Magnetic stirring device and substance concentration measuring device

Abstract

To provide a magnetic stirring device capable of sufficiently grasping an operation state of a stirring bar 2 of the magnetic stirring device, and to provide a substance concentration measuring device incorporating the magnetic stirring device.SOLUTION: A coupling magnetic flux 5 between a magnet 1 arranged in an electric motor 12 and a ferromagnetic body of a stirring bar 2 arranged inside a stirring container 3 is converted into an electric signal. Presence or absence of rotation of the stirring bar 2 is determined by comparing absolute values of the electric signals when the electric motor 12 is in standby and when it is rotating. Further, by removing a rotation period of the electric motor 12 from the electric signal, a signal derived from unstable rotation of the stirring bar 2 is extracted, and stability of the rotation of the stirring bar 2 is determined.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic stirring device technology, and more particularly to a technology for detecting and determining malfunctions related to the rotation of a stirring bar. [Background technology]

[0002] A stirrer may be used when diluting or mixing substances. There are various types of stirrers, but magnetic stirrers are often used due to their convenience. Many analytical instruments incorporating various types of magnetic stirrers are also known (see, for example, Patent Document 1 below).

[0003] In a magnetic stirrer, the magnets in the motor and the stirrer in the stirring vessel are synchronized by magnetic coupling, so that the operation of the motor is indirectly reflected in the movement of the stirrer. Because the motor and stirrer in a magnetic stirrer exist in separate spaces, one advantage is that the chemical properties of the material being stirred (e.g., strong acidity, strong alkalinity, corrosiveness, etc.) do not affect the motor. On the other hand, one disadvantage is that the operation of the motor may not be properly reflected in the stirrer, depending on the state of magnetic coupling between the magnets in the motor and the magnetic material inside the stirrer. Furthermore, due to the physical properties of the material being stirred and the surface condition of the stirring vessel and stirrer, the stirrer may stop or become unstable, even if the motor is rotating normally. In such cases, mixing is likely to be insufficient. Therefore, methods for understanding the stirring state have been explored.

[0004] A technique for monitoring the state of magnetic coupling using a magnetic sensor to monitor the stirring state of a magnetic stirrer is known (see, for example, Patent Document 2 below). Patent Document 2 describes a technique for using a magnetic sensor to know the state of the surroundings of the stirrer. Using this technique, it is possible to rotate the stirrer at the maximum rotation speed while preventing loss of synchronization. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-166162 A [Patent Document 2] Japanese Patent Application Publication No. 10-192680 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the technology of Patent Document 2, when the size of the ferromagnetic material inside the stirrer is small or the rotation speed is high, it is sometimes impossible to know the situation around the stirrer. This occurs because the magnetic force change that occurs with the rotation of the stirrer is buried in the signal waveform of the magnetic force change originating from the magnet placed in the electric motor. Furthermore, with the technology of Patent Document 2, there is also the problem that even if the electric motor is operating normally, the phenomenon of the stirrer sticking to the inner surface of the stirring vessel, resulting in stirring stopping or stirring failure, cannot be detected. As such, conventional magnetic stirring devices have the problem of being unable to fully grasp the operating status of the stirrer.

[0007] In view of the above-mentioned problems, the present invention aims to provide a magnetic stirring device that can fully grasp the operating status of the stirring bar of the magnetic stirring device, and also to provide a substance concentration measuring device incorporating this magnetic stirring device. [Means for solving the problem]

[0008] In order to solve the above problems, the magnetic stirring device of the present invention comprises a container for containing the object to be stirred, a stirrer placed in the container and containing a ferromagnetic material inside, an electric motor, a magnet placed in the electric motor and magnetically coupled to the ferromagnetic material of the stirrer, a rotation control means for controlling the operation of the electric motor, a detection means for observing the magnetic coupling state resulting from both the magnet and the ferromagnetic material inside the stirrer, a preprocessing means for processing the output signal of the detection means, and a judgment means for judging the operating status of the stirrer using the output signal of the preprocessing means, wherein the judgment means judges whether the stirrer is rotating or not by comparing the absolute value of the DC bias when the motor is in a standby state with the DC bias when the motor is in a rotating state.

[0009] In addition, in order to solve the above-mentioned problems, the magnetic stirring device of the present invention comprises a container for containing the object to be stirred, a stirrer disposed in the container and containing a ferromagnetic material therein, an electric motor, a magnet disposed in the electric motor and magnetically coupled to the ferromagnetic material of the stirrer, a rotation control means for controlling the operation of the electric motor, a detection means for observing the magnetic coupling state resulting from both the magnet and the ferromagnetic material inside the stirrer, a preprocessing means for processing the output signal of the detection means, and a judgment means for judging the operating status of the stirrer using the output signal of the preprocessing means, wherein the judgment means removes a frequency signal that coincides with the rotation speed commanded to the electric motor from the output signal of the detection means when the stirrer is in a rotating state, and judges whether "the rotation of the stirrer is stable" or "the rotation of the stirrer is unstable" by comparing the difference between the maximum and minimum values ​​of the signal during an arbitrarily determined target period with an arbitrarily determined judgment criterion.

[0010] The pre-processing means is also characterized in that it removes a frequency signal that coincides with the rotation speed commanded to the motor from the output signal of the detection means when the stirring bar is in a rotating state. In this case, the determination means makes the above determination using the output of the pre-processing means.

[0011] The target period is a period during which the electric motor rotates at a constant speed.

[0012] Furthermore, a substance concentration measuring device is characterized in that it incorporates the magnetic stirring device and has means for measuring the concentration of the stirred substance. [Effects of the Invention]

[0013] The present invention has the effect of being able to fully grasp the operating status of the stirrer, for example, whether or not the stirrer is rotating and the stability of the stirrer's rotation, in a magnetic stirring device and a substance concentration measuring device equipped with a magnetic stirrer. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of a magnetic stirring device of the present invention. [Figure 2] FIG. 2 is a hardware configuration diagram of a control unit of each device according to the embodiment of the present invention. [Figure 3] FIG. 3 is an explanatory diagram showing the behavior of the magnetic stirring device of the present invention during normal stirring. [Figure 4] FIG. 4 is an explanatory diagram of determination 1 (determination of whether the stirring bar 2 is rotating or not) in the magnetic stirring device of the present invention. [Figure 5] FIG. 5 is a process flow diagram of determination 1 (determining whether the stirring bar 2 is rotating or not) in the magnetic stirring device of the present invention. [Figure 6] FIG. 6 is an explanatory diagram for judgment 2 (judgment of the stability of rotation of the stirring bar 2) in the magnetic stirring device of the present invention. [Figure 7] FIG. 7 is an explanatory diagram for setting parameters used in judgment 2 (judging the stability of rotation of the stirring bar 2) in the magnetic stirring device of the present invention. [Figure 8] FIG. 8 is a process flow diagram of judgment 2 (judging the stability of rotation of the stirring bar 2) in the magnetic stirring device of the present invention. [Figure 9] FIG. 9 is a schematic diagram of a flow-through type electrolyte analyzer according to the second embodiment. [Figure 10] FIG. 10 is a process flow diagram of determination 1 (determination of whether the stirring bar 2 is rotating) and determination 2 (determination of the stability of the rotation of the stirring bar 2) in the flow-through type electrolyte analyzer according to the second embodiment. [Figure 11] FIG. 11 is a schematic diagram of a batch-type glucose analyzer according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following describes in detail an embodiment of the present invention, but the present invention is not limited to this.

[0016] (Configuration of the magnetic stirring device according to the present invention) FIG. 1 is a schematic diagram of a magnetic stirring device of the present invention. FIG. 1(a) is a schematic side view, and FIG. 1(b) is a schematic front view. A magnetic stirring device 100 of the present invention comprises a container 3 (sometimes abbreviated as "stirring container" in this specification) for containing an object to be stirred, a stirrer 2 including a ferromagnetic material disposed inside the stirring container 3, rotation control means 11, an electric motor 12, a magnet 1 disposed in the electric motor 12, a detection means 4 for observing the magnetic coupling state, a preprocessing means 13 for performing various processes on the output signal of the detection means 4, a determination means 14 for determining whether the stirring state is good or bad using the output signal of the preprocessing means 13, and a notification means 15 for notifying the determination result of the determination means 14. Note that other elements may be added to these components.

[0017] In the present invention, "stirring" refers to the operation of stirring a fluid or powder or granular material, regardless of the purpose. For example, the purpose may be to dissolve a solute in a solvent, dilute a solution with a solvent, mix multiple solutions of different compositions, mix multiple types of substances, or disperse a substance in a dispersion medium, but is not limited to these examples. Note that the fluid includes not only low-viscosity fluids such as aqueous solutions, but also viscous fluids.

[0018] The material of the stirring vessel 3 can be selected appropriately depending on the purpose, such as ceramic, glass, or resin. Resin is particularly suitable for small stirring devices because it is easy to process finely (e.g., polyvinyl chloride, acrylic resin, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polystyrene, AS resin, ABS resin, etc.). In addition, it is more appropriate to use a resin with high slidability (e.g., fluororesin, polyacetal, etc.) as the material for the "area where the stirring bar 2 moves," which will be described later.

[0019] The shape of the stirring vessel 3 can be appropriately selected depending on the purpose, such as cylindrical, drum-shaped, spherical, hemispherical, or inverted conical.

[0020] The area in which the stirrer 2 operates may be located anywhere on the inner surface of the stirring vessel 3, and may be located not only on the bottom but also on the wall. The area in which the stirrer 2 operates does not necessarily have to be flat, and can be selected appropriately according to the shape of the stirrer 2. For example, when using a stirrer 2 with a rotating shaft, a hole for accommodating the rotating shaft may be provided, and when using a stirrer 2 with unevenness, a guide that matches the unevenness may be provided.

[0021] The stirring bar 2 may be any material containing a ferromagnetic material. The method for molding the ferromagnetic material can be selected as appropriate. It may be molded by cutting, casting, or the like, or it may be a sintered body made by baking the magnetic material. The magnetic material may also be mixed with an organic material that is easy to process and molded (so-called rubber magnets or plastic magnets). It is even more convenient to coat the surface of the ferromagnetic molded product with a material that does not react with the object being stirred (e.g., resin, ceramic, etc.), as this prevents corrosion of the ferromagnetic molded product and prevents components of the ferromagnetic molded product from leaching into the object being stirred. Methods that can be used for coating include coating, insert molding, and embedding or embedding in resin.

[0022] The shape of the stirring bar 2 may be cylindrical, prismatic, spindle-shaped, blade-shaped, spherical with blades, cross-shaped, disc-shaped with cross-shaped protrusions, etc., but is not limited to these examples. A support rod or shaft may be attached to the center of rotation.

[0023] The rotation control means 11 is composed of software, a driver, and the like.

[0024] The electric motor 12 may be of any type as long as it can rotate a magnet placed in the electric motor, and examples thereof include an electromagnetic motor, an electrostatic motor, an ultrasonic motor, etc. There are various types of electromagnetic motors, such as DC motors, AC / DC dual-purpose motors, AC motors, and stepping motors, and any of these can be used.

[0025] A magnet 1 is placed on the electric motor 12. The magnet 1 forms a magnetic coupling with the ferromagnetic material inside the stirrer 2 placed inside the stirring vessel 3, and serves to indirectly transmit the rotational motion of the electric motor 12 to the stirrer 2. The type and size of the magnet 1 can be selected appropriately depending on the purpose.

[0026] The detection means 4 is composed of a sensor that detects magnetic force. The sensor may be a Hall element or a magnetic resistance element. The installation location of the detection means 4 can be selected appropriately as long as it can observe the magnetic coupling between the magnet placed in the motor 12 and the ferromagnetic material inside the stirrer, and is close to the end of the ferromagnetic material in the stirrer 2 during standby.

[0027] Fig. 2 is a hardware configuration diagram of a control unit of each device according to an embodiment of the present invention. The functions of the preprocessing means 13, determination means 14, notification means 15, and the rotation control means 11 and detection means 4 shown in Fig. 1 can be realized, for example, by the hardware configuration of a control unit 200 including a CPU 201, a ROM 202, a RAM 203, a display 204, and a network I / F (interface) 205 shown in Fig. 2. Each of the components 201 to 205 is connected to a bus 206. The details of the processes performed by the rotation control means 11, detection means 4, preprocessing means 13, determination means 14, and notification means 15 will be described in the following paragraphs.

[0028] (Contents of operation and processing) A feature of the magnetic stirring device 100 of the present invention is that it is possible to fully grasp the operating status of the stirring bar 2. The determination means 14 determines the following two events: the first is whether the stirring bar 2 is rotating, and the second is the stability of the rotation of the stirring bar 2. Below, we will explain the operations and processing that lead to the determination for each of the above-mentioned components.

[0029] When an electric signal is sent from the rotation control means 11 to the electric motor 12, the magnet 1 arranged in the electric motor 12 rotates, generating a rotating magnetic field. As mentioned above, the magnet 1 arranged in the electric motor 12 is magnetically coupled to the ferromagnetic material inside the stirrer 2. Therefore, under normal circumstances, the stirrer 2 inside the stirring vessel 3 rotates in synchronization with the rotation of the electric motor 12. On the other hand, if there is some kind of abnormality, the stirrer 2 may not rotate or stirring may become unstable even though the electric motor 12 is rotating.

[0030] The detection means 4 observes the state of magnetic coupling between the magnet 1 placed in the electric motor 12 and the ferromagnetic material inside the stirrer 2. The state of magnetic coupling observed here is converted into an electric signal and then sent to the pre-processing means 13. Note that depending on the characteristics of the magnetic sensor used in the detection means 4 and the settings of the electric circuit, the output signal when 0 mT is detected may be other than 0 V. In this case, the signal is corrected so that the output signal at 0 mT becomes 0 V.

[0031] FIG. 3 is an explanatory diagram of the behavior of the magnetic stirrer of the present invention during normal stirring. The signals observed by the detection means 4 during normal stirring are described below. Reference numeral 6 denotes the direction and amount of rotation of the magnet 1 disposed in the electric motor 12 (see FIG. 1), and reference numeral 7 denotes the direction and amount of rotation of the stirrer 2. Here, we will assume that the output signal of the detection means 4 is positive when the detection means 4 is penetrated in the direction of the coupling magnetic flux 5, as in State 1 shown in FIG. 3(a). When the north pole of the stirrer 2 is closest to the detection means 4, as in State 1 shown in FIG. 3(a), the output signal of the detection means 4 reaches its maximum value, as shown in FIG. 3(c). On the other hand, when the south pole of the stirrer 2 is closest to the detection means 4, as in State 2 shown in FIG. 3(b), the output signal of the detection means 4 reaches its minimum value, as shown in FIG. 3(c). During normal stirring, these states alternate, resulting in a sinusoidal waveform.

[0032] The pre-processing means 13 performs various processes on the output signal of the detection means 4 so that the subsequent determination means 14 can make an appropriate determination. Among these, the following two points are particularly important: (1) Extraction of DC bias. (2) Removal of specific frequency bands.

[0033] In the present invention, a DC bias is used in the determining means 14. Therefore, the preprocessing means 14 extracts the DC bias (above (1)). One method of extraction is, for example, calculating the average value of the output signal.

[0034] Furthermore, a process of removing a specific frequency band is performed on the output signal of the detection means 4 (above (2)). Specifically, a frequency signal that coincides with the rotation speed commanded to the electric motor 12 and high frequency noise originating from the power supply, the electric motor 12, etc., are removed. As a method of performing this process, a method of configuring a filter having band-stop and / or low-pass characteristics using an analog filter or a digital filter can be given.

[0035] The DC bias used in equation (1) of "Decision 1" described later may be (a) extracted from the output signal of the detection means 4 itself, or (b) extracted from the signal that has been subjected to the processing of (2) described above. In the case of (b), the DC bias is extracted from the signal after high-frequency noise has been removed by a low-pass filter, so it is possible to obtain a more appropriate value than in the case of (a).

[0036] There are two events that are judged by the judgment means 14. The first is whether or not the stirring bar 2 is rotating, and the second is the stability of the rotation of the stirring bar 2. The judgment means 14 judges whether or not the stirring bar 2 is rotating, and the stability of the rotation of the stirring bar 2.

[0037] The step of determining whether the stirring bar 2 is rotating or not is defined as "Determination 1," and the specific details are described below.

[0038] FIG. 4 is an explanatory diagram of judgment 1 (judging whether the stirrer 2 is rotating or not) in the magnetic stirrer of the present invention. The horizontal axis represents time, and the vertical axis represents the signal strength of the signal observed by the detection means 4. When the stirrer 2 starts to rotate in synchronization with the magnet 1 placed on the electric motor 12, the signal observed by the detection means 4 changes from a DC-like signal to a sine wave signal (FIG. 4(a)). As an example, we will explain the case where the south pole side of the magnetic material in the stirrer 2 approaches the detection means 4 during standby (i.e., the state before the stirrer 2 starts to rotate) as shown in FIG. 1(a). Note that when the north pole side approaches, this can be considered to be the same behavior with the north / south polarity reversed.

[0039] When the stirring bar 2 starts to rotate during standby, the DC bias (not shown) of the signal from the detection means 4 changes from the negative side toward 0 mV. This is because, during standby, the coupling magnetic flux 5 in Fig. 1(a) is detected by the detection means 4, causing the signal to exhibit a negative value, whereas when the stirring bar 2 is rotating at a constant speed, the output signal becomes a sine wave and its DC bias becomes 0 mV.

[0040] On the other hand, if the stirrer 2 cannot rotate due to some abnormality (for example, if the stirrer 2 is stuck to the inner surface of the stirring vessel 3 or the viscosity of the material being stirred is high), the signal observed by the detection means 4 changes from a DC signal to a sinusoidal signal, but the amplitude of the signal is small and the DC bias becomes larger on the negative side (Fig. 4(b)). This is because when the north pole of the magnet 1 attached to the motor 12 comes closest to the south pole of the stirrer 2 (α in Fig. 4(b)), the signal observed by the detection means 4 becomes the same as when in standby mode. On the other hand, when the south pole of the magnet 1 attached to the motor 12 comes closest to the south pole of the stirrer 2 (β in Fig. 4(b)), the stirrer 2 and magnet 1 repel each other, and the magnetic flux emitted from the north pole of the stirrer 2 penetrates the detection means 4 and enters the south pole of the stirrer 2. As a result, more magnetic flux penetrates the detection means 4 than when in standby mode, and the DC bias becomes larger on the negative side.

[0041] The above behavior is utilized in judgment 1. Note that the DC bias used here (hereinafter referred to as the "DC bias for judgment 1") may be extracted from the output signal of the detection means 4 itself, as described above, or extracted from a signal that has undergone processing to remove specific frequency bands. The judgment is performed by comparing the DC bias for judgment 1 during standby (hereinafter abbreviated as the "standby signal") with the DC bias for judgment 1 during rotation (hereinafter abbreviated as the "rotating signal"). Here, the absolute values ​​of each signal are used in the comparison. This makes it possible to make a judgment regardless of whether the magnetic direction of the stirring bar 2 that was close to the detection means 4 during standby was N or S. The judgment means 14 judges the situation to be normal (the stirring bar 2 is rotating) if the following formula (1) is satisfied, and judges the situation to be abnormal (the stirring bar 2 is not rotating) if not.

[0042] |Standby signal|>|Rotating signal| …Equation (1)

[0043] Fig. 5 is a process flow diagram of determination 1 (determining whether the stirring bar 2 is rotating or not) in the magnetic stirring device of the present invention. The process shown in Fig. 5 is executed by a program executed by the control unit 200 (CPU 201) shown in Fig. 2. First, the detection means 4 acquires the magnetic coupling state of the coupling magnetic flux 5 (step S501).

[0044] Next, the preprocessing means 13 filters the output signal of the detection means 4 (step S502). Next, the determination means 14 determines whether |standby signal|>|rotating signal| (step S503). If |standby signal|>|rotating signal| (step S503: Yes), the determination result of determination 1 is determined to be normal (step S504).

[0045] On the other hand, if |standby signal|>|rotating signal| is not satisfied (step S503: No), the control unit 200 determines that the determination result of determination 1 is abnormal (step S505). The control unit 200 ends the process of determination 1 based on the determination of step S504 or step S505.

[0046] The step of determining the stability of rotation of the stirring bar 2 is defined as "determination 2," and the specific contents are described below.

[0047] As mentioned above, the preprocessing means 13 removes specific frequency bands. This processing is particularly important in judgment 2. The reason is that the output signal of the detection means 4 is the combined magnetic flux originating from both the magnet 1 placed in the motor 12 and the ferromagnetic material of the stirrer 2, and if the frequency signal that coincides with the rotation speed commanded to the motor 12 is removed from this signal component, it is possible to extract a characteristic signal that is recognized in an abnormal state (in judgment 2, this refers to unstable rotation of the stirrer 2). Note that it is even more appropriate to also remove high-frequency noise originating from the power supply, the motor 12, etc. when performing the above processing.

[0048] FIG. 6 is an explanatory diagram of judgment 2 (judging the stability of the rotation of the stirring bar 2) in the magnetic stirring device of the present invention. FIG. 6 shows an example of the change over time in the output signal of the pre-processing means 13. Under normal conditions (which means that the rotation of the stirring bar 2 is stable in judgment 2), the amplitude of the signal wave sent from the pre-processing means 13 is small (FIG. 6(a)). On the other hand, under abnormal conditions, the amplitude of the signal wave becomes large (FIG. 6(b)). In judgment 2, this change in signal is used to make a judgment. The procedure is described in detail below.

[0049] FIG. 7 is an explanatory diagram for setting parameters used in Judgment 2 (judgment of the rotation stability of the stirring bar 2) in the magnetic stirring device of the present invention. First, a period T for which the operating status of the stirring bar 2 is to be monitored is determined. This period T for which the operating status of the stirring bar 2 is to be monitored varies depending on the intended use of the magnetic stirring device of the present invention and the physical properties of the object being stirred, so it is determined arbitrarily by the user. Next, a period T1 of constant-speed rotation is extracted from this period T, excluding periods tx during which the motor itself is not rotating stably (e.g., the period from the start of rotation of the motor until it reaches constant-speed rotation, or the period from constant-speed rotation until it begins to decelerate and stop). (Hereinafter, this period will be referred to as the "target period"). The maximum value (PpSmax) and minimum value (PpSmin) of the output signal from the preprocessing means 13 within the target period T1 are defined as the maximum value (PpSmax) and the minimum value (PpSmin), and the difference is calculated. This difference is defined as the stability score (hereinafter, sometimes abbreviated as "Score-S") and used for judgment.

[0050] The rotation stability of the stirring bar 2 is determined by comparing the stability score with a separately set criterion (hereinafter sometimes abbreviated as "Criteria-S") that is separately set in advance. This criterion varies depending on the intended use of the magnetic stirring device of the present invention and the physical properties of the object to be stirred, and is therefore determined at the user's discretion. For example, in fields where precise uniformity of the object to be stirred is not required, the criterion can be set high. Furthermore, by balancing the length of the target period and the criterion, it is possible to optimize the magnetic stirring device according to the intended use of the device and the physical properties of the object to be stirred.

[0051] The determining means 14 determines that the rotation of the stirring bar 2 is normal (stable) if the following formula (2) is satisfied, and determines that the rotation of the stirring bar 2 is abnormal (unstable) if not. Criteria-S≧Score-S…Formula (2)

[0052] 8 is a process flow diagram of judgment 2 (judging the rotation stability of the stirring bar 2) in the magnetic stirring device of the present invention. The process shown in FIG. 8 is executed by a program executed by the control unit 200 (CPU 201) shown in FIG. 2. First, parameters (the target period T1 and judgment criterion "Criteria-S" described above) to be used in judgment 2 (judging the rotation stability of the stirring bar 2) are set (step S801).

[0053] Next, the detection means 4 acquires the magnetic coupling state of the coupling magnetic flux 5 (step S802). Next, the preprocessing means 13 filters the output signal of the detection means 4 (step S803). Next, the determination means 14 determines whether Criteria-S≧Score-S (step S804). If Criteria-S≧Score-S (step S804: Yes), the determination result of determination 2 is determined to be normal (step S805).

[0054] On the other hand, if Criteria-S≧Score-S is not satisfied (step S804: No), the control unit 200 determines that the result of determination 2 is abnormal (step S806). The control unit 200 ends the process of determination 2 based on the determination made in step S705 or step S806.

[0055] The determination result obtained by the determination means 14 can be notified to the user or a higher-level system via the notification means 15. For example, a dedicated notification screen can be prepared and the determination result can be notified on the screen, or the determination result can be notified via serial communication with the higher-level system. Furthermore, the determination result and various operating conditions of the magnetic stirring device can be recorded on a recording medium.

[0056] (Embodiment 1: Magnetic Stirring Device) Hereinafter, an embodiment of the magnetic stirring device of the present invention will be described.

[0057] The electric motor 12 was a stepping motor, with a samarium magnet 1 attached to the tip of the motor's rotating shaft. The stirrer 2 was a plastic magnet molded from a ferromagnetic material and amide resin, coated with ABS resin. The detection means 4 consisted of a Texas Instruments linear Hall sensor DRV5055, which was placed at the bottom of the stirring vessel 3. The standby position of the stirrer 2 and the detection means 4 was set so that the south pole of the magnetic material inside the stirrer 2 was closest to the detection means (linear Hall sensor) 4. The system used here output an electrical signal of 2000 mV when detecting a magnetic field of 0 mT, an electrical signal of less than 2000 mV when detecting a magnetic field on the south pole side, and an electrical signal of more than 2000 mV when detecting a magnetic field on the north pole side. When processing the output signal of the detection means 4 in the preprocessing steps and subsequent processes, it is convenient and easy to handle the data if the output corresponding to a magnetic field of 0 mT is 0 mV. Therefore, the output signal of the detection means 4 was used as a corrected value obtained by subtracting 2000 mV. Part of the functions of the rotation control means 11, the detection means 4, the preprocessing means 13, and the notification means 15 were performed by the control unit 200.

[0058] The correctness of Judgment 1 was confirmed as follows. First, transparent polyvinyl chloride was used for a portion of the stirring vessel 3, so that the rotation of the stirring bar 2 could be visually observed. In addition, a state in which the stirring bar 2 was stopped despite the motor 12 rotating (an abnormal state) was simulated by inserting a thin, soft piece of resin into the stirring vessel 3 to hold the stirring bar 2 still.

[0059] First, a standby signal was obtained. The output value was -400 mV. Next, the control unit 200 instructed to turn on the motor 12. The rotation of the agitator 2 was visually observed through the transparent portion of the stirring vessel 3, and after confirming that the agitator 2 was rotating (normal state), a rotating signal was obtained. The signal at this time exhibited a sine wave as shown in Figure 4(a), and its DC bias was 0 mV. Comparing the two obtained signals, the absolute value of the standby signal was greater than the absolute value of the rotating signal, satisfying equation (1). Therefore, the operating status of the agitator 2 was determined to be normal by processing the flowchart shown in Figure 5. This matches the actual operating status of the agitator 2.

[0060] Next, the motor 12 was turned OFF, and the standby signal was obtained again. The output value was -400 mV. Furthermore, a thin, soft piece of resin was inserted into the stirring vessel 3 to prevent the stirrer 2 from moving, and then the motor 12 was turned ON to obtain a rotation signal. The signal obtained at this time was a sine wave, as shown in Figure 4(b), with a DC bias of -450 mV. Comparing the two obtained signals, the absolute value of the standby signal was smaller than the absolute value of the rotation signal, and did not satisfy equation (1). Processing according to the flowchart shown in Figure 5 determined that the operating status of the stirrer 2 was abnormal. This coincided with the actual operating status of the stirrer 2.

[0061] In both the normal state and the simulated abnormal state, the judgment results matched the actual operating status of the stirring bar 2, confirming that Judgment 1 worked well. Confirmation that Judgment 2 was performed correctly will be explained in the second embodiment.

[0062] (Embodiment 2: Electrolyte analyzer incorporating a magnetic stirrer) A second embodiment of an electrolyte analyzer incorporating a magnetic stirring device of the present invention will be described below.

[0063] 9 is a schematic diagram of a flow-through type electrolyte analyzer according to a second embodiment. In the second embodiment, a magnetic stirring device 100 having the same configuration as that of the first embodiment is incorporated into an electrolyte analyzer 900. A flow-through type electrolyte analyzer (manufactured by A&T Corporation) was used as the electrolyte analyzer 900. The electrolyte analyzer 900 includes a dilution liquid supply unit 901 that supplies a dilution liquid to the magnetic stirring device 100, a standard solution supply unit 902 that supplies a standard solution to the magnetic stirring device 100, a sample measurement unit (flow-through type sensor) 8, a signal processing circuit 910, a syringe pump 920, and a waste liquid unit 930.

[0064] In this electrolyte analyzer 900, a sample to be analyzed (e.g., urine, blood, plasma, cerebrospinal fluid, fermentation liquid, beverage, etc.) is diluted with a diluent (e.g., tris(hydroxymethyl)aminomethane aqueous solution, monomethanolamine aqueous solution, diethanolamine aqueous solution, triethanolamine aqueous solution, acetate, citrate, carbonate, phosphate, borate buffer, etc., or Good's buffer solution such as MOPS or HEPES) in the stirring vessel 3 of the magnetic stirrer 100 to a concentration suitable for analysis. This process requires collecting a minute amount of liquid sample and accurately preparing a dilution solution with a specified dilution ratio. Therefore, proper operation of the magnetic stirrer 100, which performs dilution, is a necessary condition for operating the electrolyte analyzer 900. Therefore, employing a magnetic stirrer 100 that allows for monitoring the operating status of the stirrer 2 offers significant advantages.

[0065] A flow path leading downstream was provided at the bottom of the stirring vessel 3, and a flow-through sensor 8 was placed at the outlet of the flow path. A sodium ion-selective electrode 8c, a potassium ion-selective electrode 8b, and a chlorine ion-selective electrode 8a were used in the flow-through sensor 8, along with a reference electrode 8r and a liquid earth electrode (omitted in Figure 9) (all manufactured by A&T Corporation). These electrodes were connected from upstream to downstream in the order of the liquid earth electrode, chlorine ion-selective electrode 8a, potassium ion-selective electrode 8b, sodium ion-selective electrode 8c, and reference electrode 8r to form a flow path.

[0066] The signal processing circuit 910 includes a signal input circuit 910a that inputs signals to the multiple electrodes of the flow-through sensor 8, a differential amplifier circuit 910b that amplifies the signals from each electrode, and a signal processing circuit 910c that processes the signals from each electrode. The electromotive force of the ion-selective electrode is calculated by a calculation circuit (not shown) as a potential difference with the potential of the reference electrode 8r set as the system ground. For example, the control unit 200 described above has the functions of the signal processing circuit 910c and the calculation circuit, and processes data during electrolyte concentration measurement.

[0067] A waste liquid section 930 was installed via a solenoid valve downstream of the sample measurement section (flow-through type sensor) 8. The liquid used for measuring the electrolyte concentration and for cleaning is discharged as waste liquid by controlling the solenoid valve (for discharging waste liquid) and syringe pump 920.

[0068] Judgment 1 was performed in the same manner as in the first embodiment, and it was confirmed that judgment 1 worked well.

[0069] The "period during which the operating status of the stirring bar 2 is desired to be ascertained" for judgment 2 was set to 3.5 seconds due to limitations on the measurement cycle of the electrolyte analyzer 900. Furthermore, by subtracting from this the period from when the motor 12 starts rotating until it reaches a constant speed, and the period from when it starts decelerating from a constant speed until it stops, the "target period" was 2.8 seconds. Criterion-S was set to 200 mV. This value was empirically determined, taking into consideration the accuracy and precision required for electrolyte measurement and the characteristics of the electrolyte analyzer 900.

[0070] The state in which the rotation of the stirring bar 2 was unstable was artificially created by adding small pieces of resin to the stirring vessel 3 to hinder the movement of the stirring bar 2. Score-S in this state was calculated to be 600 mV. As mentioned above, the set value of Criteria-S was 200 mV, so Score-S did not satisfy formula (2), and the judgment was abnormal (the rotation of the stirring bar 2 was unstable). This confirmed that Criteria-2 also functioned well.

[0071] 10 is a process flow diagram of determination 1 (determination of whether the stirring bar 2 is rotating) and determination 2 (determination of the stability of the rotation of the stirring bar 2) in the flow-through type electrolyte analyzer according to the second embodiment. The process shown in FIG. 10 is executed by a program by the control unit 200 (CPU 201) shown in FIG.

[0072] First, parameters (the above-mentioned target period T1, the judgment criterion "Criteria-S") to be used in judgment 2 (judgment of the rotation stability of the stirring bar 2) are set (step S1001).

[0073] Next, the detection means 4 acquires the magnetic coupling state of the coupling magnetic flux 5 (step S1002). Next, the preprocessing means 13 filters the output signal of the detection means 4 (step S1003). Next, the determination means 14 determines whether |standby signal|>|rotating signal| (step S1004). If |standby signal|>|rotating signal| (step S1004: Yes), the process proceeds to step S1005. On the other hand, if |standby signal|>|rotating signal| is not satisfied (step S1004: No), the process proceeds to step S1007.

[0074] In step S1005, it is determined whether Criteria-S≧Score-S (step S1005). If Criteria-S≧Score-S (step S1005: Yes), both determination results 1 and 2 are normal, and the determination result is determined to be normal (step S1006).

[0075] On the other hand, if Criteria-S≧Score-S is not satisfied (step S1005: No), the process proceeds to step S1007. In step S1007, the judgment result is judged to be abnormal (step S1007). In step S1007, if at least one of judgment results 1 and 2 is abnormal, the judgment is judged to be abnormal. Note that in the judgment processes of steps S1004 and S1005, the judgment results of judgments 1 and 2 are obtained, and therefore the judgment results of judgments 1 and 2 can be output in combination. The control unit 200 ends the above process based on the judgment of step S1006 or step S1007.

[0076] (Embodiment 3: Glucose measurement device incorporating a magnetic stirring device) An embodiment of a batch-type glucose measuring device incorporating the magnetic stirring device of the present invention will be described below.

[0077] FIG. 11 is a schematic diagram of a batch-type glucose analyzer according to the third embodiment. In the third embodiment, a magnetic stirring device 100 having the same configuration as that in the first embodiment is incorporated into a glucose measuring device 1100. A batch-type glucose measuring device (manufactured by A&T Corporation) was used as the glucose analyzing device 1100. In the glucose measuring device 1100, the stirring container 3 also serves as a measurement cell, and a glucose measuring sensor 9 is disposed on the side of the stirring container 3. The glucose measuring sensor 9 used was manufactured by A&T Corporation.

[0078] The glucose analyzer 1100 includes the aforementioned magnetic stirring device 100 having a stirring vessel 3, a sample supply unit 1110 having a crane to supply dispensed sample to the stirring vessel 3, a dilution liquid supply unit 1120 to supply dilution liquid, a cleaning liquid supply unit 1130 to supply cleaning liquid, a waste liquid unit 1140, a syringe pump, etc.

[0079] The glucose measuring device 1100 incorporates the magnetic stirring device 100 of the present invention in two locations. The first location (stirring device A) is the stirring container 3, which also serves as the measurement cell. Here, the target sample (e.g., urine, blood, plasma, cerebrospinal fluid, glucose solution, fermentation liquid, beverage, etc.) must be diluted with a diluent (e.g., tris(hydroxymethyl)aminomethane aqueous solution, monomethanolamine aqueous solution, diethanolamine aqueous solution, triethanolamine aqueous solution, acetate, citrate, carbonate, phosphate, borate buffer, etc., or Good's buffer solution such as MOPS or HEPES) to a concentration suitable for analysis. A minute amount of liquid sample must be collected and a diluted sample solution with a specified dilution ratio must be accurately prepared. Therefore, proper operation of the magnetic stirring device 100, which performs dilution during operation of the glucose analyzer, is essential. Therefore, employing a magnetic stirring device 100 that allows for monitoring the operating status of the stir bar 2 offers significant advantages.

[0080] The second part (stirring device B) incorporating the magnetic stirring device 100 of the present invention is the preheating tank 10 for the diluent. Because the glucose measuring device 1100 uses an enzyme in the sensor, the temperature of the diluted sample solution in contact with the sensor must be kept constant. Therefore, when introducing the diluent into the stirring container 3, which also serves as the measurement cell, the diluent is heated in the preheating tank 10 by a heater to a temperature suitable for the enzyme. The preheating tank 10 can store approximately 70 mL of diluent, and the amount of diluent used for measurement is sequentially replenished to the preheating tank 10. Therefore, to maintain a constant temperature in the preheating tank 10, the magnetic stirring device 100 constantly stirs the diluent. Because the preheating tank 10 requires high heat retention, a thick block of resin is used in the actual device, making it difficult to visually observe the internal stirring status. Therefore, employing the magnetic stirring device 100, which allows the operating status of the stirring bar 2 to be monitored, in this location offers significant advantages.

[0081] Judgment 1 and Judgment 2 were successfully performed in both magnetic stirring devices (stirring devices A and B) 100. Furthermore, although the two magnetic stirring devices 100 were placed within a range of about 10 cm, Judgment 1 and Judgment 2 were successfully performed even when both magnetic stirring devices 100 were operating simultaneously. [Industrial Applicability]

[0082] As described above, the magnetic stirring device according to the present invention is expected to be applied to stirring processes used in many industrial applications and to substance concentration measuring devices. [Explanation of symbols]

[0083] 1 Magnets placed in the motor 2 stirring bars 3 Mixing vessel 4. Detection methods 5. Coupled magnetic flux 6. Direction and amount of rotation of the magnets placed in the motor 7 Rotation direction and amount of the stirring bar 8 Flow-through sensor 9. Glucose measurement sensor 10 Preheating tank 12 Electric motor 100 Magnetic Stirrer 200 control section 201 CPU 202 ROM 203 RAM 204 Display 205 Network I / F 206 Bus 900 Electrolyte analyzer 1100 Glucose measuring device

Claims

1. The stirring device comprises a container for containing an object to be stirred, a stirrer disposed in the container and containing a ferromagnetic material therein, an electric motor, a magnet disposed in the electric motor and magnetically coupled to the ferromagnetic material in the stirrer, a rotation control means for controlling the operation of the electric motor, a detection means for observing the magnetic coupling state resulting from both the magnet and the ferromagnetic material inside the stirrer, a preprocessing means for processing an output signal from the detection means, and a determination means for determining the operating status of the stirrer using the output signal from the preprocessing means, The magnetic stirring device is characterized in that the determination means compares the absolute value of the standby signal when the motor is in a standby state with the absolute value of the rotating signal when the motor is in a rotating state based on the following formula (1), and determines that the stirrer is rotating if the following formula (1) is satisfied, and determines that the stirrer is not rotating if the following formula (1) is not satisfied. |Standby signal|>|Rotating signal| ...Equation (1)

2. The stirring device comprises a container for containing an object to be stirred, a stirrer disposed in the container and containing a ferromagnetic material therein, an electric motor, a magnet disposed in the electric motor and magnetically coupled to the ferromagnetic material in the stirrer, a rotation control means for controlling the operation of the electric motor, a detection means for observing the magnetic coupling state resulting from both the magnet and the ferromagnetic material inside the stirrer, a preprocessing means for processing an output signal from the detection means, and a determination means for determining the operating status of the stirrer using the output signal from the preprocessing means, The determination means calculates the difference (Score-S) between the maximum and minimum values ​​of the signal during an arbitrarily determined target period, compares the difference with an arbitrarily determined determination criterion (Criteria-S) based on the following formula (2), and determines that "the rotation of the stirrer is stable" if the following formula (2) is satisfied, and determines that "the rotation of the stirrer is unstable" if the following formula (2) is not satisfied. Criteria-S≧Score-S...Formula (2)

3. The stirring device comprises a container for containing an object to be stirred, a stirrer disposed in the container and containing a ferromagnetic material therein, an electric motor, a magnet disposed in the electric motor and magnetically coupled to the ferromagnetic material in the stirrer, a rotation control means for controlling the operation of the electric motor, a detection means for observing the magnetic coupling state resulting from both the magnet and the ferromagnetic material inside the stirrer, a preprocessing means for processing an output signal from the detection means, and a determination means for determining the operating status of the stirrer using the output signal from the preprocessing means, The determination means compares the absolute value of the standby signal when the motor is in a standby state with the absolute value of the rotating signal when the motor is in a rotating state based on the following formula (1), and determines that the stirrer is rotating if the following formula (1) is satisfied, and determines that the stirrer is not rotating if the following formula (1) is not satisfied: The magnetic stirring device is characterized by determining the difference (Score-S) between the maximum and minimum values ​​of the signal during an arbitrarily determined target period, comparing the difference with an arbitrarily determined judgment criterion (Criteria-S) based on the following formula (2), and determining that "the rotation of the stirring bar is stable" if the following formula (2) is satisfied, and determining that "the rotation of the stirring bar is unstable" if the following formula (2) is not satisfied. |Standby signal|>|Rotating signal| ...Equation (1) Criteria-S≧Score-S...Formula (2)

4. the pre-processing means removes a frequency signal that coincides with the rotation speed commanded to the electric motor from the output signal of the detection means when the stirring bar is in a rotating state; 4. The magnetic stirring device according to claim 2, wherein the determining means uses the output of the preprocessing means to make a determination according to the formula (2).

5. 4. The magnetic stirring device according to claim 2, wherein the target period is a period during which the electric motor rotates at a constant speed.

6. 6. A substance concentration measuring device, comprising means for measuring the concentration of a substance stirred by the magnetic stirring device according to any one of claims 1 to 5.

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