CN206431148U - A kind of automatic analytical instrument and its liquid detection device and detecting liquid level circuit - Google Patents
A kind of automatic analytical instrument and its liquid detection device and detecting liquid level circuit Download PDFInfo
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- CN206431148U CN206431148U CN201621273386.4U CN201621273386U CN206431148U CN 206431148 U CN206431148 U CN 206431148U CN 201621273386 U CN201621273386 U CN 201621273386U CN 206431148 U CN206431148 U CN 206431148U
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Abstract
The utility model belongs to detecting liquid level technical field, and there is provided a kind of automatic analytical instrument and its liquid detection device and detecting liquid level circuit.In the utility model, by including liquid-transfering needle, trigger module, square-wave voltage modular converter, filtration module, comparison module, the detecting liquid level circuit of host computer interface module and control module, so that detecting liquid level circuit is calibrated when receiving level detection signal to itself, and after calibration, control module is to the inceptive impulse signal after trigger module output adjustment, trigger module is according to the corresponding pulse-width signal of inceptive impulse signal output after adjustment to square-wave voltage modular converter, pulse width modulated signal conversion is output after corresponding DC voltage by square-wave voltage modular converter, DC voltage is compared by comparison module with reference voltage, and detecting liquid level signal is exported according to comparative result, its detection time is short, detection accuracy is high with antijamming capability, and easy care.
Description
Technical field
The utility model belongs to detecting liquid level technical field, more particularly to a kind of automatic analytical instrument and its detecting liquid level dress
Put and detecting liquid level circuit.
Background technology
Detecting liquid level is the essential function of automatic analytical instrument, and its main function is that control liquid-transfering needle is probeed into by liquid relief
The depth of body, so that it is high big with loading errors farthest to solve the cross pollution caused by the attaching liq of liquid-transfering needle outer surface
The problem of.Highly reliable, highly sensitive detecting liquid level system can not only reduce liquid-transfering needle outer surface liquid carrying amount, while also may be used
Avoid the misoperations such as instrument sampling system " suction " and " striker ".
At present, detecting liquid level technology mainly has contactless and two kinds of technologies of contact.Although contactless detecting liquid level
Technology, such as supercritical ultrasonics technology are ripe day by day, but its is complicated, and cost of implementation remains high, it is difficult to face typically middle-size and small-size
Promoted in bed testing instruments.Contact detecting liquid level technology is because its Detection Techniques is simple in construction, cost is low, therefore extensive use
In engineer operation.Contact detecting liquid level technology mainly has pneumatic process, mechanical vibration method, electric-resistivity method and capacitance method, wherein, gas
Platen press is mainly used in disposable feed head；Mechanical vibration method, which is suitable for liquid surface, has foam and sample tube to be stamped rubber stopper
Situation；Electric-resistivity method is directly contacted because needing electrode with liquid, so as to increase the possibility of cross pollution, and it is two interelectrode
Distance influences larger to detection system measurement accuracy；In capacitance method detecting liquid level technology, judge to adopt with the change of capacitance
Whether sample pin reaches liquid level, typically a pole plate (movable plate electrode) of the liquid-transfering needle as electric capacity, and places the metal of liquid container
Casing as another pole plate (fixed plate), the capacitance of the capacitor of the liquid-transfering needle-casing formation with liquid-transfering needle move down and by
It is cumulative big, when liquid-transfering needle touches liquid level in a flash, increase suddenly equivalent to movable plate electrode area and the distance of two-plate is unexpected
Diminish, cause capacitance to become big suddenly；Some liquid-transfering needles are designed to that bimetal pipe is nested together, by insulating between metal tube
Material isolate, double layer of metal pipe equivalent to capacitor two-plate, when liquid-transfering needle touches liquid, double layer of metal pipe formation
Condenser capacitance value abruptly increase；Liquid level contact information is just may detect by detecting the change events of capacitance, so as to realize liquid level
The function of detection, and then complete the control that liquid-transfering needle acts start and stop.
At present, existing capacitance method liquid detection device mainly includes following sections：Needle tubing, vibration and frequency dividing circuit, lock
Phase loop circuit, amplifying circuit, comparison circuit and step motor control unit.Wherein, the change of the capacitance of needle tubing causes lock phase
The frequency of oscillation of loop changes, and this is transformed into level signal, amplifies by amplifier, and the signal after amplification is through comparing
Step motor control unit is output signals to after circuit, so as to reach the purpose of detecting liquid level.But this detecting liquid level
In scheme, when the syringe needle of double-deck sampling needle tubing touches liquid level, the change of the capacitance of needle tubing causes the oscillation frequency of phase-locked loop
Rate changes, and the output of phaselocked loop has the change that a current potential increases, after this current potential increased is amplified by operational amplifier,
Compare output through comparison circuit again, output signal increases as detecting liquid level output signal due to the output current potential of phaselocked loop
Level variation is small, only about 250mV, and output is several continuous spikes, this scheme poor anti jamming capability, easily by
Occur to detect by mistake to interference.In order to increase the reliability of detection, it can only be realized by improving the comparison threshold value of comparison circuit,
But on the one hand simple improve compare threshold value and can decline detectivity, is not suitable for the detecting liquid level to a small amount of liquid,
And the requirement of development and the environmental protection with analysis detection instrument technology, laboratory uses amount of reagent less and less and sample
Amount, requirements at the higher level are proposed to detectivity.
On the other hand the liquid detection device causes the frequency of oscillation of phase-locked loop to change by the change of capacitance,
Level signal change is re-transformed into, but because the phase-locked loop chip response time is slow, the detection time about 100ms of whole device, its
, can the interior quantity detected of restricted unit time, the index of lowering apparatus in some high speed analysis detection instruments.In addition, this
When liquid detection device is assembled, the datum provided by comparison circuit needs to debug repeatedly in practical set application, and by
In season, climate change, the reason such as adjustable resistance contact aging datum can not be always maintained at stabilization, often every two or three
The moon needs manual adjustment once, adds maintenance cost.
In summary, there is detection time length, detection accuracy and anti-interference energy in existing capacitance method liquid detection device
Power it is low and not easy care the problem of.
Utility model content
The purpose of this utility model is to provide a kind of automatic analytical instrument and its liquid detection device and detecting liquid level electricity
Road, it is intended to solve existing capacitance method liquid detection device exist detection time length, detection accuracy and antijamming capability it is low with
And not easy care the problem of.
The utility model is achieved in that a kind of detecting liquid level circuit, is connected with host computer, for the liquid level to liquid
Detected, the detecting liquid level circuit includes liquid-transfering needle, trigger module, square wave-voltage transformation module, filtration module, compared
Module, host computer interface module and control module；
The first input end of the trigger module is connected with the liquid-transfering needle, the second input of the trigger module and institute
State the first output end connection of control module, the output end of the trigger module and the input of the square wave-voltage transformation module
The first input end connection of end and the control module；First output end of the square wave-voltage transformation module and the filter
The input connection of ripple module, the second output end of the square wave-voltage transformation module and the first input of the comparison module
End connection；The output end of the filtration module is connected with the second input of the control module；The second of the comparison module
Input is connected with the second output end of the control module, the output end of the comparison module and the host computer interface module
Input and the control module the 3rd input connection；4th input of the control module and the host computer
The output end connection of interface module；
When the control module receives the level detection signal that the host computer is sent, the control module controls institute
State detecting liquid level circuit and start calibration process, and inceptive impulse signal is exported to the trigger module, when the liquid-transfering needle does not connect
When touching the liquid level of the liquid, the trigger module is according to the pulse-width signal of inceptive impulse signal output first to described
Control module, the control module obtains the first pulse width according to first pulse-width signal；When the liquid-transfering needle connects
When touching the liquid level of the liquid, the trigger module is according to the pulse-width signal of inceptive impulse signal output second to described
Control module, the control module obtains the second pulse width, the control module root according to second pulse-width signal
The inceptive impulse signal is adjusted with second pulse width according to first pulse width；The control module to
Inceptive impulse signal after the trigger module output adjustment, the trigger module is according to the inceptive impulse signal after adjustment
Corresponding 3rd pulse-width signal is exported to the square wave-voltage transformation module, the square wave-voltage transformation module will be described
3rd pulse width modulated signal conversion is exports to the filtration module after the second DC voltage, the filtration module is to described second
DC voltage is exported after being filtered to the control module；It is described when the liquid-transfering needle, which leaves the liquid level, returns in situ
Trigger module is according to corresponding 4th pulse-width signal of the inceptive impulse signal output after adjustment to the square wave-voltage
4th pulse width modulated signal conversion is output after the first DC voltage by modular converter, the square wave-voltage transformation module
To the filtration module, the filtration module is exported after being filtered to first DC voltage to the control module, institute
State control module confirms input to the reference of the comparison module according to first DC voltage and second DC voltage
Voltage；
After the detecting liquid level circuit completes calibration process, the control module is to after the trigger module output adjustment
Inceptive impulse signal so that the trigger module is according to the corresponding pulsewidth modulation of inceptive impulse signal output after the adjustment
The pulse width modulated signal conversion is corresponding by signal to the square wave-voltage transformation module, the square wave-voltage transformation module
DC voltage after export to the comparison module, the comparison module is compared the DC voltage with the reference voltage
Compared with, and detecting liquid level signal is exported to the host computer according to comparative result.
Another object of the present utility model also resides in a kind of liquid detection device of offer, and the liquid detection device includes upper
State detecting liquid level circuit.
A further object of the present utility model also resides in a kind of automatic analytical instrument of offer, and the automatic analytical instrument includes upper
Position machine and above-mentioned liquid detection device.
In the utility model, by including liquid-transfering needle, trigger module, square wave-voltage transformation module, filtration module, ratio
Compared with the detecting liquid level circuit of module, host computer interface module and control module so that control module is receiving host computer hair
During the level detection signal sent, detecting liquid level circuit is calibrated to itself, and after calibration, and control module is to trigger module
Inceptive impulse signal after output adjustment, so that trigger module is adjusted according to the corresponding pulsewidth of inceptive impulse signal output after adjustment
Pulse width modulated signal conversion is corresponding DC voltage by signal processed to square wave-voltage transformation module, square wave-voltage transformation module
After export to comparison module, DC voltage is compared by comparison module with reference voltage, and according to comparative result to host computer
Detecting liquid level signal is exported, its detection time is short, detection accuracy and antijamming capability high and easy care, solves existing
Capacitance method liquid detection device exist detection time length, detection accuracy and antijamming capability it is low and not easy care the problem of.
Brief description of the drawings
Fig. 1 is the modular structure schematic diagram for the detecting liquid level circuit that the embodiment of the utility model one is provided；
Fig. 2 is the modular structure schematic diagram for the detecting liquid level circuit that another embodiment of the utility model is provided；
Fig. 3 is the electrical block diagram for the detecting liquid level circuit that the embodiment of the utility model one is provided；
Fig. 4 is the modular structure schematic diagram for the automatic analytical instrument that the embodiment of the utility model one is provided.
Embodiment
In order that the purpose of this utility model, technical scheme and advantage are more clearly understood, below in conjunction with accompanying drawing and implementation
Example, the utility model is further elaborated.It should be appreciated that specific embodiment described herein is only to explain
The utility model, is not used to limit the utility model.
Realization of the present utility model is described in detail below in conjunction with specific accompanying drawing：
Fig. 1 shows the modular structure for the detecting liquid level circuit that the embodiment of the utility model one is provided, for the ease of saying
It is bright, the related part of the utility model embodiment is illustrate only, details are as follows：
The detecting liquid level circuit 10 that the utility model embodiment is provided is connected with host computer, is entered for the liquid level to liquid
Row detection.
As shown in figure 1, the detecting liquid level circuit 10 that the utility model embodiment is provided includes liquid-transfering needle 100, trigger mode
Block 101, square wave-voltage transformation module 102, filtration module 103, comparison module 104, host computer interface module 105 and control
Module 106.
Wherein, the first input end of trigger module 101 is connected with liquid-transfering needle 100, the second input of trigger module 101 with
The first output end connection of control module 106, the output end of trigger module 101 and the input of square wave-voltage transformation module 102
And the first input end connection of control module 106；First output end of square wave-voltage transformation module 102 and filtration module 103
Input connection, the second output end of square wave-voltage transformation module 102 is connected with the first input end of comparison module 104；Filter
The output end of ripple module 103 is connected with the second input of control module 106；Second input of comparison module 104 and control
The second output end connection of module 106, the output end of comparison module 104 and the input of host computer interface module 105 and control
The 3rd input connection of molding block 106；4th input of control module 106 and the output end of host computer interface module 105
Connection.
When control module 106 receives the level detection signal of host computer (not shown) transmission, control module 106
Control detecting liquid level circuit 10 to start calibration process, and inceptive impulse signal exported to trigger module 101, when liquid-transfering needle 100 not
During the liquid level of contact liq, trigger module 101 is according to the pulse-width signal of inceptive impulse signal output first to control module
106, control module 106 obtains the first pulse width TW1 according to the first pulse-width signal；When the contact liq of liquid-transfering needle 100
During liquid level, trigger module 101 is according to the pulse-width signal of inceptive impulse signal output second to control module 106, control module
106 obtain the second pulse width TW2 according to the second pulse-width signal, and control module 106 is according to the first pulse width TW1 and the
Two pulse width TW2 are adjusted to inceptive impulse signal；Control module 106 is to initial after the output adjustment of trigger module 101
Pulse signal, trigger module 101 according to corresponding 3rd pulse-width signal of inceptive impulse signal output after adjustment to square wave-
Voltage transformation module 102, square wave-voltage transformation module 102 is by the 3rd pulse width modulated signal conversion for after the second DC voltage Va2
Output is to filtration module 103, and 103 couple of second DC voltage Va2 of filtration module is exported to control module 106 after being filtered, when
When liquid-transfering needle 100 leaves liquid level and returns in situ, control module 106 to the inceptive impulse signal after the output adjustment of trigger module 101,
Trigger module 101 according to corresponding 4th pulse-width signal of inceptive impulse signal output to square wave-voltage transformation module 102,
Square wave-voltage transformation module 102 by the 4th pulse width modulated signal conversion be the first DC voltage Va1 after export to filtration module
103,103 couple of first DC voltage Va1 of filtration module are exported after being filtered to control module 106, and control module 106 is according to
One DC voltage Va1 and the second DC voltage Va2 confirms input to the reference voltage Vref of comparison module 104；
Detecting liquid level circuit 10 complete calibration process after, control module 106 to after the output adjustment of trigger module 101 just
Initial pulse signal, so that trigger module 101 is according to the corresponding pulse-width signal of inceptive impulse signal output after adjustment to side
Pulse width modulated signal conversion is defeated after corresponding DC voltage by ripple-voltage transformation module 102, square wave-voltage transformation module 102
Go out to comparison module 104, DC voltage is compared by comparison module 104 with reference voltage Vref, and according to comparative result to
Host computer exports detecting liquid level signal.
Further, as the preferred embodiment of the utility model one, as shown in Fig. 2 detecting liquid level circuit 10 also includes
Indicating module 107, the output end of indicating module 107 is connected with the 3rd output end of control module 106, indicating module 107 it is defeated
Enter end and receive external input voltage VCC.
Specifically, after the completion of detecting liquid level circuit 10 is calibrated, when PC control liquid-transfering needle 100 is moved down and contacts liquid level
When, the output indication message of indicating module 107.
In the present embodiment, by setting indicating module 107 in detecting liquid level circuit 10 so that detecting liquid level circuit 10
It can be pointed out after the completion of calibration by indicating module 107 to user, be easy to user to understand the state of detecting liquid level circuit 10.
Further, as the preferred embodiment of the utility model one, detecting liquid level circuit 10 as shown in Figure 2 also includes pressing
Key module 108, the output end of key-press module 108 is connected with the 5th input of control module 106, the input of key-press module 108
End receives the operation signal of user's input.
Believe specifically, key-press module 108 exports corresponding level detection according to the button operation of user to control module 106
Number.
In the present embodiment, pass through in detecting liquid level circuit 10 set key-press module 108 so that user can by by
Control module 106 of the key into detecting liquid level circuit 10 sends control message, and then enriches the control of detecting liquid level circuit 10
Mode.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, trigger module 101 includes：555 determine
When device U1, first resistor R1, second resistance R2, the first electric capacity C1 and the second electric capacity C2；
Wherein, first resistor R1 first end is the first input end of trigger module 101, first resistor R1 the second end with
First end, 555 timer U2 threshold value end THR and 555 timer U1 that second electricity R2 hinders discharge end DISC connect altogether, and second
Resistance R2 the second end receives operating voltage VDD, and first end with the first electric capacity C1,555 timer U1 feeder ear VDD with
And 555 the reset terminal RST of timer connect altogether, the first electric capacity C1 the second end ground connection, 555 timer U1 triggering end TRI is tactile
The second input of module 101 is sent out, 555 timer U1 control end CV is connected with the second electric capacity C2 first end, the second electric capacity
C2 the second end and 555 timer U1 earth terminal GND are connected to ground altogether, and 555 timer U1 output end OUT is trigger module
101 output end.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, square wave-voltage transformation module 102
Including：3rd resistor R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, the 3rd electric capacity C3, the 4th electric capacity C4, the 5th electricity
Hold C5, the 6th electric capacity C6, the 7th electric capacity C7, the 8th electric capacity C8, operational amplifier U2A and first voltage follower U2B；
Wherein, 3rd resistor R3 first end and the 4th resistance R4 first end connect to form square wave-voltage transformation module altogether
102 input, 3rd resistor R3 the second end receives operating voltage VDD, the 4th resistance R4 the second end and the 5th resistance R5
First end and the 3rd electric capacity C3 first end connect altogether, the 5th resistance R5 the second end and the 4th electric capacity C4 first end connect altogether
In operational amplifier U2A in-phase input end, the 3rd electric capacity C3 the second end and operational amplifier U2A inverting input, fortune
Calculate amplifier U2A output end and the 6th electric capacity C6 first end be connected to first voltage follower U2B in-phase input end altogether,
Operational amplifier U2A positive voltage terminal receives operating voltage VDD, and is connected with the 5th electric capacity C5 first end, operational amplifier
U2A negative voltage side ground connection, second end at the 4th electric capacity C4 the second end, the 5th electric capacity C5 the second end and the 6th electric capacity C6
Ground, the of first voltage follower U2B inverting input and the 7th electric capacity C7 first end and the 6th resistance R6 are connected to altogether
One end connects the first output end to form square wave-voltage transformation module 102 altogether, and the 6th resistance R6 the second end is with the 8th electric capacity C8's
First end connects the second output end to form square wave-voltage transformation module 102, the 7th electric capacity C7 the second end and the 8th electric capacity C8 altogether
The second end be connected to ground altogether.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, filtration module 103 includes：7th
Resistance R7 and the 9th electric capacity C9；
Wherein, the 7th resistance R7 first end is the input of filtration module 103, the 7th resistance R7 the second end and the 9th
Electric capacity C9 first end connects the output end to form filtration module 103, the 9th electric capacity C9 the second end ground connection altogether.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, comparison module 104 includes：Tenth
Electric capacity C10, the 11st electric capacity C11, the 12nd electric capacity C12, second voltage follower U3B and comparator U3A；
Wherein, comparator U3A normal phase input end is the first input end of comparison module 104, and comparator U3A's is anti-phase defeated
Enter end and the tenth electric capacity C10 first end, second voltage follower U3B inverting input and second voltage follower U3B
Output end connect altogether, the tenth electric capacity C10 the second end ground connection, comparator U3A positive voltage terminal receives operating voltage VDD, and with
11st electric capacity C11 first end connection, the 11st electric capacity C11 the second end ground connection, comparator U3A output end is to compare mould
The output end of block 104, comparator U3A negative voltage side ground connection, second voltage follower U3B in-phase input end and the 12nd electricity
The first end for holding C12 connects the second input to form comparison module 104, the 12nd electric capacity C12 the second end ground connection altogether.
In the present embodiment, second voltage follower U3B can improve the impedance of comparison module 104, and then cause for control
The reference voltage that module 106 is exported is stable.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, control module 106 includes：Micro-control
Device U4 processed, the 13rd electric capacity C13, the 14th electric capacity C14, the 15th electric capacity C15, the 8th resistance R8 and crystal oscillator X1；
Wherein, microcontroller U4 the first signal output part PB0 is the first output end of control module 106, microcontroller
U4 the first signal input part PD2 is the first input end of control module 106, microcontroller U4 analog-to-digital conversion input
ADCIN0 is the second input of control module 106, and microcontroller U4 digital-to-analogue conversion output end DACOUT is control module 106
The second output end, microcontroller U4 secondary signal input PD5 is the 3rd input of control module 106, microcontroller
U4 the 4th signal input part PD7 is the 4th input of control module 106, and microcontroller U4 low-voltage end VSS ground connection is micro-
Controller U4 voltage end VDD receives external input voltage VCC, and is connected with the 15th electric capacity C15 first end, the 15th electricity
Hold C15 the second end ground connection, microcontroller U4 crystal oscillation signal input OSCIN and crystal oscillator X1 first end and the 13rd electricity
Hold C13 first end connection, microcontroller U4 crystal oscillation signal output end OSCOUT is connected with the 8th resistance R8 first end, the
Eight resistance R8 the second end is connected with the first end at crystal oscillator X1 the second end and the 14th electric capacity C14, the 13rd electric capacity C13's
Second end and the 14th electric capacity C14 the second end are connected to ground altogether.
Further, microcontroller U4 the first signal output part PB3 is the 3rd output end end of control module 106, micro-
Controller U4 the 5th signal input part PD6 is the 5th input of control module 106, in addition, microcontroller U4 other letters
Number equal sky in port connects, and is no longer described one by one herein.
Further, as the preferred embodiment of the utility model one, microcontroller U4 can use model
STML151K4U6 control chip is realized.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, indicating module 107 includes：It is luminous
Diode (LED) and the 9th resistance R9；
Wherein, the negative electrode of LED is the output end of indicating module 107, the anode of LED and the
Nine resistance R9 the second end connection, the 9th resistance R9 first end is the input of indicating module 107.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, key-press module 108 includes the tenth electricity
Hinder R10, the 16th electric capacity C16 and the first key switch S1；
Wherein, the of the tenth resistance R10 first end and the 16th electric capacity C16 first end and the first key switch S1
One end connects the output end to form key-press module 108 altogether, and the tenth resistance R10 the second end receives external input voltage VCC, the 16th
Electric capacity C16 the second end ground connection, the first key switch S1 the second end ground connection, the first key switch S1 the 3rd end is button mould
The input of block 108.
Further, as the preferred embodiment of the utility model one, as shown in figure 3, host computer interface module 105 includes
Interface stand J1, the 17th electric capacity and the 18th electric capacity；
Wherein, interface stand J1 first end 1 is grounded, and interface stand J1 the second end 2 is host computer interface module 105
Input, interface stand J1 the 3rd end 3 is the output end of host computer interface module 105, and interface stand J1 the 4th end 4 is received
Operating voltage VDD, and first end and the first end C18 of the 18th electric capacity with the 17th electric capacity C17 connect altogether, the 17th electric capacity
C17 the second end is connected to ground altogether with the 18th electric capacity C18 the second end.
The work of the detecting liquid level circuit 10 provided below by taking the circuit structure shown in Fig. 3 as an example the utility model embodiment
Make principle to illustrate, details are as follows：
First, the operation principle to the 555 timer U1 single-shot trigger circuits constituted is illustrated.Specifically, working as liquid
It is electric in face detection circuit 10, and liquid-transfering needle 100 not in contact with liquid level when, the monostable that microcontroller U4 is constituted to 555 timer U1
The triggering end TRI of triggers circuit applies an inceptive impulse signal, and the frequency of the inceptive impulse signal is 10KHZ, low level arteries and veins
Width is rushed less than 5 microseconds；When triggering end TRI voltage is less than input voltage VCC, the monostable that 555 timer U1 are constituted is touched
Power Generation Road is triggered into transient state, and 555 timer U1 output end Out exports a high level, while discharge end DIS ends,
Power supply passes through space environment and the spatial distribution electric capacity of circuit system formation by 1M Ω resistance second resistance R2 to liquid-transfering needle 100
Charging, when spatial distribution electric capacity both end voltage charges to 2/3rds more than or equal to input voltage VCC by 0V, 555 determine
When device U1 output end Out output by high level upset be low level, with time space point discharge end DIS of the electric capacity by conducting
0V is discharged to, the single-shot trigger circuit that 555 timer U1 are constituted enters stable state, is that standard is carried out in the arrival of trigger pulse next time
It is standby.When second trigger signal cycle arrives, said process is repeated again.The transient state duration tw ≈ of the single-shot trigger circuit
1.1RC, R be second resistance R2 resistance, C for spatial distribution electric capacity capacitance (R units M Ω, C unit pF in this example, then t
Unit is ms).
Secondly, when microcontroller U4 receives the level detection signal of host computer transmission, microcontroller U4 control liquid levels
Detection circuit 10 starts calibration process, and the single-shot trigger circuit constituted to 555 timer U1 exports inceptive impulse signal；When
Liquid-transfering needle 100 not in contact with liquid liquid level when, 555 timer U1 constitute single-shot trigger circuit it is defeated according to inceptive impulse signal
Go out the first pulse-width signal to microcontroller U4, operational amplifier U2A and first voltage follower U2B, microcontroller U4 roots
The first pulse width TW1 is obtained according to the first pulse-width signal.
When the liquid level of the contact liq of liquid-transfering needle 100, the single-shot trigger circuit that 555 timer U1 are constituted is according to initial arteries and veins
The pulse-width signal of signal output second is rushed to microcontroller U4, microcontroller U4 is according to the second pulse-width signal acquisition second
Pulse width, and inceptive impulse signal is adjusted with the second pulse width according to the first pulse width.
After microcontroller U4 is adjusted to inceptive impulse signal, and liquid-transfering needle 100 is when also contacting liquid level, microcontroller
Inceptive impulse signal after the single-shot trigger circuit output adjustment that U4 is constituted to 555 timer U1, what 555 timer U1 were constituted
Corresponding 3rd pulse-width signal of inceptive impulse signal output after single-shot trigger circuit output adjustment is to operational amplifier
U2A and first voltage follower U2B, operational amplifier U2A and first voltage follower U2B are by the 3rd pulse width modulated signal conversion
To be exported after the second DC voltage Va2 to filter circuit, filter circuit is exported to micro- after being filtered to the second DC voltage Va2
Controller U4.
When liquid-transfering needle 100, which leaves liquid level, returns in situ, the monostable trigger that microcontroller U4 is constituted to 555 timer U1
Inceptive impulse signal after circuit output adjustment, the single-shot trigger circuit that 555 timer U1 are constituted is according to inceptive impulse signal
Corresponding 4th pulsewidth pulse-width signal is exported to operational amplifier U2A and first voltage follower U2B, operational amplifier
4th pulse width modulated signal conversion is to export to filtered electrical after the first DC voltage Va1 by U2A and first voltage follower U2B
Road, filter circuit is exported after being filtered to the first DC voltage Va1 to microcontroller U4, and microcontroller U4 is according to the first direct current
Voltage Va1 and the second DC voltage Va2 confirms input to comparator U3A reference voltage Vref.
It should be noted that in the present embodiment, having two timers inside microcontroller U4, a timer is used for
To 555 timer U1 single-shot trigger circuit output trigger signal, i.e. the inceptive impulse signals constituted and the initial arteries and veins after adjustment
Signal is rushed, another timer is used to measure the pulse width for the single-shot trigger circuit output that now 555 timer U1 are constituted,
Specific practice is 256 data of single-shot trigger circuit output when continuous measurement liquid-transfering needle 100 is not in contact with liquid level respectively, and
256 data of single-shot trigger circuit output when liquid-transfering needle 100 contacts liquid level, and two groups of 256 measurement data are entered respectively
Line number word filtering process obtains the first average value and the second average value, and first average value is the first pulse width TW1, second
Average value is the second pulse width TW2.
In addition, microcontroller U4 is believed inceptive impulse according to the first pulse width TW1 and the second pulse width TW2 of measurement
Number it is adjusted specially：It is defeated that microcontroller U4 adjusts its according to the first pulse width TW1 and the second pulse width TW2 of measurement
The inceptive impulse signal gone out, the repetition period for making the inceptive impulse signal of output is 1.5 times of the second pulse width TW2, low electricity
Flat width is the repetition week of the inceptive impulse signal after the adjustment that the 1/2 of the first pulse width TW1, i.e. microcontroller 4 are exported
Phase have to be larger than the modulating pulse width of the single-shot trigger circuit output of 555 timer U1 compositions, the low level of trigger signal
Width should be less than monostable temporary steady time.
Further, it is additionally provided with analog-to-digital conversion measuring circuit inside microcontroller U4.Microcontroller U4 is turned by modulus
Change measuring circuit to liquid-transfering needle 100 not in contact with liquid level when filter circuit output DC voltage measure, it can continuously be measured
256 data, and digital filtering processing, to obtain the first DC voltage average value, first direct current are carried out to 256 data
It is the first DC voltage Va1 to flatten average, and microcontroller U4 can also be by analog-to-digital conversion measuring circuit to liquid-transfering needle 100
The DC voltage of filter circuit output is measured during contact liquid level, and it can continuously measure 256 data, and to 256 data
Digital filtering processing is carried out, to obtain the second DC voltage average value, second DC voltage average value is the second direct current
Press Va2.
In addition, microcontroller U4 confirms input to comparator according to the first DC voltage Va1 and the second DC voltage Va2
U3A reference voltage Vref is specially：Microcontroller U4 is according to the first DC voltage Va1 measured twice value and the second direct current
Voltage Va2 value, it is Va2 to set its output to comparator U3A reference voltage<Vref<Va1, preferably Vref=(Va1+
Va2)/2。
Pulsewidth, cycle and reference voltage of output of inceptive impulse signal after microcontroller U4 determines adjustment etc.
After parameter, above-mentioned parameter can be stored in its internal EEPROM by microcontroller U4
In (Electrically Erasable Programmable Read-Only Memory, EEPROM), and mark is set.
After detecting liquid level circuit 10 completes calibration process, when liquid-transfering needle 100 moves down the liquid level of contact liq again, liquid
Face detection indicator lamp LED is bright, represents that liquid detection device is calibrated successfully, while microcontroller U4 can detect the mark of its setting,
And automatic pulsewidth, cycle and the reference voltage of the output parameter that corresponding inceptive impulse signal is read from EEPROM, and to
Inceptive impulse signal after the single-shot trigger circuit output adjustment that 555 timer U1 are constituted, so that single-shot trigger circuit root
According to the corresponding pulse-width signal of inceptive impulse signal output after adjustment to operational amplifier U2A and first voltage follower
Pulse width modulated signal conversion is output after corresponding DC voltage by U2B, operational amplifier U2A and first voltage follower U2B
To comparator U3A, DC voltage is compared by comparator U3A with the microcontroller U4 reference voltage Vrefs exported, and according to
Comparative result exports detecting liquid level signal to host computer.
It should be noted that communication between detecting liquid level circuit 10 and host computer include level detection output signal,
Level detection reset signal and detection sensitivity setting signal.Level detection output signal is that comparator directly exports level detection
Signal is to host computer.Level detection reset signal is host computer input signal, is connected to a microcontroller U4 external interrupt
Pin, for controlling this detecting liquid level circuit 10 to re-start calibration.Detection sensitivity setting signal is host computer input signal,
It is connected to a microcontroller U4 I/O pin, the detection sensitivity for controlling detecting liquid level circuit 10, when detection liquid measure is few
When, may be configured as high sensitivity pattern, the cycle of the trigger signal of microcontroller U4 outputs closer to the second pulse width TW2,
The reference voltage Vref of output is closer to the second DC voltage Va2, and the sensitivity of detecting liquid level is higher.
In the present embodiment, in the present embodiment, microcontroller U4 measures liquid-transfering needle 100 by timer and probeed into before liquid level
Output signal pulsewidth TW1 and TW2 when afterwards, dynamic adjustment microcontroller is exported to 555 timer U1 trigger signal, triggering letter
Number cycle is with slightly larger than the second pulse width TW2, and the width of negative electricity flat pulse less than the first pulse width TW1 is preferred, is entered
And probe into output signal pulse width variations Liang ⊿ TW (⊿ TW=TW2-TW1 before and after liquid level by improving liquid-transfering needle 100) it is whole just
Duty change ratio in the initial pulse signal period so that the rear square wave-DC voltage pressure modulus of conversion in face of Fluid Contacting of liquid-transfering needle 100
The output level transition rise of block 102 increases, when the cycle of inceptive impulse signal is 1.5*TW2, transition level variation
Size has more than 600mV, under high sensitivity pattern, when the cycle of inceptive impulse signal is 1.2*TW2, the change of transition level
The size of amount is up to 1.0V, and transition level variation is bigger, and the antijamming capability of detecting liquid level circuit 10 is stronger, and can improve inspection
Survey sensitivity.
In addition, the ADC measurement liquid-transfering needles that microcontroller is included probe into square wave-DC voltage pressure modular converter before and after liquid level
First DC voltage Va1 of the DC voltage of 102 outputs value and the second DC voltage Va2 value, determines comparator U3A ginseng
Level is examined, the size of datum is slightly straight close to first between the first DC voltage Va1 and the second DC voltage Va2
Voltage Va2 is flowed, providing controllable and stable datum as comparator U3A exports.
On the other hand, the detecting liquid level time of the detecting liquid level circuit 10 based on the technical program is fast.When liquid-transfering needle 100 with
Liquid levels contact time space distribution capacity abruptly increase becomes big, the single-shot trigger circuit output pulse width that 555 timer U1 are constituted
I.e. time-varying is big, exports transition level after square wave-DC voltage pressure conversion, is calculated by simulation analysis, about by 8 or so
Pulse-width modulated output signal can generate the change of transition level, and the adjustable inceptive impulse signal frequency of microcontroller U4 outputs is in school
After standard be typically larger than 5KHz, the pulse-width signal cycle with the inceptive impulse signal period, the response time be transition level change when
Between be less than 2ms；The simple electronic device composition in addition, the detecting liquid level circuit 10 that the utility model embodiment is provided is sampled, its
It is simple in construction, it is easy to safeguard.
Further, the utility model embodiment also provides a kind of liquid detection device, and the liquid detection device includes upper
The detecting liquid level circuit 10 stated.
Further, Fig. 4 shows the modular structure for the automatic analytical instrument 20 that the embodiment of the utility model one is provided,
For convenience of description, the part related to the utility model embodiment is illustrate only, details are as follows：
As shown in figure 4, the automatic analytical instrument 20 that is provided of the utility model embodiment include liquid detection device 11 with
Host computer 12.By the automatic analytical instrument 20 that the utility model embodiment is provided is that liquid detection device 11 is realized, and
Liquid detection device 11 is that the detecting liquid level circuit 10 provided based on Fig. 1 to Fig. 3 is realized, accordingly, with respect to the utility model
The principle for the automatic analytical instrument 20 that embodiment is provided refers to above-mentioned Fig. 1 into Fig. 3 to the specific of detecting liquid level circuit 10
Description, here is omitted.
In the utility model, by including liquid-transfering needle, trigger module, square wave-voltage transformation module, filtration module, ratio
Compared with the detecting liquid level circuit of module, host computer interface module and control module so that control module is receiving host computer hair
During the level detection signal sent, detecting liquid level circuit is calibrated to itself, and after calibration, and control module is to trigger module
Inceptive impulse signal after output adjustment, so that trigger module is adjusted according to the corresponding pulsewidth of inceptive impulse signal output after adjustment
Pulse width modulated signal conversion is corresponding DC voltage by signal processed to square wave-voltage transformation module, square wave-voltage transformation module
After export to comparison module, DC voltage is compared by comparison module with reference voltage, and according to comparative result to host computer
Detecting liquid level signal is exported, its detection time is short, detection accuracy and antijamming capability high and easy care, solves existing
Capacitance method liquid detection device exist detection time length, detection accuracy and antijamming capability it is low and not easy care the problem of.
Preferred embodiment of the present utility model is the foregoing is only, it is all at this not to limit the utility model
Any modifications, equivalent substitutions and improvements made within the spirit and principle of utility model etc., should be included in the utility model
Protection domain within.
Claims (10)
1. a kind of detecting liquid level circuit, is connected with host computer, detected for the liquid level to liquid, it is characterised in that described
Detecting liquid level circuit includes：
Liquid-transfering needle, trigger module, square wave-voltage transformation module, filtration module, comparison module, host computer interface module and control
Molding block；
The first input end of the trigger module is connected with the liquid-transfering needle, the second input of the trigger module and the control
The first output end connection of molding block, the input of the output end of the trigger module and the square wave-voltage transformation module with
And the first input end connection of the control module；First output end of the square wave-voltage transformation module and the filtering mould
The input connection of block, the second output end of the square wave-voltage transformation module connects with the first input end of the comparison module
Connect；The output end of the filtration module is connected with the second input of the control module；Second input of the comparison module
End is connected with the second output end of the control module, and the output end of the comparison module is defeated with the host computer interface module
Enter the 3rd input connection of end and the control module；4th input of the control module and the host computer interface
The output end connection of module；
When the control module receives the level detection signal that the host computer is sent, the control module controls the liquid
Face detection circuit starts calibration process, and exports inceptive impulse signal to the trigger module, when the liquid-transfering needle is not in contact with institute
When stating the liquid level of liquid, the trigger module is according to the pulse-width signal of inceptive impulse signal output first to the control
Module, the control module obtains the first pulse width according to first pulse-width signal；When the liquid-transfering needle contacts institute
When stating the liquid level of liquid, the trigger module is according to the pulse-width signal of inceptive impulse signal output second to the control
Module, the control module obtains the second pulse width according to second pulse-width signal, and the control module is according to institute
The first pulse width is stated to be adjusted the inceptive impulse signal with second pulse width；The control module is to described
Inceptive impulse signal after trigger module output adjustment, the trigger module is according to the inceptive impulse signal output after adjustment
Corresponding 3rd pulse-width signal is to the square wave-voltage transformation module, and the square wave-voltage transformation module is by the described 3rd
Pulse width modulated signal conversion is exports to the filtration module after the second DC voltage, the filtration module is to second direct current
Voltage is exported after being filtered to the control module；When the liquid-transfering needle, which leaves the liquid level, returns in situ, the triggering
Module is according to corresponding 4th pulse-width signal of the inceptive impulse signal output after adjustment to the square wave-voltage conversion
Module, the square wave-voltage transformation module is by the 4th pulse width modulated signal conversion to be exported after the first DC voltage to institute
Filtration module is stated, the filtration module is exported after being filtered to first DC voltage to the control module, the control
Molding root tuber confirms input to the reference voltage of the comparison module according to first DC voltage and second DC voltage；
The detecting liquid level circuit complete calibration process after, the control module to after the trigger module output adjustment just
Initial pulse signal, so that the trigger module is according to the corresponding pulse-width signal of inceptive impulse signal output after the adjustment
To the square wave-voltage transformation module, the pulse width modulated signal conversion is corresponding straight by the square wave-voltage transformation module
Exported after stream voltage to the comparison module, the DC voltage is compared by the comparison module with the reference voltage,
And detecting liquid level signal is exported to the host computer according to comparative result.
2. detecting liquid level circuit according to claim 1, it is characterised in that the detecting liquid level circuit also includes indicating mould
Block, the output end of the indicating module is connected with the 3rd output end of the control module, the input termination of the indicating module
Receive external input voltage；
After the completion of the detecting liquid level circuit calibration, when liquid-transfering needle described in the PC control is moved down and contacts liquid level, institute
State indicating module output indication message.
3. detecting liquid level circuit according to claim 1 or 2, it is characterised in that the trigger module includes：555 timings
Device, first resistor, second resistance, the first electric capacity and the second electric capacity；
The first end of the first resistor is the first input end of the trigger module, the second end of the first resistor with it is described
The discharge end of the first end of second resistance, the threshold value end of 555 timer and 555 timer connects altogether, and described second
Second end of resistance receives operating voltage, and first end, the feeder ear of 555 timer and institute with first electric capacity
The reset terminal for stating 555 timers connects altogether, the second end ground connection of first electric capacity, and the triggering end of 555 timer is described
Second input of trigger module, the control end of 555 timer is connected with the first end of second electric capacity, and described second
The earth terminal of second end of electric capacity and 555 timer is connected to ground altogether, and the output end of 555 timer is the trigger mode
The output end of block.
4. detecting liquid level circuit according to claim 1 or 2, it is characterised in that the square wave-voltage transformation module bag
Include：
3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance, the 3rd electric capacity, the 4th electric capacity, the 5th electric capacity, the 6th electric capacity,
7th electric capacity, the 8th electric capacity, operational amplifier and first voltage follower；
The first end of the 3rd resistor and the first end of the 4th resistance connect to form the square wave-voltage transformation module altogether
Input, the second end of the 3rd resistor receives operating voltage, the second end and the 5th resistance of the 4th resistance
First end and the first end of the 3rd electric capacity connect altogether, the second end of the 5th resistance and the first end of the 4th electric capacity
It is connected to the in-phase input end of the operational amplifier altogether, the second end of the 3rd electric capacity is anti-phase defeated with the operational amplifier
The first end for entering end, the output end of the operational amplifier and the 6th electric capacity is connected to the first voltage follower altogether
In-phase input end, the positive voltage terminal of the operational amplifier receives the operating voltage, and with the first end of the 5th electric capacity
Connection, the operational amplifier negative voltage side ground connection, the second end of the 4th electric capacity, the second end of the 5th electric capacity with
And the second end of the 6th electric capacity is connected to ground, the inverting input of the first voltage follower and the 7th electric capacity altogether
First end and the first end of the 6th resistance connect the first output end to form the square wave-voltage transformation module altogether, described
The first end of second end of the 6th resistance and the 8th electric capacity connects the second output to form the square wave-voltage transformation module altogether
End, the second end of the 7th electric capacity is connected to ground altogether with the second end of the 8th electric capacity.
5. detecting liquid level circuit according to claim 1 or 2, it is characterised in that the filtration module includes：
7th resistance and the 9th electric capacity；
The first end of 7th resistance is the input of the filtration module, the second end and the described 9th of the 7th resistance
The first end of electric capacity connects the output end to form the filtration module, the second end ground connection of the 9th electric capacity altogether.
6. detecting liquid level circuit according to claim 1 or 2, it is characterised in that the comparison module includes：
Tenth electric capacity, the 11st electric capacity, the 12nd electric capacity, second voltage follower and comparator；
The normal phase input end of the comparator be the comparison module first input end, the inverting input of the comparator with
The first end of tenth electric capacity, the inverting input of the second voltage follower and the second voltage follower it is defeated
Go out end to connect altogether, the second end of the tenth electric capacity ground connection, the positive voltage terminal of the comparator receives operating voltage, and with described the
The first end connection of 11 electric capacity, the second end ground connection of the 11st electric capacity, the output end of the comparator is the comparison
The output end of module, the negative voltage side ground connection of the comparator, the in-phase input end of the second voltage follower and described the
The first end of 12 electric capacity connects the second input to form the comparison module, the second end ground connection of the 12nd electric capacity altogether.
7. detecting liquid level circuit according to claim 1 or 2, it is characterised in that the control module includes：
Microcontroller, the 13rd electric capacity, the 14th electric capacity, the 15th electric capacity, the 8th resistance and crystal oscillator；
First signal output part of the microcontroller is the first output end of the control module, the first of the microcontroller
Signal input part is the first input end of the control module, and the analog-to-digital conversion input of the microcontroller is the control mould
Second input of block, the digital-to-analogue conversion output end of the microcontroller is the second output end of the control module, described micro-
The secondary signal input of controller is the 3rd input of the control module, the 4th signal input part of the microcontroller
For the 4th input of the control module, the low-voltage end of the microcontroller is grounded, the voltage termination of the microcontroller
External input voltage is received, and is connected with the first end of the 15th electric capacity, the second end ground connection of the 15th electric capacity is described
The crystal oscillation signal input of microcontroller is connected with the first end of the first end of the crystal oscillator and the 13rd electric capacity, described
The crystal oscillation signal output end of microcontroller is connected with the first end of the 8th resistance, the second end of the 8th resistance with it is described
The first end connection of second end of crystal oscillator and the 14th electric capacity, the second end and the described 14th of the 13rd electric capacity
Second end of electric capacity is connected to ground altogether.
8. detecting liquid level circuit according to claim 2, it is characterised in that the indicating module includes：
Light emitting diode and the 9th resistance；
The negative electrode of the light emitting diode is the output end of the indicating module, the anode of the light emitting diode and the described 9th
The second end connection of resistance, the first end of the 9th resistance is the input of the indicating module.
9. a kind of liquid detection device, it is characterised in that the liquid detection device is included such as any one of claim 1 to 8 institute
The detecting liquid level circuit stated.
10. a kind of automatic analytical instrument, including host computer, it is characterised in that the automatic analytical instrument includes also including as weighed
Profit requires the liquid detection device described in 9.
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| CN201621273386.4U CN206431148U (en) | 2016-11-24 | 2016-11-24 | A kind of automatic analytical instrument and its liquid detection device and detecting liquid level circuit |
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| CN201621273386.4U CN206431148U (en) | 2016-11-24 | 2016-11-24 | A kind of automatic analytical instrument and its liquid detection device and detecting liquid level circuit |
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| CN108732631A (en) * | 2018-07-30 | 2018-11-02 | 优利德科技(中国)股份有限公司 | A kind of wall measuring apparatus and measurement method |
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| CN109764934A (en) * | 2019-03-05 | 2019-05-17 | 蓝怡科技集团股份有限公司 | A kind of liquid level detection circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108732631A (en) * | 2018-07-30 | 2018-11-02 | 优利德科技(中国)股份有限公司 | A kind of wall measuring apparatus and measurement method |
| CN109596848A (en) * | 2018-12-21 | 2019-04-09 | 苏州长光华医生物医学工程有限公司 | Reaction cup detects jamproof system and its application method |
| CN111380916A (en) * | 2018-12-29 | 2020-07-07 | 深圳市帝迈生物技术有限公司 | Liquid level detection device and liquid level detection method |
| CN111380916B (en) * | 2018-12-29 | 2023-09-15 | 深圳市帝迈生物技术有限公司 | Liquid level detection device and liquid level detection method |
| CN109764934A (en) * | 2019-03-05 | 2019-05-17 | 蓝怡科技集团股份有限公司 | A kind of liquid level detection circuit |
| CN111795727A (en) * | 2020-07-08 | 2020-10-20 | 中国计量大学 | Method and circuit for indirectly measuring ultrasonic wave transmission time |
| CN111795727B (en) * | 2020-07-08 | 2022-01-28 | 中国计量大学 | Method and circuit for indirectly measuring ultrasonic wave transmission time |
| CN114599132A (en) * | 2022-05-09 | 2022-06-07 | 中国工程物理研究院流体物理研究所 | Imaging illumination light source driving pulse generation device and photographic illumination device |
| CN114599132B (en) * | 2022-05-09 | 2022-07-29 | 中国工程物理研究院流体物理研究所 | Imaging illumination light source driving pulse generation device and photographic illumination device |
| CN115235579A (en) * | 2022-07-18 | 2022-10-25 | 深圳市万臣科技有限公司 | Liquid level detection effectiveness judgment method and related device |
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