CN107290027A - Liquid level sensor and detection method and Full-automatic picking sampling device - Google Patents
Liquid level sensor and detection method and Full-automatic picking sampling device Download PDFInfo
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- CN107290027A CN107290027A CN201610199898.9A CN201610199898A CN107290027A CN 107290027 A CN107290027 A CN 107290027A CN 201610199898 A CN201610199898 A CN 201610199898A CN 107290027 A CN107290027 A CN 107290027A
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- liquid level
- probe
- capacitance
- testing result
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
- G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/10—Devices for withdrawing samples in the liquid or fluent state
- G01N1/14—Suction devices, e.g. pumps; Ejector devices
Abstract
The invention discloses a kind of liquid level sensor, including probe, for contacting tested liquid level and exporting selfcapacity, switch module, one end of probe and one end of switch module are connected, there are the other end of switch module multiple incoming ends to be connected respectively the interface channel in the input of a capacitance detector, tdm controller output Time-sharing control signal, one end of controlling switch module switching probe and at least two capacitance detectors between any one capacitance detector；The output end of each capacitance detector is all connected with decision device, electric capacity or the testing result of capacitance variations that detection probe is produced, and the testing result is sent into decision device；Decision device is according at least two testing results exported at least two capacitance detectors, it is determined that the final detection result of tested liquid level.Present invention also offers a kind of liquid level checking method and Full-automatic picking sampling device, using the embodiment of the present invention, the anti-interference of circuit is improved, the accuracy of measurement is improved, the sensitivity of measurement is ensured.
Description
Technical field
The present invention relates to liquid surface sensing device, more particularly, to Full-automatic picking sampling device is examined in sampling process
The detection circuit and method of this liquid level of test sample.
Background technology
Automatic clinical chemistry analyzer, immunity analysis instrument etc. in analysing body fluid, it is necessary to first sample, liquid absorbing probe
It is descending in test tube under the drive of motor, when touching liquid level, to prevent needle tubing from penetrating too deep bring clearly
The problem of washing difficulty increase (if clear do not wash clean can trigger cross pollution), motor must stop, and needle tubing is inhaled
The up return under the drive of motor after body fluid is taken, so liquid level inspection must be carried out when full-automatic biochemical is analyzed
Survey, when needle tubing touches liquid level, it is necessary to export contact liquid level indication signal to motor control unit, so as to
Controlled motor stops.The existing level detection technology of full-automatic biochemical, immunity analysis instrument mainly includes electric capacity and become
Change type level detection, pressure sensing type level detection and wireless transmitter receiver type level detection etc., wherein,
Detect liquid level by the capacitance variations of liquid absorbing probe, with sensitivity it is high, do not influence sample-adding precision the features such as,
It is current mainstream technology, is widely adopted.
In the prior art scheme, probe electric capacity is detected using phaselocked loop, when probe touches liquid level
When, the capacitance of probe electric capacity changes, by measuring whether phaselocked loop output voltage can determine whether probe
Contact liquid level.In this design, by the way that voltage signal is significantly amplified, it is possible to achieve compared with high detection
Sensitivity, detection micro liquid, but in full-automatic biochemical, immunity analysis instrument, because system architecture needs,
Probe is generally designed to elongated metallic tubular, and length can turn into sensitivity up to more than 100mm, at this moment probe
Antenna, easily introduces interference, the particularly Radio frequency interference in electromagnetic interference so that flase drop occurs in detection circuit,
Cause testing result mistake.
The content of the invention
The embodiment of the present invention provides a kind of liquid level sensor and detection method and Full-automatic picking sampling device.Can be with
The anti-interference of circuit is improved, the accuracy of measurement is improved, the sensitivity of measurement is ensured.
A kind of liquid level sensor that the present invention is provided, it includes probe, switch module, at least two electric capacity
Detector and decision device, wherein：
Probe, for contacting tested liquid level and exporting selfcapacity,
Switch module, one end of the probe is connected with one end of the switch module, the switch module
There are the other end multiple incoming ends to be connected respectively the input of a capacitance detector, and
The tdm controller being connected with the switch module, the tdm controller exports Time-sharing control signal,
For control the switch module switch one end of the probe with it is any at least two capacitance detector
Interface channel between one capacitance detector；
The output end of each capacitance detector is all connected with decision device, for detect electric capacity that the probe produces or
The testing result of capacitance variations, and the testing result is sent to the decision device；
The decision device is according at least two testing results exported at least two capacitance detector, really
Surely it is tested the final detection result of liquid level.
Second aspect of the present invention provides a kind of Full-automatic picking sampling device, and the analyzer includes：
Above-mentioned liquid level sensor；
Needle tubing motion control mechanism, for receiving the indication signal exported from the liquid level sensor, root
Moved according to indication signal control probe relative to the fluid to be measured.
Third aspect present invention provides a kind of liquid level checking method, and methods described includes：
Multichannel electric capacity sense channel is set, for being produced between detection probe and tested liquid level because of distance change
Electric capacity or capacitance variations, multigroup testing result is obtained in preset time period；
According at least two testing results, it is determined that the final detection result of tested liquid level.
Using the embodiment of the present invention, tdm controller first exports Time-sharing control signal, for controlling switch mould
Connection in one end of block switching probe and at least two capacitance detectors between any one capacitance detector is led to
Road；Then the output end of each capacitance detector is all connected with decision device, for detection probe produce electric capacity or
The testing result of capacitance variations, and the testing result is sent to decision device；Terminal decision device is according at least two
At least two testing results exported in individual capacitance detector, it is determined that the final detection result of tested liquid level.It is logical
Cross and integrate multiple testing results to determine final result, so as to improve the anti-interference of circuit, improve measurement
Accuracy, ensures the sensitivity of measurement.
Brief description of the drawings
In order to illustrate the technical solution of the embodiments of the present invention more clearly, below will be to needed for embodiment description
The accompanying drawing to be used is briefly described, it should be apparent that, drawings in the following description are some of the present invention
Embodiment, for those of ordinary skill in the art, on the premise of not paying creative work, may be used also
To obtain other accompanying drawings according to these accompanying drawings.
Fig. 1 is a kind of structural representation for liquid level sensor that the embodiment of the present invention is proposed；
Fig. 2 is the structural representation for another liquid level sensor that the embodiment of the present invention is proposed；
Fig. 3 is the structural representation for another liquid level sensor that the embodiment of the present invention is proposed；
Fig. 4 is a kind of structural representation for capacitance detector that the embodiment of the present invention is proposed；
Fig. 5 is the structural representation for another capacitance detector that the embodiment of the present invention is proposed；
Fig. 6 is a kind of structural representation for multiple capacitance detectors that the embodiment of the present invention is proposed；
Fig. 7 is the structural representation for another multiple capacitance detectors that the embodiment of the present invention is proposed.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear
Chu, it is fully described by, it is clear that described embodiment is a part of embodiment of the invention, rather than all
Embodiment.Based on the embodiment in the present invention, those of ordinary skill in the art are not making creative labor
The every other embodiment obtained under the premise of dynamic, belongs to the scope of protection of the invention.
Full-automatic picking sampling device generally can be used in the equipment such as automatic clinical chemistry analyzer, full-automatic immune instrument,
It generally includes liquid absorbing probe, detection circuit and needle tubing motion control mechanism.The suction obtained according to detection circuit
Whether liquid probe contacts the testing result of fluid to be measured, needle tubing motion control mechanism control liquid absorbing probe relative to
The fluid to be measured motion.Liquid absorbing probe considers chemical compatibility, usually stainless steel or titanium alloy, its
Can be single tube pin or double-deck liquid absorbing probe.
Fig. 1 is refer to, Fig. 1 is a kind of structural representation for liquid level sensor that the embodiment of the present invention is proposed.
As shown in figure 1, circuit includes control circuit 101, at least two capacitance detectors 102 in the embodiment of the present invention
And decision device 103, wherein：
Control circuit 101 includes probe, for contacting tested liquid level and exporting selfcapacity, in order to improve
The antijamming capability of liquid absorbing probe capacitance detecting, in certain embodiments, liquid absorbing probe are visited using double-deck imbibition
Needle tubing and conductive inner needle tube and intermediate insulating layer outside pin, its equivalent to one capacitor, including conduction.
In some embodiments of the present invention, probe can be double-deck needle tubing structure, and the conductive inner needle tube connection of probe is opened
Module is closed, and conductive outer needle tubing can be grounded, or it is earth-free.Further, in some of the invention
In embodiment, probe includes conductive inner needle tube and conductive outer needle tubing, and the length of conductive inner needle tube is than conductive outer pin
The length of pipe is long, and the length of conductive inner needle tube and conductive outer needle tubing differs by more than 3 centimetres.
Control circuit 101 includes switch module, and one end of probe and one end of switch module are connected, switch
There are the other end of module multiple incoming ends to be connected respectively the input of a capacitance detector, Yi Jiyu
The connected tdm controller of switch module, tdm controller output Time-sharing control signal, for controlling switch mould
Connection in one end of block switching probe and at least two capacitance detectors between any one capacitance detector is led to
Road.Circuit 101 is controlled to include follower, one end of above-mentioned conductive inner needle tube connects above-mentioned switching molding
One end of block and the input of follower, the output end of follower connect the above-mentioned outer needle tubing of conduction.
The output end of each capacitance detector 102 is all connected with decision device 103, is produced for detecting the probe
The testing result of electric capacity or capacitance variations, and the testing result is sent to decision device 103.
Specifically, the circuit parameter of at least two capacitance detectors 102 can be consistent or not
Consistent.In one of embodiment of the present invention, the circuit of above-mentioned at least two capacitance detector 102
The corresponding sensitive frequency of parameter is differed.Sensitive frequency refers to the Frequency point being easily disturbed, generally circuit work
The integral multiple of working frequency, on these Frequency points, circuit easily resonates with interfering frequency.Utilize circuit
At least two inconsistent capacitance detectors 102 of parameter, take consistency detection result defeated after being detected respectively
Go out to characterize the indication signal of another end in contact fluid to be measured of probe, can more improve the precision of level detection.
Optionally, capacitance detector 102 can include the oscillating circuit for being used to produce resonance signal, described to shake
Swing circuit and connect corresponding incoming end on the other end of the switch module；It is connected with oscillating circuit output
Measuring circuit, resonant frequency or resonant frequency for measuring resonance signal that the oscillating circuit is produced
Change；And the detection decision circuitry being connected with the measuring circuit, for according to the resonant frequency or humorous
The change of vibration frequency, obtains and exports the testing result of the electric capacity produced about the probe or capacitance variations.
For example, the electric capacity of probe output works as spy as a part for the electric capacity in the voltage-controlled RC oscillators of phaselocked loop
When pin touches liquid level, electric capacity changes, and RC frequencies of oscillation change therewith, but the phase discriminator of phaselocked loop and
The control voltage of the voltage-controlled RC oscillators of negative-feedback festival-gathering adjust automatically so that RC frequencies of oscillation and reference frequency
Reach unanimity, may determine that whether probe touches liquid level by measuring control voltage, can select not in addition
Same reference frequency, can realize the different response characteristics to different frequency electromagnetic interference.Or, probe output
Electric capacity as a part for RC charge-discharge circuit, when probe touches liquid level, electric capacity changes,
RC time constants change therewith, and frequency of oscillation is measured by RC oscillators, or set time measurement RC fills
Electric discharge amplitude, so as to judge whether probe touches liquid level, can select different R, C parameters in addition, real
Existing different RC time constants, reach the different response characteristics to different frequency electromagnetic interference.Then, electric capacity
Detector 102 can use the capacitance detector measured based on LC resonant frequencies, the electric capacity inspection based on phaselocked loop
Survey one of device and the capacitance detector measured based on RC time constants etc..
This paper circuit parameter can include frequency-measurement time, the capacitance detector for being used to measure resonant frequency
In oscillating circuit parameter (L and C parameter value, the voltage of phase-locked loop circuit of such as LC resonance circuits are set
The parameter value of definite value, LC drive circuits) etc. in any one parameter value.
Decision device 103, according at least two testing results exported at least two capacitance detector, really
Surely the final detection result of liquid level is tested, i.e. whether one end about probe touches the detection knot of tested liquid level
Really.
The division in control circuit 101 in the present embodiment only function as pronoun region, and should not be limited to
The a certain physical circuit formed.It is any in switch module, capacitance detector and decision device in the present embodiment
More than two combinations can be integrated on same integrated functionality chip to realize, or can also be using respective
Independent separating chips are realized.
As shown in Fig. 2 in the accuracy in order to improve level detection result, the present embodiment, carrying out liquid level
During detection, under the Time-sharing control of controller, probe is consecutively connected to different capacitance detectings by switch module
On device 102, the corresponding capacitance detector 102 of connection is respectively detected to probe, exports testing result.
This process circulates progress once and again, and the connection between one end of probe and any one capacitance detector is led to
The holdup time in road is usually a millisecond magnitude so that the total time control of circulation primary is of practical meaning at one
Scope.Decision device 103 receives and judges at least two testing results from capacitance detector 102, and
The final detection result of tested liquid level is exported according to consistency checking result.In each capacitance detector 102
Testing result is consistent, and decision device 103 exports the consistent final detection result.For example, in the present invention
Some of embodiments in, the resonant frequency or humorous that decision device 103 is exported at least two capacitance detectors
The change of vibration frequency meets the first preparatory condition simultaneously when, export another end in contact fluid to be measured for characterizing probe
Indication signal.Here the first preparatory condition can be that the change of above-mentioned resonant frequency or resonant frequency is more than
First predetermined threshold value, or in the first preset range, etc..
In addition, above-mentioned at least two testing result includes the first testing result and the second testing result, described the
One testing result is that the probe touches liquid level, and second testing result is the probe not in contact with to liquid
Face, can obtain the first number of first testing result and the second number of second testing result；
According to first number and second number, the final result of the level detection is determined.Further
, if first number is more than second number, the final result of the level detection is visited to be described
Pin touches liquid level, if first number is not more than second number, the level detection it is final
As a result it is the probe not in contact with to liquid level.It should be noted that can also using other decision methods come pair
Multiple testing results are judged.
Fig. 3 is refer to, Fig. 3 is the structural representation for another liquid level sensor that the embodiment of the present invention is proposed.
As illustrated, in the embodiment of the present invention circuit include control circuit 301, at least two capacitance detectors 302 with
And decision device 303, wherein：Control circuit 301 includes：
Probe, for contacting tested liquid level and exporting selfcapacity；
Switch module, one end of probe and one end of switch module are connected, and the other end of switch module is with more
Individual incoming end is connected respectively the input of a capacitance detector, and
The tdm controller being connected with switch module, tdm controller output Time-sharing control signal, for controlling
In one end of switch module switching probe and at least two capacitance detectors between any one capacitance detector
Interface channel.
The output end of each capacitance detector 302 is all connected with decision device 303, is produced for detecting the probe
The testing result of electric capacity or capacitance variations, and the testing result is sent to decision device 303.Wherein, at least two
Individual capacitance detector 302 can include a variety of capacitive detection circuits, and every kind of capacitive detection circuit can be using not
Same circuit structure, such as：LC Resonance detectors circuit, the capacitance detector based on phaselocked loop, based on RC when
Between constant capacitance detector etc..
Specifically, as shown in figure 4, capacitance detector 302 can include LC resonance circuits 221, for
Probe electric capacity occurs resonance and produces resonance signal, and resonance signal is output into shaping circuit 223；Shaping electricity
Road 223, is connected with LC resonance circuits 221, for the resonance signal to be converted into data signal, and will
The data signal is output to the process circuit；Process circuit 224, is connected with shaping circuit 223, is used for
The change of resonant frequency or resonant frequency is determined according to the data signal, and according to the resonant frequency or humorous
The change of vibration frequency obtains the testing result that the probe contacts liquid level.In the present embodiment, decision device 303 can
To be integrated with process circuit 224, handled by same integrated chip, such a deformation program according to
So disclosed in the claims in the present invention in protection domain.
With reference to Fig. 4 and Fig. 6, LC resonance circuits include LC resonant drivers 222, contain at least one electric capacity
Or the capacitive branch and inductive branch containing at least one inductance or variable inductance of variable capacitance, switch module
One end, one end of capacitive branch and the inductive branch of 240 other end respectively with LC resonant drivers 222
One end connection, the other end of inductive branch and the other end of capacitive branch respectively with LC resonant drivers
222 other end connection.
With reference to Fig. 5, the capacitance detector 302 of liquid level sensor can also include shielding line 228, follower
227th, LC resonant drivers 222, the capacitive branch of at least one electric capacity or variable capacitance and at least one is contained
The inductive branch of inductance or variable inductance, the other end of switch module 240 is connected with one end of shielding line 228,
The other end of shielding line 228 one end respectively with capacitive branch, one end of inductive branch, LC resonant drivers
222 one end and the input connection of follower 227, output end and the shielding line 228 of follower 227
External shielding layer is connected, the other end of inductive branch and the other end of capacitive branch respectively with LC resonant drivers
222 other end connection.
It should be noted that in actual use scene, probe 210 generally has certain distance with circuit,
The two is connected by wire, in order to reach good anti-jamming effectiveness, therefore between probe 210 and circuit
Increase coaxial cable or shielding line to drive.But, if cable is longer, the distribution capacity of cable easily drops
Low detection sensitivity, therefore by the way of shielding line 228 and follower 227, the external screen of shielding line 228
Cover layer and be followed device 227 and be driven rather than ground connection, follower 228 followed from LC resonance circuits 221
Signal so that do not have potential difference between the external shielding layer and inner core of shielding line 228, exists i.e. without electric field,
The electric capacity of itself of shielding line 228 is eliminated, so as to reach jamproof purpose.Referred to herein as follower adopt
With the operational amplification circuit that multiplication factor is one.
It is, of course, also possible to using the variant shown in Fig. 6, by shielding line 228, follower 227 as spy
Between pin 210 and switch module 240, one end of probe passes through shielding line 228 and the one of switch module 240
There are end connection, the other end of switch module 240 multiple incoming ends to be connected respectively a capacitance detector
302 input, one end of the input connecting valve module 240 of follower 227, follower 227 it is defeated
Go out end to be connected with the external shielding layer of shielding line 228.
In the present embodiment, by the electric capacity produced by the change of the distance between probe 210 and tested liquid level or
Capacitance variations, are added on LC resonance circuits 221, obtain be mixed with probe 210 generation capacitance information or
The resonance signal of capacitance variation information, data signal is converted into by the resonance signal；Data signal is measured, is obtained
Obtain the change of the resonant frequency or resonant frequency of resonance signal；Finally, according to resonant frequency or resonant frequency
Whether change, the other end of output sign probe contacts the indication signal of fluid to be measured.Below will be with LC resonance
Circuit 221 is to describe the general principle of the present embodiment in detail exemplified by LC antiresonant circuits.
In the present embodiment, LC resonance circuits 221 can be LC antiresonant circuits, above-mentioned LC resonance electricity
Road can include inductance L and electric capacity C, by one end of switch module probe one end respectively with inductance L,
Electric capacity C one end and one end connection of LC resonant drivers 222, inductance the L other end and electric capacity C
The other end of the other end respectively with LC resonant drivers 222 be connected.
It should be noted that electric capacity C, inductance L and LC resonant driver constitute core front-end detection circuit,
Constant-current source, under the excitation of LC resonant drivers, electric capacity C and inductance L can be used in LC resonant drivers
Generation resonance, original resonance frequency is
Wherein L, C represent electric capacity C, inductance L value respectively, in addition, probe is connected in LC resonance circuits,
Extra electric capacity C1 (selfcapacity for representing probe output) is introduced to LC resonance circuits, this is stylish
LC resonant frequencies are
Wherein, LC resonance circuits use resonance principle, are second order frequency selection circuit, due to electric capacity C, electricity
Feel the resonance current inside L and be much larger than external drive electric current, therefore the stability and antijamming capability of waveform
Far above conventional single order RC oscillators, so that the antijamming capability of this circuit is improved, and LC resonance electricity
Line structure is simple, reduces circuit cost.
The output of LC resonance circuits 221 is usually voltage signal, is expressed as sine wave, passes through shaping circuit 223
It is shaped as after data signal, is output to frequency measurement circuit 225 and carries out frequency measurement.Frequency measurement circuit 225
Included in capacitance detector, but it is not limited in process circuit 224, can also be separated with process circuit
Set.The measurement of frequency includes but is not limited to fixed time method and phaselocked loop method.Wherein, fixed time method is
Refer to：One section of set time is selected, periodic signal number is added up, count value divided by time are obtained into frequency
Rate., can be by way of hardware circuit or software programming, by frequency measurement circuit to realize this method
The periodic signal number by counting the above-mentioned data signal in preset duration is set to, and periodic signal is individual
Several divided by described preset duration, calculates the change for obtaining above-mentioned resonant frequency or resonant frequency.According to hardware
The mode of circuit, can be the periodic signal for employing counters to count the above-mentioned data signal in preset duration
Number, the periodic signal number divided by the preset duration for then again being obtained counter by divider, meter
Calculate the change for obtaining above-mentioned resonant frequency or resonant frequency.
Or, process circuit 224 can also measure the change of resonant frequency or resonant frequency by phaselocked loop method
Change.For example, as shown in figure 3, set phase-locked loop circuit and tension measuring circuit in process circuit 224, lock
Phase loop circuit and tension measuring circuit are sequentially connected in series, and are located between shaping circuit 223 and process circuit 224,
Phase-locked loop circuit by the frequency change of the output signal of above-mentioned shaping circuit by being converted into voltage signal, voltage
Measuring circuit obtains the magnitude of voltage of the voltage signal, and passes through the default magnitude of voltage of phase-locked loop circuit and resonance
The ratio value of frequency, calculates the change of above-mentioned resonant frequency or resonant frequency.Further, it can also pass through
Frequency dividing and lock mutually cause the magnitude of voltage of the output signal of above-mentioned shaping circuit to be directly proportional to resonant frequency, will export
The magnitude of voltage of signal divided by above-mentioned magnitude of voltage and the ratio value of resonant frequency, which are calculated, obtains above-mentioned resonant frequency.
In embodiments of the present invention, can by extending the time of measuring of resonant frequency, do not change circuit,
Do not increase and valid data digit is significantly improved under conditions of cost, lift detection resolution, realize to denier
The detection of liquid.Therefore, in some embodiments of the invention, use can be obtained by human-computer interaction device
Setting of the family to frequency measurement cycle or time, such as to above by the above-mentioned numeral in statistics preset duration
Preset time in the periodic signal number step of signal is arbitrarily set, and user passes through human-computer interaction device
The regulating command to the preset duration is inputted before inspection starts, and the regulating command is exported to processing electricity
Road, process circuit counts the periodic signal number in the preset duration that the regulating command is specified, based on
Calculate the change of resonant frequency or resonant frequency.According to this mode user can arbitrarily regulating frequency measure duration,
Improve the measurement accuracy of detection circuit.
The change that the resonant frequency or resonant frequency of acquisition are calculated in the present embodiment can be a value, also can table
Change up to for continuous waveform in the range of certain time.And the change of resonant frequency can obtain for current calculate
Frequency change relative to the frequency at moment before, or the current frequency obtained that calculates is relative to because of LC resonance
Electric capacity and the variable quantity of the original resonance frequency caused by inductance value in driver.According to above-mentioned formula (2),
Would know that, the change of resonant frequency or resonant frequency that above-mentioned calculating is obtained export relative to probe 210 itself
There is certain proportionate relationship in electric capacity C1.
According to aforementioned formula, in the case of f', L, C are known, itself electricity of probe output can be calculated
Holding C1 is：
Thus according to the change for calculating the resonant frequency obtained or resonant frequency, probe 210 can be intuitively reacted
The selfcapacity C1 of output change, therefore both proportionate relationships can be known according to methods such as calibrations, from
And based on the change for calculating resonant frequency or resonant frequency, to judge whether probe contacts the finger of fluid to be measured
Show signal.For example, process circuit 224 may determine that whether the change of above-mentioned resonant frequency or resonant frequency meets
First preparatory condition, if, then it represents that probe touches fluid to be measured, and output characterizes probe contact test solution
The indication signal of body.Here the first preparatory condition can be that the change of above-mentioned resonant frequency or resonant frequency is big
In the first predetermined threshold value, or in the first preset range, etc..
The capacitance detector 302 mentioned in the present embodiment can also be according to the resonant frequency or resonance for calculating acquisition
The change of the change of frequency, output capacitance or electric capacity, it can be a value, can also be expressed as certain time
In the range of waveform change.And the electric capacity that the change of electric capacity can obtain for current calculating is relative to the moment before
Electric capacity change, or current ground original capacitance when calculating the electric capacity obtained relative to probe noncontact liquid level
Variable quantity.For example, the change of electric capacity is included：The capacitance after detection capacitance contact to liquid level is characterized with touching
The capacitance change of the difference of capacitance before to liquid level；Or unit interval interior detection capacitance contact is characterized to liquid
The rate of change of capacitance variation amount after in front.
The electric capacity obtained is calculated for current, can be according to above-mentioned formula (3), by said frequencies measuring circuit
Electric capacity and inductance parameters value in 224 resonant frequency f` and the LC resonance circuits obtained substitute into above-mentioned formula (3)
Calculate and obtain afterwards.
Based on the change of the electric capacity or electric capacity calculated, to judge whether probe contacts the instruction letter of fluid to be measured
Number.For example, process circuit 224 may determine that whether the change of electric capacity or electric capacity that above-mentioned calculating is obtained meets
Second preparatory condition, if, then it represents that probe touches fluid to be measured, and output characterizes probe contact test solution
The indication signal of body.Here the second preparatory condition can be that to be more than second pre- for the change of above-mentioned electric capacity or electric capacity
If threshold value, or in the second preset range, etc..
Also such as, in certain embodiments, according to the resonant frequency, the capacitance variations of the probe are calculated
Amount/rate of change of capacitance；If capacitance change/the rate of change of capacitance exceedes predetermined threshold value, it is determined that the probe
End thereof contacts to liquid level, if the capacitance change/rate of change of capacitance is not less than predetermined threshold value, it is determined that institute
One end of probe is stated not in contact with to liquid level.
It should be noted that when the end thereof contacts of probe are to liquid level, the capacitance C1 of probe changes,
So as to cause the resonant frequency of detection circuit also to change, therefore, by the resonance frequency for obtaining detection circuit
Rate, can calculate the capacitance change/rate of change of capacitance for obtaining probe, and then judge whether one end of probe connects
Contact liquid level.
Optionally, probe output capacitance (abbreviation probe electric capacity) is used as the electricity in the voltage-controlled RC oscillators of phaselocked loop
A part for appearance, when probe touches liquid level, electric capacity changes, and RC frequencies of oscillation change therewith, but
The control voltage of the voltage-controlled RC oscillators of phase discriminator and negative-feedback festival-gathering adjust automatically of phaselocked loop so that RC vibrates
Frequency reaches unanimity with reference frequency, may determine that whether probe touches liquid level by measuring control voltage,
Different reference frequencies can be selected in addition, can realize the different response characteristics to different frequency electromagnetic interference.
Or, probe electric capacity is as a part for RC charge-discharge circuit, and when probe touches liquid level, electric capacity occurs
Change, RC time constants change therewith, and frequency of oscillation, or set time measurement RC are measured by RC oscillators
Discharge and recharge amplitude, so as to judge whether probe touches liquid level, can select different R, C parameters in addition,
Different RC time constants are realized, the different response characteristics to different frequency electromagnetic interference are reached.
Optionally, capacitance detector 302 can also include self-inspection decision circuitry, for detecting the resonance frequency
The change of rate or resonant frequency or the validity of the testing result, generate efficiency assessment result and defeated
Go out to the detection decision circuitry；The detection decision circuitry determines to be according to the efficiency assessment result
It is no to export the testing result to the decision device.The detection mode of validity has many kinds, for example, pass through number
According to analysis, test result is in particular, in the given time test result with the presence or absence of interference
With the presence or absence of regular cyclic fluctuation, if then representing to be interfered, testing result needs to query, instead
Then testing result can be assumed that to be desirable, be not affected by interference.
Decision device 303, for being tied according at least two detections exported at least two capacitance detector
Really, it is determined that the final detection result of tested liquid level.
In the present embodiment, in order to improve the accuracy of level detection result, when carrying out level detection, in control
Under the Time-sharing control of device processed, probe is consecutively connected on different capacitance detectors 302 by switch module, is connect
Logical corresponding capacitance detector 302 is respectively detected to probe, exports testing result.This process is repeatedly
Constantly circulation is carried out, during the delay of the interface channel between one end of probe and any one capacitance detector
Between be usually millisecond magnitude so that total time of circulation primary is controlled in a scope of practical meaning.Sentence
Certainly device 303 receives and judges at least two testing results from least two capacitance detectors 302, and root
The final detection result of tested liquid level is exported according to consistency checking result.In the inspection of each capacitance detector 302
It is consistent to survey result, and decision device 303 exports the consistent final detection result.For example, the present invention's
In some of embodiments, resonant frequency or resonance that decision device 303 is exported at least two capacitance detectors
The change of frequency meets above-mentioned first preparatory condition simultaneously when, export another end in contact test solution for characterizing probe
The indication signal of body.The circuit parameter of at least two capacitance detectors 302 can be it is consistent or
Inconsistent.Using at least two inconsistent capacitance detectors, consistency detection is taken after being detected respectively
As a result come export characterize probe another end in contact fluid to be measured indication signal, can more improve liquid level inspection
The precision of survey.Here it is humorous that circuit parameter can include frequency-measurement time (i.e. above-mentioned preset duration), LC
Shake L and C parameter value, the voltage setting value of phase-locked loop circuit, parameter value of LC drive circuits of circuit etc.
Any one parameter value in.Here the first preparatory condition can be above-mentioned resonant frequency or resonant frequency
Change be more than the first predetermined threshold value, or in the first preset range, etc..
In addition, above-mentioned at least two testing result includes the first testing result and the second testing result, described the
One testing result is that the probe touches liquid level, and second testing result is the probe not in contact with to liquid
Face, can obtain the first number of first testing result and the second number of second testing result；
According to first number and second number, the final result of the level detection is determined.Further
, if first number is more than second number, the final result of the level detection is visited to be described
Pin touches liquid level, if first number is not more than second number, the level detection it is final
As a result it is the probe not in contact with to liquid level.It should be noted that can also using other decision methods come pair
Multiple testing results are judged.
Certainly, as indicated earlier, when liquid absorbing probe is using double-deck liquid absorbing probe, the effect of conductive outer needle tubing can
For substituting above-mentioned shielding line 228, then the embodiment shown in Fig. 6 can be deformed into the mode shown in Fig. 7.
In the figure 7, probe 210 includes conductive inner needle tube 211 and conductive outer needle tubing 212.In the conduction of probe 210
One end of needle tubing 211 is connected with one end of switch module 240 and the input of follower 227, follower 227
The outer needle tubing 212 of conduction of output end and probe 210 be connected.Conductive outer needle tubing 212 can connect signal ground,
Signal ground can not also be connect.Remaining attachment structure is referring to related description above about Fig. 6.
The instruction letter that tested liquid level whether is touched for characterizing probe provided based on each above-mentioned embodiment
Number, after being received by the needle tubing motion control mechanism in Full-automatic picking sampling device, probe is controlled according to indication signal
Relative to fluid to be measured motion, for example, perform stop motion, either up (away from tested liquid level) or
Descending (close to tested liquid level) etc..
In the structure of above-mentioned multiplexed detection circuit design, present invention also offers a kind of liquid level checking method,
It includes：
Multichannel electric capacity sense channel is set, for being produced between detection probe and tested liquid level because of distance change
Electric capacity or capacitance variations, multigroup testing result is obtained in preset time period；
According at least two testing results, it is determined that the final detection result of tested liquid level.As to how according to extremely
Few two testing results, it is determined that the final detection result of tested liquid level, reference can be made to related description above.
Certainly, in some embodiments of the invention, the above method can also comprise the following steps：To described
The step of self-inspection being carried out per the testing result of road capacitance detecting passage output：
The detection testing result per the output of road capacitance detecting passage is with the presence or absence of disturbing, if not, then it represents that
Testing result effectively, exports the testing result, conversely, testing result is refused to adopt.
Validity or interfering detection mode have many kinds, such as by data analysis, test result
With the presence or absence of interference, it is in particular to detect the testing result with the presence or absence of regular in the given time
Cyclic fluctuation, if then representing to be interfered, testing result needs to query, and on the contrary then testing result can be with
Regard as desirable, be not affected by interference.
It should be noted that for each foregoing embodiment of the method, in order to be briefly described, therefore by its all table
State as a series of combination of actions, but those skilled in the art should know, the present invention is not by described
Sequence of movement limitation because according to the present invention, certain some step can using other orders or simultaneously
Carry out.Secondly, those skilled in the art should also know, embodiment described in this description belongs to excellent
Embodiment is selected, involved action and the module not necessarily present invention are necessary.
In the above-described embodiments, the description to each embodiment all emphasizes particularly on different fields, without detailed in some embodiment
The part carefully described, may refer to the associated description of other embodiment.
One of ordinary skill in the art will appreciate that all or part of step in the various methods of above-described embodiment
It can be by program to instruct the hardware of correlation to complete, the program can be stored in one and computer-readable deposit
In storage media, storage medium can include：Flash disk, read-only storage (English：Read-Only Memory,
Referred to as：ROM), random access device (English：Random Access Memory, referred to as：RAM)、
Disk or CD etc..
The content download method and relevant device that are there is provided above the embodiment of the present invention, system have been carried out in detail
Introduce, specific case used herein is set forth to the principle and embodiment of the present invention, and the above is real
The explanation for applying example is only intended to the method and its core concept for helping to understand the present invention；Simultaneously for this area
Those skilled in the art, according to the present invention thought, have change in specific embodiments and applications
Become part, in summary, this specification content should not be construed as limiting the invention.
Claims (16)
1. a kind of liquid level sensor, it is characterised in that the liquid level sensor includes probe, switching molding
Block, at least two capacitance detectors and decision device, wherein：
Probe, for contacting tested liquid level and exporting selfcapacity,
Switch module, one end of the probe is connected with one end of the switch module, the switch module
There are the other end multiple incoming ends to be connected respectively the input of a capacitance detector, and
The tdm controller being connected with the switch module, the tdm controller exports Time-sharing control signal,
For control the switch module switch one end of the probe with it is any at least two capacitance detector
Interface channel between one capacitance detector；
The output end of each capacitance detector is all connected with decision device, for detect electric capacity that the probe produces or
The testing result of capacitance variations, and the testing result is sent to the decision device；
The decision device is according at least two testing results exported at least two capacitance detector, really
Surely it is tested the final detection result of liquid level.
2. liquid level sensor as claimed in claim 1, it is characterised in that the decision device to it is described extremely
The uniformity of few two testing results is judged, and exports tested liquid level most according to consistency checking result
Whole testing result.
3. liquid level sensor as claimed in claim 1, it is characterised in that at least two detections knot
Fruit includes the first testing result and the second testing result, and first testing result is that the probe touches liquid
Face, second testing result be the probe not in contact with to liquid level, the decision device specifically for：
Obtain the first number of first testing result and the second number of second testing result；
According to first number and second number, the final result of the level detection is determined.
4. liquid level sensor as claimed in claim 3, it is characterised in that the decision device specifically for：
If first number is more than second number, the final result of the level detection is visited to be described
Pin touches liquid level.
5. liquid level sensor as claimed in claim 1, it is characterised in that each capacitance detector
Including：
Oscillating circuit for producing resonance signal, the oscillating circuit connects the other end of the switch module
Upper corresponding incoming end；
The measuring circuit being connected is exported with the oscillating circuit, for measuring the resonance that the oscillating circuit is produced
The change of the resonant frequency or resonant frequency of signal；And
The detection decision circuitry being connected with the measuring circuit, for according to the resonant frequency or resonant frequency
Change, obtain and export about the probe produce electric capacity or capacitance variations testing result.
6. liquid level sensor as claimed in claim 5, it is characterised in that each capacitance detector
Also include：
Self-inspection decision circuitry, change or the detection for detecting the resonant frequency or resonant frequency
As a result validity, generates efficiency assessment result and exports to the detection decision circuitry；
The detection decision circuitry decides whether to export the testing result according to the efficiency assessment result
To the decision device.
7. liquid level sensor as claimed in claim 1, it is characterised in that the liquid level sensor is also
Including follower,
The probe includes conductive inner needle tube and conductive outer needle tubing, and one end connection of the conductive inner needle tube is described
One end of switch module and the input of the follower, the output end connection of the follower are described conductive outer
Needle tubing.
8. liquid level sensor as claimed in claim 1, it is characterised in that each capacitance detector includes
LC Resonance detector circuits, the LC Resonance detectors circuit includes LC resonance circuits, shaping circuit and place
Circuit is managed, wherein：
The LC resonance circuits, for occurring resonance with the probe electric capacity and producing the resonance signal, and
The resonance signal is output to the shaping circuit；
The shaping circuit, is connected with the LC resonance circuits, for the resonance signal to be converted into numeral
Signal, and the data signal is output to the process circuit；
The process circuit, is connected with the shaping circuit, for determining resonance frequency according to the data signal
The change of rate or resonant frequency, and connect according to the change of the resonant frequency or resonant frequency acquisition probe
Touch the testing result of liquid level.
9. liquid level sensor as claimed in claim 8, it is characterised in that the LC resonance circuits bag
Include LC resonant drivers, the capacitive branch containing at least one electric capacity or variable capacitance and containing at least one electricity
Sense or the inductive branch of variable inductance, the other end of the switch module respectively with the LC resonant drivers
One end, one end of the capacitive branch and the inductive branch one end connection, the inductive branch it is another
The other end of the other end of one end and the capacitive branch respectively with the LC resonant drivers is connected.
10. liquid level sensor as claimed in claim 8, it is characterised in that the liquid level sensor
Including shielding line, follower, the probe includes conductive inner needle tube and conductive outer needle tubing；The probe is led
One end of electric inner needle tube is connected with one end of the switch module and the input of the follower, described to follow
The output end of device is connected with the outer needle tubing of conduction of the probe.
11. the liquid level sensor as described in claim 8-10 any one, it is characterised in that the place
Manage circuit specifically for:
According to the resonant frequency, capacitance change/rate of change of capacitance of the probe electric capacity is calculated；
If capacitance change/the rate of change of capacitance exceedes predetermined threshold value, it is determined that the probe touches liquid level.
12. liquid level sensor as claimed in claim 1, it is characterised in that at least two electric capacity
The corresponding sensitive frequency of circuit parameter of detector is differed.
13. a kind of Full-automatic picking sampling device, it is characterised in that the Full-automatic picking sampling device includes：
Liquid level sensor described in claim 1 to any one claim described in claim 12；
Needle tubing motion control mechanism, for receiving the indication signal exported from the liquid level sensor, root
Moved according to indication signal control probe relative to the fluid to be measured.
14. a kind of liquid level checking method, it is characterised in that methods described includes：
Multichannel electric capacity sense channel is set, for being produced between detection probe and tested liquid level because of distance change
Electric capacity or capacitance variations, multigroup testing result is obtained in preset time period；
According at least two testing results, it is determined that the final detection result of tested liquid level.
15. method as claimed in claim 14, it is characterised in that methods described also includes：To described every
The step of testing result of road capacitance detecting passage output carries out self-inspection：
The detection testing result per the output of road capacitance detecting passage is with the presence or absence of disturbing, if not, then it represents that
Testing result effectively, exports the testing result, conversely, testing result is refused to adopt.
16. method as claimed in claim 15, it is characterised in that the detection is described per road capacitance detecting
The step of testing result of passage output is with the presence or absence of interference includes：
Detect that the testing result whether there is regular cyclic fluctuation in the given time, if then table
Show in the presence of interference, otherwise represent not receiving interference.
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| CN201610199898.9A CN107290027A (en) | 2016-03-31 | 2016-03-31 | Liquid level sensor and detection method and Full-automatic picking sampling device |
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