JP3869112B2 - Liquid suction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid suction method suitable for application to a sample dispensing apparatus that dispenses a sample such as serum contained in a sample container in a reaction container in an automatic chemical analyzer, for example.
[0002]
[Prior art]
In a sample dispensing apparatus in an automatic chemical analyzer, an injection needle with a thin tip is generally used as a dispensing nozzle. This dispensing nozzle is easily deformed or damaged when the tip of the dispensing nozzle comes into contact with the bottom of the sample container. For example, when the dispensing nozzle is lowered into the sample container to suck the sample, the tip of the nozzle is The lowering of the dispensing nozzle is controlled so as to stop at a position somewhat away from the container bottom.
[0003]
In this case, in order to be able to aspirate a desired amount from a small amount of sample accommodated in the sample container, it is necessary to take into account variations in each part that determines the dimensions of the dispensing nozzle and the bottom of the sample container. It is necessary that the tip of the dispensing nozzle and the bottom of the specimen container do not come into contact with each other and come closest to each other. However, since there are actually many parts that determine the dimensions of the dispensing nozzle and the sample container, it is not possible to aspirate all the sample in the sample container even if the variation is minimized. There is a problem that a desired amount may not be aspirated when the amount of sample contained in the sample container is small, such as a sample.
[0004]
For example, Japanese Patent Application Laid-Open No. 55-39029 and Japanese Utility Model Application Laid-Open No. 58-54558 disclose that a sample container and a dispensing nozzle are supported by an elastic body. There has been proposed an apparatus in which a very small amount of sample is aspirated by elastically contacting the tip of the nozzle with the bottom of the sample container.
[0005]
[Problems to be solved by the invention]
However, according to various experimental studies by the present inventor, as described above, a method for aspirating a small amount of sample by elastically bringing the tip of the dispensing nozzle into contact with the bottom of the sample container, for example, an automatic chemical analyzer It has been found that there is a problem as described below when it is adopted in the sample dispensing apparatus in No. 1.
[0006]
That is, in the sample dispensing device used in the automatic chemical analyzer, the amount of sample contained in the sequential sample containers to be dispensed varies, so a liquid level detection mechanism is generally provided in the dispensing nozzle. The level at which the dispensing nozzle is lowered at a constant speed (liquid level detection operation speed) while detecting the liquid level, and once the liquid level is detected, the descent is stopped and then a desired amount of sample can be aspirated. Only the dispensing nozzle is lowered again to aspirate a desired amount of sample.
[0007]
Here, assuming that the height of the sample container is 100 mm, in the case of a small amount of sample, the moving distance until the dispensing nozzle reaches the bottom of the sample container from the top dead center is 100 mm or more. On the other hand, when the cycle time for dispensing the specimens in the specimen container sequentially with the specimen dispensing apparatus is 4.5 seconds, for example, the time given for lowering the dispensing nozzle to detect the liquid level is, for example, Since it is about 500 msec, the descending speed in this case is 200 mm / sec or more. Therefore, in the case of a small amount of specimen, in order to bring the nozzle tip into contact with the bottom of the specimen container and suck it, the tip of the nozzle is brought into contact with the bottom of the specimen container after the lowering operation of 100 mm or more. In order to maintain the cycle time, the lowering of the dispensing nozzle is not temporarily stopped when the liquid level is detected, but the operation of lowering to detect the liquid level is extended, that is, the lowering of 200 mm / sec or more. The tip of the nozzle is brought into contact with the bottom of the sample container at a speed.
[0008]
For this reason, even if the dispensing nozzle and the sample container bottom can be elastically brought into contact with each other, the dispensing nozzle and the sample container may be damaged, so that the sample dispensing at a high speed cannot be performed. Further, even if the contact is not broken once or twice, the dispensing nozzle may be deformed to adversely affect the dispensing accuracy or cause fatigue failure. Such a problem becomes a larger problem when the cycle time is further shortened in order to improve the processing capability of the automatic chemical analyzer.
[0009]
The present invention has been made by paying attention to such conventional problems, and can effectively remove a small amount of liquid contained in the container without causing deformation, breakage, or fatigue failure of the suction nozzle and the container. An object of the present invention is to provide a liquid suction method capable of suction.
[0010]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention lowers a suction nozzle that can be raised and lowered into a container that contains liquid, and sucks the liquid in the container with the suction nozzle. When the nozzle is lowered from the dead center at a predetermined lowering speed and reaches a predetermined lowering level that is highly likely to come into contact with the bottom of the container before the nozzle tip reaches the liquid surface, the suction nozzle is moved to the predetermined nozzle . The lowering speed is lower than the lowering speed.
[0011]
Further, according to the present invention, when the suction nozzle that can be moved up and down is lowered into a container that stores liquid, and the liquid in the container is sucked by the suction nozzle , the liquid level of the liquid stored in the container However, when the nozzle tip of the suction nozzle is lower than a preset lowering level that is likely to contact the bottom of the container , the suction nozzle is normally moved from its top dead center to just before the lowering level. The lowering speed is lower than the normal lowering speed, and thereafter the lowering speed is lower than the normal lowering speed.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a configuration of a main part of a sample dispensing device of an automatic analyzer that performs a liquid suction method according to the present invention. This sample dispensing apparatus dispenses samples sequentially from a plurality of sample containers 2 (only one is shown in the figure) held in the sample container storage unit 1 to a plurality of reaction containers (not shown). The dispensing nozzle 3 is supported by being biased downward so as to be relatively movable up and down relative to the lifting arm 5 via an elastic member 4 made of, for example, a coil spring. A syringe pump is connected to the dispensing nozzle 3 via a switching valve 6. 7 and the washing water tank 8 are connected. The elevating arm 5 is moved up and down via a nozzle vertical movement drive motor 12 under the control of the control unit 11, and the switching valve 6 controls the switching operation under the control of the control unit 11, and the syringe The pump 7 is caused to perform an intake / exhaust operation via the syringe pump drive motor 13 under the control of the control unit 11.
[0014]
In addition, the dispensing nozzle 3 is provided with a known liquid level detection mechanism (not shown, but capable of detecting, as an electrical signal, that the tip of the nozzle is in contact with the liquid level, such as a capacitance or air type). The liquid level detection signal is supplied to the control unit 11. Furthermore, in order to detect the contact between the dispensing nozzle 3 and the sample container 2, for example, the photo interrupter 15 is shielded from the lifting arm 5 and the optical path of the photo interrupter 15 is shielded from the dispensing nozzle 3 in a non-contact state. Each of the light shielding plates 16 is provided to constitute a contact detection mechanism 17, and the contact detection signal is supplied to the control unit 11.
[0015]
Thus, for example, in a state where the pipe line including the dispensing nozzle 3 is filled with the washing water, first, the dispensing nozzle 3 and the syringe pump 7 are communicated with each other by the switching valve 6, and in this state, the dispensing is performed. The nozzle 3 is lowered from the top dead center position into the sample container 2 at the sample aspirating position, and the syringe pump 7 is aspirated to aspirate a desired amount of sample. Next, after the dispensing nozzle 3 is raised to the top dead center position, the dispensing nozzle 3 is rotated in a horizontal plane by a rotation mechanism (not shown) and positioned at a predetermined sample discharge position, and the syringe pump 7 is discharged in that state. By doing so, the aspirated desired amount of specimen is discharged into a reaction container (not shown). Thereafter, the dispensing nozzle 3 is rotated by a rotation mechanism to be positioned at the nozzle cleaning position, the dispensing nozzle 3 is lowered at the nozzle cleaning position, and the nozzle tip portion enters a cleaning layer (not shown), A cleaning operation is performed by discharging the syringe pump 7 and discharging cleaning water from the dispensing nozzle 3. Thereafter, in a state where the syringe pump 7 and the washing water tank 8 are communicated with each other by the switching valve 6, the syringe pump 7 is aspirated to suck a predetermined amount of washing water to prepare for the next sample dispensing.
[0016]
In the first embodiment of the present invention, a lowering level of the dispensing nozzle 3 that is highly likely to contact the bottom of the sample container 2 is set in advance in the control unit 11, and the set lowering level is set. Based on the liquid level detection signal from the liquid level detection mechanism (not shown) and the contact detection signal from the contact detection mechanism 17, the lowering of the dispensing nozzle 3 when the sample is aspirated is controlled. Here, the set lowering level of the dispensing nozzle 3 is set on the basis of the container bottom level considering the variation of the bottom according to the shape of the sample container 2 and the like.
[0017]
That is, as shown in the flowchart in FIG. 2, first, the dispensing nozzle 3 is lowered at a predetermined lowering speed (liquid level detecting operation speed) while detecting the liquid level from the top dead center (step S1), and the setting is lowered. It is detected whether the liquid level has been detected before reaching the level (step S2). Here, when the liquid level is detected before reaching the set lowering level, it is determined that the sample is a normal sample, and after the descent is stopped at that time (step S3), a desired amount of the sample can be aspirated. The dispensing nozzle 3 is lowered again by the level (step S4), and a desired amount of sample is aspirated.
[0018]
On the other hand, if the liquid level is not detected before reaching the set lower level in step S2, the dispensing nozzle 3 is lowered at the liquid level detecting operation speed until the set lower level is reached in step S5. Here, when it is detected that the set lowering level has been reached, it is determined that the sample is a trace amount sample, and at that time, the lowering speed is made lower than the liquid level detection operation speed, and the dispensing nozzle 3 is lowered (step S6). Thereafter, the tip of the nozzle comes into contact with the bottom of the container, the lifting arm 5 further moves down against the elastic force of the elastic member 4, and the light shielding plate 16 retreats from the optical path of the photo interrupter 15, thereby In synchronization with the generated contact detection signal, the descent of the elevating arm 5 is stopped and the sample is aspirated. In this case, if there is a sample in the sample container 2 during the low speed descent, a liquid level detection signal is generated. In this case, the liquid level detection signal is used, for example, for the presence or absence of the sample. Therefore, it is not used for the lowering control of the dispensing nozzle 3.
[0019]
Thus, the sample dispensing device automatically detects that the sample is a trace amount, and the tip of the dispensing nozzle 3 is slower than the liquid level detection operation speed (for example, less than 200 mm / sec, preferably 10 to 150 mm). / sec, particularly 50 to 100 mm / sec), the sample is aspirated by being brought into contact with the bottom of the sample container 2, thereby causing deformation, breakage, and fatigue destruction of the dispensing nozzle 3 and the sample container 2. For example, even a trace amount liquid with a sample amount of 100 μl or less can be effectively aspirated. In addition, when the cycle time of the sample dispensing apparatus, that is, the normal total time of suction, discharge and nozzle cleaning for one sample is 4.5 sec, for example, an integer multiple, for example 2 times, is required for dispensing a small amount of sample. 9 sec. Of 1 sec., And a half cycle of 4.5 sec is allocated to the sample aspirating operation, so that the contact speed of the dispensing nozzle 3 to the bottom of the sample container 2 can be sufficiently slowed and all the sample discharges are performed thereafter. By performing control so as to be shifted by one cycle, which is a cycle corresponding to the extended timing, it is possible to perform an analysis operation while mixing with other normal samples. Even in this case, since the number of trace samples in all samples is generally small, considering the advantage that trace samples can be reliably aspirated without causing any support, a slight decrease in processing capacity is not a problem. Don't be.
[0020]
In the second embodiment of the present invention, as in the first embodiment, the lowering level of the dispensing nozzle 3 where the tip of the dispensing nozzle 3 is likely to come into contact with the bottom of the sample container 2 is set in the control unit 11. In addition to setting in advance, in this embodiment, the control unit 11 is made to recognize that the sample container 2 contains a small amount of sample whose liquid level is lower than the set lowering level . Here, as a method for causing the apparatus to recognize that the sample is a minute sample, for example, the operator inputs the sample container 2 of the minute sample into the control unit 11 from a keyboard or the like (not shown), or attaches the sample container 2 to the sample container 2. The control unit 11 automatically recognizes the read barcode.
[0021]
In this way, when aspirating a minute sample, as shown in the flowchart in FIG. 3, first, the control unit 11 determines whether or not the sample to be dispensed is a minute sample (step S21). When the sample is not a sample, the lowering operation of the dispensing nozzle 3 is controlled as the normal sample dispensing mode in the same manner as the lowering operation for the normal sample described in the first embodiment (step S22), and the sample is aspirated. . On the other hand, if it is determined in step S21 that the sample is a very small amount, the dispensing nozzle 3 is lowered at a speed higher than the normal liquid level detection operation speed from the top dead center to immediately before the set lowering level (step S23). Then, when the set lowering level is reached (step S24), the lowering speed is lowered at that time, for example, lower than the normal liquid level detecting operation speed, and the dispensing nozzle 3 is lowered (step S25). As in the first embodiment, the tip of the nozzle comes into contact with the bottom of the container, and the elevating arm 5 descends against the elastic force of the elastic member 4 to generate a contact detection signal from the contact detection mechanism 17. Then, at that time, the descent of the elevating arm 5 is stopped and the sample is aspirated.
[0022]
In this way, the sample dispensing apparatus is made to recognize in advance that the sample is a minute sample, and when the sample is aspirated, the dispensing nozzle 3 is lowered at a speed higher than the normal liquid level detection operation speed until just before the set lowering level. Thereafter, the sample is lowered at a lower speed than the liquid level detection operation speed, and the tip of the nozzle is brought into contact with the bottom of the sample container 2 to suck the sample, as in the first embodiment. A trace amount of liquid can be effectively aspirated without causing deformation, breakage, or fatigue destruction of the nozzle 3 or the sample container 2. In addition, in this embodiment, in the case of a small amount of sample, the dispensing nozzle 3 is lowered at a speed higher than the normal liquid level detection operation speed until immediately before the set lowering level. Regardless of this, sample dispensing can always be processed in a short time, and dispensing can be performed with a normal cycle time.
[0023]
In the reference example developed together with the present invention , the lowering level of the dispensing nozzle 3 where the tip of the dispensing nozzle 3 is likely to come into contact with the bottom of the sample container 2 is set in the control unit 11 as in the second embodiment. While being set in advance, the control unit 11 is made to recognize that the sample container 2 contains a small amount of sample. In this reference example , when the sample container 2 is a small amount of sample, the dispensing nozzle 3 is moved from its top dead center. The nozzle is lowered at a lower speed than the normal lowering speed, that is, lower than the liquid level detection operation speed, the nozzle tip is brought into elastic contact with the bottom of the sample container 2, and a minute amount of sample is aspirated in this state.
[0024]
Therefore, also in this reference example , a trace amount of liquid can be effectively aspirated without causing deformation, breakage, or fatigue destruction of the dispensing nozzle 3 or the sample container 2. In the case of this reference example , since the descending speed of the dispensing nozzle 3 at the time of aspirating a small amount of sample is slow, it cannot be dispensed with a normal cycle time, but the cycle time in this case is the same as that of the first embodiment. In addition, if it is set to an integral multiple of the normal cycle time, the consistency of the analysis operation can be ensured, so that the dispensing operation can be performed while being mixed with the normal sample.
[0025]
In addition, this invention is not limited only to embodiment mentioned above, Many changes or deformation | transformation are possible. For example, in the first or second embodiment, the speed is switched stepwise above and below the set drop level, but control may be performed so that the vehicle continuously decelerates at the set drop level. In addition, when a plurality of types of containers are used as the sample container 2, a set lowering level that is highly likely to cause the tip of the dispensing nozzle 3 to contact the bottom of the sample container 2 is set in advance according to the type of the container. It is also possible to select and use a corresponding set lowering level according to the type of container used. For example, when a micro sample is set in the sample container storage unit 1, there is a case where a cup for a micro sample is placed on the vacuum blood collection tube without using the normally used vacuum blood collection tube. In such a case, the set lowering level may be changed to a corresponding one prior to the start of dispensing. By doing so, it is possible to effectively prevent the occurrence of troubles such as the dispensing nozzle sticking into the trace sample cup.
[0026]
Further, in FIG. 1, the dispensing nozzle 3 and the specimen container 2 can be elastically contacted by supporting the dispensing nozzle 3 on the lifting arm 5 via the elastic member 4. As shown, the dispensing nozzle 3 is fixed to the lifting arm 5 and does not change elastically with the weight of the sample container 2 containing an arbitrary amount of sample in the sample container storage unit 1, but elastic with the amount of downward force of the dispensing nozzle. It is also possible to provide an appropriate elastic material 21 having elasticity that changes, and to store the sample container 2 thereon. In this case, when a plurality of types of sample containers are used, the bottom dead center of the lowering of the dispensing nozzle 3 may be set according to the type. In the second embodiment, the fact that a small amount of sample is contained is recognized in advance by using a keyboard or a barcode. However, light is projected so as to cross a position slightly higher than the bottom surface from the side surface of the sample container 2. Then, the transmitted light may be received, or an ultrasonic wave may be projected from above the sample container 2 into the container to receive the reflected wave, and only the determination of whether or not the sample is a minute sample may be performed in advance. Furthermore, the present invention can be effectively applied not only to the specimen dispensing device of the automatic chemical analyzer described above but also to various suction devices that suck liquid.
[0027]
【The invention's effect】
According to the present invention, when sucking in a small amount of liquid whose liquid level is lower than a preset lowering level at which at least the tip of the suction nozzle is likely to come into contact with the bottom of the container, after the lowering level , the suction nozzle Since the nozzle is lowered at a low speed, the impact when the nozzle tip comes into contact with the bottom of the container can be reduced. Therefore , it is possible to effectively suck a small amount of liquid stored in the container without causing deformation, breakage, or fatigue destruction of the suction nozzle and the container.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a main part of a sample dispensing device of an automatic analyzer that performs a liquid suction method according to the present invention.
FIG. 2 is a flowchart for explaining the first embodiment of the present invention by the sample dispensing apparatus shown in FIG. 1;
FIG. 3 is a flowchart for explaining the second embodiment in the same manner.
FIG. 4 is a diagram showing a main part of a modified example of the sample dispensing apparatus shown in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Specimen container storage part 2 Specimen container 3 Dispensing nozzle 4 Elastic member 5 Elevating arm 6 Switching valve 7 Syringe pump 8 Washing water tank 11 Control unit 12 Nozzle vertical drive motor 13 Syringe pump drive motor 15 Photo interrupter 16 Light shielding plate 17 Contact detection mechanism 21 Elastic material

Claims (2)

A suction nozzle that can be moved up and down is lowered into a container that stores liquid, and the liquid in the container is sucked by the suction nozzle.
When the suction nozzle is lowered at a predetermined lowering speed from its top dead center and reaches a preset lowering level that is likely to come into contact with the bottom of the container before the nozzle tip reaches the liquid surface , A liquid suction method, wherein the suction nozzle is lowered at a speed lower than the predetermined lowering speed. A suction nozzle that can be moved up and down is lowered into a container that stores liquid, and the liquid in the container is sucked by the suction nozzle.
When the liquid level of the liquid contained in the container is lower than a preset lowering level where the nozzle tip of the suction nozzle is likely to come into contact with the bottom of the container , the suction nozzle is A liquid suction method comprising: lowering from a dead point to immediately before the lowering level at a lower speed than a normal lowering speed, and thereafter lowering at a lower speed than a normal lowering speed.

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