JP2008026220A - Liquid level detector and autoanalyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid level detector and an autoanalyzer, capable of precisely detecting the liquid level of a liquid stored in a container, in addition to bubbles generated in the upper side of the liquid level. <P>SOLUTION: This liquid level detector/autoanalyzer is provided with the first electrode formed by using a conductive material and for sucking and delivering the liquid, and a determination means for electrically detecting the contact of the first electrode with the liquid stored in the container at two different sensitivities, and for determining a contact state between the first electrode and the liquid, based on the detection result therein. The first electrode is a probe for suction and delivering the liquid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid level detection device that detects a liquid level of a liquid contained in a predetermined container, and an automatic analyzer including the liquid level detection device.

  Conventionally, in an automatic analyzer that analyzes the components of a sample by reacting the sample with a reagent, as a technique for detecting the liquid level of the liquid when the liquid such as the sample or the reagent is aspirated by a thin tube probe, There are known a conduction system that detects the liquid level using the conductivity of the liquid and a capacitance system that detects the liquid level based on a change in capacitance between conductors via the liquid.

  Among these, in the conduction method, a voltage is applied between a probe having conductivity and a conductor rod (electrode) fixed in the vicinity of the probe so that the probe and the conductor rod are in contact with the liquid surface. At this time, the liquid level is detected by a change in the output voltage from the probe to be electrically conducted through the liquid (see, for example, Patent Document 1).

  On the other hand, in the capacitance method, the liquid level is detected by detecting a change in capacitance between the probe itself or an electrode provided in the vicinity of the probe and an electrode provided in the vicinity of the container for storing the liquid. It detects (for example, refer patent document 2).

JP-A-10-132640 JP 2003-57096 A

  However, in the conventional liquid level detection technique based on the conduction method, when bubbles are generated above the liquid level, the bubbles cannot be detected. For this reason, when the probe descends until it detects the liquid level, bubbles may adhere to portions of the outer surface of the probe and the inner surface of the probe that are not normally cleaned. If the next dispensing is performed with the bubbles still attached in this manner, contamination may occur, and therefore a technology that can detect not only the liquid level but also the bubbles has been awaited.

  Moreover, in the liquid level detection technique based on the electrostatic capacity method, when bubbles are generated above the liquid level, there is a problem that the bubbles are detected as the liquid level. In this case, since air is mixed when the liquid is sucked by the probe and normal suction is not performed, a technique capable of accurately distinguishing and detecting the liquid surface and the bubble has been desired.

  This invention is made in view of the above, Comprising: In addition to the liquid level of the liquid accommodated in the container, the liquid level detection which can detect correctly the bubble which generate | occur | produced above the liquid level It is an object of the present invention to provide an automatic analyzer including the apparatus and the liquid level detection device.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is a liquid level detection device for detecting the liquid level of a liquid contained in a container, which is formed using a conductive material. The first electrode and the contact between the first electrode and the liquid are electrically detected with two different sensitivities, and the contact state between the first electrode and the liquid is determined based on the detected result. Determining means for determining.

  The “liquid” in the present invention includes a liquid containing a trace amount of a solid component.

  According to a second aspect of the invention, in the first aspect of the invention, the first electrode is a probe for sucking and discharging a liquid.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the invention is formed using a conductive material, and is fixed in the vicinity of the first electrode so as to be separated from the first electrode. A second electrode having an end near the end of the first electrode; and an oscillation circuit that is connected to the first or second electrode and generates a signal having a predetermined frequency. The means outputs the output voltages output from the first electrode to each other when the first and second electrodes are in contact with the liquid and the first and second electrodes are conducted through the liquid. It has the 1st and 2nd comparison circuit which compares with the 1st and 2nd reference voltage which has a different value, respectively, It is characterized by the above-mentioned.

  The invention according to claim 4 is the invention according to claim 3, wherein the first and second reference voltages are the output voltage when the first and second electrodes are in contact with the liquid surface of the liquid. The magnitude relationship between the output voltage and the output voltage when the first and second electrodes are in contact with the liquid bubble is different.

  “Bubble” in the present invention means that a part of the liquid contained in the container forms a thin film above the liquid surface, and between the bubbles and the bubbles or between the bubbles and the liquid surface. Has an air layer.

  According to a fifth aspect of the present invention, in the first or second aspect of the present invention, a second electrode is formed using a conductive material, and is provided integrally with or in the vicinity of the container. An oscillation circuit that generates a frequency signal and supplies the generated signal to at least the first electrode; and a resistor connected in series between the first electrode and the oscillation circuit. In addition, the determination means may be provided from both ends of the resistor due to a change in capacitance between the first electrode and the second electrode caused by the first electrode coming into contact with the liquid. The first and second comparison circuits for comparing the difference between the output voltages with the first and second reference voltages having different values from each other, respectively.

  According to a sixth aspect of the present invention, in the fifth aspect, the first and second reference voltages are output from both ends of the resistor when the first electrode is in contact with the liquid level of the liquid. While the magnitude relation with the voltage difference is the same, the magnitude relation with the difference in output voltage from both ends of the resistor when the first electrode is in contact with the liquid bubble is different.

  The invention according to claim 7 is an automatic analyzer that analyzes the components of the specimen by reacting the specimen with a reagent, and the liquid level detecting device according to any one of claims 1 to 6 is used. And a reagent dispensing means for dispensing the reagent as a liquid.

  The invention according to claim 8 is the invention according to claim 7, comprising the liquid level detection device according to any one of claims 1 to 6, and a sample dispensing means for dispensing the sample as a liquid. It is further provided with a feature.

  According to the liquid level detection device and the automatic analyzer according to the present invention, two different contacts between the first electrode formed using the conductive material and the liquid contained in the first electrode and the container are provided. And a determination unit that electrically detects the sensitivity and determines a contact state between the first electrode and the liquid based on the detection result, thereby providing a liquid surface of the liquid contained in the container. In addition, it is possible to accurately detect bubbles generated above the liquid level.

  The best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described below with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a liquid level detection device according to Embodiment 1 of the present invention. The liquid level detection device 1 shown in FIG. 1 detects that a conductive probe that sucks or discharges liquid and an electrode provided in the vicinity of the probe conducts through the liquid when it reaches the liquid level. By doing this, it is an apparatus that determines the presence or absence of contact between the probe and the liquid surface and the contact state when there is contact. The “liquid” referred to here includes a liquid containing a small amount of a solid component, and specifically, a specimen and a reagent as described later are assumed. In addition, the liquid in this Embodiment 1 shall have electroconductivity.

  The liquid level detection device 1 is made of a conductive material such as metal, and has a tubular probe 2 (first electrode) that sucks or discharges the liquid Lq accommodated in the container 20 and the same conductivity as the probe 2. A rod-like electrode 3 (second electrode) which is made of a material and is fixed in the vicinity of the probe 2 so as to be spaced apart from the probe 2 and can be interlocked with the probe 2 without changing the relative position with respect to the probe 2; 2 and the electrode 3 as a pair, the vertical movement and horizontal rotation are performed, and the probe 2 and the electrode 3 are transferred to the transfer unit 4 and connected to the electrode 3 to generate an AC signal of a predetermined frequency. The oscillation circuit 5, the determination unit 6 for determining the contact state between the probe 2 and the liquid Lq according to the conduction state of the probe 2, and the operation control of the liquid level detection device 1 according to the output from the determination unit 6. CPU, RAM for And a control unit 7 constructed of a ROM or the like, an output unit 8 for outputting a predetermined information.

  The determination unit 6 determines the output voltages output from the probe 2 when the probe 2 and the electrode 3 are in contact with the liquid Lq and the probe 2 and the electrode 3 are brought into conduction via the contacted liquid Lq. And a comparison circuit 61 (first comparison circuit) and a comparison circuit 62 (second comparison circuit) that respectively compare with the second reference voltage, and signal processing for performing predetermined signal processing on outputs from the comparison circuits 61 and 62 Circuit 63.

FIG. 2 is a diagram illustrating a configuration of the comparison circuit 61. The comparison circuit 61 shown in the figure is connected to the probe 2 on the negative-phase terminal (−) side, and inputs the output voltage V from the probe 2 and the positive-phase terminal (+) side of the comparator 611. And a voltage dividing circuit 614 that divides a predetermined voltage V _ref by resistors 612 and 613. The voltage dividing circuit 614 inputs a reference voltage V ₁ (> 0) that is a first reference voltage to the comparator 611. The comparison circuit 62 has the same configuration as the comparison circuit 62. In the comparison circuit 62, the reference voltage V ₂ (> 0) as the _second reference voltage is input from the voltage dividing circuit connected to the positive phase terminal side. The values of the _two reference voltages V ₁ and V ₂ are different and satisfy V ₁ <V ₂ . The values of the reference voltages V ₁ and V ₂ are determined by adjusting the resistance values of the voltage dividing circuits included in the comparison circuits 61 and 62.

The determination unit 6 determines whether the probe 2 is in contact with the liquid level of the liquid Lq by using the _two reference voltages V ₁ and V ₂ , or whether the probe 2 is in contact with bubbles generated above the liquid level of the liquid Lq. judge. Hereinafter, this point will be described. When the probe 2 comes into contact with the liquid level of the liquid Lq, the tip of the probe 2 is set so as to descend (crop) by a predetermined amount from the liquid level. For this reason, when the probe 2 comes into contact with the liquid surface of the liquid Lq, the contact area between the probe 2 and the liquid Lq increases accordingly. On the other hand, when the probe 2 comes into contact with bubbles generated above the liquid surface, the surface of the bubble is a thin film, and the air inside the bubble (between the bubbles and the bubbles or between the bubbles and the liquid surface) is air. Therefore, a thin film-like liquid Lq is only attached to the tip of the probe 2. As a result, the contact area between the probe 2 and the liquid Lq is significantly smaller than when the probe 2 is in contact with the liquid surface of the liquid Lq. It can be said that the contact area between the electrode 3 and the liquid Lq is the same as the contact area between the probe 2 and the liquid Lq described here.

From the above description, the resistance value between the probe 2 and the electrode 3 when the probe 2 and the electrode 3 are brought into conduction by the contact with the liquid Lq is greater when the probe 2 is in contact with the liquid surface of the liquid Lq. It can be seen that the probe 2 is smaller than the case where the bubble-like liquid Lq is in contact. Therefore, the amplitude V ₀ of the output voltage V of the probe 2 is greater when the probe 2 is in contact with the liquid surface than when the probe 2 is in contact with the bubble. In this sense, the two reference voltages V ₁ and V ₂ indicate the contact state between the probe 2 and the liquid Lq, that is, whether the probe 2 is in contact with the liquid surface of the liquid Lq or the bubble of the liquid Lq. It is set as a discriminable value.

FIGS. 3 and 4 are diagrams showing the time change of the output voltage V of the probe 2. In these figures, the horizontal axis represents time t, and the vertical axis represents the output voltage V from the probe 2. 3 and 4 show a case where contact with the liquid Lq starts at time t ₁ .

FIG. 3 is a diagram illustrating a case where the probe 2 is in contact with the liquid surface of the liquid Lq. The amplitude V ₀ of the output voltage V after the contact is larger than the reference voltage V ₂ of the comparison circuit 62 (V ₀ > V ₂ ). On the other hand, FIG. 4 is a diagram showing a case where the probe 2 is in contact with a bubble made of the liquid Lq. The amplitude V ₀ of the output voltage V after the contact is larger than the reference voltage V ₁ of the comparison circuit 61. It is smaller than the reference voltage V ₂ of the comparison circuit 62 (V ₂ > V ₀ > V ₁ ). 3 and 4 schematically show a case where a sine wave is supplied from the oscillation circuit 5, a rectangular wave may be supplied from the oscillation circuit 5.

The signal processing circuit 63 outputs a detection signal corresponding to the determination result to the control unit 7 by performing predetermined signal processing on the outputs from the comparison circuits 61 and 62. For example, when the amplitude V ₀ of the output voltage V satisfies V ₀ > V ₂ , that is, when the time changes as shown in FIG. 3, a detection signal corresponding to the determination result “liquid level” is sent to the control unit 7. Send. Further, when the amplitude V ₀ of the output voltage V satisfies V ₂ > V ₀ > V _1, that is, when the time changes as shown in FIG. 4, a detection signal corresponding to the determination result of “bubble” is sent to the control unit 7. Send.

  It is also possible to provide a noise reduction filter before the determination unit 6. In this case, an output range above a certain value that can be determined as noise is cut, but the output range to be cut may be set in advance according to the performance of the machine.

  Next, the configuration of the liquid level detection device 1 will be described. The liquid level detection device 1 connects a syringe 9 that performs a suction / discharge operation of a cleaning liquid Wa, which is a pressure transmission medium that transmits pressure to the probe 2, and a tube 10 that connects the probe 2 and the syringe 9 to form a flow path of the cleaning liquid Wa. And comprising. The cleaning liquid Wa as the pressure transmission medium is made of an incompressible fluid such as ion exchange water or distilled water.

  The syringe 9 has a cylinder 9a and a piston 9b. The piston 9b is slid vertically in the vertical direction in FIG. 1 by the piston drive unit 11, and is transmitted to the probe 2 through the cleaning liquid Wa. To generate power. The syringe 9 is also connected to a tube 12 different from the tube 10. The other end of the tube 12 is connected to an electromagnetic valve 13 that adjusts the flow rate of the cleaning liquid Wa. The electromagnetic valve 13 is a three-way valve, and two tubes 14 and 15 are connected in addition to the tube 12. The other end of the tube 14 is connected to a pump 16 that performs an operation of sucking and discharging the cleaning liquid Wa. The pump 16 is further connected to another tube 17, and the other end of the tube 17 reaches a cleaning liquid tank 18 that stores the cleaning liquid Wa. On the other hand, the other end of the tube 15 is connected to a probe cleaning unit 19 that cleans the probe 2 and the electrode 3 together. The operations of the electromagnetic valve 13 and the pump 16 are controlled by the control unit 7.

  When the liquid level detection device 1 having the above configuration sucks or discharges the liquid Lq, it is not first connected to the tube 15 among the three valves of the electromagnetic valve 13 under the control of the control unit 7. The two valves are opened, the cleaning liquid Wa is sucked by the pump 16, the cleaning liquid Wa is sequentially introduced and filled in the order of the syringe 9, the tube 10 and the probe 2, and then the two valves opened by the electromagnetic valve 13 are closed and pumped The operation of 16 is finished. Thereafter, when the probe 2 sucks or discharges the liquid Lq, the piston drive unit 11 is driven to move the piston 9b of the syringe 9 under the control of the control unit 7 to move the piston 9b through the cleaning liquid Wa. An appropriate suction pressure (negative pressure) or discharge pressure (positive pressure) is generated at the tip of the probe 2. When the liquid Lq is sucked at the tip of the probe 2, an air layer is interposed between the liquid Lq and the cleaning liquid Wa, so that the liquid Lq is mixed with the cleaning liquid Wa when the liquid Lq is sucked or discharged. There is no.

  Next, an outline of the liquid level detection process performed by the liquid level detection device 1 will be described with reference to the flowchart shown in FIG. In the following, a case where the liquid level detection device 1 performs the liquid level detection process in the process of dispensing the liquid Lq once will be described.

  First, the transfer unit 4 is driven in accordance with a control signal from the control unit 7, and the probe 2 is lowered at a predetermined suction position (step S101). In step S101, it goes without saying that the electrode 3 is also interlocked when the probe 2 is lowered. Even in the steps described later, when the probe 2 is raised, lowered, or stopped, the electrode 3 is also interlocked.

Thereafter, the probe 2 is lowered until the liquid level is detected or a predetermined upper limit value h _max is reached. Specifically, when the descending amount Δh from the initial position of the probe 2 is smaller than the upper limit value h _max (Δh <h _max ) (Yes in step S102), if the detection signal is output from the determination unit 6 ( In step S103, Yes), the probe 2 is stopped because of contact with the liquid Lq (step S104). On the other hand, if the detection signal is not output from the determination unit 6 (No in step S103), the process returns to step S101 and the probe 2 continues to descend. In this sense, the upper limit h _max of the lowering amount, which is a criterion for determination in step S102, is set as a value that should stop the lowering even when the liquid Lq is not contained in the container 20 and is empty. preferable.

The control unit 7 performs control based on the detection signal output from the signal processing circuit 63 of the determination unit 6. First, when the amplitude V ₀ of the output voltage V from the probe 2 is equal to or higher than the reference voltage V ₂ in the comparison circuit 62 and is determined as “liquid level” ((A) in step S105), the amount of the liquid Lq by the probe 2 is determined. A note operation is performed (step S106). Specifically, under the control of the control unit 7, the piston 9b is driven to generate a suction pressure (negative pressure) at the tip of the probe 2, and a predetermined amount of the liquid Lq is sucked. Thereafter, the transfer unit 4 transfers the probe 2 to a predetermined discharge position, drives the piston 9b to generate discharge pressure (positive pressure) at the tip of the probe 2, and holds the liquid held at the tip of the probe 2. Lq is discharged into a predetermined container. Subsequently, the transfer unit 4 transfers the probe 2 to the probe cleaning unit 19 and cleans the probe 2 (and the electrode 3) (step S107). The cleaned probe 2 is transferred to the initial position of the next dispensing by the transfer unit 4 under the control of the control unit 7 (step S108). At this time, the initial position to which the probe 2 is transferred varies depending on the content of the next dispensing operation.

On the other hand, when the amplitude V ₀ of the output voltage V from the probe 2 is larger than the reference voltage V ₁ and smaller than the reference voltage V ₂ and the contacted liquid Lq is determined to be “bubble” ((B) in step S105). Dispensing abnormality processing is performed (step S110). The dispensing abnormality process mentioned here includes a process of outputting and notifying that the bubbles are present above the liquid level of the liquid Lq. After such dispensing abnormality processing, cleaning of the probe 2 (step S107) and transfer of the probe 2 to the initial position of the next dispensing (step S108) are performed, and the series of processing ends.

Up to this point, when the descending amount Δh from the initial position of the probe 2 is smaller than the upper limit value h _max , the subsequent processing has been described. However, the descending amount Δh from the initial position of the probe 2 reaches the upper limit value h _max . If it has been (No in step S102), there is no possibility of contact with the liquid Lq even if the probe 2 is further lowered, so the probe 2 is stopped (step S109), dispensing abnormality processing (step S110), A probe cleaning process (step S107) and a transfer process to the initial position of the next dispensing (step S108) are sequentially performed. In this case, since the probe 2 does not come into contact with the liquid Lq, the process proceeds to step S108 without performing the dispensing abnormality process or the cleaning process, and the probe 2 is transferred to the initial position of the next dispensing. It may be.

In the liquid level detection process described above, by using _two different reference voltages V ₁ and V ₂ , when the tip portions of the probe 2 and the electrode 3 are in contact with the liquid Lq, the liquid Lq in contact with the liquid Lq is the liquid level. It is possible to discriminate whether it is foam or foam. Therefore, even when the probe 2 comes into contact with the bubble of the liquid Lq, it is possible to prevent the bubble from adhering to the upper side of the probe 2 by further lowering the probe 2. As a result, even if dispensing abnormality due to bubbles existing above the liquid level of the liquid Lq occurs, it is not necessary to perform a special cleaning process, and contamination can be prevented.

  The liquid level detection apparatus 1 according to the first embodiment can be applied to an automatic analyzer that analyzes a component of a specimen. FIG. 6 is a diagram schematically showing the configuration of the main part of the automatic analyzer according to the embodiment of the present invention. An automatic analyzer 100 shown in FIG. 1 includes a measurement mechanism 101 that dispenses a sample and a reagent corresponding to the liquid Lq into predetermined containers, and performs optical measurement on the liquid contained in the container. And a control analysis mechanism 102 for controlling the automatic analyzer 100 including the measurement mechanism 101 and analyzing the measurement result in the measurement mechanism 101, and by coordinating these two mechanisms, the components of a plurality of specimens are analyzed. It is a device that performs biochemical analysis automatically and continuously.

  First, the measurement mechanism 101 of the automatic analyzer 100 will be described. The measurement mechanism 101 includes a sample transport unit 31 that houses and sequentially transfers a plurality of racks 22 on which sample containers 21 that mainly store general samples are mounted, and various samples other than general samples (standard samples for creating calibration curves, A sample container holding part 32 for holding a sample container 23 for storing a quality control specimen, an emergency specimen, a STAT specimen, a retest specimen, etc.), a reagent container holding part 33 for holding a reagent container 24, and a specimen and a reagent. A reaction container holding unit 34 that holds the reaction container 25 that is a reaction container, a stirring unit 35 that stirs the liquid contained in the reaction container 25, and the intensity for each wavelength component of light that has passed through the reaction container 25. And a photometric unit 36 for measuring and the like.

  In addition, the measurement mechanism 101 includes a sample dispensing unit 37 that dispenses a sample contained in the sample container 21 on the sample transfer unit 31 and the sample container 23 on the sample container holding unit 32 into the reaction container 25, and a reagent container holding A reagent dispensing unit 38 that dispenses the reagent contained in the reagent container 24 on the unit 33 into the reaction container 25, and a container cleaning unit 39 that cleans the reaction container 25 are provided. Among these, the sample dispensing unit 37 and the reagent dispensing unit 38 have the same functional configuration as the liquid level detection device 1 described above, and include the probe 2 and the probe cleaning unit 19, respectively. The sample dispensing unit 37 detects the liquid level of the sample stored in the sample container 21 as the liquid Lq, while the reagent dispensing unit 38 is a reagent stored in the reagent container 24 as the liquid Lq. The liquid level is detected.

  Each of the sample containers 21 and 23 is affixed with an information code recording medium (not shown) in which identification information for identifying a sample accommodated therein is encoded and recorded in an information code such as a barcode or a two-dimensional code. . Similarly, an information code recording medium in which identification information for identifying a reagent contained in the reagent container 24 is encoded and recorded in an information code is also attached to the reagent container 24 (not shown). Therefore, the measurement mechanism 101 is affixed to the information code reader CR1 that reads the information code affixed to the sample container 21, the information code reader CR2 that reads the information code affixed to the sample container 23, and the reagent container 24. An information code reading unit CR3 for reading the information code is provided.

  The sample container holding part 32, the reagent container holding part 33, and the reaction container holding part 34 are attached to a wheel for accommodating and holding the sample container 23, the reagent container 24, and the reaction container 25, and the center of the bottom surface of the wheel. Driving means for rotating the wheel about the vertical line passing through the rotation axis (not shown).

  The inside of each container holding part is kept at a constant temperature. For example, the inside of the reagent container holding unit 33 is set to a temperature lower than room temperature in order to suppress deterioration and denaturation of the reagent. In addition, the inside of the reaction container holding unit 34 is set to a temperature that is comparable to the human body temperature.

  The photometry unit 36 is a light source that emits white light, a spectroscopic optical system that splits the white light that has passed through the reaction vessel 25, and a light receiving device that receives light separated by the spectroscopic optical system for each component and converts it into an electrical signal. Device.

  Note that when performing biochemical analysis of the components of the specimen, two types of reagents are often used for one specimen, so the reagent container holding unit 33 for the first reagent and the reagent for the second reagent You may provide the container holding | maintenance part 33 separately. In this case, two reagent dispensing units 38 corresponding to the individual reagent container holding units 33 may be provided. In addition, a plurality of agitation units 35 may be provided in order to simultaneously agitate the liquid in the plurality of reaction vessels 25 at an appropriate timing after dispensing of the specimen or reagent.

  By the way, in FIG. 6, since the main purpose is to schematically show the main components of the measurement mechanism 101, the positional relationship between the components is not necessarily accurate. The exact positional relationship between the components is a design matter that should be determined according to various conditions such as the number of reagent container holding portions 33 and the rotation mode of the wheel of the reaction container holding portion 34 in the interval of the dispensing operation.

  Next, the control analysis mechanism 102 of the automatic analyzer 100 will be described. The control analysis mechanism 102 includes an input unit 41 that receives input of information necessary for sample analysis, information including an operation instruction signal of the automatic analyzer 100, an output unit 42 that outputs information related to sample analysis, and a measurement mechanism. A data generation unit 43 that generates sample analysis data based on the measurement result in 101, a storage unit 44 that stores various types of information including information about sample analysis and information about the automatic analyzer 100, and a control analysis mechanism 102 And a control unit 45 that controls each function or each means and performs drive control of the measurement mechanism 101.

  The input unit 41 has a keyboard and a mouse. The input unit 41 may further include a pointing device such as a trackball or a trackpad, or a user interface such as a voice input microphone.

  The output unit 42 includes a display device such as liquid crystal, plasma, organic EL, or CRT that displays various types of information. The output unit 42 may further include an audio output speaker or a printer that prints and outputs information on paper or the like. The output unit 42 also has the function of the output unit 8 of the liquid level detection device 1.

  The data generation unit 43 performs an analysis operation on the measurement result received from the photometry unit 36 of the measurement mechanism 101. In this analytical calculation, the absorbance of the liquid inside the reaction vessel 25 is calculated based on the measurement result sent from the photometry unit 36, or the reaction is performed using the absorbance calculation result and various information such as a calibration curve and analysis parameters. Analytical data for each specimen is generated by performing a component amount calculation process for quantitatively determining the liquid components in the container 25. The analysis data generated in this way is output from the output unit 42 and is written and stored in the storage unit 44.

  The storage unit 44 stores analysis items, sample information, reagent types, sample and reagent dispensing amounts, sample and reagent expiration dates, information on calibration curves used for analysis, calibration curve expiration dates, and reference to each analysis item Parameters necessary for analysis such as values and allowable values, analysis data generated by the data generation unit 43, and the like are stored.

  The control unit 45 reads out various programs stored in the storage unit 44 from the storage unit 44, thereby executing various operations of the automatic analyzer 100 and calculations. The control unit 45 also has the function of the control unit 7 of the liquid level detection device 1.

  In the automatic analyzer 100 having the above configuration, when the generation of the bubble of the liquid Lq is detected, the probe 2 is washed without lowering the probe 2 any more. Can be washed. For this reason, there is no fear that bubbles may be attached to the portion above the probe 2 and not cleaned during normal cleaning, and unnecessary cleaning is not necessary. Therefore, an increase in cleaning time can be suppressed and the analysis speed can be improved. In addition, it is possible to reduce the consumption of the cleaning liquid Wa used for cleaning, thereby realizing cost reduction.

  By the way, when the reagent container 24 is transported, the reagent inside the reagent container 24 shakes and bubbles are easily generated. For this reason, in the conventional automatic analyzer, it is necessary to check whether or not bubbles are generated when the reagent container 24 is installed in the reagent container holding unit, which is a burden on the operator. On the other hand, in the automatic analyzer 100 according to the first embodiment, after the reagent container 24 is installed in the reagent container holding unit 33, the bubble detection is automatically performed before the dispensing operation. Therefore, the burden on the operator is reduced and more efficient analysis can be performed. In addition, the cost required for maintenance of the automatic analyzer 100 can be reduced. In view of this point, it is possible to adopt a configuration in which only the reagent dispensing unit 38 has the function of the liquid level detection device 1.

  According to the first embodiment of the present invention described above, a probe (first electrode) that is formed using a conductive material and sucks and discharges a liquid, and the probe and the liquid contained in the container A determination means for electrically detecting contact with two different sensitivities and determining a contact state between the probe and the liquid based on the detected result, thereby providing a liquid surface of the liquid contained in the container; In addition, it is possible to accurately detect bubbles generated above the liquid level.

  Further, according to the first embodiment, since the liquid level is detected by the conduction method, an effect of being resistant to noise can be obtained.

(Embodiment 2)
FIG. 7 is a diagram showing a configuration of the liquid level detection device according to Embodiment 2 of the present invention. The liquid level detection device 51 shown in the figure is between a conductive probe (first electrode) for sucking or discharging a liquid and an electrode (second electrode) provided in the vicinity of a container for storing the liquid. This is a device that determines the presence or absence of contact between the probe and the liquid surface and the contact state when there is contact based on the change in the electrostatic capacity. In addition, in FIG. 7, about the site | part which has the same structure as the liquid level detection apparatus 1 demonstrated in the said Embodiment 1, the same code | symbol is attached | subjected.

  The liquid level detection device 51 according to the second embodiment generates an alternating-current signal having a predetermined frequency and supplies the generated signal to the probe 2 in series between the probe 2 and the oscillation circuit 52. The reference circuit 54 connected in parallel with the resistor 53 from the oscillation circuit 52 side to the end of the resistor 53 that is connected to the oscillation circuit 52 and the end of the resistance 53 And a voltage changing circuit 55 connected in parallel to the resistor 53 from the probe 2 side to the end connected to the probe 2 and having the same configuration as the reference circuit 54, and an output voltage of the reference circuit 54 A determination unit 56 that determines the presence / absence of contact between the probe 2 and the liquid Lq by comparing the output voltage of the voltage change circuit 55 and the contact state when there is contact, and a container 20 that contains the liquid Lq. Electrode 57 , Comprising a.

  The resistance value of the resistor 53 is set such that a sufficient difference is generated between the output of the reference circuit 54 and the output of the voltage change circuit 55 when the probe 2 comes into contact with the liquid Lq.

  The reference circuit 54 and the voltage change circuit 55 have the same configuration, and specifically include a rectifier and a smoothing capacitor, and send a DC signal to the determination unit 56.

  The determination unit 56 includes a differential amplifier 561 that differentially amplifies the output voltage of the reference circuit 54 and the output voltage of the voltage change circuit 55, and first and second reference voltages that are different from each other in the output of the differential amplifier 561. Detection obtained by performing predetermined signal processing on the comparison circuit 562 (first comparison circuit) and the comparison circuit 563 (second comparison circuit) to be compared with each other and the outputs from the two comparison circuits 562 and 563, respectively. And a signal processing circuit 564 for sending a signal to the control unit 7. The positive phase terminal side of the differential amplifier 561 is connected to the reference circuit 54, while the negative phase terminal side of the differential amplifier 561 is connected to the voltage change circuit 55.

The configuration of comparison circuits 562 and 563 is the same as that of comparison circuit 61 in the first embodiment (see FIG. 2). The comparison circuit 562 inputs the output from the differential amplifier 561 to the negative phase terminal side, and compares the magnitude with the reference voltage ΔV ₁ (> 0) that is the first reference voltage input to the positive phase terminal side. . Further, the comparison circuit 563 inputs the output from the differential amplifier 561 to the negative phase terminal side, and compares it with the reference voltage ΔV ₂ (> 0) that is the second reference voltage input to the positive phase terminal side. Compare. The values of the _two reference voltages ΔV ₁ and ΔV ₂ are different and satisfy ΔV ₁ <ΔV ₂ . The values of the reference voltages ΔV ₁ and ΔV ₂ are determined by adjusting the resistance values of the voltage dividing circuits included in the comparison circuits 562 and 563, respectively.

The determination unit 56 determines whether the probe 2 is in contact with the liquid level of the liquid Lq by using the _two reference voltages ΔV ₁ and ΔV ₂ , or whether the probe 2 is in contact with bubbles generated above the liquid level of the liquid Lq. judge. Hereinafter, this point will be described. When the probe 2 is not in contact with the liquid Lq, the output of the reference circuit 54 and the output of the voltage change circuit 55 are substantially the same (hereinafter, this output voltage is referred to as V _air ). When the probe 2 comes into contact with the liquid Lq, the capacitance between the probe 2 and the electrode 57 increases, so that the output of the voltage change circuit 55 decreases and a voltage drop occurs. On the other hand, the output of the reference circuit 54 is substantially constant regardless of the presence or absence of contact between the probe 2 and the liquid Lq.

The capacitance change between the probe 2 and the electrode 57 when the probe 2 is in contact with the liquid Lq is such that the probe 2 is in contact with the bubble of the liquid Lq when the probe 2 is in contact with the liquid surface of the liquid Lq. It is bigger than the case. Therefore, when the output voltage of the voltage changing circuit 55 after contact with the liquid Lq and V _Lq, the value of the V _Lq is better when the probe 2 is in contact with the surface of the liquid Lq is, bubbles of liquid Lq contact It becomes smaller than the case. The reference voltages ΔV ₁ and ΔV ₂ in the comparison circuits 562 and 563 are the values of the output from the differential amplifier 561 after the probe 2 contacts the liquid Lq, that is, the voltage drop ΔV = V _air −V _Lq , and the liquid of the probe 2. It is set as a value that can be discriminated depending on the contact state with Lq, more specifically, depending on whether it is in contact with the liquid surface of liquid Lq or in contact with bubbles.

8 and 9 are diagrams showing the time change of the output voltage V of the voltage change circuit 55. FIG. In these figures, the horizontal axis indicates time t, and the vertical axis indicates the output voltage V of the voltage change circuit 55. Further, in FIGS. 8 and 9 show a case where the time t ₂ begins to contact with the liquid Lq.

FIG. 8 is a diagram illustrating a case where the probe 2 is in contact with the liquid surface of the liquid Lq. In this case, the output voltage V _Lq of the voltage change circuit 55 after contact is smaller than the output voltage V ₄ (= V _air −ΔV ₂ ) of the comparison circuit 563 when not in contact. In other words, the output ΔV = V _air −V _Lq from the differential amplifier 561 after contact is larger than ΔV ₂ = V _air −V ₄ (ΔV> ΔV ₂ ).

FIG. 9 is a diagram illustrating a case where the probe 2 is in contact with the liquid surface of the liquid Lq. In this case, the output voltage V _Lq after the contact is smaller than the output voltage V ₃ (= V _air −ΔV ₁ ) of the comparison circuit 562 in the non-contact state, and the output voltage V ₄ (= V _air −ΔV ₂ ). In other words, the output ΔV = V _air −V _Lq from the differential amplifier 561 after the contact is larger than ΔV ₁ = V _air −V _{3 and} smaller than ΔV ₂ = V _air −V ₄ (ΔV ₂ > ΔV). > ΔV ₁ ).

Next, the configuration of the determination unit 56 will be described. The signal processing circuit 564 outputs a detection signal corresponding to the determination result to the control unit 7 by performing predetermined signal processing on the outputs from the comparison circuits 562 and 563. For example, when the output voltage ΔV from the differential amplifier 561 satisfies ΔV> ΔV _2, that is, when the output voltage V of the voltage change circuit 55 causes a voltage drop as shown in FIG. 8, it corresponds to the determination result “liquid level”. The detected signal is transmitted to the control unit 7. When the output voltage ΔV from the differential amplifier 561 satisfies ΔV ₂ >ΔV> ΔV _1, that is, when the output voltage V of the voltage change circuit 55 causes a voltage drop as shown in FIG. A detection signal corresponding to is transmitted to the control unit 7.

  In FIG. 7, the electrode 57 has a flat plate shape, but may have a shape other than the flat plate shape, for example, a shape that covers the container 20. Moreover, you may combine the function of the electrode 57 by forming the container 20 with an electroconductive material. Further, a metal portion (sheet metal) constituting the casing of the liquid level detection device 1 may be used as the electrode 57.

  An outline of the liquid level detection process performed by the liquid level detection device 51 having the above configuration will be described. The liquid level detection process in the second embodiment has the same processing flow as the liquid level detection process described in the first embodiment (see FIG. 5). Therefore, only the differences from the first embodiment will be described below, and the same step numbers as those in FIG. 5 are used.

When the determination unit 56 outputs a detection signal in step S103 (Yes in step S103), in step S105, the determination unit 56 causes the voltage drop ΔV of the voltage change circuit 55 after contact with the liquid Lq and the reference voltages ΔV ₁ and ΔV _2. And the presence or absence of contact with the liquid Lq, and the contact state (“liquid level” or “bubble”) with the liquid Lq when there is contact are determined. In this determination, if the voltage drop ΔV satisfies ΔV> ΔV ₂ , the signal processing circuit 564 sends a detection signal corresponding to the determination of “liquid level” to the control unit 7. On the other hand, if the voltage drop ΔV satisfies ΔV ₂ >ΔV> ΔV ₁ , the signal processing circuit 564 sends a detection signal corresponding to the determination of “bubble” to the control unit 7.

According to the liquid level detection process described above, by using _two different reference voltages ΔV ₁ and ΔV ₂ , when the tip of the probe 2 comes into contact with the liquid Lq, the liquid Lq that is in contact with the liquid level is a bubble. Can be discriminated. Therefore, even when the probe 2 comes into contact with the bubble of the liquid Lq, it is possible to prevent the bubble from adhering to the upper side of the probe 2 by further lowering the probe 2. As a result, even if dispensing abnormality due to bubbles existing above the liquid level of the liquid Lq occurs, it is not necessary to perform a special cleaning process, and contamination can be prevented.

  The liquid level detection device 51 according to the second embodiment can be applied to an automatic analyzer that analyzes the components of the specimen, similarly to the liquid level detection device 1 according to the first embodiment.

  According to the second embodiment of the present invention described above, a probe (first electrode) that is formed using a conductive material and sucks and discharges a liquid, and the probe and the liquid contained in the container A determination means for electrically detecting contact with two different sensitivities and determining a contact state between the probe and the liquid based on the detected result, thereby providing a liquid surface of the liquid contained in the container; In addition, it is possible to accurately detect bubbles generated above the liquid level.

  Further, according to the second embodiment, the liquid is traced by differentially amplifying the difference between the output of the reference circuit arranged in the previous stage of the resistor and the output of the voltage changing circuit arranged in the subsequent stage of the resistor. Even in this case, it is possible to accurately detect a change in capacitance, and to realize highly accurate liquid level detection. It is also suitable for downsizing the apparatus.

(Other embodiments)
The best mode for carrying out the present invention has been described in detail so far, but the present invention should not be limited only by the above two embodiments. For example, a rod-shaped member different from the probe may be disposed as the first electrode. In this case, the probe may not have conductivity.

  Further, the liquid level detection device according to the present invention may be applied to a dispensing mechanism of an automatic analyzer for immunoassay. In this case, the automatic analyzer includes a B / F cleaning unit that performs B / F cleaning necessary for immunoassay using a heterogeneous reaction, and a photomultiplier tube that counts the light emission amount of the luminescent substance as a photometric unit. May be provided. Except for these points, the configuration of the automatic analyzer is almost the same as the configuration of the automatic analyzer described above.

  Thus, the present invention can include various embodiments and the like not described herein, and various design changes and the like can be made without departing from the technical idea specified by the claims. It is possible to apply.

It is a figure which shows typically the structure of the liquid level detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of a comparison circuit. It is a figure which shows the time change of the output voltage from a probe when a probe contacts a liquid level. It is a figure which shows the time change of the output voltage from a probe when a probe contacts a bubble. It is a flowchart which shows the outline | summary of the liquid level detection process which the liquid level detection apparatus which concerns on Embodiment 1 of this invention performs. It is a figure which shows typically the structure of the automatic analyzer principal part which concerns on Embodiment 1 of this invention. It is a figure which shows typically the structure of the liquid level detection apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the time change of the output voltage of a voltage change circuit when a probe contacts the liquid level. It is a figure which shows the time change of the output voltage of a voltage change circuit when a probe contacts a bubble.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 Liquid level detection apparatus 2 Probe 3, 57 Electrode 4 Transfer part 5, 52 Oscillation circuit 6, 56 Judgment part 7, 45 Control part 8 Output part 9 Syringe 9a Cylinder 9b Piston 10, 12, 14, 15, 17 Tube DESCRIPTION OF SYMBOLS 11 Piston drive part 13 Electromagnetic valve 16 Pump 18 Cleaning liquid tank 19 Probe cleaning part 20 Container 21, 23 Sample container 22 Rack 24 Reagent container 25 Reaction container 31 Specimen transfer part 32 Specimen container holding part 33 Reagent container holding part 34 Reaction container holding part 35 Stirring unit 36 Photometric unit 37 Sample dispensing unit 38 Reagent dispensing unit 39 Container washing unit 41 Input unit 42 Output unit 43 Data generation unit 44 Storage unit 53, 612, 613 Resistance 54 Reference circuit 55 Voltage change circuit 61, 62, 562, 563 Comparison circuit 63, 564 Signal processing circuit 100 Automatic analyzer 10 DESCRIPTION OF SYMBOLS 1 Measurement mechanism 102 Control analysis mechanism 561 Differential amplifier 611 Comparator 614 Voltage dividing circuit CR1, CR2, CR3 Information code reading part Lq Liquid Wa Cleaning liquid

Claims (8)

A liquid level detection device for detecting a liquid level of a liquid contained in a container,
A first electrode formed using a conductive material;
Determination means for electrically detecting contact between the first electrode and the liquid with two different sensitivities, and determining a contact state between the first electrode and the liquid based on the detected result;
A liquid level detection device comprising:   The liquid level detection device according to claim 1, wherein the first electrode is a probe that sucks and discharges liquid. A second electrode formed using a conductive material, fixed in the vicinity of the first electrode and spaced from the first electrode, and having an end near the end of the first electrode When,
An oscillation circuit connected to the first or second electrode and generating a signal of a predetermined frequency;
Further comprising
The determination means outputs an output voltage output from the first electrode when the first and second electrodes are in contact with the liquid and the first and second electrodes are conducted through the liquid. The liquid level detection device according to claim 1, further comprising first and second comparison circuits that respectively compare with first and second reference voltages having different values.   The first and second reference voltages have the same magnitude relationship with the output voltage when the first and second electrodes are in contact with the liquid level, while the first and second reference voltages are the same. The liquid level detection device according to claim 3, wherein a magnitude relationship with the output voltage when the electrode comes into contact with the liquid bubble is different. A second electrode formed using a conductive material and disposed integrally with or near the container;
An oscillation circuit for generating a signal having a predetermined frequency and supplying the generated signal to at least the first electrode;
A resistor connected in series between the first electrode and the oscillation circuit;
Further comprising
The determination means outputs an output voltage from both ends of the resistor due to a change in capacitance between the first electrode and the second electrode caused by the first electrode coming into contact with the liquid. 3. The liquid level detection device according to claim 1, further comprising first and second comparison circuits that respectively compare the difference between the first and second reference voltages having different values.   While the first and second reference voltages have the same magnitude relationship with the difference in output voltage from both ends of the resistor when the first electrode is in contact with the liquid surface of the liquid, 6. The liquid level detection device according to claim 5, wherein a magnitude relationship with a difference in output voltage from both ends of the resistance when the electrode contacts the bubble of the liquid is different. An automatic analyzer that analyzes the components of the specimen by reacting the specimen with a reagent,
An automatic analyzer comprising the liquid level detection device according to any one of claims 1 to 6 and comprising reagent dispensing means for dispensing the reagent as a liquid.   The automatic analyzer according to claim 7, further comprising a sample dispensing unit that includes the liquid level detection device according to claim 1, and that dispenses the sample as a liquid. .

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