CN103675023B - Detection circuit and detection method of total dissolved solids (TDS) - Google Patents
Detection circuit and detection method of total dissolved solids (TDS) Download PDFInfo
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- CN103675023B CN103675023B CN201210337744.3A CN201210337744A CN103675023B CN 103675023 B CN103675023 B CN 103675023B CN 201210337744 A CN201210337744 A CN 201210337744A CN 103675023 B CN103675023 B CN 103675023B
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Abstract
The invention discloses a detection circuit and a detection method of total dissolved solids (TDS). The detection circuit comprises a water quality probe, a TDS detection unit with three branches and a processing unit, wherein a first end of a first branch is connected with a first end of the water quality probe; a first end of the second branch is connected with a second end of the water quality probe; a first end of the third branch is connected with the first end and/or second end of the water quality probe; a first output end of the processing unit is connected with a second end of the first branch; a second output end of the processing unit is connected with a second end of the second branch; a first input end of the processing unit is connected with a second end of the third branch; the two output ends of the processing unit are used for alternately outputting pulse signals; the input end of the processing unit are used for acquiring the TDS signal detected by the TDS detection unit. According to the detection circuit, voltage is alternately applied to two ends of the water quality probe to drive the water quality probe to work, electrolytic reaction caused by the operation of continuously applying direct current voltage to the water quality probe is avoided, the detection precision of the TDS in the water is improved, the influence on the water quality during detection is avoided, and the service life of the water quality probe is prolonged.
Description
Technical field
The present invention relates to water treatment field, the detection circuit and detection method in particular to a kind of TDS.
Background technology
Total dissolved solid (TDS, Total Dissolved Solids) refers to the total amount of the solid being dissolved in the water, and surveys
Amount unit is parts per millions or mg/L, milligram/Liter, and physical significance is dissolved with how many millis in 1 liter of water
Gram total dissolved solid.Popular says, TDS values represent solute impurity content in water, and TDS values are bigger, illustrates miscellaneous in water
Matter content is big, water quality inferiority, conversely, impurity content is little, water quality is good.
At present, for the maximally effective criterion of water quality is the size of the TDS values of water, as TDS values are bigger, water is led
Electrical also better, its conductivity value is also bigger；TDS values are less, and electric conductivity is poorer, and electrical conductivity is also less, thus, it is possible to pass through to adopt
Sample circuit obtains the conductivity degree of water obtaining the TDS values of water.
At this stage, the water quality detection of drinking water need detection office of country or corresponding testing agency using it is special,
Accurate detecting instrument being detected and analyzed to water quality, but, due to special, accurate detecting instrument cost intensive,
It is difficult to be popularized on including products such as water purifier, water dispensers.And when adopting sample circuit of the prior art, due to water quality
Two syringe needle one end of probe can persistently be loaded a DC voltage, cause water quality probe tip that electrolysis can occur in water anti-
Should, in cell reaction, the syringe needle of water quality shorting pin loaded voltage one end persistently can lose electronics, promote water quality shorting pin loaded electricity
The syringe needle of pressure one end and then loss, so that affect the service life of water quality probe；Meanwhile, in the generating process of cell reaction,
Ion concentration (ion concentration near water quality probe tip) in water can change with continuing for cell reaction, so as to
Affect accuracy of detection；3rd, the cell reaction of persistence increases a large amount of harmful ions and ionic compound, shadow in promoting water
The degree of purity of Xiangshui County's matter, and increased the pollution of water body.
There is cell reaction during for detecting on TDS in correlation technique and affect the service life of water quality probe, affect inspection
Survey precision and affect the problem of water quality degree of purity, not yet propose effective solution at present.
The content of the invention
Present invention is primarily targeted at a kind of detection circuit of TDS and detection method are provided, during solving to detect TDS
There is cell reaction and affect the service life of water quality probe, affect accuracy of detection and affect water quality degree of purity.
To achieve these goals, according to an aspect of the invention, there is provided a kind of TDS detection circuits.
TDS detections circuit of the invention includes：Water quality probe, is arranged in aqueous solution；TDS detector units, have
Tie point, the second branch road and the 3rd branch road, wherein, the first end of tie point is connected with the first end of water quality probe, the
The first end of two branch roads is connected with the second end of water quality probe, the first end of the 3rd branch road and the first end of water quality probe and/
Or second end be connected；And processing unit, the first outfan of processing unit is connected with the second end of tie point, is processed
Second outfan of unit is connected with the second end of the second branch road, and the second of the first input end of processing unit and the 3rd branch road
End is connected, and the first outfan is used for replacing output pulse signal with the second outfan, and first input end is used for obtaining TDS detections
The TDS signals that unit is detected.
Further, the detection circuit also includes：Temperature-sensitive bag；And temperature detecting unit, with temperature-sensitive bag and processing unit
It is respectively connected with, for gathering the temperature of aqueous solution, wherein, processing unit also includes the second input, the second input and temperature
Degree detector unit is connected, and processing unit is additionally operable to determine the TDS values of aqueous solution according to the temperature of TDS signals and aqueous solution.
Further, the 3rd branch road includes：Rectification circuit, is connected with water quality probe；And filter circuit, first end with
Rectification circuit is connected, and the second end is connected with the first input end of processing unit.
Further, filter circuit includes：First electric capacity, first end connection rectification circuit, the second termination of the first electric capacity
Ground；Second electric capacity, first end connection rectification circuit, the second end ground connection of the second electric capacity；First resistor, first end connection rectified current
Road, the second end ground connection of first resistor；Second resistance, first end connection rectification circuit, the second end connection of second resistance are processed
The first input end of unit；And the 3rd electric capacity, first end is connected to primary nodal point, the second end ground connection of the 3rd electric capacity, wherein,
Primary nodal point is the node between the second end of second resistance and processing unit.
Further, rectification circuit includes：First diode, positive pole connect the first end of water quality probe, the first diode
Negative pole connect the first electric capacity first end；And second diode, positive pole connects the second end of water quality probe, the second diode
Negative pole connect the first electric capacity first end.
Further, rectification circuit includes：3rd diode, the first end of positive pole connection water quality probe or the second end, the
The negative pole of three diodes connects the first end of the first electric capacity.
Further, rectification circuit includes：4th diode, positive pole connect the first end of water quality probe, the 4th diode
Negative pole connect the first end of the first electric capacity, the 5th diode, plus earth, the negative pole connection water quality probe of the 5th diode
Second end；6th diode, positive pole connect the second end of water quality probe, and the negative pole of the 6th diode connects the first of the first electric capacity
End；And the 7th diode, plus earth, the negative pole of the 7th diode connect the first end of water quality probe.
Further, tie point includes 3rd resistor, and the first end of 3rd resistor is connected with the first end of water quality probe
Connect, the second end of 3rd resistor is connected with the first outfan of processing unit；And second branch road include the 4th resistance, the 4th is electric
The first end of resistance is connected with the second end of water quality probe, and the 4th the second end of resistance is connected with the second outfan of processing unit
Connect.
Further, temperature detecting unit includes：4th electric capacity, first end connection temperature-sensitive bag, the second end of the 4th electric capacity
Ground connection；5th electric capacity, first end connection temperature-sensitive bag, the second end ground connection of the 5th electric capacity；5th resistance, first end connection temperature-sensitive
Bag, the second end ground connection of the 5th resistance；6th resistance, first end connection temperature-sensitive bag, the second end connection of the 6th resistance process single
Second input of unit；And the 6th electric capacity, first end is connected to secondary nodal point, the second end ground connection of the 6th electric capacity, wherein, the
Two nodes are the node between the second end of the 6th resistance and processing unit.
To achieve these goals, according to a further aspect in the invention, there is provided a kind of TDS detection methods.
TDS detection methods of the invention include：Replace the two ends of on-load voltage to water quality probe, to drive water quality to visit
Pin detects the TDS of aqueous solution；The voltage signal that water quality probe in detecting is arrived is obtained, to obtain TDS signals；And according to TDS signals
Determine the TDS values of aqueous solution.
Further, the TDS detection methods also include：The temperature of collection aqueous solution, wherein, determines water according to TDS signals
The TDS values of solution include：The TDS values of aqueous solution are determined according to the temperature of TDS signals and aqueous solution.
By the present invention, using the TDS detection circuits for including following part：The water quality probe being arranged in aqueous solution；Tool
There are the TDS detector units of tie point, the second branch road and the 3rd branch road, wherein, first end and the water quality probe of tie point
First end is connected, and the first end of the second branch road is connected with the second end of water quality probe, the first end and water quality of the 3rd branch road
The first end of probe and/or the second end are connected；And processing unit, the of the first outfan of processing unit and tie point
Two ends are connected, and the second outfan of processing unit is connected with the second end of the second branch road, the first input end of processing unit
It is connected with the second end of the 3rd branch road, the first outfan is used for replacing output pulse signal, the first input with the second outfan
Hold for obtaining the TDS signals that TDS detector units are detected, output pulse signal is replaced to water quality probe by processing unit
Two ends replace on-load voltage, it is to avoid due to persistently loading DC voltage and caused cell reaction to water quality probe, it is right to solve
There is cell reaction when detecting and affect the service life of water quality probe, affect accuracy of detection and affect water quality degree of purity in TDS
Problem, and then impact to water quality and extend water quality probe and make when having reached TDS accuracy of detection of increasing water quality, having avoided detecting
With the effect in life-span.
Description of the drawings
The accompanying drawing for constituting the part of the application is used for providing a further understanding of the present invention, the schematic reality of the present invention
Apply example and its illustrate, for explaining the present invention, not constituting inappropriate limitation of the present invention.In the accompanying drawings：
Fig. 1 is the theory diagram that TDS according to a first embodiment of the present invention detects circuit；
Fig. 2 is the theory diagram that TDS according to a second embodiment of the present invention detects circuit；
Fig. 3 is the water quality sampling value-TDS curve synoptic diagrams under different temperatures；
Fig. 4 is the connection diagram that TDS according to a first embodiment of the present invention detects circuit；
Fig. 5 is the connection diagram that TDS according to a second embodiment of the present invention detects circuit；
Fig. 6 is the connection diagram that TDS according to a third embodiment of the present invention detects circuit；
Fig. 7 is the connection diagram that TDS according to a fourth embodiment of the present invention detects circuit；And
Fig. 8 is the flow chart of TDS detection methods according to embodiments of the present invention.
Specific embodiment
It should be noted that in the case where not conflicting, the feature in embodiment and embodiment in the application can phase
Mutually combine.Below with reference to the accompanying drawings and in conjunction with the embodiments describing the present invention in detail.
Fig. 1 is the theory diagram that TDS according to a first embodiment of the present invention detects circuit, as shown in figure 1, the TDS is detected
Circuit includes water quality probe, TDS detector units and processing unit.
Water quality probe is arranged in aqueous solution, is driven by drive voltage signal, for detecting the TDS of aqueous solution, wherein,
The drive voltage signal can replace on-load voltage at the two ends of water quality probe.Specifically, drive voltage signal is by processing unit
Produce, the processing unit has the first outfan and the second outfan, two outfans replace output pulse signals, and first defeated
Go out end to be connected with the first end of water quality probe via the tie point of TDS detector units, the second outfan is single via TDS detections
Second branch road of unit is connected with the second end of water quality probe, wherein, when the first outfan exports high level, water quality probe
First end is high level, and the second end is low level；When the second outfan exports high level, the second end of water quality probe is high electricity
Flat, first end is low level, so as to realize alternately two ends of the on-load voltage to water quality probe.
Water quality probe produces the detection voltage for characterizing aqueous solution TDS under the driving of drive voltage signal, and TDS detections are single
3rd branch road one end connection water quality probe of unit, the other end are connected to the first input end of processing unit, the 3rd branch road collection water
The detection voltage that matter probe is produced to form TDS signals, and by the TDS signal inputs to processing unit, so that processing unit root
The TDS values of aqueous solution are determined according to the TDS signals.
Wherein, processing unit logically includes signal generation point and signal processing, can respectively by different cores
Piece is realized, also can be realized by same chip.
In this embodiment, replace output pulse signal by the two of processing unit delivery outlets, replace on-load voltage
To the two ends of water quality probe, water quality probe is caused to be sent out in aqueous so as to avoid persistently loading DC voltage to water quality probe
Raw cell reaction, and then impact when improve water quality TDS accuracy of detection, avoiding detecting to water quality water quality probe can be extended
Service life.
The TDS detection circuits provided using the embodiment, it is to avoid provide voltage drive for water quality probe using DC voltage
Dynamic signal such that it is able to prevent water quality probe from cell reaction occurring when water quality detection is carried out to drinking water, electrolysis is separated out
Ion and ionic compound secondary pollution is produced to drinking water, and the detection syringe needle of water quality probe can be examined using grade-safe
Measure and monitor the growth of standing timber material, be further ensured that the precision of water quality detection and prevent which from chemical reaction occurring in water.
As the embodiment can avoid water quality probe from producing the reacting phenomenon of electrolysis in water, it is possible to extending water quality
The service life of probe；Meanwhile, the voltage of alternative expression drives the water quality probe that promotes that can be stable to carry out the sampling of TDS values, no
Water quality ion concentration can be caused to change due to cell reaction, and sampling precision during interference water quality probe in detecting.This friendship
Voltage driving mode for formula is driven similar to exchange, detection be all the 1/f frequency of pulse signal (f for) moment sampling
Value, quick sampling can be avoided because shadow of the mobility of the ion generated in water body or liquid to stability of sampling
Ring.
Fig. 2 is the theory diagram that TDS according to a second embodiment of the present invention detects circuit, as shown in Fig. 2 the TDS is detected
Circuit includes water quality probe, TDS detector units, temperature-sensitive bag, temperature detecting unit and processing unit.
Wherein, water quality probe is arranged in aqueous solution, is driven by drive voltage signal, for detecting the TDS of aqueous solution,
The drive voltage signal is produced by processing unit, and is loaded onto water quality probe via TDS detector units, with alternately on-load voltage extremely
The two ends of water quality probe.Water quality probe produces the detection voltage for characterizing aqueous solution TDS, TDS under the driving of drive voltage signal
Detector unit gathers the detection voltage of water quality probe generation to form TDS signals, and by the TDS signal inputs to processing unit.
While water quality probe in detecting aqueous solution TDS, by arranging the temperature of temperature-sensitive bag real-time detection aqueous solution.Temperature
Detector unit is respectively connected with temperature-sensitive bag and processing unit, gathers the temperature of the aqueous solution that temperature-sensitive bag is detected, and will detection
To temperature be input into processing unit, processing unit determines the TDS values of aqueous solution according to the temperature of aqueous solution and TDS signals.
Jing inventor's research finds, as shown in figure 3, for identical water quality TDS, when water temperature is different, TDS signals correspondence
TDS sampled values it is different, for example, when TDS is 25mg/L, the sampled value that water temperature is obtained when being 1 DEG C is 185, and water temperature is 25
DEG C when the sampled value that obtains less than 175, thus, when water quality TDS detect, discounting for the impact of water temperature, then process singly
The TDS that unit determines is inaccurate.
In this embodiment, using the temperature of aqueous solution as the condition for determining TDS, to overcome water temperature accurate to TDS
Property impact, so as to improve water quality TDS detection accuracy.
Preferably, processing unit determines water according to the temperature and TDS sampled values (the corresponding sampled value of TDS signals) of aqueous solution
During the TDS values of solution, the temperature adjustmemt water quality sampling value first according to aqueous solution, then according to revised sampled value and in advance
If sampled value-TDS curves, determine the TDS of aqueous solution, wherein, when default sampled value-TDS curves, to be water temperature warm for first
During sampled value-TDS curves when spending, included using below equation amendment according to the temperature adjustmemt water quality sampling value of aqueous solution：
TDS_ADAfter amendment=TDS_ADBefore amendment+(TWater-T1) % △ T
Wherein, TDS_ADAfter amendmentFor revised water quality sampling value, TDS_ADBefore amendmentFor the water quality sampling value for getting, TWaterFor
The temperature of aqueous solution, T1For the first temperature, △ T are predesigned compensation temperature.
As shown in figure 3, as, when the temperature of aqueous solution is less than 20 DEG C, under identical TDS, the water quality measured during different temperatures is adopted
Sample value differs greatly, it is further preferred that when the temperature of aqueous solution is less than 20 DEG C, the above-mentioned amendment sampled value of processing unit sampling
Method determine the TDS values of aqueous solution.
For example, by detecting difference at 1 DEG C and 10 DEG C of special conductivity meter (the high precision, expensive) detection of water quality TDS
Water quality sampling value during TDS values, obtains default sampled value-TDS curves, and when the temperature of aqueous solution is 4 DEG C, processing unit connects
After receiving TDS signals, the corresponding sampled value of TDS signals is modified：TDS_ADAfter amendment=TDS_ADBefore amendment+ (4-1) %2, so
Determine the TDS of aqueous solution afterwards by the sampled value-TDS curves at 1 DEG C；When the temperature of aqueous solution is 15 DEG C, processing unit connects
After receiving TDS signals, the corresponding sampled value of TDS signals is modified：TDS_ADAfter amendment=TDS_ADBefore amendment+ (15-10) %2,
Then the TDS of aqueous solution is determined by the sampled value-TDS curves at 10 DEG C.
Preferably, processing unit presets multiple temperature ranges, and the different fiducial temperature of different temperatures scope correspondence is prestored
Sampled value-TDS curves during each fiducial temperature, temperature and TDS sampled value (TDS signal pair of the processing unit according to aqueous solution
The sampled value answered) when determining the TDS values of aqueous solution, first determine which temperature range is the temperature of aqueous solution be in, then basis
It is determined that temperature range determine the corresponding fiducial temperature of the temperature of aqueous solution, finally according to water quality sampling value and determine benchmark temperature
Sampled value-TDS the curves of degree, determine the TDS of aqueous solution.
As shown in figure 3, due to, when the temperature of aqueous solution is more than or equal to 20 DEG C, under identical TDS, measuring during different temperatures
Water quality sampling value difference is different less, then replace the actual water quality sampling value for obtaining to determine using water quality sampling value during similar temperature
The TDS of aqueous solution, method are simple and little on the accuracy impact of TDS, therefore, it is further preferred that when the temperature of aqueous solution is big
In or during equal to 20 DEG C, the above-mentioned method for presetting multiple fiducial temperatures of processing unit sampling determines the TDS values of aqueous solution.
For example, default certain temperature range is 27 DEG C～31 DEG C, and the corresponding fiducial temperature of the temperature range is 29 DEG C, is led to
Water quality sampling value during difference TDS at 29 DEG C of special conductivity meter (the high precision, expensive) detection of detection water quality TDS is crossed, is obtained
To default sampled value-TDS curves, when the temperature of aqueous solution is 28 DEG C, processing unit determines water temperature in 27 DEG C～31 DEG C,
And then determine that fiducial temperature is 29 DEG C, finally according to water quality sampling value and 29 DEG C of sampled value-TDS curves, determine aqueous solution
TDS。
Using above-mentioned preferred embodiment, a sampled value-TDS curve that need to be prestored under fiducial temperature, and it is water-soluble in difference
Liquid temp determines the TDS values of aqueous solution using different methods, just can be accurately obtained the TDS values of aqueous solution, by simple inspection
Slowdown monitoring circuit is capable of achieving somewhat complex design instrument Detection results, simple and convenient, saves the testing cost of TDS.
Fig. 4 is the connection diagram that TDS according to a first embodiment of the present invention detects circuit, as shown in figure 4, TDS detections
The water quality probe CN1 of circuit is used for detecting the TDS of aqueous solution that its drive voltage signal to be by processing unit via TDS detector units
There is provided.
Processing unit realized by single-chip microcomputer (not shown), with the first delivery outlet Q-A, the second delivery outlet Q-B and
First input port Q-TDS.
The tie point of TDS detector units includes 3rd resistor R3, and the first end of 3rd resistor R3 is with water quality probe CN1's
First end is connected, and the second end of 3rd resistor R3 is connected to the first delivery outlet Q-A of single-chip microcomputer.
Second branch road of TDS detector units includes the 4th resistance R4, and the first end of the 4th resistance R4 is with water quality probe CN1's
Second end is connected, and the 4th the second ends of resistance R4 are connected to the second delivery outlet Q-B of single-chip microcomputer.
3rd branch road of TDS detector units includes the first diode D1, the second diode D2, the first electric capacity C1, second electric
Hold C2, the 3rd electric capacity C3, first resistor R1 and second resistance R2, wherein, the positive pole connection water quality probe CN1 of the first diode D1
First end, the negative pole of the first diode D1 connects the first end of the first electric capacity C1；The positive pole connection water quality of the second diode D2
Second end of probe CN1, the negative pole of the second diode D2 connect the first end of the first electric capacity C1；The first end of the first electric capacity C1 with
The negative pole of the first diode D1 and the second diode D2 is all connected with, the second end ground connection of the first electric capacity C1；Second electric capacity C2 and
One resistance R1 is in parallel with the first electric capacity C1 respectively；The first end of second resistance R2 is with the first diode D1's and the second diode D2
Negative pole is all connected with, and the second end of second resistance R2 connects the first input port Q-TDS of single-chip microcomputer；At the second end of second resistance R2
One node is set between single-chip microcomputer, and the first end of the 3rd electric capacity C3 is connected to the node, second termination of the 3rd electric capacity C3
Ground.
The operation principle of the circuit is as follows：During the first input port Q-A input high levels in circuit is detected, corresponding the
Two input port Q-B inputs are low level, and then the electrical conductivity by 3rd resistor R3 with measurement solution adds the total resistances of the 4th resistance R4
To carry out partial pressure, voltage is through the first diode D1, and the first electric capacity C1 and the second electric capacity C2 are filtered after filtering, then
Voltage detecting is carried out through second resistance R2 (i.e. current-limiting resistance) and the 3rd electric capacity C3 (i.e. filter capacitor) and by chip detection mouth；
Conversely, when the second input port Q-B input high levels in detection circuit, corresponding first input port Q-A inputs are low level,
Then add the total resistance of 3rd resistor R3 to carry out partial pressure with the electrical conductivity of measurement solution by the 4th resistance R4, voltage is through the two or two
Pole pipe D2, and the first electric capacity C1 and the second electric capacity C2 are filtered after filtering, then through second resistance R2 and the 3rd electric capacity
C3 simultaneously carries out voltage detecting by chip detection mouth, and first resistor R1 is the discharge resistance of the first electric capacity and the second electric capacity, and electricity
The frequency of road input low and high level is 50KHz.
Single-chip microcomputer alternately exports the pulse signal of certain frequency, such as sinusoidal wave pulse signal or square by two delivery outlets
Shape wave pulse signal, replaces on-load voltage to the two ends of water quality probe, causes water quality to be visited so as to avoid lasting direct current from acting on
There is cell reaction in aqueous in pin.
Fig. 5 is the connection diagram that TDS according to a second embodiment of the present invention detects circuit, as shown in figure 5, TDS detections
The water quality probe CN1 of circuit is used for detecting the TDS of aqueous solution that its drive voltage signal to be by processing unit via TDS detector units
There is provided.
Processing unit realized by single-chip microcomputer (not shown), with the first delivery outlet Q-A, the second delivery outlet Q-B and
First input port Q-TDS.
The tie point of TDS detector units includes 3rd resistor R3, and the first end of 3rd resistor R3 is with water quality probe CN1's
First end is connected, and the second end of 3rd resistor R3 is connected to the first delivery outlet Q-A of single-chip microcomputer.
Second branch road of TDS detector units includes the 4th resistance R4, and the first end of the 4th resistance R4 is with water quality probe CN1's
Second end is connected, and the 4th the second ends of resistance R4 are connected to the second delivery outlet Q-B of single-chip microcomputer.
3rd branch road of TDS detector units includes the 3rd diode D3, the first electric capacity C1, the second electric capacity C2, the 3rd electric capacity
C3, first resistor R1 and second resistance R2, wherein, the first end of the positive pole connection water quality probe CN1 of the 3rd diode D3, the 3rd
The negative pole of diode D3 connects the first end of the first electric capacity C1；The first end of the first electric capacity C1 is connected with the negative pole of the 3rd diode D3
Connect, the second end ground connection of the first electric capacity C1；Second electric capacity C2 and first resistor R1 are in parallel with the first electric capacity C1 respectively；Second resistance
The first end of R2 is connected with the negative pole of the 3rd diode D3, and the second end of second resistance R2 connects the first input port Q- of single-chip microcomputer
TDS；One node is set between the second end of second resistance R2 and single-chip microcomputer, and the first end of the 3rd electric capacity C3 is connected to the section
Point, the second end ground connection of the 3rd electric capacity C3.
The operation principle of the circuit is as follows：During the first input port Q-A input high levels in circuit is detected, corresponding the
Two input port Q-B inputs are low level, and then the electrical conductivity by 3rd resistor R3 with measurement solution adds the total resistances of the 4th resistance R4
To carry out partial pressure, voltage is through the 3rd diode D3, and the first electric capacity C1 and the second electric capacity C2 are filtered after filtering, then
Voltage detecting is carried out through current-limiting resistance R2 and filter capacitor C3 and by chip detection mouth；Conversely, when second in detection circuit
During the Q-B input high levels of input port, corresponding first input port Q-A inputs are low level, then by the 4th resistance R4 and measurement
The electrical conductivity of solution adds the total resistance of 3rd resistor R3 to carry out partial pressure, voltage through the 3rd diode D3, and after filtering first
Electric capacity C1 and the second electric capacity C2 are filtered, and then carry out electricity through current-limiting resistance R2 and filter capacitor C3 and by chip detection mouth
Pressure detection；First resistor R1 is the discharge resistance of the first electric capacity and the second electric capacity, and the frequency of circuit input low and high level is
50KHz。
Fig. 6 is the connection diagram that TDS according to a third embodiment of the present invention detects circuit, as shown in fig. 6, TDS detections
The water quality probe CN1 of circuit is used for detecting the TDS of aqueous solution that its drive voltage signal to be by processing unit via TDS detector units
There is provided.
Processing unit realized by single-chip microcomputer (not shown), with the first delivery outlet Q-A, the second delivery outlet Q-B and
First input port Q-TDS.
The tie point of TDS detector units includes 3rd resistor R3, and the first end of 3rd resistor R3 is with water quality probe CN1's
First end is connected, and the second end of 3rd resistor R3 is connected to the first delivery outlet Q-A of single-chip microcomputer.
Second branch road of TDS detector units includes the 4th resistance R4, and the first end of the 4th resistance R4 is with water quality probe CN1's
Second end is connected, and the 4th the second ends of resistance R4 are connected to the second delivery outlet Q-B of single-chip microcomputer.
3rd branch road of TDS detector units include the 4th diode D4, the 5th diode D5, the 6th diode D6, the 7th
Diode D7, the first electric capacity C1, the second electric capacity C2, the 3rd electric capacity C3, first resistor R1 and second resistance R2, wherein, the four or two
The positive pole of pole pipe D4 connects the first end of water quality probe CN1, and the negative pole of the 4th diode D4 connects the first end of the first electric capacity C1；
The plus earth of the 5th diode D5, the negative pole of the 5th diode D5 connect second end of water quality probe CN1；6th diode D6
Positive pole connect second end of water quality probe CN1, the negative pole of the 6th diode D6 connects the first end of the first electric capacity C1；Seven or two
The plus earth of pole pipe D7, the negative pole of the 7th diode D7 connect the first end of water quality probe CN1；The first end of the first electric capacity C1
It is respectively connected with the negative pole of the 4th diode D4 and the 6th diode D6, the second end ground connection of the first electric capacity C1；Second electric capacity
C2 and first resistor R1 are in parallel with the first electric capacity C1 respectively；The first end of second resistance R2 and the 4th diode D4 and the six or two pole
The negative pole of pipe D6 is all connected with, and the second end of second resistance R2 connects the first input port Q-TDS of single-chip microcomputer；In second resistance R2
One node is set between the second end and single-chip microcomputer, and the first end of the 3rd electric capacity C3 is connected to the node, the of the 3rd electric capacity C3
Two ends are grounded.
The operation principle of the circuit is as follows：During the first input port Q-A input high levels in circuit is detected, corresponding the
Two input port Q-B inputs are low level, and then the electrical conductivity by 3rd resistor R3 with measurement solution adds the total resistances of the 4th resistance R4
To carry out partial pressure, voltage is through the 4th diode D4, and the first electric capacity C1 and the second electric capacity C2 are filtered after filtering, then
Voltage detecting is carried out through current-limiting resistance R2 and filter capacitor C3 and by chip detection mouth；Conversely, when second in detection circuit
During the Q-B input high levels of input port, corresponding first input port Q-A inputs are low level, then by the 4th resistance R4 and measurement
The electrical conductivity of solution adds the total resistance of 3rd resistor R3 to carry out partial pressure, voltage through the 6th diode D6, and after filtering first
Electric capacity C1 and the second electric capacity C2 are filtered, and then carry out electricity through current-limiting resistance R2 and filter capacitor C3 and by chip detection mouth
Pressure detection；First resistor R1 is the discharge resistance of the first electric capacity and the second electric capacity, and the frequency of circuit input low and high level is
50KHz。
Fig. 7 is the connection diagram that TDS according to a fourth embodiment of the present invention detects circuit, and the embodiment includes Fig. 4 extremely
Water quality probe and TDS detector units that in Fig. 6, any embodiment is provided, also including temperature-sensitive bag CN2 and temperature sensing circuit.
Processing unit realized by single-chip microcomputer (not shown), with the first delivery outlet Q-A, the second delivery outlet Q-B,
One input port Q-TDS and the second input port Q-T.
Wherein, the TDS detector units in the embodiment are hereinbefore described in detail, are not repeated herein.Such as Fig. 7 institutes
Show, temperature detecting unit includes the 4th electric capacity C4, the 4th electric capacity C5, the 6th electric capacity C6, the 5th resistance R5 and the 6th resistance R6, its
In, one end connection temperature-sensitive bag of the 4th electric capacity C4, other end ground connection；5th electric capacity C5 and the 5th resistance R5 are respectively at the 4th electric capacity
C4 is in parallel；The first end of the 6th resistance R6 is connected with CN2, and second end of the 6th resistance R6 connects the second input port Q- of single-chip microcomputer
T；One node is set between second end of the 6th resistance R6 and single-chip microcomputer, and the first end of the 6th electric capacity C6 is connected to the section
Point, the second end ground connection of the 6th electric capacity C6.
The operation principle of the circuit is as follows：One termination+5V power supplys of temperature-sensitive bag, another termination filter capacitor, discharge resistance
And current-limiting resistance.When temperature is different, i.e., the resistance presented by the critesistor in temperature-sensitive bag is also different, i.e.+5V is through warm
Voltage after quick electric resistance partial pressure is filtered through the 4th electric capacity C4 and the 5th electric capacity C5, then through current-limiting resistance R6 and filtered electrical
Hold C6, voltage detecting is carried out by chip detection port then.5th resistance R5 is the discharge resistance of the 4th electric capacity and the 5th electric capacity,
And the frequency of circuit input low and high level is 50KHz,
While water quality probe in detecting aqueous solution TDS, by arranging the temperature of temperature-sensitive CN2 bag real-time detection aqueous solutions,
Single-chip microcomputer determines the TDS values of aqueous solution according to the temperature of aqueous solution and TDS signals.
Fig. 8 is the flow chart of TDS detection methods according to embodiments of the present invention, as shown in figure 8, the method include it is following
Step S102 is to step S106：
Step S102：Replace the two ends of on-load voltage to water quality probe, to drive the TDS of water quality probe in detecting aqueous solution,
Wherein, water quality probe is arranged in aqueous solution, is driven by drive voltage signal, and the drive voltage signal can be in water quality probe
Two ends replace on-load voltage.
Step S104：The voltage signal that water quality probe in detecting is arrived is obtained, to obtain TDS signals.
Water quality probe under the driving of drive voltage signal produces the detection voltage for characterizing aqueous solution TDS, obtains the voltage
Signal obtains TDS signals.
Step S106：The TDS values of aqueous solution are determined according to TDS signals.
In this embodiment, by the two ends of alternately on-load voltage to water quality probe driving water quality probe in detecting aqueous solution
TDS, cause water quality probe that cell reaction occurs in aqueous so as to avoid persistently loading DC voltage to water quality probe,
And then impact to water quality the service life of water quality probe can be extended when improve water quality TDS accuracy of detection, avoiding detecting.
Preferably, the step of TDS detection methods also include the temperature of collection aqueous solution, wherein, according to step S106
The temperature of TDS signals and aqueous solution determines the TDS values of aqueous solution.
Using the preferred embodiment, using the temperature of aqueous solution as the condition for determining TDS, to overcome water temperature to TDS
The impact of accuracy, so that improve the accuracy of water quality TDS detection.
It is further preferred that when the TDS values of aqueous solution are determined according to the temperature of TDS signals and aqueous solution, can adopt upper
The method of the amendment sampled value described in text determines the TDS values of aqueous solution, the default multiple benchmark being outlined above of can also sampling
The method of temperature determines the TDS values of aqueous solution, and here is omitted for detailed process.
As can be seen from the above description, present invention achieves following technique effect：It is defeated by the two of processing unit
Outlet replaces output pulse signal, replaces the two ends of on-load voltage to water quality probe, so as to avoid that water quality probe is persistently added
Carry DC voltage and cause water quality probe that cell reaction occurs in aqueous, and then improve water quality TDS accuracy of detection, avoid
The service life that affect and can extend water quality probe during detection to water quality.
The preferred embodiments of the present invention are the foregoing is only, the present invention is not limited to, for the skill of this area
For art personnel, the present invention can have various modifications and variations.It is all within the spirit and principles in the present invention, made any repair
Change, equivalent, improvement etc., should be included within the scope of the present invention.
Claims (9)
1. a kind of TDS detects circuit, it is characterised in that include：
Water quality probe, is arranged in aqueous solution；
TDS detector units, with tie point, the second branch road and the 3rd branch road, wherein, the first end of the tie point and institute
The first end for stating water quality probe is connected, and the first end of second branch road is connected with the second end of the water quality probe, institute
State the first end of the 3rd branch road to be connected with the first end of the water quality probe and/or the second end；And
Processing unit, the first outfan of the processing unit are connected with the second end of the tie point, described to process single
Second outfan of unit is connected with the second end of second branch road, the first input end of the processing unit and the described 3rd
Second end of branch road is connected, and first outfan and second outfan are used for replacing output pulse signal, and described the
One input is used for obtaining the TDS signals that the TDS detector units are detected；
The TDS detections circuit also includes：Temperature-sensitive bag；And
Temperature detecting unit, is respectively connected with the temperature-sensitive bag and the processing unit, for gathering the temperature of the aqueous solution
Degree,
Wherein, the processing unit also includes the second input, and second input is connected with the temperature detecting unit,
The processing unit is additionally operable to determine the TDS values of the aqueous solution according to the temperature of the TDS signals and the aqueous solution；
The processing unit is modified to the TDS values of aqueous solution by equation below：
TDS_ADAfter amendment=TDS_ADBefore amendment+(TWater-T1) % △ T；
Wherein, TDS_ADAfter amendmentFor revised water quality sampling value, TDS_ADBefore amendmentFor the water quality sampling value for getting, TWaterFor water-soluble
The temperature of liquid, T1For the first temperature, △ T are predesigned compensation temperature；
The TDS values of the aqueous solution are determined according to the revised water quality sampling value and default water quality sampling value curve.
2. TDS according to claim 1 detects circuit, it is characterised in that the 3rd branch road includes：
Rectification circuit, is connected with the water quality probe；And
Filter circuit, first end are connected with the rectification circuit, and the second end is connected with the first input end of the processing unit
Connect.
3. TDS according to claim 2 detects circuit, it is characterised in that the filter circuit includes：
First electric capacity (C1), first end connect the rectification circuit, the second end ground connection of the first electric capacity (C1)；
Second electric capacity (C2), first end connect the rectification circuit, the second end ground connection of the second electric capacity (C2)；
First resistor (R1), first end connect the rectification circuit, the second end ground connection of first resistor (R1)；
Second resistance (R2), first end connect the rectification circuit, and second end of second resistance (R2) connects the process
The first input end (Q-TDS) of unit；And
3rd electric capacity (C3), first end are connected to primary nodal point, and the second end ground connection of the 3rd electric capacity (C3) is wherein, described
Primary nodal point is the node between the second end of the second resistance (R2) and the processing unit.
4. TDS according to claim 3 detects circuit, it is characterised in that the rectification circuit includes：
First diode (D1), positive pole connect the first end of the water quality probe, the negative pole connection of the first diode (D1)
The first end of the first electric capacity (C1)；And
Second diode (D2), positive pole connect the second end of the water quality probe, the negative pole connection of the second diode (D2)
The first end of the first electric capacity (C1).
5. TDS according to claim 3 detects circuit, it is characterised in that the rectification circuit includes：
3rd diode (D3), positive pole connect the first end of the water quality probe or the second end, the 3rd diode (D3)
Negative pole connects the first end of the first electric capacity (C1).
6. TDS according to claim 3 detects circuit, it is characterised in that the rectification circuit includes：
4th diode (D4), positive pole connect the first end of the water quality probe, the negative pole connection of the 4th diode (D4)
The first end of the first electric capacity (C1),
5th diode (D5), plus earth, the negative pole of the 5th diode (D5) connect the second end of the water quality probe；
6th diode (D6), positive pole connect the second end of the water quality probe, the negative pole connection of the 6th diode (D6)
The first end of the first electric capacity (C1)；And
7th diode (D7), plus earth, the negative pole of the 7th diode (D7) connect the first end of the water quality probe.
7. TDS according to claim 1 detects circuit, it is characterised in that
The tie point includes 3rd resistor (R3), the first end of 3rd resistor (R3) and the first of the water quality probe
End is connected, and 3rd resistor (R3) second end is connected with first outfan (Q-A) of the processing unit；And
Second branch road includes the 4th resistance (R4), the first end of the 4th resistance (R4) and the second of the water quality probe
End is connected, and second end of the 4th resistance (R4) is connected with second outfan (Q-B) of the processing unit.
8. TDS according to claim 1 detects circuit, it is characterised in that the temperature detecting unit includes：
4th electric capacity (C4), first end connect the temperature-sensitive bag, the second end ground connection of the 4th electric capacity (C4)；
5th electric capacity (C5), first end connect the temperature-sensitive bag, the second end ground connection of the 5th electric capacity (C5)；
5th resistance (R5), first end connect the temperature-sensitive bag, the second end ground connection of the 5th resistance (R5)；
6th resistance (R6), first end connect the temperature-sensitive bag, and the second end connection of the 6th resistance (R6) is described to process single
Second input (Q-T) of unit；And
6th electric capacity (C6), first end are connected to secondary nodal point, and the second end ground connection of the 6th electric capacity (C6) is wherein, described
Secondary nodal point is the node between the second end of the 6th resistance (R6) and the processing unit.
9. a kind of TDS detection methods, it is characterised in that include：
Replace the two ends of on-load voltage to water quality probe, to drive the TDS of the water quality probe in detecting aqueous solution；
The voltage signal that the water quality probe in detecting is arrived is obtained, to obtain TDS signals；And
The TDS values of the aqueous solution are determined according to the TDS signals；
The TDS detection methods also include：The temperature of the aqueous solution is gathered,
Wherein, determine that the TDS values of the aqueous solution include according to the TDS signals：According to the TDS signals and the aqueous solution
Temperature determine the TDS values of the aqueous solution,
The TDS values of the aqueous solution are modified by equation below：
TDS_ADAfter amendment=TDS_ADBefore amendment+(TWater-T1) % Δ T；
Wherein, TDS_ADAfter amendmentFor revised water quality sampling value, TDS_ADBefore amendmentFor the water quality sampling value for getting, TWaterFor water-soluble
The temperature of liquid, T1For the first temperature, Δ T is predesigned compensation temperature；
The TDS values of the aqueous solution are determined according to the revised water quality sampling value and default water quality sampling value curve.
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| CN104698040A (en) * | 2015-03-23 | 2015-06-10 | 滁州东润电子科技有限公司 | Water quality testing probe with TDS and temperature sensing functions |
| CN105954485B (en) * | 2016-04-29 | 2017-12-26 | 上海海纳通物联网科技有限公司 | A kind of circuit with monitoring TDS water quality functions |
| CN105862321B (en) * | 2016-05-26 | 2018-04-06 | 北京小米移动软件有限公司 | parameter adjusting method and device |
| CN106153847B (en) * | 2016-08-19 | 2018-07-03 | 深圳大学 | A kind of water quality testing meter |
| CN106248171A (en) * | 2016-08-30 | 2016-12-21 | 福建金源泉科技发展有限公司 | The detection device of liquid capacity is measured in a kind of electric coupling |
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| CN113531910B (en) * | 2020-04-21 | 2022-06-03 | 芜湖美的厨卫电器制造有限公司 | TDS electrode circuit, water heater, control method of water heater and readable storage medium |
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