CN113218470A

CN113218470A - Test tube liquid level detection device and detection method

Info

Publication number: CN113218470A
Application number: CN202110416407.2A
Authority: CN
Inventors: 孙逊
Original assignee: Shanghai Institute of Technology
Current assignee: Shanghai Institute of Technology
Priority date: 2021-04-19
Filing date: 2021-04-19
Publication date: 2021-08-06
Anticipated expiration: 2041-04-19
Also published as: CN113218470B

Abstract

The invention relates to a test tube liquid level detection device and a detection method, wherein a shell top plate of the device is provided with a circular plug-in pipe hole, a measurement and control circuit, a pipe placing table and a servo motor are arranged in a shell; the MCU in the measurement and control circuit can control the servo motor to drive the horizontal lead screw adopting the Down's thread to rotate clockwise or anticlockwise, and the left slide block and the right slide block which are arranged on the lead screw and the left hoop and the right hoop on the slide block do linear motion of separation or clamping. When the left hoop and the right hoop are clamped, the tube to be tested placed on the tube placing table can be vertically clamped, and the capacitor plates embedded in the inner sides of the left hoop and the right hoop are tightly attached to the outer wall of the test tube and depend on the capacitor C in the test tube₁The MCU detects the dielectric constant epsilon r of the liquid in the test tube and depends on the capacitor C on the basis₂Further detecting the liquid level height H of the liquid in the test tube; then the sampling needle is inserted below the liquid level for sampling according to the H value; after sampling, the left hoop and the right hoop are separated, and the released test tube can be taken out.

Description

Test tube liquid level detection device and detection method

Technical Field

The invention relates to a device for detecting liquid level in a small container in real time without contact, in particular to a device for detecting liquid level in a small container such as a test tube in real time, and belongs to the field of material level detection.

Background

In the medical examination, in order to reduce the possibility of infection of medical staff and to reduce the contamination rate of a sample, it is necessary to sample a biological body fluid such as blood enclosed in a test tube without opening a cover and then perform sampling and examination using medical electronic equipment such as a biochemical analyzer and a urine analyzer. In the current contact detection, an electromechanical device needs to be attached to a sampling needle, the liquid level height is determined at the moment when the electromechanical device jointly extends into a test tube to contact liquid, and the defects of easy sample pollution, inconvenient reuse after disinfection, high disposable cost, air suction and firing pin when the liquid level is too low exist; the non-contact detection of common container external ultrasonic method and laser method, etc. is not easy to popularize and use for the measurement object in the small test tube because of the mechanical parts such as sampling needle, etc. right above the test tube mouth.

Therefore, it is necessary to invent a device for non-contact detection of the liquid level in small containers such as test tubes and reagent bottles, which allows a sampling needle to pierce a top cover for sampling.

Disclosure of Invention

The invention provides a test tube liquid level detection device and a test tube liquid level detection method.

The technical scheme of the invention is as follows: the utility model provides a test tube liquid level detection device, includes the measurement and control circuit in detector casing, the casing that has circular picture peg hole on the roof, fixes and put a tub platform and servo motor on the casing bottom plate, servo motor's output shaft connects horizontal lead screw, be connected with right slider and left slider on the horizontal lead screw, right hoop concave surface on the slider of the right side is interior from up inlaying the electric capacity C of vertical interval 1mm down₁、C_0a、C₂、C_0bThe right polar plate, a left polar plate embedded in the left hoop concave surface on the left sliding block is used as a capacitor C₁、C_0a、C₂、C_0bA common electrode plate of (a); the concave surfaces of the left hoop and the right hoop are opposite, the convex surfaces of the left hoop and the right hoop are fixed on the corresponding sliding blocks through reinforcing ribs, and the left hoop, the right hoop and the reinforcing ribs can be integrally formed in an injection molding mode; the top plate of the shell is provided with a vertically through insertion pipe hole, an axis extension line of the insertion pipe hole is perpendicular to the bottom plate, is vertically intersected with the axis of a horizontal lead screw below, and serves as a symmetrical axis of a moving part on the horizontal lead screw, the horizontal lead screw adopts a Down's screw thread, and the left sliding block and the right sliding block are arranged on two sides of the extension line of the insertion pipe hole axisThe left sliding block and the left hoop thereof, the right sliding block and the right hoop thereof sequentially perform constant-speed horizontal linear motion mutually clamped or separated on the horizontal screw rod when the horizontal screw rod is driven by the servo motor to rotate clockwise or anticlockwise; the measurement and control circuit comprises a liquid height H detection module, a dielectric constant epsilon r detection module, an equipotential module, an MCU, a communication module, a display, a motor forward and reverse rotation module and a microswitch Ka and Kb circuit; the dielectric constant epsilonr detection module consists of an oscillator 1 and a comparator 1, and the liquid height H detection module consists of an oscillator 2 and a comparator 2; the capacitor C₁Is the variable capacitance of the oscillator 1 of the dielectric constant ε r detection module, the capacitance C₁The right polar plate of the capacitor is connected with a dielectric constant epsilon r detection module, and the circuit oscillation frequency of the dielectric constant epsilon r detection module is a capacitor C₁A single-valued function of the dielectric constant of the liquid to be measured between the plates; the capacitor C₂Is the variable capacitance of the oscillator 2 of the liquid height H detection module, the capacitance C₂The right pole plate is connected with a liquid height H detection module, and the circuit oscillation frequency of the liquid height H detection module is a capacitor C₂A single-valued function of the liquid level of the liquid to be measured between the plates, as the capacitance C₂When the test tube section hooped by the polar plate is air, the oscillator 2 has an initial frequency f₂₀(ii) a The capacitor C_0aAnd C_0bThe right polar plate is connected with the equipotential module; the liquid height H detection module, the dielectric constant epsilon r detection module and the equipotential module are respectively connected with the MCU, and the MCU is connected with the servo motor through the motor forward and backward rotation module.

Furthermore, the longitudinal edges of the left hoop and the right hoop are parallel to the axis extension line of the insertion tube hole, the outer sides of the two longitudinal edges of the right hoop are respectively provided with a normally open microswitch Ka and a normally open microswitch Kb which are the same in specification and protrude to the longitudinal edges, and the normally open microswitch Ka and the normally open microswitch Kb are respectively connected to the input end I of the MCU in the measurement and control circuit through wires₄And I₅(ii) a Normally open microswitch Ka normally open rule I₄End high level, normally open microswitch Ka closed then I₄A terminal low level; normally open microswitch Kb normally open rule I₅End high level, normally open microswitch Kb closed then I₅A terminal low level; left hoopThe corresponding positions of the outer sides of the middle parts of the two longitudinal edges are respectively provided with a stop block of a normally open microswitch Ka and a normally open microswitch Kb, and each capacitor plate embedded in the concave surfaces of the left hoop and the right hoop is a curved copper foil plate with an exposed concave surface and a smooth curved surface; in the process of the left slider and the right slider moving towards each other, the left hoop and the right hoop are clamped towards the axial line extension line of the plug tube hole until the normally open micro switch Ka and the normally open micro switch Kb are impacted by the stop block and closed, the left hoop and the right hoop are isolated by the outward convex normally open micro switch Ka and the outward convex normally open micro switch Kb, and two longitudinal gaps with the width of 1mm are formed between the left hoop and the right hoop; the concave surfaces of the left hoop and the right hoop form a cavity which can just hold a tested tube, namely if the tested tube is placed in the concave surfaces of the left hoop and the right hoop, the outer wall of the test tube is hooped and tightly attached by the concave surfaces and the polar plates embedded in the concave surfaces, and the capacitor C_0a、C₂And C_0bHooping the cylindrical section of the test tube, and having a capacitor C₁Hooping the cambered surface at the bottom of the test tube, and enabling the axis of the test tube to coincide with the axis of the tube inserting hole.

Further, the capacitor C₁、C_0a、C₂、C_0bThe right polar plate of the capacitor is four separated independent blocks, and the capacitor C₂Lower edge of right electrode plate and capacitor C₁The lowest part of the right polar plate has a height difference of L₀And L is₀>7mm, and the left polar plate is a polar plate which has the same radius and central angle with the right polar plate on the same horizontal plane, but is communicated up and down; the leading-out wires of the polar plates penetrate out of the convex surfaces of the hoops, the left polar plate is connected with the zero potential of the measurement and control circuit, and the capacitor C_0a、C_0bAnd C₂The right polar plate of (A) is a coaxial cylindrical surface with equal radius but unequal height and superposed in horizontal projection, wherein the capacitor C₂The height of the right polar plate is L₁(ii) a Capacitor C_0aAnd C_0bAre respectively used as capacitors C₂Equipotential plates at upper and lower edges of right plate, and capacitor C_0aThe polar plate is also used as a capacitor C₁An equipotential plate at the upper edge of the plate.

Further, the liquid level of the liquid to be measured in the test tube is H, and the measurable range of H is L₀<H<L₀+L₁。

Furthermore, the top plate of the tube placing table is supported by a table support which is positioned at two sides of the axis of the horizontal lead screw and fixed at the bottom of the detection device shell, so that the height of the top plate of the tube placing table is fixed, the top plate of the tube placing table is provided with a groove which penetrates through the top plate and separates the top plate of the tube placing table into two symmetrical halves, the central line of the groove is superposed with the horizontal projection of the axis of the horizontal lead screw, and the width of the groove allows reinforcing ribs on the left sliding block and the right sliding block to move left and right in the groove without friction.

Further, the MCU in the measurement and control circuit is firstly transmitted to the input end I of the MCU by the upper computer through the communication module before each batch of measurement₃Sending the initial value f of the oscillation frequency of the batch₂₀And a standby instruction; after the tested tube is inserted into the tube inserting hole, the bottom of the test tube falls on a tube placing table top plate above the screw rod, and the upper part of the test tube leans against one side of the tube inserting hole; and then the upper computer sends a detection instruction to the MCU through the communication module, and primary liquid level detection is started.

A liquid level detection method adopting a test tube liquid level detection device comprises the following specific steps: first, MCU passes O₄The end instruction forward and reverse rotation control module drives the servo motor to rotate clockwise, so that a left sliding block and a right sliding block on the horizontal lead screw are clamped towards the middle of the lead screw, a left hoop and a right hoop shovel the test tube in the process and clamp the test tube gradually until the test tube is vertical and is attached to each capacitor plate, the normally open microswitch Ka and the normally open microswitch Kb are closed by impact, and the I of the MCU is enabled to be closed₄And I₅The terminals are all turned from high level to low level, at the moment, the MCU passes through O₄The end instruction motor positive and negative rotation module drives the servo motor to immediately stop rotating; second, MCU drives output end O₁Outputting low level to make the input end of the voltage follower in the equipotential module switched on to the capacitor C of the oscillator 2 of the liquid level H detection module by the electronic switch J₂Terminal, the output of the voltage follower is ensured to be the capacitor C_0a、C_0bAnd C₂Equipotential of the polar plate; thirdly, the output signal of the oscillator 2 in the liquid height H detection module is input into the input end I of the MCU through the comparator 2₂The MCU then detects andstorage I₂End signal frequency f₂(ii) a The fourth step, if the MCU judges f₂＝f₂₀Indicating that the liquid level of the liquid to be measured has not exceeded the minimum value L₀When the MCU is started, the MCU passes through an output end O₂And O₃Respectively instructing the communication module to give an alarm to the upper computer, instructing the display to give an alarm to the local computer, and outputting the alarm through an O₄The end instruction motor positive and negative rotation module drives a servo motor shaft to rotate anticlockwise for N circles, a test tube is loosened, and the test tube is waited to be taken out and reset; if f₂≠f₂₀Indicating that the liquid level has exceeded the height L₀When the MCU drives O₁The terminal outputs high level, so that the input end of a voltage follower in the equipotential module is switched on to a capacitor C of an oscillator 1 of the epsilon detection module by an electronic switch J₁Terminal, the output of the voltage follower is ensured to be the capacitor C_0aAnd C₁Equipotential of the polar plate; fifthly, the output signal of the oscillator 1 in the dielectric constant epsilon r detection module is input into the input end I of the MCU through the comparator 1₁The MCU detects I₁End signal frequency f₁And calculating the dielectric constant ε r of the liquid to be measured, and then calculating the dielectric constant ε r of the liquid to be measured from L₀ε r and f₂Calculating the liquid level height H of the liquid to be measured, if H ═ L₁+L₀Indicating that its level exceeds a measurable upper limit, said MCU passing O₂And O₃The terminal respectively instructs the communication module to give an alarm to the upper computer, instructs the display to give an alarm to the local, and outputs the alarm through the O₄The end instruction motor positive and negative rotation module drives a servo motor shaft to rotate anticlockwise for N circles, a test tube is loosened, and the test tube is waited to be taken out and reset; if L is₀<H<L₁+L₀Then the MCU passes O₂And O₃The upper computer can calculate the descending distance of the sampling needle according to the fixed values and the H value, the instruction sampling needle is vertically inserted into the test tube and extends into the position below the liquid level H of the liquid to be detected by a plurality of millimeters, and then the instruction sampling needle instructs the sampling needle to send the H value to the upper computer, and the instruction display sends the H value to local personnelVertically moving upwards to separate from the test tube, and finishing one-time sampling; finally, the MCU passes O₄The positive and negative rotation module of the end instruction positive motor drives the servo motor shaft to rotate anticlockwise for N circles, the test tube is loosened, the tube is waited to be taken and detected next time, the normally open microswitch Ka and the normally open microswitch Kb are separated from the stop block at the moment, the contact point is recovered to be normally open, and then the I of the MCU₄And I₅The terminals are all restored to high.

The invention has the beneficial effects that: although the epsilon r of body fluid such as blood of each person is different, the device can calculate and obtain the position of the liquid level through secondary non-contact measurement, so that the sampling needle can accurately descend below the liquid level, and the automatic sampling of the liquid is realized; as the hospital generally adopts test tubes with the same specification for the same body fluid, the device can realize continuous measurement in batches. The left hoop, the right hoop and the shape of the embedded capacitor plate are changed, and the technology can also be popularized to the non-contact measurement of the liquid level in other miniature non-metal closed or open containers.

Drawings

FIG. 1 is a block diagram of a detection system of the present invention;

FIG. 2 is a schematic top view and partial cross-sectional view of the test tube liquid level detection apparatus of the present invention;

FIG. 3 is a schematic cross-sectional view A-A of FIG. 2 (with the test tube inserted) of the present invention;

FIG. 4 is a cross-sectional view of the test tube of FIG. 3 in a clamped state according to the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples.

The detection system shown in fig. 1 is composed of an MCU and its peripheral circuit, the object to be detected is the liquid level in a cylindrical micro container such as a test tube, the MCU can use LPC824M201JHI33 and other chips, and the H detection module, the epsilonr detection module and the equipotential module in the MCU peripheral circuit all use positive and negative dual power supplies.

The right pole plate of each capacitor pole plate is four separated and independent, and a capacitor C₂Lower edge of right electrode plate and capacitor C₁The lowest part of the right polar plate is at a distance L₀The left polar plate is the radius and circle of the right polar plate on the same horizontal planeThe core angles are all equal, but the two pole plates are communicated up and down. The leading-out wires of the pole plates penetrate out of the convex surfaces of the hoops, and the left pole plate is connected with the zero potential and the capacitance C of the measurement and control circuit₁The right pole plate is connected with the dielectric constant Epsilon detection module of the measurement and control circuit and the capacitor C₂The right pole plate is connected with a liquid level H detection module and a capacitor C of the measurement and control circuit_0aAnd C_0bThe right polar plate is connected with the equipotential module of the measurement and control circuit. Capacitor C_0a、C_0bAnd C₂The right polar plate is a coaxial arc surface with equal radius but unequal height and superposed in horizontal projection, wherein the capacitor C₂The height of the right polar plate is L₁(ii) a Capacitor C_0aAnd C_0bAre respectively used as capacitors C₂Equipotential plates at upper and lower edges of right plate, and capacitor C_0aThe polar plate is also used as a capacitor C₁An equipotential plate at the upper edge of the plate.

Before each batch of measurement, the upper computer firstly transmits the measurement to the I of the MCU through the communication module₃End, sending the initial value f of the oscillation frequency of the batch₂₀And a standby instruction. And after the tested pipe 15 is inserted from the pipe inserting hole, the upper computer sends a detection instruction to the MCU through the communication module, and primary liquid level detection is started.

In the first step of liquid level detection, MCU passes through O₄End instruction is control module that just reverses, drive servo motor clockwise rotation, makes left slider and right slider on the lead screw press from both sides to the lead screw centre and hold together, and the strengthening rib gets into from two sides and puts a tub platform overhead tank on it, and left hoop and right hoop will in this process the test tube 15 is shoveled to progressively press from both sides tightly, until the test tube is vertical and hugged closely by each electric capacity polar plate, the liquid level that awaits measuring liquid in the test tube 15 at that moment is H, be located the normally open micro switch Ka and the Kb in right hoop vertical edge outside, when colliding with the corresponding dog that is located left hoop and the contact is closed, MCU's I₄And I₅The terminals are all turned from high level to low level, and the MCU passes through the O₄The end instruction forward and reverse rotation control module drives the servo motor to stop rotating immediately, so that the test tube 15 is prevented from being clamped tightly and cracked; second, MCU drives O₁The terminal outputs low level, so that the input end of the voltage follower in the equipotential module is switched on to the H detection module by an electronic switch JC of the oscillator 2 of the block₂Terminal, the output of which ensures a capacitance C_0a、C_0bAnd C₂The equipotential of the polar plate avoids C₂Edge effect of the polar plate; thirdly, the output signal of the oscillator 2 in the H detection module is input into the I of the MCU through the comparator 2₂The MCU then detects and stores I₂End signal frequency f₂The frequency is C₂A single valued function of; the fourth step, if the MCU judges f₂＝f₂₀Is represented by H<L₀That is, the liquid level of the liquid to be measured does not reach the minimum value L₀，C₂All the test tube section is filled with air, and in order to prevent the sampling needle from firing a fault, the MCU passes through the O₂And O₃The terminal respectively instructs the communication module to give an alarm to the upper computer, instructs the display to give an alarm to the local, and outputs the alarm through the O₄The end instruction forward and reverse rotation control module drives a servo motor shaft to rotate anticlockwise for N circles, the test tube 15 is loosened, and the test tube is waited to be taken out and reset; if f₂≠f₂₀Indicating that the liquid level has exceeded the height L₀，C₂The section of the test tube to be clamped contains liquid. At that time, the MCU drives O₁The terminal outputs high level, so that the input end of a voltage follower in the equipotential module is switched on to C of the oscillator 1 of the epsilon detection module by an electronic switch J₁Terminal, the output of which ensures a capacitance C_0aAnd C₁Equipotential of the polar plate; fifthly, the output signal of the oscillator 1 in the epsilonr detection module is input into the I of the MCU through the comparator 1₁End, the MCU then detects I₁End signal frequency f₁The frequency is C₁The dielectric constant epsilonr of the liquid to be measured is calculated by the MCU, and then the L is used₀ε r and f₂And (4) calculating the liquid level height H of the liquid to be measured. If H ═ L₁+L₀Is represented by C₂The liquid level in the 15 sections of the clamped test tubes exceeds the measurable upper limit, and the MCU passes through O₂And O₃The terminal respectively instructs the communication module to give an alarm to the upper computer, instructs the display to give an alarm to the local, and outputs the alarm through the O₄The end instruction forward and reverse rotation control module drives a servo motor shaft to rotate anticlockwise for N circles to loosen the test tubeWaiting for the tube taking to be reset, and avoiding the phenomenon that the sampling needle enters the tube too deeply and is polluted due to the unknown liquid level; if L is₀<H<L₁+L₀If the measured value is within the measurable range, the MCU passes through O₂And O₃And the terminal respectively instructs the communication module to send the H value to the upper computer and instructs the display to send the H value to local personnel. Because the initial height of the sampling needle, the height of the tube placing table, the thickness and the height of the left hoop and the right hoop, the specification and the size of each capacitor plate and the like are fixed values, the upper computer can calculate the descending distance of the sampling needle according to the fixed values and the H value at the moment, instruct the sampling needle to vertically pierce through the test tube cover, insert into the test tube and stretch into the position, which is a plurality of millimeters, for example, 5mm, below the liquid level H of the liquid to be tested for sampling, and then instruct the sampling needle to vertically move upwards to separate from the test tube 15 to finish one sampling.

Then, after host computer instruction sampling needle breaks away from test tube 15, MCU instruction positive reverse control module drive servo motor shaft anticlockwise rotation N circles, is loosened the test tube and waits to take out, and microswitch Ka 11 and Kb4 break away from the dog and the contact resumes normally to open at the time, MCU's I₄And I₅The terminals are all restored to high.

Of course, the device can also be used in situations where only the liquid level is measured without the need to sample the liquid in the tube.

Fig. 2 is a schematic plan view and a partial sectional view of the test tube liquid level detection device, wherein a detector housing 12 with a circular tube inserting hole 1 is arranged on a top plate, the circular tube inserting hole 1 vertically penetrates through the top plate of the detector housing 12, an axial extension line of the circular tube inserting hole is vertical to a bottom plate, and the axial extension line of the circular tube inserting hole is vertically intersected with an axial line of a lead screw 2 below the circular tube inserting hole. The tube placing table top plate right below the circular tube inserting hole 1 is supported by a table support column 19 which is positioned on two sides of the axis of the screw rod and fixed at the bottom of the detection shell device, the height of the tube placing table top plate is fixed, the tube placing table top plate penetrates through a groove 3 of the top plate and penetrates through the top plate to separate the tube placing table top plate into two symmetrical halves, the central line of the groove 3 is overlapped with the horizontal projection of the axis of the screw rod, and the screw rod 2 adopting a Down's screw thread is right below the groove 3. One end of the screw rod is driven by the servo motor 7 to rotate, and the other end of the screw rod is provided with a support 13 so as to realize that the screw rod 2 is horizontal. The lead screw 2 adopts the Down's screw (the Down's screw is formed by compounding a left-handed screw thread and a right-handed screw thread on the same thread section, and the existing left-handed screw threadThe screw thread has the characteristics of right-handed screw thread, and can be matched with left-handed screw thread and right-handed screw thread. The tang thread can utilize the features of the thread itself to solve the anti-loosening problem). The right part of the screw rod 2 is provided with a right slide block 9, a right hoop 5 with an opening concave surface towards the left is arranged on the right slide block, and a convex surface of the right slide block 9 is fixed on the right slide block by a reinforcing rib 8 which is integrally formed with the right slide block through injection molding. The outer sides of two longitudinal edges of the right hoop 5 are respectively provided with normally open microswitches Ka 11 and Kb4 which are provided with the same specification and protrude the longitudinal edges, and the normally open microswitches Ka 11 and Kb4 are respectively connected to the I of the MCU in the measurement and control circuit 6 through leads₄And I₅And (4) an end. The right plate of each capacitor is embedded in the concave surface of the right hoop 5, and the bottommost part of the right plate is the capacitor C₁And a right plate 10.

When the servo motor 7 drives the screw rod 2 to rotate clockwise or anticlockwise, the left slide block 21 and the right slide block 9 perform constant-speed linear motion towards the back or towards the back on the screw rod, and the width of the pipe placing table top groove 3 allows the reinforcing ribs 8 on the slide blocks to move left and right in the groove without friction.

The measurement and control circuit 6 is fixed beside the servo motor 7.

Fig. 3 is a schematic sectional view of the insertion side of the test tube 15, which includes a detector housing 12 having a circular insertion hole 1 on the top plate, a tube placing table fixed on the bottom plate of the housing, and a servo motor 7. The jack hole 1 vertically penetrates through the top plate of the shell 12, the axis extension line of the jack hole is vertical to the bottom plate and is vertically crossed with the axis of a horizontal screw rod 2 below the jack hole to be used as a symmetrical shaft of a moving part on the screw rod 2, the left slide block 21 and the right slide block 9 are symmetrically distributed on two sides of the axis extension line of the jack hole 1, when the screw rod is driven by the servo motor 7 to rotate clockwise or anticlockwise, the two slide blocks perform constant-speed linear motion which is mutually clamped or separated on the screw rod 2, and the left hoop 24 and the right hoop 5 perform axisymmetric constant-speed horizontal linear motion along with the slide blocks. The bottom of the test tube 15 is placed on the top plate of the tube placing table, and the upper end of the test tube leans against one side of the tube inserting hole 1.

A left slide block 21 and a right slide block 9 which are arranged on a horizontal screw rod 2 connected with a motor shaft, a left polar plate 22 which is embedded in the concave surface of a left hoop 24 on the left slide block is used as a capacitor common polar plate, and a capacitor C with a longitudinal interval of 1mm is embedded in the concave surface of a right hoop 5 on the right slide block 9 from bottom to top₁Right polar plate 10, C_0aRight polar plate 18, C₂Right polar plate 17, C_0bThe right electrode plate 16 and each capacitor electrode plate embedded in the two hoop concave surfaces are curved copper foil electrode plates with the concave surfaces exposed and the peripheral curved surfaces leveled and smooth. Capacitor C_0aAnd C_0bAre respectively used as capacitors C₂Equipotential plates at upper and lower edges of right plate, and capacitor C_0aThe polar plate is also used as a capacitor C₁An equipotential plate at the upper edge of the plate. The concave surfaces of the left hoop 24 and the right hoop 5 are opposite, and the longitudinal edges of the left hoop 24 and the right hoop 5 are parallel to the axial extension line of the cannula hole 1. The normally open microswitch Kb4 protruding the longitudinal edge is arranged on the outer side of one longitudinal edge of the right hoop, the stop dog 23 of the microswitch Kb4 is respectively arranged on the corresponding position on the outer side of the middle part of one longitudinal edge of the left hoop 24, the convex surfaces of the two hoops are fixed on the corresponding slide blocks through the reinforcing ribs 8, and each hoop and the reinforcing ribs can be integrally injection molded.

The cross-sectional view of the test tube in FIG. 4 on the pinched side is a continuation of the working condition of FIG. 3. In the process of the opposite movement of the left slider 21 and the right slider 9, the left hoop 24 and the right hoop are drawn towards the axial extension line of the plug tube hole 1 until the normally open contacts of the microswitches Ka 11 and Kb4 are closed by collision, the concave surfaces of the left hoop 24 and the right hoop 5 form a cavity which can exactly hoop a vertical test tube 15, and the left hoop 24 and the right hoop 5 are isolated by the convex microswitches Ka 11 and Kb4 and are not in contact with each other, so that a gap with the width of 1mm is formed between the two hoops. The outer wall of the test tube is hooped and tightly attached by the concave surface and each embedded polar plate, and the capacitor C_0a、C₂And C_0bHooping the cylindrical section of the test tube, and having a capacitor C₁Hooping the cambered surface at the bottom of the test tube, enabling the tube axis to coincide with the axis of the tube inserting hole 1, and enabling the test tube 15 to be in a vertical state.

In the state of fig. 4, the MCU makes the input end of the voltage follower in the equipotential module be connected to C of the oscillator 2 of the H detection module by the electronic switch J₂Terminal, the output of which ensures a capacitance C_0a、C_0bAnd C₂Equipotential of the plate. If MCU detects C₂Air is filled in 15 sections of the clamped test tubes, the MCU gives out a warning, and simultaneously the MCU instructs the forward and reverse rotation control module to drive the servo motor shaft to rotate anticlockwise NAnd (4) looping, releasing the test tube, and restoring the test tube to the state in the figure 3 to wait for tube taking and resetting. If MCU detects C₂If liquid exists in the section of the clamped test tube 15, the MCU enables the electronic switch J to be connected to the oscillator 1C of the epsilon r detection module₁Terminal, the output of which ensures a capacitance C_0aAnd C₁The equipotential of the plate, so that the MCU can detect the epsilonr of the liquid in the test tube 15 and further detect the level H of the liquid 20 to be measured in the test tube. If MCU detects H ═ L₁+L₀And when the liquid level H exceeds the limit, the MCU gives out a warning, the control module instructs the forward and reverse rotation control module to drive the servo motor shaft to rotate anticlockwise for N circles, the test tube is loosened, and the test tube is restored to the state shown in the figure 3 to wait for tube taking and resetting. If MCU detects C₂Liquid level L in 15 sections of clamped test tubes₀<H<L₁+L₀The MCU informs the upper computer to instruct the sampling needle 25 to vertically pierce the test tube cover 14, insert the test tube 15 and extend several millimeters, for example 5mm, below the liquid level H of the liquid to be measured for sampling; after sampling, the MCU instructs the forward and reverse rotation control module to drive the servo motor shaft to rotate anticlockwise for N circles, the test tube is loosened, the test tube is recovered to the state shown in the figure 3, and the test tube is waited to be taken away.

Claims

1. The utility model provides a test tube liquid level detection device, includes the measurement and control circuit in detector casing, the casing that has circular picture peg hole on the roof, fixes putting pipe stand and servo motor on the casing bottom plate, its characterized in that: the output shaft of the servo motor is connected with a horizontal lead screw, the horizontal lead screw is connected with a right sliding block and a left sliding block, and a capacitor C with a longitudinal interval of 1mm is embedded in a right hoop concave surface on the right sliding block from bottom to top₁、C_0a、C₂、C_0bThe right polar plate, a left polar plate embedded in the left hoop concave surface on the left sliding block is used as a capacitor C₁、C_0a、C₂、C_0bA common electrode plate of (a); the concave surfaces of the left hoop and the right hoop are opposite, the convex surfaces of the left hoop and the right hoop are fixed on the corresponding sliding blocks through reinforcing ribs, and the left hoop, the right hoop and the reinforcing ribs can be integrally formed in an injection molding mode; the top plate of the shell is provided with a vertically through-going pipe-inserting hole, and the axis extension line of the pipe-inserting hole is vertical to the bottom plate and is vertical to the horizontal screw shaft below the bottom plateThe lines are vertically intersected and used as a symmetrical shaft of a moving part on the horizontal screw rod, the horizontal screw rod adopts a Down's screw thread, the left sliding block and the right sliding block are symmetrically distributed on two sides of the extension line of the axis of the inserting pipe hole, and when the horizontal screw rod is driven by the servo motor to rotate clockwise or anticlockwise, the left sliding block and a left hoop thereof, the right sliding block and a right hoop thereof sequentially perform mutually clamped or separated horizontal linear motion with constant speed on the horizontal screw rod; the measurement and control circuit comprises a liquid height H detection module, a dielectric constant epsilon r detection module, an equipotential module, an MCU, a communication module, a display, a motor forward and reverse rotation module and a microswitch Ka and Kb circuit; the dielectric constant epsilonr detection module consists of an oscillator 1 and a comparator 1, and the liquid height H detection module consists of an oscillator 2 and a comparator 2; the capacitor C₁Is the variable capacitance of the oscillator 1 of the dielectric constant ε r detection module, the capacitance C₁The right polar plate of the capacitor is connected with a dielectric constant epsilon r detection module, and the circuit oscillation frequency of the dielectric constant epsilon r detection module is a capacitor C₁A single-valued function of the dielectric constant of the liquid to be measured between the plates; the capacitor C₂Is the variable capacitance of the oscillator 2 of the liquid height H detection module, the capacitance C₂The right pole plate is connected with a liquid height H detection module, and the circuit oscillation frequency of the liquid height H detection module is a capacitor C₂A single-valued function of the liquid level of the liquid to be measured between the plates, as the capacitance C₂When the test tube section hooped by the polar plate is air, the oscillator 2 has an initial frequency f₂₀(ii) a The capacitor C_0aAnd C_0bThe right polar plate is connected with the equipotential module; the liquid height H detection module, the dielectric constant epsilon r detection module and the equipotential module are respectively connected with the MCU, and the MCU is connected with the servo motor through the motor forward and backward rotation module.

2. Test tube liquid level detection device according to claim 1, characterized in that: the longitudinal edges of the left hoop and the right hoop are parallel to the axis extension line of the insertion tube hole, the outer sides of the two longitudinal edges of the right hoop are respectively provided with a normally open microswitch Ka and a normally open microswitch Kb which are the same in specification and protrude out of the longitudinal edges, and the normally open microswitch Ka and the normally open microswitch Kb are respectively connected to the measuring and controlling electricity through leadsInput end I of MCU in circuit₄And I₅(ii) a Normally open microswitch Ka normally open rule I₄End high level, normally open microswitch Ka closed then I₄A terminal low level; normally open microswitch Kb normally open rule I₅End high level, normally open microswitch Kb closed then I₅A terminal low level; the corresponding positions of the outer sides of the middle parts of the two longitudinal edges of the left hoop are respectively provided with a stop block of a normally open microswitch Ka and a normally open microswitch Kb, and each capacitor plate embedded in the concave surfaces of the left hoop and the right hoop is a curved copper foil plate with an exposed concave surface and a smooth surface flush with the surrounding curved surface; in the process of the left slider and the right slider moving towards each other, the left hoop and the right hoop are clamped towards the axial line extension line of the plug tube hole until the normally open micro switch Ka and the normally open micro switch Kb are impacted by the stop block and closed, the left hoop and the right hoop are isolated by the outward convex normally open micro switch Ka and the outward convex normally open micro switch Kb, and two longitudinal gaps with the width of 1mm are formed between the left hoop and the right hoop; the concave surfaces of the left hoop and the right hoop form a cavity which can just hold a tested tube, namely if the tested tube is placed in the concave surfaces of the left hoop and the right hoop, the outer wall of the test tube is hooped and tightly attached by the concave surfaces and the polar plates embedded in the concave surfaces, and the capacitor C_0a、C₂And C_0bHooping the cylindrical section of the test tube, and having a capacitor C₁Hooping the cambered surface at the bottom of the test tube, and enabling the axis of the test tube to coincide with the axis of the tube inserting hole.

3. Test tube liquid level detection device according to claim 1, characterized in that: the capacitor C₁、C_0a、C₂、C_0bThe right polar plate of the capacitor is four separated independent blocks, and the capacitor C₂Lower edge of right electrode plate and capacitor C₁The lowest part of the right polar plate has a height difference of L₀And L is₀>7mm, and the left polar plate is a polar plate which has the same radius and central angle with the right polar plate on the same horizontal plane, but is communicated up and down; the leading-out wires of the polar plates penetrate out of the convex surfaces of the hoops, the left polar plate is connected with the zero potential of the measurement and control circuit, and the capacitor C_0a、C_0bAnd C₂The right polar plate of (A) is a coaxial cylindrical surface with equal radius but unequal height and superposed in horizontal projection, wherein the capacitorC₂The height of the right polar plate is L₁(ii) a Capacitor C_0aAnd C_0bAre respectively used as capacitors C₂Equipotential plates at upper and lower edges of right plate, and capacitor C_0aThe polar plate is also used as a capacitor C₁An equipotential plate at the upper edge of the plate.

4. Test tube liquid level detection device according to claim 3, characterized in that: the liquid level of the liquid to be measured in the test tube is H, and the measurable range of H is L₀<H<L₀+L₁。

5. Test tube liquid level detection device according to claim 1, characterized in that: the top plate of the tube placing table is supported by a table support which is positioned at two sides of the axis of the horizontal lead screw and fixed at the bottom of the detection device shell, so that the height of the top plate is fixed, the top plate of the tube placing table is provided with a groove which penetrates through the top plate, the top plate of the tube placing table is separated into two symmetrical halves, the central line of the groove is superposed with the horizontal projection of the axis of the horizontal lead screw, and the width of the groove allows reinforcing ribs on the left sliding block and the right sliding block to move left and right in the groove without friction.

6. Test tube liquid level detection device according to claim 1, characterized in that: the MCU in the measurement and control circuit is firstly transmitted to the input end I of the MCU by the upper computer through the communication module before each batch of measurement₃Sending the initial value f of the oscillation frequency of the batch₂₀And a standby instruction; after the tested tube is inserted into the tube inserting hole, the bottom of the test tube falls on a tube placing table top plate above the screw rod, and the upper part of the test tube leans against one side of the tube inserting hole; and then the upper computer sends a detection instruction to the MCU through the communication module, and primary liquid level detection is started.

7. A liquid level detection method adopting the test tube liquid level detection device of claim 6 is characterized by comprising the following specific steps: first, MCU passes O₄The end instruction forward and reverse rotation control module drives the servo motor to rotate clockwise so as to enable the left sliding block and the right sliding block on the horizontal lead screw to rotateThe test tube is clamped in the middle of the screw rod, the left hoop and the right hoop shovel the test tube in the process and clamp the test tube gradually until the test tube is vertical and is clung to each capacitor plate, and the normally open microswitch Ka and the normally open microswitch Kb are closed by impact, so that the I of the MCU is enabled to be closed₄And I₅The terminals are all turned from high level to low level, at the moment, the MCU passes through O₄The end instruction motor positive and negative rotation module drives the servo motor to immediately stop rotating; second, MCU drives output end O₁Outputting low level to make the input end of the voltage follower in the equipotential module switched on to the capacitor C of the oscillator 2 of the liquid level H detection module by the electronic switch J₂Terminal, the output of the voltage follower is ensured to be the capacitor C_0a、C_0bAnd C₂Equipotential of the polar plate; thirdly, the output signal of the oscillator 2 in the liquid height H detection module is input into the input end I of the MCU through the comparator 2₂The MCU then detects and stores I₂End signal frequency f₂(ii) a The fourth step, if the MCU judges f₂＝f₂₀Indicating that the liquid level of the liquid to be measured has not exceeded the minimum value L₀When the MCU is started, the MCU passes through an output end O₂And O₃Respectively instructing the communication module to give an alarm to the upper computer, instructing the display to give an alarm to the local computer, and outputting the alarm through an O₄The end instruction motor positive and negative rotation module drives a servo motor shaft to rotate anticlockwise for N circles, a test tube is loosened, and the test tube is waited to be taken out and reset; if f₂≠f₂₀Indicating that the liquid level has exceeded the height L₀When the MCU drives O₁The terminal outputs high level, so that the input end of a voltage follower in the equipotential module is switched on to a capacitor C of an oscillator 1 of the epsilon detection module by an electronic switch J₁Terminal, the output of the voltage follower is ensured to be the capacitor C_0aAnd C₁Equipotential of the polar plate; fifthly, the output signal of the oscillator 1 in the dielectric constant epsilon r detection module is input into the input end I of the MCU through the comparator 1₁The MCU detects I₁End signal frequency f₁And calculating the dielectric constant ε r of the liquid to be measured, and then calculating the dielectric constant ε r of the liquid to be measured from L₀ε r and f₂Calculating the liquid level height H of the liquid to be measured, if H ═ L₁+L₀Indicating that its liquid level exceedsPassing a measurable upper limit, said MCU passing O₂And O₃The terminal respectively instructs the communication module to give an alarm to the upper computer, instructs the display to give an alarm to the local, and outputs the alarm through the O₄The end instruction motor positive and negative rotation module drives a servo motor shaft to rotate anticlockwise for N circles, a test tube is loosened, and the test tube is waited to be taken out and reset; if L is₀<H<L₁+L₀Then the MCU passes O₂And O₃The upper computer can calculate the descending distance of the sampling needle according to the fixed values and the H value, instruct the sampling needle to be vertically inserted into the test tube and extend into the position below the liquid level H of the liquid to be tested by a plurality of millimeters, and then instruct the sampling needle to vertically move upwards to separate from the test tube to finish one-time sampling; finally, the MCU passes O₄The positive and negative rotation module of the end instruction positive motor drives the servo motor shaft to rotate anticlockwise for N circles, the test tube is loosened, the tube is waited to be taken and detected next time, the normally open microswitch Ka and the normally open microswitch Kb are separated from the stop block at the moment, the contact point is recovered to be normally open, and then the I of the MCU₄And I₅The terminals are all restored to high.