wave analog voltage signal；
Two voltage/current modular converters, are electrically connected at correspondingly two digital analog converters, described in two
The two-way sine wave analog voltage signal is accordingly converted to two sinusoidal currents by voltage/current modular converter respectively
After signal, accordingly export to two light sources to drive two light source luminescents.
8. liquid turbidity measurement apparatus as claimed in claim 6, it is characterised in that each photosensitive unit is included：
Photoreceptor, it is described that the transmitted light and another light source that respectively correspondingly light source described in collection one is sent sends
Scattered light；
Gain amplifier, is electrically connected at the photoreceptor, and the gain amplifier respectively correspondingly amplifies described in the one of collection
The scattered light that the transmitted light and another light source that light source is sent sends；
Analog-digital converter, is electrically connected at the gain amplifier, and the analog-digital converter is respectively by after amplification
The transmitted light and scattered light described in another light source that light source described in is sent is converted to the data signal all the way.
9. liquid turbidity measurement apparatus as claimed in claim 6, it is characterised in that the control process unit output control letter
Number to the driver element, the driver element exports two sinusoidal current signals according to the control signal.
10. liquid turbidity measurement apparatus as claimed in claim 6, it is characterised in that the control process unit is according to as follows
Formula obtains the liquid turbidity：
Wherein, N is liquid turbidity；K is turbidity conversion coefficient, and K is by experimental calibration acquisition；R42、R53Respectively two light sources
Transmitted intensity parameter；R43、R52The scattered light intensity parameter of respectively two light sources.
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| 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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