Nozzle cleaner and automatic analyzer using the same

A nozzle cleaner includes: a cleaning tank which stores a cleaning solution; a first conductive member that is disposed to be immersed into the cleaning solution stored in the cleaning tank when the nozzle is cleaned; an ultrasonic wave generating mechanism which is disposed so that at least a part of a second conductive member is immersed into the cleaning solution stored in the cleaning tank when the nozzle is cleaned and generates an ultrasonic vibration in the cleaning solution stored in the cleaning tank; a first voltage control unit which controls a potential applied to the first conductive member; and a second voltage control unit which controls a potential applied to the second conductive member, wherein the first voltage control unit applies a second potential V2 higher than a first potential V1 applied to the nozzle when the nozzle is cleaned to the first conductive member.

TECHNICAL FIELD

The present invention relates to a nozzle cleaner for cleaning a nozzle that dispenses such sample as serum and urine, and an automatic analyzer provided with the nozzle cleaner for conducting component analysis of a sample-reagent mixture.

BACKGROUND ART

As the automatic analyzer is configured to dispense the sample by using the same nozzle repeatedly, a tip portion of the nozzle is cleaned before suction of another sample. Insufficient cleaning of the tip portion of the nozzle leads to carry-over of the component of the previously dispensed sample into the next sample, resulting in deteriorated measurement accuracy. Patent Literature 1 discloses the method of removing the stain on the inner or outer surface of the tip portion of the nozzle not only by washing with deionized water but also immersing the tip portion of the nozzle in a detergent stored in a part of the cleaning tank.

Patent Literature 2 discloses the ultrasonic cleaner for nozzle in the form of the ultrasonic cleaning tank having piezoelectric elements (vibrator array) disposed in the cleaning tank capable of storing liquid.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In most cases, the nozzle made of metal excellent in mechanical wear resistance and chemical corrosion resistance has been employed for the automatic analyzer. Furthermore, in order to detect the liquid level of the sample or the reagent, a liquid level detection method utilizing change in electric characteristics such as electrostatic capacity and resistance value between timings before and after contact of the nozzle with the liquid. The above-described liquid level detection method allows liquid level detection by applying a predetermined voltage to the metallic (conductive) nozzle.

It is assumed that the cleaning solution which contains an electrolyte is stored in the cleaning tank as disclosed in Patent Literature 1, and the nozzle is cleaned by the cleaning mechanism as disclosed in Patent Literature 2. As the cleaning mechanism disclosed in Patent Literature 2 has the vibrator array provided with the metallic member disposed inside the cleaning tank, the metallic nozzle is immersed together with the metallic member (vibrator array) of the cleaning mechanism in the same electrolyte aqueous solution upon cleaning of the nozzle. When enabling the liquid level detection function of the nozzle for monitoring normal immersion of the nozzle in the electrolyte aqueous solution in the above-described state, the nozzle side becomes the positive electrode through application of the predetermined voltage to the nozzle. This may cause the risk of electric corrosion on the nozzle surface. As described above, the change in the nozzle surface state may adversely affect the carry-over and accuracy in the dispensing amount.

The present invention provides the nozzle cleaner for cleaning the nozzle, which includes the liquid level detection function so as to prevent unintended electric corrosion, and the automatic analyzer provided with the nozzle cleaner.

Solution to Problem

The nozzle cleaner for cleaning a nozzle of a dispensing mechanism having a liquid level detection function includes a cleaning tank which stores a cleaning solution, a first conductive member disposed to be immersed in the cleaning solution stored in the cleaning tank in cleaning the nozzle, and a first voltage control unit for controlling a potential to be applied to the first conductive member. The first voltage control unit applies a second voltage to the first conductive member. The second potential is higher than the first potential to be applied to the nozzle in cleaning the nozzle.

The nozzle cleaner further includes an ultrasonic generation mechanism provided with a second conductive member disposed so as to be at least partially immersed in the cleaning solution stored in the cleaning tank in cleaning the nozzle for generating ultrasonic vibration in the cleaning solution stored in the cleaning tank, and a second voltage control unit for controlling the potential to be applied to the second conducive member. The second voltage control unit applies the potential equal to the first potential, or a third potential higher than the first potential to the second conductive member.

It is possible to apply the second potential to the second conductive member as a substitute for the first conductive member.

Advantageous Effects of Invention

It is possible to use both the detergent which contains electrolyte with high cleaning effect and the ultrasonic cleaner provided with the metallic member in the cleaning tank while retaining the liquid level detection function of the nozzle, thus providing the nozzle cleaner exhibiting high cleaning effect.

DESCRIPTION OF EMBODIMENT

An embodiment according to the present invention will be described in detail referring to the drawings.

FIG.1is a schematic diagram of an automatic analyzer100. The biological sample to be analyzed such as blood and urine (hereinafter simply referred to as a sample) is stored in a sample container15. One or more sample containers15are mounted on a sample rack16, and transferred by a sample transfer mechanism17. A reagent used for sample analysis is stored in a reagent bottle10. Multiple reagent bottles10are circumferentially arranged on a reagent disk9. The sample and the reagent are mixed for reaction in a reaction vessel2. Multiple reaction vessels2are circumferentially arranged on a reaction disk1. The sample container15is transferred to a sample dispensing position by the sample transfer mechanism17. Then the sample is dispensed from the sample container15to the reaction vessel2by a first or a second sample dispensing mechanism11or12. Meanwhile, the reagent is dispensed from the reagent bottle10to the reaction vessel2by reagent dispensing mechanisms7,8. A mixture liquid (reaction liquid) of the sample and the reagent which have been dispensed to the reaction vessel2is stirred by stirring mechanisms5,6. The transmitted light from a not shown light source through the reaction liquid in the reaction vessel2is measured by a spectrophotometer4so that absorbance of the reaction liquid is measured. The automatic analyzer100executes an analysis process by calculating the predetermined constituent concentration of the analysis item corresponding to the reagent in accordance with the absorbance of the mixture liquid (reaction liquid) measured by the spectrophotometer4. The measured reaction vessel2is cleaned by a cleaning mechanism3.

The first (second) sample dispensing mechanism11(12) includes a sample nozzle11a(12a) which is disposed having its tip portion directed downward. A sample pump19is connected to the sample nozzle11a(12a). The first (second) sample dispensing mechanism11(12) is structured to be horizontally rotated, and vertically operated so that the sample nozzle11a(12a) is inserted into the sample container15for suction of the sample, and inserted into the reaction vessel2for discharging the sample. The sample is then dispensed from the sample container15to the reaction vessel2. An ultrasonic cleaner (nozzle cleaner)23(24) for cleaning the sample nozzle11a(12a) with cleaning solution is disposed in an operation range of the first (second) sample dispensing mechanism11(12). A cleaning tank13(14) is disposed for cleaning the sample nozzle11a(12a) so that the cleaning solution other than water is washed out with water.

The reagent dispensing mechanisms7,8include reagent nozzles7a,8a, respectively each tip portion of which is directed downward. A reagent pump18is connected to the reagent nozzles7a,8a. The reagent dispensing mechanisms7,8are structured to be horizontally rotated, and vertically operated so that the sample nozzles7a,8aare inserted into the reagent bottles10for suction of the reagent, and inserted into the reaction vessels2for discharging the sample. The sample is then dispensed from the reagent bottle10to the reaction vessel2. Cleaning tanks32,33for cleaning the sample nozzles7a,8awith the cleaning solution are disposed in operation ranges of the reagent dispensing mechanisms7,8, respectively.

The stirring mechanisms5,6are structured to be horizontally rotated, and vertically operated. They are inserted into the reaction vessel2so that the mixture liquid (reaction liquid) of the sample and the reagent is stirred. Cleaning tanks30,31for cleaning the stirring mechanisms5,6with the cleaning solution are disposed in operation ranges of the stirring mechanisms5,6. A cleaning pump20is connected to the cleaning mechanism3.

Overall operations of the automatic analyzer100are controlled by a control unit21.FIG.1omits a connection portion between the respective mechanisms and the control unit21which constitute the automatic analyzer100for simplifying the illustration.

A structure example of the ultrasonic cleaners23,24will be described referring toFIGS.2A to2D.FIG.2Ais a perspective view of the ultrasonic cleaner23or24.FIG.2Bis a top view.FIG.2Cis a cross-sectional view taken along a line A-A′ (FIG.2B).FIG.2Dis a side view of the ultrasonic transducer and the vibration head.

Each of the ultrasonic cleaners23,24includes an ultrasonic transducer (BLT: Bolt-clamped Langevin Type Transducer)205having one or more piezoelectric elements203tightened between a front mass201and a back mass202with a bolt204, a vibration head209, and a base portion207on which a cleaning tank206which stores the cleaning solution is disposed. In this case, an axial direction of the bolt204of the ultrasonic transducer205is designated as an X-direction, a direction perpendicular to the X-direction with respect to the top surface (horizontal plane) of the base portion207is designated as a Y-direction, and a direction perpendicular to the horizontal plane, that is, the vertical direction is designated as a Z-direction.

The ultrasonic transducer205includes a flange portion208, and is fixed to the base portion207. As the drawing shows, the ultrasonic transducer is fixed to the base portion207at the lower side of the flange portion208. A member for fixing the flange may be provided at the upper side of the flange portion208so as to be connected to the base portion207for uniform fixation with entire circumference of the flange portion208.

The ultrasonic transducer205includes a vibration head209attached to a tip portion at the front mass side while being extended toward the cleaning tank206. A tip portion210of the vibration head209has a cylindrical shape, and is positionally adjusted to be immersed in the cleaning solution stored in the cleaning tank206while being not in contact with the cleaning tank206. The cylindrical vibration head tip portion210has a cylindrical hole larger than an outer diameter of the tip portion of the sample nozzle. The metal block (201,202) and the vibration head209are metallic members. It is possible to produce the front mass201and the vibration head209individually, and fix them with a bolt or the like. Alternatively, they may be integrally produced. The cleaning tank206includes a pipe212for supplying the cleaning solution. The cleaning solution inside the cleaning tank206is overflown by supply of a constant amount of cleaning solution for replacement of the solution. Specifically, the cleaning solution supplied from the cleaning solution supply pipe212overflows from the upper end of a side wall of the cleaning tank206, and further flows into a liquid receiver213at an outer periphery of the cleaning tank206so as to be discharged from a drainage214. As a result, the height (liquid level) of the cleaning solution inside the cleaning tank206is fixed at each supply of the cleaning fluid. It is possible to use resin for forming the cleaning tank206, and the base portion207in a non-restricted manner.

Although not shown in the drawing, an electrode (for example, a copper plate) is interposed between a metal block (201,202) and the piezoelectric element203, and between the piezoelectric elements203. A sinusoidal voltage at a predetermined frequency is applied to the above-described electrode to drive the ultrasonic transducer205in the axial direction of the bolt204. Especially, it has been known that the front mass201is formed into a horn shape (diameter at the side of the piezoelectric element203is changed to be different from the diameter at the vibration head side) to ensure increase in the amplitude generated by the piezoelectric element203. The large amplitude may be obtained with less electric power by designing the length or shape of the horn in accordance with the required frequency for driving. Although the drawing shows the conical horn shape, any other shape (exponential horn) is usable without causing problems.

The long narrow vibration head209is attached to the tip portion of the horn-shaped front mass201, and vibrated resonantly in synchronization with vibration of the ultrasonic transducer205so as to allow large displacement at the vibration head tip portion210. This makes it possible to convert the electric energy applied to the ultrasonic transducer205efficiently into vibration (kinetic energy) of the vibration head tip portion210.

When cleaning the sample nozzles11a,12ausing the ultrasonic cleaners23,24, the piezoelectric element203is driven at the predetermined low frequency to insert the sample nozzles into the cylindrical hole211of the vibration head tip portion210so as to be immersed in a cleaning range (about 5 mm from the tip portion of the sample nozzles) for a predetermined time period. The stain adhered to the outer periphery of the sample nozzles is removed by the cavitation. After cleaning, the sample nozzles is pulled out from the ultrasonic cleaner to allow the cleaning solution inside the cleaning tank206to be overflown and replaced so that the next sample nozzles is cleaned with new cleaning solution while suppressing the carry-over. The above-described control is executed by the control unit21in accordance with the predetermined device sequence.

The ultrasonic cleaners23,24drive the piezoelectric elements203at the frequency ranging from 20 to 100 kHz suitable for generation of the cavitation in the cleaning solution so as to vibrate the vibration head209resonantly inside the cleaning tank206. The resultant largely displaced vibration (the frequency equal to the drive frequency) generates the ultrasonic vibration. Accordingly, the cavitation occurs around the vibration head209, especially a vibration antinode (the part at the largest amplitude). The vibration head tip portion210as the open end corresponds to the vibration antinode. Therefore, the cavitation generated in the cylindrical hole211serves to intensively clean the tip portion of the sample nozzle. The use of water as the cleaning solution also provides high cleaning effect by the cavitation as well. For example, the use of warm water is effective for removing the protein originated stain. It is possible to use the cleaning solution adapted to the intended cleaning effect.

FIG.3shows the state in which the sample nozzle11ais immersed in the cleaning solution inside the cleaning tank206. As the sample nozzle12ahas the same function as that of the sample nozzle11a, the explanation will be made with respect to the sample nozzle11aas a representative example.

According to the embodiment, the control unit21includes a liquid level detection control unit301, a first voltage control unit302, and a second voltage control unit303.

The sample nozzle11ahas a liquid level detection function which is enabled in cleaning the nozzle for monitoring the normal nozzle cleaning so as to confirm that the nozzle has been immersed in the cleaning solution inside the cleaning tank. The liquid level detection control unit301applies a predetermined potential V1to the sample nozzle11a. Meanwhile, the ultrasonic cleaner23is disposed on a stage305made of metal at a reference potential GND (±0 V). The electrostatic capacity between the sample nozzle11aand the stage305which face with each other via air is different from the one between the sample nozzle11aand the stage305which face with each other via the cleaning solution. Detection of change in the electrostatic capacity allows confirmation with respect to immersion of the nozzle in the cleaning solution inside the cleaning tank.

In using the cleaning solution that contains the electrolyte for the structure according to the embodiment, as the metallic sample nozzle11aand the metallic vibration head209are immersed in the same electrolyte solution, and the predetermined voltage is applied to the sample nozzle11afor liquid level detection, there may cause the risk of electric corrosion of the sample nozzle11a. Consequently, in the embodiment, a metallic member221in contact with the cleaning solution inside the cleaning tank206is disposed so as to receive application of a predetermined potential V2to the metallic member221from the first voltage control unit302. In this case, the potential V2applied to the metallic member221is made higher than the potential V1applied to the sample nozzle11ato be protected so that the corrosion of the sample nozzle11ais suppressed. In the case of setting the potential V1applied to the sample nozzle11ato +5 V, for example, the potential V2applied to the metallic member221is controlled to be set to +15 V.

If the potential applied to the vibration head209is lower than the potential V1applied to the sample nozzle11a(for example, 0 V), the risk of corrosion of the sample nozzle11astill exists. It is therefore preferable to apply the potential equal to the potential V1applied to the sample nozzle11a, or a potential V3higher than the potential V1to the vibration head209from the second voltage control unit303. Establishment of the correlation among the potential values of V1≤V3<V2secures the effect of preventing corrosion of both the sample nozzle11aand the vibration head209.

On the other hand, if the corrosion of the vibration head209is tolerated, the use of the metallic member221as shown inFIG.3is omittable. That is, the first voltage control unit302applies the potential V2higher than the potential V1applied to the sample nozzle11ato the vibration head209as a substitute for the metallic member221.

Each of the above-described potentials V1, V2, V3has the reference potential GND in common, for example, the potential of a casing of the automatic analyzer having the ultrasonic cleaner disposed is usable as the reference potential GND.

With the structure having the metallic member221omitted as shown inFIG.3, in the case that the cleaning solution is brought into a floating state through isolation from the periphery so as to control that the potential applied to the vibration head209to be equal to the one applied to the sample nozzle11a, the effect of preventing the corrosion may be obtained theoretically. However, in the case of the automatic analyzer configured to perform cleaning of the sample nozzle11aand replacement of the cleaning solution inside the cleaning tank206after cleaning repeatedly in accordance with the predetermined sequence, it is actually difficult to bring the potential of the cleaning solution into a complete floating state. Although not shown, actually, electromagnetic valves, pumps, branch pipes, and any other pipe members are wetted in the cleaning solution for supplying the cleaning solution to the cleaning tank206. If any part of the above-described components is grounded or made of the conductive material, potential difference occurs in the electrolyte solution even if the vibration head209and the sample nozzle11ahave been controlled to be at the same potential, causing the risk of corrosion. For controlling the vibration head209and the sample nozzle11ato be at the same potential, it is preferable to allow the metallic member221which receives application of the potential higher than those of the vibration head209and the sample nozzle11ato be disposed in the cleaning solution so as to be in the wetted state as the structure ofFIG.3shows.

FIG.4shows an example that the metallic member221in contact with the cleaning solution is disposed in the pipe212for supplying the cleaning solution. The above-described arrangement allows the metallic member221to be disposed upstream of the cleaning tank206so as to secure the wetted state before the sample nozzle11a. In the case that the metallic member221is disposed at the upper side of the cleaning tank206, insufficient amount of the cleaning solution, if any, may bring only the sample nozzle11ainto the wetted state in the cleaning solution, thus causing the risk of corrosion. As the wetted portion of the metallic member221is brought into contact with the atmosphere, there may cause the risk of precipitation of the cleaning solution component on the metallic member221. The structure as shown inFIG.4is capable of solving the above-described problems.

The present invention is not limited to the structures of the embodiment as described above. It is possible to prepare the metallic cleaning tank206so as to serve as the metallic member221. The ultrasonic generation mechanism has been explained in detail by taking the structure for allowing the vibration head209to vibrate in the cleaning solution so as to generate ultrasonic vibration as an example. However, it is possible to dispose the ultrasonic transducer in the cleaning tank as disclosed in Patent Literature 2. Furthermore, the metallic member221does not have to be necessarily disposed at the side of the cleaning tank. It is possible to be horizontally and perpendicularly driven together with the sample nozzle11aof the sample dispensing mechanism11so as to be brought into the wetted state in the cleaning solution inside the cleaning tank206, thus providing the effects.

The first voltage control unit302and the second voltage control unit303do not have to constantly apply the predetermined potential. Instead, the control may be executed by starting the voltage application just before immersion of the sample nozzle11ain the cleaning solution, and stopping the voltage application immediately after desorption of the sample nozzle11afrom the cleaning solution after cleaning. This makes it possible to provide the effect of reducing the corrosion of the metallic member221.

Arbitrary materials may be used for forming the sample nozzle11a, the ultrasonic head209, and the metallic member221. The use of the similar material or the one with almost the same ionization tendency may provide the effect of suppressing the corrosion of the component in preparation for the potentiality that they are kept immersed in the cleaning solution that contains the electrolyte in the power shutdown. Furthermore, as the components provide the effect for suppressing the corrosion so long as they exhibit conductivity, they do not necessarily have to be made of metal.

In the above-described embodiment, the ultrasonic cleaner provided with the ultrasonic transducer has been described as an example. It is also possible to employ the water level sensor or the liquid property sensor. The above-described structure is applicable to the cleaner having at least one conductive member to be wetted in the cleaning solution simultaneously with the sample nozzle11ato be immersed therein.

The present invention is not limited to the embodiment as described above, but includes various modifications so long as they do not deviate from the spirit of the present invention. For example, the present invention is not limited to the one with all the structures that have been described above, but includes the structure, a part of which is omitted in the range that the effect of the present invention is not degraded.

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