Automatic analyzing device and position measurement method therefor

Abstract

The purpose of the present invention is to provide an automatic analyzing device capable of highly precisely measuring the position of an object with respect to a stirring mechanism. In order to achieve the foregoing, the present invention provides an automatic analyzing device comprising a stirring mechanism that uses ultrasonic waves to stir a specimen and a reagent, wherein the stirring mechanism comprises: a plurality of ultrasonic elements that oscillate the ultrasonic waves; an amplifier that applies a voltage to the ultrasonic elements; a detection unit that detects an electric signal generated from the ultrasonic elements that have received reflected waves generated by the ultrasonic waves being reflected by an object to be measured; and an arithmetic unit that measures the relative position of the stirring mechanism and the object to be measured, said measurement being made on the basis of the electric signal related to the reflected waves detected via the plurality of ultrasonic elements with respect to the ultrasonic waves oscillated from the plurality of ultrasonic elements.

Description

Automatic analyzer and its position measurement method

[0001] The present invention relates to an automatic analyzer and a position measurement method thereof.

[0002] Automated analyzers equipped with a stirring mechanism that uses ultrasonic waves to stir samples and reagents in a reaction vessel are known. Ultrasound has the advantage of being able to stir samples and reagents without contact, thereby preventing carryover of the sample or reagent. Also known is a technique that uses ultrasonic waves emitted by the stirring mechanism to estimate the presence or absence of a mixed liquid containing a sample and a reagent and its liquid level. For example, Patent Document 1 discloses a technique in which a piezoelectric element, which is an ultrasonic oscillation source, is provided with multiple electrodes in the height direction, and the liquid level is estimated based on the electrical impedance measured when a voltage is applied to the electrodes.

[0003] Japanese Patent Application Laid-Open No. 2023-97912

[0004] In the technology described in Patent Document 1, an electrode to be measured is selected, a voltage is applied to the selected electrode to generate an ultrasonic wave, and the electrical impedance of the selected electrode is measured. As a result, the target (mixed liquid) can only be detected at the position of the electrode, and the detection accuracy depends on the pitch of the electrodes.

[0005] An object of the present invention is to provide an automatic analyzer that can measure the position of an object relative to a stirring mechanism with high accuracy.

[0006] In order to solve the above-mentioned problems, the present invention provides an automatic analyzer having a stirring mechanism that stirs a sample and a reagent using ultrasound, wherein the stirring mechanism comprises a plurality of ultrasonic elements that emit the ultrasound, an amplifier that applies a voltage to the ultrasonic elements, a detection unit that detects an electrical signal generated from the ultrasonic elements that receive a reflected wave generated when the ultrasound is reflected by the object to be measured, and a calculation unit that measures the relative position between the stirring mechanism and the object to be measured based on the electrical signal related to the reflected wave detected via the plurality of ultrasonic elements in response to the ultrasound emitted from the plurality of ultrasonic elements.

[0007] According to the present invention, it is possible to provide an automatic analyzer that can measure the position of an object relative to a stirring mechanism with high accuracy.

[0008] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0009] The present invention relates to an automatic analyzer, an automatic analyzer, and an automatic analyzer for detecting reflected waves of ultrasonic waves emitted for position measurement.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that substantially the same or similar components are denoted by the same reference numerals, and redundant descriptions may be omitted.

[0011] <Overall Configuration of the Automated Analyzer> Fig. 1 is a top view showing the schematic configuration of the automated analyzer. As shown in Fig. 1, the automated analyzer mainly comprises a specimen loading section 11, a specimen dispensing mechanism 18, a reagent storage section 12, a reagent dispensing mechanism 19, a reaction section 13, a stirring mechanism 14, a measurement section 15, and a washing section 16, and the operation of each section is controlled by an analyzer control section 23.

[0012] The reaction unit 13 has a rotatable reaction disk, and reaction vessels 6 are arranged circumferentially on the reaction disk. The reaction unit 13 also has a constant temperature bath (water bath) that holds constant temperature water 8 at a specified temperature, and the constant temperature water 8 circulating in the constant temperature bath comes into contact with the reaction vessels 6, thereby maintaining the reaction vessels 6 at a predetermined temperature (see FIG. 2). In this embodiment, constant temperature water 8 is used as the liquid that transmits ultrasound, but water other than constant temperature water or a liquid other than water may also be used.

[0013] The specimen dispensing mechanism 18 aspirates the specimen 17 in an amount required for analysis from the specimen stacking section 11 and dispenses the aspirated specimen 17 into a reaction vessel 6 (reaction cell) at a specimen dispensing position 20. Meanwhile, the reagent dispensing mechanism 19 aspirates the reagent in an amount required for analysis from the reagent storage section 12 and dispenses the aspirated reagent into the reaction vessel 6 at a reagent dispensing position 21.

[0014] The reaction vessel 6 into which the specimen 17 and reagent have been discharged is moved to the stirring position 22 by the rotation of the reaction disk, and then stirred by ultrasonic waves emitted from the ultrasonic element of the stirring mechanism 14. The specimen 17 stirred by the stirring mechanism 14 is subjected to component analysis in the measurement unit 15. After the analysis is completed, the reaction vessel 6 is washed in the washing unit 16 and is reused for another analysis.

[0015] <Stirring mode> Fig. 2 is a diagram showing the schematic configuration of the stirring mechanism in the stirring mode (normal mode). As shown in Fig. 2, the stirring mechanism 14 is provided on the outer periphery of the reaction unit 13 (constant temperature bath), and mainly includes a piezoelectric element 4, an electrode 5, a power supply unit 2, an electrode selector 3, and a stirring mechanism control unit 1.

[0016] The piezoelectric element 4 is attached to the side wall of the thermostatic bath or the like and emits ultrasonic waves. The electrodes 5 drive the piezoelectric element 4 when a voltage is applied, and multiple electrodes 5 are arranged vertically. The power supply unit 2 is composed of an amplifier that applies voltage to the electrodes 5. The electrode selector 3 is connected to the multiple electrodes 5 and selects the electrode 5 to which voltage should be applied. The stirring mechanism control unit 1 controls the operation of the power supply unit 2 and the electrode selector 3.

[0017] In the stirring mode, a mixture 7 of a specimen and a reagent is contained in the reaction vessel 6, and the outside of the reaction vessel 6 (between the reaction vessel 6 and the piezoelectric element 4) is filled with constant-temperature water 8. In this state, the stirring mechanism control unit 1 selects one or more electrodes 5 at appropriate positions based on the liquid level (of the mixture 7) detected in advance, and controls the power supply unit 2 and electrode selector 3 to apply a voltage to the selected electrodes 5. The electrode 5 to which the voltage is applied drives the piezoelectric element 4 in accordance with the voltage value, and ultrasonic waves are emitted from the piezoelectric element 4. The ultrasonic waves propagate to the reaction vessel 6 via the constant-temperature water 8, stirring the mixture 7 in the reaction vessel 6.

[0018] In this embodiment, a configuration will be described in which multiple electrodes 5 are attached to a common piezoelectric element 4 and ultrasonic waves are generated by applying a voltage to each electrode 5, but a configuration in which multiple piezoelectric elements are used and each piezoelectric element is driven by applying a voltage may also be used. In either case, it can be considered that multiple ultrasonic elements are provided and ultrasonic waves are generated by applying a voltage to each ultrasonic element. Furthermore, in this embodiment, an example in which five electrodes are provided will be described, but the number of electrodes is not limited to five.

[0019] <Position Measurement Mode> Here, when installing or performing maintenance on the stirring mechanism 14 or reaction unit 13, the relative position between the stirring mechanism 14 (electrode 5) and the reaction vessel 6 may deviate from the reference position assumed at the time of design. If the relative position between the reaction vessel 6 and the ultrasonic element changes, the stirring performance of the stirring mechanism 14 also changes, which affects the analytical accuracy. Therefore, it is necessary to position the stirring mechanism 14 and the reaction unit 13 with high precision during installation, etc. Therefore, in this embodiment, a position measurement mode can be executed to measure the relative position between the stirring mechanism 14 and the measurement object (reaction vessel 6) on the reaction unit 13 side.

[0020] When the position measurement mode is executed, for example, a service person or operator removes the wiring connecting each electrode 5 to the electrode selector 3 and the wiring connecting the stirring mechanism control unit 1 to the power supply unit 2 and the electrode selector 3. The service person then installs the waveform control unit 32 (phase control unit), amplifier 33, detection unit 39, calculation unit 40, memory unit 41, and display unit 42 as the stirring mechanism 14, in place of the power supply unit 2 and electrode selector 3. At this time, each electrode 5 is connected to the amplifier 33 and detection unit 39 via wiring. By switching the wiring between the stirring mechanism control unit 1 and each electrode 5 between the stirring mode (normal operation) and the position measurement mode (installation, etc.), it is possible to prevent power from being consumed by unnecessary circuits.

[0021] Alternatively, instead of changing the wiring, the circuit used in the stirring mode and the circuit used in the position measurement mode may be connected in parallel, and a switch may be used to switch between the circuits for each mode. This configuration not only allows for positioning during installation, but also enables periodic (e.g., once a day) position checks during operation of the automated analyzer.

[0022] Next, the configuration of the stirring mechanism 14 in the position measurement mode (positioning) will be described. Fig. 3 is a schematic diagram showing the state of the stirring mechanism when ultrasonic waves are emitted for position measurement, and Fig. 4 is a schematic diagram showing the state of the stirring mechanism when reflected waves of ultrasonic waves emitted for position measurement are detected. Here, the case of measuring the height position of the bottom surface of the reaction vessel 6 relative to the ultrasonic elements of the stirring mechanism 14 will be described as an example.

[0023] As shown in Figures 3 and 4, the stirring mechanism 14 mainly includes an amplifier 33, a piezoelectric element 4, an electrode 5, and a stirring mechanism control unit 1, as well as a waveform control unit 32, a detection unit 39, a calculation unit 40, a memory unit 41, and a display unit 42.

[0024] The waveform control unit 32 controls the waveform (including the phase) of the voltage applied by the amplifier 33 to the electrode 5 for each electrode 5. The detection unit 39 detects an electrical signal generated from the electrode 5 that receives a reflected wave generated when ultrasonic waves are reflected by the object to be measured (the bottom surface of the reaction vessel 6). The calculation unit 40 measures the relative position of the stirring mechanism 14 (ultrasonic elements) and the object to be measured (the bottom surface of the reaction vessel 6) based on the electrical signal related to the reflected wave detected via the multiple ultrasonic elements in response to ultrasonic waves emitted from the multiple ultrasonic elements. The memory unit 41 stores the measurement results of the calculation unit 40, and the display unit 42 displays the measurement results of the calculation unit 40.

[0025] Next, the operation of the stirring mechanism 14 in the position measurement mode (positioning) will be described.

[0026] First, the waveform control unit 32 generates a waveform (including phase) signal under the conditions specified by the stirring mechanism control unit 1. At this time, the waveform control unit 32 controls the phase of the ultrasonic waves emitted from the ultrasonic elements located at a height farther from the predetermined position so that it is more advanced than the phase of the ultrasonic waves emitted from the ultrasonic elements located at a height closer to the predetermined position. Note that the predetermined position is the reference position of the reaction unit 13 (bottom surface of the reaction vessel 6) relative to the stirring mechanism 14 (ultrasonic elements), which is determined at the time of design as a condition that can guarantee stirring performance.

[0027] Next, the amplifier 33 amplifies the waveform signal generated by the waveform control unit 32 to a power level sufficient to drive the ultrasonic elements, and supplies the amplified waveform to the plurality of electrodes 5 as drive electrical signal waveforms 34 having a phase shift, as shown in Fig. 3. Then, the plurality of electrodes 5 drive the piezoelectric elements 4 in accordance with the respective drive electrical signal waveforms 34, and generate ultrasonic waves.

[0028] Ultrasonic waves (waves indicated by dotted lines in FIG. 3) emitted from a plurality of ultrasonic elements gradually converge to form a composite wave 35 (wave indicated by solid lines in FIG. 3), forming a focal point at a predetermined position (position indicated by the tip of the arrow in FIG. 3). Note that, since the height position of the bottom surface of the reaction vessel 6 is the object of measurement, it is sufficient that the focal point is formed at the reference height of the bottom surface of the reaction vessel 6, and the horizontal position of the focal point does not have to be the center of the reaction vessel 6.

[0029] Here, ultrasonic waves are reflected at positions where a difference in acoustic impedance occurs, depending on the magnitude of that difference. That is, ultrasonic waves are mainly reflected at gas-liquid interfaces, solid-liquid interfaces, and gas-solid interfaces. Although it is possible to detect the reflected wave using only ultrasonic waves emitted from a single ultrasonic element, the intensity of the reflected wave is weak, so the detection accuracy is not high.

[0030] However, if a focal point is formed by the composite wave 35 and the focal point is positioned at the interface, the ultrasonic wave is largely reflected at the interface. The reflected wave 36 at this time spreads spherically with a large amplitude, as shown in FIG. 4 , and reaches multiple ultrasonic elements arranged in the vertical direction. The intensity of the reflected wave reaching each ultrasonic element is relatively strong, resulting in high detection accuracy. Furthermore, because there is a difference in the time at which the reflected wave reaches each ultrasonic element, there is also a difference in the time at which it is converted into an electrical signal at each electrode 5. Therefore, as shown in FIG. 4 , received electrical signal waveforms 37 having a phase shift are sent from each electrode 5 to a detection unit 39. The detection unit 39 transmits information such as amplitude and phase regarding the received electrical signal waveforms 37 acquired from each electrode 5 to a calculation unit 40.

[0031] The calculation unit 40 calculates the reflectance of the ultrasonic wave at the focal position based on the conditions specified by the stirring mechanism control unit 1 and the information on the reflected wave received from the detection unit 39. Here, the memory unit 41 stores the reflectance of the ultrasonic wave at each position around the reaction vessel 6, which has been acquired in advance. Therefore, the calculation unit 40 can identify the relative position of the bottom of the reaction vessel 6 by comparing the reflectance stored in the memory unit 41 with the reflectance that matches the actually calculated reflectance.

[0032] The calculation unit 40 may perform position measurement using a method other than that described above. For example, the calculation unit 40 may calculate another physical quantity instead of calculating the reflectance. The calculation unit 40 may also compare a physical quantity calculated based on the electrical signal actually detected by the detection unit 39 with a physical quantity expected when the reaction vessel 6 is at the reference position, and measure the degree of deviation from the reference position based on the difference.

[0033] Furthermore, if the acoustic impedance of the mixed liquid 7 is close to that of the reaction vessel 6, there is a possibility that the accuracy of measuring the position of the reaction vessel 6 may be reduced. In such a case, the position measurement mode may be performed in an empty state where the mixed liquid 7 is not present in the reaction vessel 6 (a state where the reaction vessel 6 is filled only with a gas such as air).

[0034] The relative position (deviation from the reference position) of the bottom surface of the reaction vessel 6 measured by the calculation unit 40 is stored in the memory unit 41 and displayed on the display unit 42. The service person or the like manually adjusts the position of the ultrasonic element or the reaction vessel 6 while checking the display content of the display unit 42. In this case, an output unit (speaker) that outputs the measurement results by the calculation unit 40 as audio may be provided separately from the display unit 42. The output unit changes the frequency or amplitude of the sound emitted depending on the degree of deviation from the reference position, allowing the service person or the like to focus their gaze on the object to be positioned, improving work efficiency.

[0035] Furthermore, the position of the ultrasonic element or the reaction vessel 6 may be determined by a separately provided actuator rather than manually. Positioning is possible when the actuator automatically moves the ultrasonic element or the reaction vessel 6 according to the deviation from the reference position. Furthermore, instead of positioning by the actuator, the stirring performance may be automatically adjusted by reflecting information on the relative position in the selection of the ultrasonic element to be oscillated in the stirring mode or in the waveform of the voltage to be applied to the selected ultrasonic element.

[0036] The position measurement mode may be performed not only at the time of installation or maintenance, but also periodically (once a year, for example) when changes over time are expected. In particular, when positioning and the like can be performed automatically, the position measurement mode may be performed at short intervals, such as once a day or after each stirring operation. For example, each time a predetermined number of reaction vessels 6 are stirred, the relative positions of the reaction vessels 6 may be read from the storage unit 41, and the positions of the ultrasonic elements, etc. may be automatically adjusted.

[0037] <Effects of this embodiment> The effects of the automatic analyzer according to this embodiment will be described below.

[0038] The pitch of the electrodes arranged in the height direction is usually about 1 mm. Therefore, in the conventional method of measuring electrical impedance by generating ultrasonic waves only from specific electrodes, the accuracy of measuring the position of the liquid level, etc. is only about 1 mm, which is the pitch of the electrodes.

[0039] On the other hand, in the method of this embodiment, voltage is applied to all ultrasonic elements simultaneously and the reflected waves are detected by each ultrasonic element, enabling highly accurate position measurement regardless of the electrode pitch. In particular, by controlling the phase of ultrasonic waves emitted from multiple ultrasonic elements to form a focal point at the reference position of the object to be measured, the intensity (amplitude) of the reflected waves from the object to be measured can be increased, significantly improving the resolution when detecting the reflected waves at each ultrasonic element. Therefore, even slight deviations (e.g., 0.1 mm or less) in the relative positions of the stirring mechanism 14 (ultrasonic elements) and the reaction unit 13 (bottom surface of the reaction vessel 6) can be measured. In other words, more accurate positioning is possible, ensuring high stirring performance by the stirring mechanism 14 and maintaining high analytical accuracy.

[0040] The present invention is not limited to the above-described embodiment, and includes various modifications. For example, in the above-described embodiment, the height (vertical position) of the bottom surface of the reaction vessel 6 is measured in the position measurement mode, but the horizontal position of the reaction vessel 6 may also be measured. Furthermore, the object to be measured is not limited to the reaction vessel 6, but may also be the mixed liquid 7 contained in the reaction vessel 6, and the electrode 5 to which a voltage should be applied in the stirring mode may be selected using information on the liquid level height measured in the position measurement mode.

[0041] Furthermore, in the above-described embodiment, the position is measured by a single ultrasonic oscillation and detection, but more detailed position information can be obtained by multiple oscillations and detections. For example, the waveform control unit 32 may control the focal point to change (scan) in the vertical direction or horizontal direction, and the calculation unit 40 may compare the actually calculated reflectance for each focal point. This allows the position coordinates of each boundary where the difference in acoustic impedance becomes large to be identified with high accuracy, and therefore, for example, it is possible to output an image of the positional relationship of the entire reaction vessel 6 on the display unit 42.

[0042] 1...Stirring mechanism control unit, 2...Power supply unit, 3...Electrode selector, 4...Piezoelectric element, 5...Electrode, 6...Reaction vessel, 7...Mixed liquid, 8...Constant temperature water, 11...Specimen placement unit, 12...Reagent storage unit, 13...Reaction unit, 14...Stirring mechanism, 15...Measurement unit, 16...Cleaning unit, 17...Specimen, 18...Specimen dispensing mechanism, 19...Reagent dispensing mechanism, 20...Specimen discharge position, 21...Reagent discharge position, 22...Stirring position, 23...Analyzer control unit, 32...Waveform control unit, 33...Amplifier, 34...Driving electrical signal waveform, 35...Synthesized wave, 36...Reflected wave, 37...Received electrical signal waveform, 39...Detection unit, 40...Calculation unit, 41...Storage unit, 42...Display unit

Claims

1. An automatic analyzer having a stirring mechanism that stirs a specimen and a reagent by ultrasonic waves, wherein the stirring mechanism comprises: a plurality of ultrasonic elements that emit the ultrasonic waves; an amplifier that applies a voltage to the ultrasonic elements; a detection unit that detects an electrical signal generated from the ultrasonic elements that receive a reflected wave generated when the ultrasonic waves are reflected by an object to be measured; and a calculation unit that measures the relative position of the stirring mechanism and the object to be measured based on the electrical signal related to the reflected wave detected via the plurality of ultrasonic elements in response to the ultrasonic waves emitted from the plurality of ultrasonic elements.

2. An automatic analyzer according to claim 1, further comprising a phase control section that controls the phase of the voltage applied by the amplifier to each of the ultrasonic elements for each of the ultrasonic elements.

3. An automatic analyzer according to claim 2, wherein the ultrasonic waves emitted from the plurality of ultrasonic elements form a focus at a predetermined position.

4. An automatic analyzer according to claim 3, wherein the plurality of ultrasonic elements are arranged in a height direction, and the phase control unit controls the phase of the ultrasonic waves emitted from the ultrasonic elements located at a height farther from the predetermined position so that the phase of the ultrasonic waves emitted from the ultrasonic elements located at a height closer to the predetermined position is more advanced than the phase of the ultrasonic waves emitted from the ultrasonic elements located at a height closer to the predetermined position.

5. An automatic analyzer according to claim 3, wherein the object to be measured is a reaction vessel into which the sample and the reagent are dispensed, the predetermined position is a reference position of the reaction vessel relative to the stirring mechanism, and the calculation unit measures the deviation from the reference position by comparing a physical quantity calculated based on the actually detected electrical signal with the physical quantity assumed when the reaction vessel is in the reference position.

6. An automatic analyzer according to claim 5, further comprising an output unit that outputs the measurement results obtained by the calculation unit, wherein the output unit changes the frequency or amplitude of the sound it emits depending on the degree of deviation from the reference position.

7. An automatic analyzer according to claim 5, further comprising an actuator for moving the stirring mechanism or the reaction vessel, wherein the actuator automatically moves the stirring mechanism or the reaction vessel in accordance with a deviation from the reference position.

8. An automatic analyzer according to claim 3, wherein the object to be measured is a reaction vessel into which the specimen and the reagent are dispensed, the plurality of ultrasonic elements are arranged in a vertical direction, the phase control unit controls the focal point to scan in the vertical direction, and the calculation unit measures the position of the bottom surface of the reaction vessel relative to the stirring mechanism by comparing, for each focal point, a physical quantity calculated based on the actually detected electrical signal.

9. An automatic analyzer according to claim 1, wherein the amplifier applies the voltage to all of the ultrasonic elements simultaneously.

10. A position measurement method for an automatic analyzer having a stirring mechanism that stirs a sample and a reagent using ultrasound, comprising the steps of: an amplifier applying a voltage to a plurality of ultrasonic elements to cause the plurality of ultrasonic elements to emit ultrasound; a detection unit detecting an electrical signal generated from the ultrasonic elements that receive a reflected wave generated when the ultrasound is reflected by an object to be measured; and a calculation unit measuring the relative position of the stirring mechanism and the object to be measured based on the electrical signal related to the reflected wave detected via the plurality of ultrasonic elements.

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