Stirring apparatus, abnormality determining method of same, and analyzer

A stirring apparatus includes an acoustic wave generating unit that is provided in a vessel keeping a liquid and generates an acoustic wave toward the liquid, the liquid being stirred by the acoustic wave; a driving unit that drives the acoustic wave generating unit; a detecting unit that detects a reflected power reflected from the acoustic wave generating unit; and a determining unit that determines a presence of an abnormality based on the reflected power detected by the detecting unit. The determining unit determines the presence of the abnormality when a difference between an in-operation reflected power which is reflected from, during an operation, the acoustic wave generating unit and a reference reflected power of the acoustic wave generating unit at a same driving frequency exceeds a predetermined value.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stirring apparatus, an abnormality determining method of the same, and an analyzer.

2. Description of the Related Art

Conventionally, as a stirring apparatus used in an analyzer, a stirring apparatus which, to avoid what is called a sample carry-over, uses a surface acoustic wave element to perform a noncontact stirring with respect to a liquid kept in a vessel has been known, for example in Japanese Patent Application Laid-Open No. 2005-257406. This stirring apparatus feeds a power having a resonance frequency and drives the surface acoustic wave element to stir the liquid kept in the vessel.

SUMMARY OF THE INVENTION

A stirring apparatus according to an aspect of the present invention includes an acoustic wave generating unit that is provided in a vessel keeping a liquid and generates an acoustic wave toward the liquid, the liquid being stirred by the acoustic wave; a driving unit that drives the acoustic wave generating unit; a detecting unit that detects a reflected power reflected from the acoustic wave generating unit; and a determining unit that determines a presence of an abnormality based on the reflected power detected by the detecting unit. The determining unit determines the presence of the abnormality when a difference between an in-operation reflected power which is reflected from, during an operation, the acoustic wave generating unit and a reference reflected power of the acoustic wave generating unit at a same driving frequency exceeds a predetermined value.

An abnormality determining method according to another aspect of the present invention is for a stirring apparatus which includes an acoustic wave generating unit that is provided in a vessel keeping a liquid and generates an acoustic wave toward the liquid, and a driving unit that drives the acoustic wave generating unit, and stirs the liquid by the acoustic wave. The abnormality determining method includes detecting an initial frequency characteristic of a reference reflected power of the acoustic wave generating unit; detecting an in-operation reflected power reflected from, during an operation, the acoustic wave generating unit; and calculating a difference between the in-operation reflected power and the reference reflected power at a same driving frequency, and determining a presence of an abnormality when the difference exceeds a predetermined value.

An analyzer according to still another aspect of the present invention stirs a plurality of different liquids to cause a reaction and analyzes a reaction liquid. The analyzer analyzes the reaction liquid by using the stirring apparatus to stir and react the plurality of different liquids.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The inventor of the present invention has been dedicated to studying characteristics of a surface acoustic wave element. A result of the study is as follows. A surface acoustic wave element causes a reflection phenomenon in which a part of power is reflected to a power source due to an inconsistency of a circuit constant in an electric circuit. The reflected power generated by this reflection phenomenon has frequency characteristics of becoming the smallest when a driving frequency of the surface acoustic wave element is at a resonance frequency and becoming larger as the driving frequency gets away from the resonance frequency.

Meanwhile, the surface acoustic wave element, when used in a stirring apparatus, is bonded to a wall surface of a vessel, for example a cuvette, by an adhesive agent serving as an acoustic matching layer. The surface acoustic wave element normally causes a self-heating as being driven and a calorific value depends on the power to be applied and a driving frequency. On this occasion, when there is no change in physical characteristics including a bonding condition of the surface acoustic wave element to the wall surface of the cuvette and an amount of the liquid kept in the cuvette, there is no major change in a thermal conductivity through the adhesive agent and the wall surface in the stirring apparatus. Therefore, an in-operation reflected power at the time when the surface acoustic wave element causes the self-heating as being driven changes with initial frequency characteristics of a reference reflected power before the self-heating retained, and a temperature change of the surface acoustic wave element falls within a certain range.

However, when an abnormality such as a detachment of the surface acoustic wave element from the vessel and an absence of the liquid in the cuvette is present, a transmission of energy of an acoustic wave generated by the operation of the surface acoustic wave element to the cuvette and to the liquid is blocked in the stirring apparatus. Thus, the surface acoustic wave element itself overheats due to the block of the energy transmission and the reflected power at the same driving frequency changes to be larger in the stirring apparatus. Consequently, the fact is found out that as long as the stirring apparatus measures initial frequency characteristics of the reference reflected power before the self-heating in advance and compares the reference reflected power and the in-operation reflected power at the same driving frequency, a presence of the abnormality in the surface acoustic wave element can be determined.

Exemplary embodiments of a stirring apparatus, an abnormity determining method of the same, and an analyzer according to the present invention will be explained in detail below with reference to the accompanying drawings.FIG. 1is a schematic diagram of a structure of an automatic analyzer according to a first embodiment which performs an analysis by using a stirring apparatus of the present invention.FIG. 2is a block diagram showing a schematic structure of the stirring apparatus used in the automatic analyzer shown inFIG. 1and a perspective view of a reaction vessel.FIG. 3shows frequency characteristics of a reference reflected power, an in-operation reflected power in a normal case, and an in-operation reflected power in an abnormal case of a surface acoustic wave element attached to the reaction vessel.

An automatic analyzer1includes reagent tables2and3, a cuvette wheel4, a specimen vessel transporting mechanism8, an analyzing optical system12, a cleansing mechanism13, a control unit15, and a stirring apparatus20as shown inFIG. 1.

As shown inFIG. 1, the reagent tables2and3respectively have a plurality of reagent vessels2aand3aarranged in a circumferential direction, and carry the reagent vessels2aand3ain the circumferential direction by being rotated by a driving unit. On this occasion, the reagent vessels2aeach of which holds a first reagent are arranged in the reagent table2and the reagent vessels3aeach of which holds a second reagent are arranged in the reagent table3.

In the cuvette wheel4as shown inFIG. 1, a plurality of holders which arrange the reaction vessels5along a circumferential direction are formed in the circumferential direction and rotated by a driving unit, which is not shown, in a direction shown by an arrow to carry the reaction vessels5. In the cuvette wheel4, photometry holes4afacing in pairs in a radius direction are formed at a position corresponding to a bottom part of each holder and arranged along the circumferential direction at the same intervals with the holders. A reagent is dispensed into the reaction vessel5from each of the reagent vessels2aand3aof the reagent tables2and3respectively by reagent dispensing mechanisms6and7which are provided in the vicinity of the reaction vessel5. The cuvette wheel4turns around in a counterclockwise direction by (one lap—one cuvette)/4 in one cycle and reaches a position clockwise by one reaction vessel5from an original position in four cycles.

The reaction vessel5is a vessel which, in a quadrangular hollow prism shape, has a liquid retainer5aformed of a material, for example a glass including a heat-resistant glass and a synthetic resin such as a cyclic olefin and a polystyrene, which allows a transmission of 80% or more of a light of an analyzing light (340 nm to 800 nm) emitted from the analyzing optical system12. In the reaction vessel5, a surface acoustic wave element27(seeFIG. 2) which is attached onto a side wall5bvia an adhesive agent and the like serving as an acoustic matching layer is driven by the stirring apparatus20.

The reagent dispensing mechanisms6and7are provided with probes6band7bfor dispensing reagents in arms6aand7awhich turn in the horizontal plane in directions shown by arrows respectively, and provided with cleansing units which clean the probes6band7brespectively with cleansing water.

The specimen vessel transporting mechanism8is a transporting mechanism which transports a plurality of racks10arranged in a feeder9one by one along a direction shown by an arrow as shown inFIG. 1, and moves the rack10forward to perform the transportation. The rack10holds a plurality of specimen vessels10aeach storing a specimen. Here, whenever the moving of the rack10transported by the specimen vessel transporting mechanism8stops, the specimen in the specimen vessel10ais dispensed into each reaction vessel5by a specimen dispensing mechanism11having an arm ha which turns around in the horizontal direction and a probe11b. Therefore, the specimen dispensing mechanism11includes a cleansing unit which cleans the probe11bwith cleansing water.

The analyzing optical system12emits an analyzing light (340 nm to 800 nm) for analyzing a liquid sample in the reaction vessel5in which the reagent and the specimen are reacted, and includes a light emitting part12a, a spectroscopic part12b, and a light receiving part12cas shown inFIG. 1. The analyzing light emitted from the light emitting part12apasses through the liquid sample in the reaction vessel5and received by the light receiving part12cprovided at a position facing the spectroscopic part12b. The light receiving part12cis connected to the control unit15.

By repeatedly pouring and absorbing a cleansing liquid and the like such as a detergent and cleansing water through a nozzle13aafter absorbing and discharging the liquid sample in the reaction vessel5through the nozzle13a, the cleansing mechanism13cleans the reaction vessel5which has undergone the analysis performed by the analyzing optical system12.

The control unit15serves as a part which controls an operation of each unit in the automatic analyzer1and analyzes a constituent concentration and the like of the specimen based on an absorbance of the liquid sample in the reaction vessel5based on an amount of the light emitted by the light emitting part12aand an amount of the light received by the receiving part12c, and a microcomputer and the like are used for example. The control unit15is connected to the input unit16such as a keyboard and to the display unit17such as a display panel as shown inFIG. 1.

The input unit16serves as a part which performs an operation of inputting a test item and the like to the control unit15, and a keyboard and a mouse are used for example. The input unit16is also used for an operation of switching a frequency of a driving signal input to the surface acoustic wave element27of the stirring apparatus20. The display unit17displays an analysis content, an alarm, and the like and a display panel is used for example.

The stirring apparatus20includes a stirring control unit21and the surface acoustic wave element27as shown inFIG. 2, and an operation of the surface acoustic wave element27is controlled by the stirring control unit21. The stirring control unit21changes a frequency of a driving signal to be output to the surface acoustic wave element27based on information, such as a test item, a property, and an amount of the liquid sample, input from the input unit16via the control unit15, and includes a communication circuit22, a controller23, a signal generating circuit24, an amplifying circuit25, and a detecting circuit26.

The communication circuit22transfers a control signal with the control unit15and transfers data and the like by connecting the automatic analyzer1to an implementer's host computer via an online network.

The controller23uses a computerized controller (CPU) with built-in memory and timer, and includes a determining unit23awhich determines a presence of an abnormality such as a detachment of the surface acoustic wave element27from the reaction vessel5and an absence of the liquid sample in the reaction vessel5based on a reference reflected power before a self-heating and an in-operation reflected power. The controller23controls operations of the communication circuit22, the signal generating circuit24, the amplifying circuit25, and the detecting circuit26. On this occasion, the controller23controls a voltage and an electric current of the driving signal to be output by the signal generating circuit24to the surface acoustic wave element27. By controlling the operation of the signal generating circuit24, the controller23controls characteristics (a frequency, an intensity, a phase, and a wave property), waveforms (a sine wave, a triangular wave, a square wave, a burst wave, and the like), and modulations (an amplitude modulation and a frequency modulation) of an acoustic wave generated by the surface acoustic wave element27, for example. Besides, the controller23can change a frequency of a high-frequency signal oscillated by the signal generating circuit24according to the built-in timer.

The signal generating circuit24has an oscillating circuit whose oscillation frequency can be changed based on the control signal input from the controller23, generates a signal of 100 MHz to 160 MHz, divides the signal into half, and outputs a driving signal of 50 MHz to 80 MHz to the surface acoustic wave element27. Together with the signal generating circuit24, the amplifying circuit25constitutes the driving unit which drives the surface acoustic wave element27and amplifies, by a predetermined gain, the driving signal to be output from the signal generating circuit24to the surface acoustic wave element27.

The detecting circuit26has a coupler; a detector which detects a power of the driving signal output after being amplified by the amplifying circuit25and outputs to the determining unit23aas power data; and a detector which detects a power reflected from a transducer27bof the surface acoustic wave element27and outputs to the determining unit23aas reflected power data. The power data and the reflected power data output from the detecting circuit26in this manner are stored in the determining unit23a.

In the surface acoustic wave element27, the transducer27bconstituted by a comb-shaped electrode (an interdigital transducer) is formed on a surface of a piezoelectric substrate27aas shown inFIG. 2. The transducer27bserves as a sound producing part which converts the driving signal input from the stirring control unit21into a surface acoustic wave (acoustic wave), and a plurality of fingers constituting the transducer27bare arranged along a longitudinal direction of the piezoelectric substrate27a. Besides, the surface acoustic wave element27is connected to the stirring control unit21via a pair of input terminals27c. The transducer27bis connected to the input terminals27cvia a bus bar27d. The surface acoustic wave element27is attached to the side wall5bof the reaction vessel5with an intervention of an acoustic matching layer such as an epoxy resin.

In the automatic analyzer1constituted in the way described above, the reagent dispensing mechanisms6and7sequentially dispense the reagents from the reagent vessels2aand3ainto the plurality of reaction vessels5conveyed by the rotating cuvette wheel4along the circumferential direction. Then, whenever the cuvette wheel4stops, a driving signal is output from the stirring control unit21via the pair of input terminals27c. Therefore, the dispensed reagent and the specimen are sequentially stirred by the stirring apparatus20and reacted in the reaction vessel5. In the automatic analyzer1, an amount of the specimen is normally smaller than that of the reagent and the smaller amount of specimen dispensed into the reaction vessel5is mixed into the larger amount of reagent due to a series of flow generated in the liquid by the stirring, so that the reaction between the specimen and the reagent is accelerated.

The reaction liquid generated through the reaction between the specimen and the reagent in this manner goes through the analyzing optical system12when the cuvette wheel4starts turning around again, and the beam emitted from the light emitting part12apasses through the reaction liquid. On this occasion, the reaction liquid of the reagent and the specimen in the reaction vessel5is subjected to a photometry by the light receiving part12cand the constituent concentration and the like are analyzed by the control unit15. The reaction vessel5which has undergone the analysis is cleaned by the cleansing mechanism13and then used for the analysis of another specimen again.

On this occasion, the determining unit23adetermines a presence of an abnormality such as a detachment of the surface acoustic wave element27from the reaction vessel5and an absence of the liquid sample in the reaction vessel5in the stirring apparatus20. In other words, the surface acoustic wave element27causes a reflection phenomenon in which a part of the applied power is reflected by the transducer27band returns to the stirring control unit21due to an inconsistency of a circuit constant in an electric circuit. This reflection phenomenon generates a reference reflected power WI, which has frequency characteristics of becoming the smallest when the driving frequency of the surface acoustic wave element27is at a resonance frequency fr and becoming larger as the driving frequency gets away from the resonance frequency fr as shown by a solid line inFIG. 3.

Meanwhile, the surface acoustic wave element27normally causes a self-heating with its operation and a calorific value depends on the power to be applied and the driving frequency. On this occasion, when there is no change in physical characteristics including a bonding condition of the surface acoustic wave element27to the side wall5bof the reaction vessel5and an amount of the liquid sample kept in the reaction vessel5, there is no major change in a thermal conductivity through the adhesive agent and the side wall5bin the stirring apparatus20. Therefore, an in-operation reflected power WN at the time when the surface acoustic wave element27causes the self-heating in a normal state changes with initial frequency characteristics of the reference reflected power WI before the self-heating retained, and a temperature change of the surface acoustic wave element27falls within a certain range.

However, when an abnormality such as a detachment of the surface acoustic wave element27from the reaction vessel5and an absence of the liquid sample in the reaction vessel5is present, a transmission of an energy of an acoustic wave generated by the operation of the surface acoustic wave element27to the reaction vessel5and to the liquid sample is blocked in the stirring apparatus20. Thus, the surface acoustic wave element27overheats due to the block of the energy transmission. An in-operation reflected power WAN in an abnormal case having this overheat changes to be larger than the in-operation reflected power WN at the resonance frequency fr as shown by an alternate long and two short dashes line inFIG. 3. Consequently, as long as the stirring apparatus20measures initial frequency characteristics of the reference reflected power WI before the self-heating in advance, stores the characteristics in the controller23, and compares the in-operation reflected power and the reference reflected power WI at the same driving frequency by calculating their difference by the determining unit23a, a presence of an abnormality in the surface acoustic wave element27can be determined.

On this occasion, a difference ΔWN between the in-operation reflected power WN and the reference reflected power WI is smaller than a difference ΔWAN between the in-operation reflected power WAN and the reference reflected power WI shown by the alternate long and two short dashes line at the resonance frequency fr of the surface acoustic wave element27as shown inFIG. 3. Therefore, a threshold value T is determined in advance with respect to the difference between the in-operation reflected power measured in the operation of the surface acoustic wave element27and the reference reflected power WI thereof at the same driving frequency, and stored in the determining unit23ain the stirring apparatus20according to the present invention. When the difference between the in-operation reflected power and the reference reflected power WI at the same driving frequency exceeds the threshold value T, the determining unit23adetermines that an abnormality such as a detachment of the surface acoustic wave element27from the reaction vessel5and an absence of the liquid sample in the reaction vessel5is present.

A series of steps performed by the stirring control unit21for the abnormal determination described above will be explained below with reference to a flowchart. First, the stirring control unit21detects initial frequency characteristics of the reference reflected power WI of the surface acoustic wave element27before the self-heating (step S102). For the initial frequency characteristics, after the stirring apparatus20is mounted to the automatic analyzer1or after the stirring apparatus20itself is assembled, a reflected power reflected by and returning from the transducer27bis detected by the detecting circuit26while the driving frequency of the surface acoustic wave element27is changed, and is output to the determining unit23ato be stored therein as reflected power data.

Next, the stirring control unit21detects the in-operation reflected power which is reflected from the surface acoustic wave element27in stirring the liquid sample kept in the reaction vessel5by the detecting circuit26(step S104). The in-operation reflected power detected by the detecting circuit26is output to and stored in the determining unit23aas reflected power data. Here, in contrast to the detection of the initial frequency characteristics which is an operation performed right after the assembly of the automatic analyzer1and the stirring apparatus20, the detection of the in-operation reflected power is an operation to be performed in actually analyzing the specimen by using the automatic analyzer1and the stirring apparatus20. The stirring control unit21then calculates the difference between the in-operation reflected power and the reference reflected power WI at the same driving frequency (step S106). The difference between the in-operation reflected power and the reference reflected power WI is calculated by the determining unit23abased on the stored reflected power data.

Thereafter, the stirring control unit21determines whether the difference between the in-operation reflected power and the reference reflected power WI exceeds the threshold value T by the determining unit23a(step S108). When the difference between the in-operation reflected power and the reference reflected power WI exceeds the threshold value T (“Yes” at step S108) as a result of the determination, the determining unit23adetermines a presence of an abnormality (step S110). In this case, the determining unit23aoutputs the effect to the control unit15, makes the effect displayed on the display unit17via the control unit15, and makes the operation of the automatic analyzer1stop via the control unit15.

On the other hand, when the difference between the in-operation reflected power and the reference reflected power WI does not exceed the threshold value T (“No” at step S108) as a result of the determination, the determining unit23adoes not determine a presence of an abnormality and goes back to step S104, and the stirring control unit21detects an in-operation reflected power for a subsequent new specimen. By repeating the steps described above, the stirring apparatus20can easily determine a presence of an abnormality such as a detachment of the surface acoustic wave element27from the reaction vessel5and an absence of the liquid sample in the reaction vessel5.

It should be noted that, though a case of using two reagent tables is explained in the automatic analyzer1, the number of the reagent table may be one. Besides, the automatic analyzer according to the present invention may be configured, by taking the automatic analyzer1as one unit, to have a plurality of units in combination.