CN2927005Y

CN2927005Y - Liquid-level detection circuit device

Info

Publication number: CN2927005Y
Application number: CN 200620042765
Authority: CN
Inventors: 姚冬; 姚凡
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-06-13
Filing date: 2006-06-13
Publication date: 2007-07-25
Anticipated expiration: 2016-06-13

Abstract

A liquid level detection circuit device comprises an oscillating circuit, a transmitting line, a probe, a receiving circuit, a rectification circuit, a lowpass filter circuit, an amplifying circuit and a digital filter circuit. The probe is arranged above the detected liquid level to form two polar plates of the capacitance C in the equivalent circuit together with the instrument base plate fully grounded, and the transmitting line issues sine wave oscillating signals through the probe. When the probe contacts with the liquid level, the receiving circuit will immediately receive the jumping signals that are transformed into the output signals of the probe mechanism through rectification, filtering and amplification. The utility model has applied the probe in a single-needle structure and circuit structure that is based on capacitance method so as to eliminate residual liquid from suspending, to avoid the cross contamination between specimens and at the same time increase the accuracy and sensitivity of the liquid level detection. The utility model has the advantages of a rapid response speed and a low operating error rate, which can be widely applied for detecting the liquid liquid level with various kinds of conductive capabilities in the medical lab analytic instrument.

Description

The detecting liquid level circuit arrangement

Technical field:

The utility model relates to the member in a kind of medical laboratory analytical instrument, is specifically related to the detecting liquid level circuit arrangement in a kind of medical laboratory analytical instrument.

Background technology:

Various medical laboratories analytical instrument, blood coagulation analyzer for example, when work, all must take a sample, sampling process is to be finished automatically by the High-Speed Automatic sampling system of instrument in the automatical analysis instrument, because the sample size that analytical instrument needs is often very little, so, require probe when touching the sample liquid level, to judge rapidly for fear of cross pollution and raising sampling efficiency.When automatic analytical instrument was taken a sample, originally probe promptly removed the liquid level near tested sample down, when touching liquid level, and the automatic stop motion of probe meeting, probe promptly leaves liquid level fast after picking sample.In order to finish above-mentioned sampling action, all be provided with the detecting liquid level circuit in the automatic sample handling system of automated chemical analyser, this circuit can send detectable signal immediately when probe touches liquid level, thus the motion of control and change probe mechanism.

Traditional liquid detection device normally is made up of probe and detection circuit two parts; This probe is for the crosspointer structure, and it is made of a sample introduction needle and an auxiliary electrode pin, this two parallel close proximity of pin and all be conductor, and they are connected respectively in the detection circuit as two electrodes and go.Crosspointer during work on the probe is simultaneously and rapidly to motion of melt surface, when crosspointer all touched liquid level, liquid between the crosspointer formed electrolytic cell, made the detection circuit conducting that is connected with crosspointer and produced electric current, touch the signal of liquid level thereby having provided pops one's head in, this signal controlling topworks stops probe movement.The crosspointer structure that this conduction probe method is adopted and the effect of detection circuit thereof are unsatisfactory: at first if fluid to be measured has good wellability for probe, then after each sampling, tend to adhere to residual drop between the crosspointer, this will influence the accuracy of detecting liquid level next time, produce the disconnected phenomenon of erroneous judgement, also can cause the cross pollution between the different tested samples simultaneously; Secondly, if the electric conductivity of fluid to be measured is relatively poor, then to touch the circuit turn-on signal that liquid level sends just insensitive for probe, thereby can reduce the response speed of detecting liquid level.

Summary of the invention:

At having the defective that liquid detection device can adhere to residual drop, incompatibility low electric conductivity liquid now, the utility model provides a kind of detecting liquid level circuit arrangement based on the capacitance method principle with single needle formula probe, and it has degree of accuracy height, highly sensitive and do not have an advantage of cross pollution.

The technical scheme in the invention for solving the technical problem is as follows:

A kind of detecting liquid level circuit arrangement, it comprises: oscillatory circuit, in order to produce square-wave signal S as the total system clock signal ₀Transtation mission circuit is in order to receive the square-wave signal S that oscillatory circuit produces ₀, and with this square-wave signal S ₀Be converted into the sine wave signal S of same frequency and amplitude ₁Probe, be suspended in tested liquid level top with near and survey liquid level, it forms two pole plates of capacitor C in the equivalent electrical circuit jointly with the abundant instrument base plate of ground connection, in order to the sine wave signal S of transmission from transtation mission circuit ₁Receiving circuit is in order to receive and to send the response signal S that produces on the capacitor C in the equivalent electrical circuit ₂Rectification circuit is in order to receive the response signal S from receiving circuit ₂, and it is carried out rectification obtain rectified signal S ₃Low-pass filter circuit is in order to receive and to handle the rectified signal S of self-rectifying circuit ₃Thereby, obtain dc level signal S ₄Amplifying circuit is in order to receive and to amplify dc level signal S from low-pass filter circuit ₄, and obtain amplifying signal S ₅Digital filter circuit is in order to receive the amplifying signal S from amplifying circuit ₅, and to filtering obtain representing the output signal S of liquid level position ₆

Contain CPU (central processing unit) in the digital filter circuit of detecting liquid level circuit arrangement described in the utility model; The square-wave signal S that described oscillatory circuit produces ₀Dutycycle be 50%; Described probe can be a Metallic rod, also can be hollow metal pipe, and its surface attachment has not wellability material layer of teflon.

Unlike the prior art, the utility model has adopted the probe of single needle formula structure, has therefore eliminated the residual drop phenomenon that the crosspointer structure causes, and has also just avoided the cross-contamination issue between sample, has improved the accuracy of result of detection simultaneously.In addition, detecting liquid level circuit arrangement described in the utility model is a utmost point with metal probe, instrument base with ground connection is another utmost point, form the electric capacity in the equivalent electrical circuit, transtation mission circuit sends the sine-wave oscillation signal by probe, when probe touches liquid level and has changed the dielectric in the equivalent circuit capacitance, receiving circuit can receive the signal of transition immediately, therefore the utility model not only can adapt to the fluid to be measured of various different electric conductivity, and has improved the response speed of detection circuit, the sensitivity that has improved detecting liquid level.

Description of drawings:

Fig. 1 is a circuit structure block scheme of the present utility model.

Embodiment:

Now with specific embodiment the utility model is described in further detail in conjunction with the accompanying drawings.

See also Fig. 1 circuit structure block scheme of the present utility model, diagram detecting liquid level circuit arrangement comprises oscillatory circuit 1, transtation mission circuit 2, probe 3, receiving circuit 4, rectification circuit 5, low-pass filter circuit 6, amplifying circuit 7 and digital filter circuit 8.Described oscillatory circuit 1 is in order to produce the square-wave signal S as the total system clock signal ₀, this square-wave signal S ₀Frequency is that 500KHz, amplitude are that 0.5v, dutycycle are 50%.Described transtation mission circuit 2 is connected on the oscillatory circuit 1 to receive the square-wave signal S that oscillatory circuit 1 transmission comes ₀, it is with this square-wave signal S ₀Be converted into the sine wave signal S that frequency is identical with amplitude with it ₁, and with this sine wave signal S ₁Be delivered to probe 3.This probe 3 is suspended in the top of tested liquid level, by the motion of mechanical mechanism its can rise and descend so as near and survey tested liquid level; Probe 3 is connected with transtation mission circuit 2 with reception sine wave signal S ₁, this probe 3 constitutes pole plate of capacitor C in equivalent electrical circuit and in order to the sine wave signal S of transmission from transtation mission circuit 2 ₁And fully the instrument base plate 9 of ground connection be arranged at the probe corresponding with it position, 3 belows on, it constitutes another pole plate of capacitor C in the equivalent electrical circuit, so any material between probe 3 and instrument base plate 9, comprise fluid to be measured, all formed the dielectric between these capacitor C the two poles of the earth; In the present embodiment, described probe 3 is a Metallic rod, and its outside surface is attached with not wellability material layer, reducing fluid to be measured to popping one's head in 3 infiltration, thereby avoids the drop residual phenomena, this not the wellability material layer be teflon; In addition, probe 3 also can be a hollow metal pipe, and its surfaces externally and internally all is attached with not wellability material layer, this not the wellability material layer can also be teflon.Described receiving circuit 4 is connected with probe 3 with transtation mission circuit 2, in order to receive and to send the response signal S that produces on the capacitor C in the equivalent electrical circuit ₂Described rectification circuit 5 is connected on the receiving circuit 4 to receive response signal S ₂, and to this response signal S ₂Carry out rectification and obtain rectified signal S ₃Described low-pass filter circuit 6 is connected on the rectification circuit 5 to receive rectified signal S ₃, and to this rectified signal S ₃Obtain dc level signal S after handling ₄Described amplifying circuit 7 is connected so that receive dc level signal S with low-pass filter circuit 6 ₄Thereby, and it is amplified obtain amplifying signal S ₅Described digital filter circuit 8 is connected on the amplifying circuit 7 to receive amplifying signal S ₅, CPU (central processing unit) (MCU) is contained in its inside, 8 couples of amplifying signal S of this digital filter circuit ₅Carry out filtering and obtain representing the output signal S of liquid level position ₆, and export in the control circuit of control probe 3 mechanism kinematics.

The existing brief description course of work of the present utility model.Before testing began, the measuring cup that the operator will fill the fluid to be measured sample placed on the instrument base plate 9 of abundant ground connection, and probe 3 is suspended in the top of tested liquid level.After described detecting liquid level circuit arrangement starts, this probe 3 has formed the capacitor C in the equivalent electrical circuit with instrument base plate 9, be in all materials in the space between them, all become the dielectric between the two-plate in this capacitor C as air, measuring cup and fluid to be measured etc., obviously the variation of this dielectric and position thereof all can influence the capacity of capacitor C in the equivalent electrical circuit.After testing began, probe 3 descended rapidly under the driving of mechanical mechanism near tested liquid level; Meanwhile, oscillatory circuit 1 generation one frequency is that 500KHz, amplitude are that 0.5v, dutycycle are 50% square-wave signal S ₀Be delivered to transtation mission circuit 2 as system-wide clock signal; Transtation mission circuit 2 is with this square-wave signal S ₀Be converted into the sine wave signal S of same 500KHz frequency and same 0.5v amplitude ₁, this sine wave signal S ₁Sent and be loaded onto probe 3 and externally transmission; Receiving circuit 4 receives the response signal S that produces therefrom on the capacitor C in the equivalent electrical circuit ₂, and with this response signal S ₂Be transferred to rectification circuit 5, this response signal S ₂Also be a sine wave, its frequency is 500KHz, and amplitude is than sine wave signal S ₁Little; 5 couples of response signal S of rectification circuit ₂Carry out obtaining rectified signal S after the rectification ₃, and with this rectified signal S ₃Be transferred to low-pass filter circuit 6; This low-pass filter circuit 6 is with rectified signal S ₃In AC portion further filter out, obtain dc level signal S ₄Described amplifying circuit 7 is with the dc level signal S that receives ₄Gain amplify and to obtain amplifying signal S ₅And transfer to digital filter circuit 8; The 8 couples of amplifying signal S of digital filter circuit that contain CPU (central processing unit) MCU ₅Further filtering, and provide output signal S ₆When probe 3 touches tested liquid level, because the specific inductive capacity and the air of liquid have very big-difference, so sudden change has appearred in the capacity of capacitor C at this moment in the equivalent electrical circuit, so output signal S ₆Will produce transition, this transition indicates that probe 3 has touched liquid level.The output signal S that transition occurs ₆Can be used as control signal and be transferred to the control circuit of motion, this circuit control mechanical system is carried out next step action.

In sum, detecting liquid level circuit arrangement described in the utility model has adopted the probe of single needle structure and based on the circuit structure of capacitance method, thereby eliminated the raffinate extension and stayed phenomenon, avoided the cross pollution between sample, the accuracy and the sensitivity of level detection have been improved simultaneously, have the advantage that response speed is fast, the misoperation rate is low, can be widely used in medical laboratory's analytical instrument detection the liquid levels of various electric conductivities.

Claims

1, a kind of detecting liquid level circuit arrangement, it is characterized in that: it comprises:

Oscillatory circuit is in order to produce the square-wave signal S as the total system clock signal ₀

Transtation mission circuit is in order to receive the square-wave signal S that oscillatory circuit produces ₀, and with this square-wave signal S ₀Be converted into the sine wave signal S of same frequency and amplitude ₁

Probe, be suspended in tested liquid level top with near and survey liquid level, it forms two pole plates of capacitor C in the equivalent electrical circuit jointly with the abundant instrument base plate of ground connection, in order to the sine wave signal S of transmission from transtation mission circuit ₁

Receiving circuit is in order to receive and to send the response signal S that produces on the capacitor C in the equivalent electrical circuit ₂

Rectification circuit is in order to receive the response signal S from receiving circuit ₂, and it is carried out rectification obtain rectified signal S ₃

Low-pass filter circuit is in order to receive and to handle the rectified signal S of self-rectifying circuit ₃Thereby, obtain dc level signal S ₄

Amplifying circuit is in order to receive and to amplify dc level signal S from low-pass filter circuit ₄, and obtain amplifying signal S ₅

Digital filter circuit is in order to receive the amplifying signal S from amplifying circuit ₅, and to filtering obtain representing the output signal S of liquid level position ₆

2, detecting liquid level circuit arrangement according to claim 1 is characterized in that: described probe is a Metallic rod, and its outside surface is attached with not wellability material layer.

3, detecting liquid level circuit arrangement according to claim 1 is characterized in that: described probe is a hollow metal pipe, and its surfaces externally and internally is attached with not wellability material layer.

4, according to claim 2 or 3 described detecting liquid level circuit arrangements, it is characterized in that: described not wellability material layer is a teflon.

5, detecting liquid level circuit arrangement according to claim 1 is characterized in that: contain CPU (central processing unit) in the described digital filter circuit.

6, detecting liquid level circuit arrangement according to claim 1 is characterized in that: the square-wave signal S that described oscillatory circuit produces ₀Dutycycle be 50%.