JP2010256200A - Dispensing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispensing system for effectively reducing occurrence of liquid dripping and air gaps. <P>SOLUTION: The dispensing system 10 includes: a nozzle tip 30; a moving mechanism 20 for moving the nozzle tip 30; a dispensing pump 16 for executing suction and discharge of liquid by varying internal pressure of the nozzle tip 30; a storage part 25; and a control part 24 for controlling drive of the moving mechanism 20 and the dispensing pump 16. The storage part 25 stores air suction conditions including an air suction speed for canceling an increase in internal pressure following evaporation of liquid generated in the nozzle tip as air suction setting information during a period from completion of suction of liquid by the nozzle tip 30 to start of discharge of liquid. The control part instructs the dispensing pump 16 to perform air suction under air suction conditions prescribed in the air suction setting information during a period from the completion of suction of liquid by the nozzle tip 30 to start of discharge of liquid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dispensing device that sucks and discharges liquid with a nozzle by changing the internal pressure of a piping system including the nozzle with a pump.

  2. Description of the Related Art Conventionally, dispensing devices that suck a liquid from a suction source container and discharge the liquid to a discharge destination container are widely known. In such a dispensing apparatus, it is possible to reliably prevent liquid dripping, an air gap, and, in turn, a liquid pool that accumulates at the tip of the nozzle through the air gap between the time the liquid is sucked and discharged from the nozzle. It is hoped to do.

  Here, as one of the causes of dripping, the sucked liquid evaporates (vaporizes) in the nozzle. That is, while the nozzle moves from the suction source container to the discharge destination container, in other words, when the tip of the nozzle is away from the liquid surface (in the air), the liquid in the nozzle evaporates. The internal pressure of the piping system increases. With this increase, when the internal pressure of the piping system exceeds a certain peak pressure, liquid may be pushed out from the opening at the tip of the nozzle and dripping may occur. When this dripping occurs, the device becomes dirty, the liquid is wasted, and the dripped liquid drops enter other containers, causing contamination, so it is necessary to prevent dripping. .

  In order to prevent the occurrence of such dripping, it has been proposed to cause the dispensing pump to perform a certain amount of suction (spill prevention suction) while moving the nozzle that sucked the liquid to the discharge destination container. Yes. However, if the suction amount at the time of liquid dripping prevention suction is large, air may flow from the nozzle tip opening and create an air gap at the nozzle tip. If an air gap is created, a liquid pool is created at the nozzle tip opening through the air gap over time, so that bubbles are formed when liquid is discharged or liquid drops are generated when dripping occurs. Instead, the bubbles are ejected from the opening at the tip of the nozzle, and the bubbles are blown to cause the sample to scatter and cause contamination.

JP 2003-194835 A Japanese Patent No. 2005-321342 Japanese Patent No. 2005-300236 Japanese Patent No. 2939180

  Therefore, Patent Documents 1 to 3 and the like disclose a technique of monitoring the pressure after suction and performing air suction with a pump so as to offset the pressure increase. According to such a technique, the above-described problems such as dripping can be somewhat reduced. However, the pressure immediately after suction acquired as a reference often does not show a correct value due to mechanical vibration or leakage in the piping system. Moreover, the peak pressure at which liquid dripping occurs is not necessarily constant depending on the liquid pressure and the state of the nozzle. For this reason, it has been difficult to effectively prevent liquid dripping, an air gap, and the like in the conventional method of controlling the air suction amount by monitoring the pressure.

  Patent Document 4 discloses a technique for preventing liquid dripping by continuously sucking air at a minute flow rate after sucking liquid with a nozzle and continuously generating bubbles in the liquid in the chip. . However, since such microbubbles may cause an error in the discharge amount, there are cases in which a suitable dispensing process cannot be performed with this technology.

  Then, an object of this invention is to provide the dispensing apparatus which can reduce the generation | occurrence | production of a liquid dripping and an air gap effectively.

  A dispensing device that sucks and discharges liquid, wherein a nozzle that holds liquid therein, a moving mechanism that moves the nozzle, and an internal pressure of a piping system that includes the nozzle change the nozzle. A pump for performing liquid suction and discharge at the nozzle, and at least an air suction speed in the nozzle capable of offsetting an increase in internal pressure caused by liquid evaporation occurring in the nozzle between completion of liquid suction at the nozzle and start of liquid discharge Storage means for storing air suction conditions including air suction setting information in advance, and control means for controlling driving of the moving mechanism and the pump, from the completion of liquid suction at the nozzle to the start of liquid discharge. Control means for instructing the pump to perform air suction under air suction conditions defined in the air suction setting information.

  In a preferred aspect, the air suction condition further includes an upper limit value of the amount of air to be sucked, and the control means, when the air suction amount to be sucked by the air suction reaches the upper limit value, Even before the start of discharge, the air suction is stopped.

  In another preferred aspect, the air suction setting information stores a plurality of different air suction conditions for each liquid suction condition at the nozzle, and the control unit is based on a condition of the actually performed liquid suction. The air suction conditions suitable for the actual liquid suction are selected. In this case, it is desirable that the liquid suction conditions include at least one of a liquid suction amount, a liquid type, a nozzle type, temperature, and humidity.

  In another preferred aspect, the air suction speed is a variable value that changes in accordance with an elapsed time from the completion of the liquid suction. In another preferred aspect, the control unit resets the air suction condition when the amount of liquid in the nozzle changes as the dispensing process proceeds.

  According to the present invention, since air suction can be performed at an air suction speed that can cancel the increase in internal pressure due to liquid evaporation, it is possible to effectively reduce the occurrence of liquid dripping and air gap.

It is a schematic block diagram of the dispensing apparatus which is embodiment of this invention. It is a schematic block diagram around a piping system. It is a graph which shows an example of change of piping system internal pressure. It is a graph which shows the relationship between the amount of liquid suction, and limit elapsed time. It is a figure which shows an example of air suction setting information. It is a graph which shows an example of air suction speed. It is a flowchart which shows the flow of a dispensing process. It is a flowchart which shows the flow of a dispensing process. It is a flowchart which shows the flow of another dispensing process. It is a flowchart which shows the flow of another dispensing process.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a dispensing apparatus 10 according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram in which only the piping system 14 including the nozzle portion 12 and the periphery of the dispensing pump 16 are extracted from the dispensing apparatus 10.

  The dispensing device 10 is a device that sucks a liquid stored in the suction source container 100, for example, a body fluid such as blood, a chemical solution, or the like with the nozzle tip 30, discharges the liquid into one or more discharge destination containers 102, and dispenses it. is there. As is apparent from FIG. 1, the dispensing apparatus 10 includes a piping system 14 including a nozzle unit 12 and a piping 34, a dispensing pump 16, a moving mechanism 20, an input unit 26, an output unit 28, and a control unit 24. I have.

  The nozzle unit 12 includes a nozzle chip 30 that actually sucks and discharges a liquid, a mounting unit 32 on which the nozzle chip 30 is mounted, and the like. Here, in the present embodiment, a disposable nozzle chip 30 that can be discarded and replaced each time it is used is used as the nozzle chip 30. Therefore, a large number of unused nozzle tips 30 are stored in the rack 50 or the like in or near the dispensing apparatus 10. A dust space (not shown) for storing the used nozzle tip 30 is formed in or near the dispensing device 10, and the nozzle chip 30 is disposed in the vicinity of the dust space. The chip disposal position for this is set.

  Of course, instead of the disposable nozzle chip 30, a nozzle chip 30 that is used repeatedly while cleaning may be used. Whichever nozzle tip 30 is used, a differently shaped nozzle tip 30 is appropriately selected according to the required liquid suction amount and discharge amount (target liquid suction amount and target liquid discharge amount). It is desirable to be able to do it. That is, when a relatively large amount of liquid needs to be sucked and discharged, a large-sized nozzle tip 30 is used. When a relatively small amount of liquid is required to be sucked and discharged, a small-sized nozzle tip 30 is used. It is desirable to configure so that it can be used.

  The nozzle tip 30 is attached by fitting to the other end of the tip attachment portion 32 whose one end is connected to the pipe 34. The nozzle portion 12 including the nozzle tip 30 and the tip mounting portion 32 is moved three-dimensionally by the moving mechanism 20. The driving of the moving mechanism 20 is controlled by the control unit 24.

  The nozzle unit 12 is connected to the dispensing pump 16 via a pipe 34. The dispensing pump 16 varies the internal pressure of the piping system 14 including the nozzle portion 12 and the piping 34. The type of the dispensing pump 16 is not particularly limited as long as the internal pressure can be appropriately changed. In the present embodiment, the dispensing pump 16 includes a cylinder 40 and a plunger 42 and uses a syringe pump. The driving of the dispensing pump 16 is controlled by the control unit 24 via the pump driving unit 18. A pressure sensor 22 for measuring the internal pressure of the piping system 14 is provided between the nozzle unit 12 and the dispensing pump 16. The value detected by the pressure sensor 22 is appropriately output to the control unit 24 and used for various controls such as liquid level detection.

  The input unit 26 is a part of a user interface that receives an instruction from the user, and can include a keyboard, a touch panel, and the like. The user operates the input unit 26 to input a type of liquid to be sucked, a dispensing condition such as a target liquid suction amount, a target liquid discharge amount, and the number of discharges. The input dispensing conditions are input to the control unit 24, and the control unit 24 controls the driving of each unit based on the dispensing conditions. The output unit 28 is a part of a user interface that presents various types of information to the user, and can include a display, a speaker, an LED lamp, and the like.

  The control unit 24 controls the driving of the entire dispensing apparatus 10. More specifically, the control unit 24 controls the driving of the dispensing pump 16 and the moving mechanism 20 based on an instruction input via the input unit 26. Then, the dispensing process is executed.

  The control unit 24 includes a storage unit 25 including a memory, a hard disk, and the like. The storage unit 25 stores air suction setting information described later. The air suction setting information includes information including air suction conditions (air suction parameters) performed by the dispensing pump 16 in order to prevent or reduce the occurrence of liquid dripping from the tip of the nozzle tip 30 or an air gap. However, this will be described in detail later.

  Next, a rough flow of the dispensing process performed by the dispensing apparatus 10 will be described. When the start of the dispensing process is instructed by the user, the control unit 24 drives the moving mechanism 20 to move the nozzle unit 12 with the new nozzle tip 30 attached to the suction source container 100. In this state, the dispensing pump 16 is driven to suck a target liquid suction amount of liquid into the nozzle tip. When the target liquid suction amount can be sucked, subsequently, the moving mechanism 20 is driven to move the nozzle tip 30 to the discharge destination container 102. Then, the dispensing pump 16 is driven to discharge a target liquid discharge amount of liquid from the nozzle tip 30 to the discharge destination container 102.

  Here, conventionally, after the completion of the liquid suction by the nozzle tip 30, liquid dripping or the like in which liquid is pushed out from the tip of the nozzle tip 30 may occur during the movement of the nozzle portion 12 to the discharge destination container 102. When such dripping occurs, there is a problem that the apparatus becomes dirty, the liquid is wasted, or the dripped liquid droplets are mixed into another container to cause contamination.

  Such dripping is considered to occur due to the reason that the liquid sucked in the nozzle tip evaporates. That is, when the liquid suction by the nozzle tip 30 is completed, evaporation occurs thereafter from the liquid surface in the nozzle tip. Then, the vapor diffuses inside the nozzle tip 30, thereby increasing the internal pressure of the piping system. When the force with which the liquid in the nozzle tip is pushed outward by this piping system internal pressure exceeds the critical value of the surface tension at the tip of the nozzle tip 30, dripping occurs.

  FIG. 3 is a graph showing an example of a change in the internal pressure of the piping system before and after the occurrence of the dripping. The horizontal axis represents the elapsed time from the completion of the liquid suction and the tip of the nozzle tip 30 has moved away from the liquid surface, and the vertical axis represents the amount of pressure increase based on the piping system internal pressure at time 0. As shown in FIG. 3, after the nozzle tip 30 moves away from the liquid surface at time 0, the liquid sucked into the nozzle tip evaporates (vaporizes) with a slight amount, so that the internal pressure of the piping system gradually increases. To do. This increase in internal pressure increases exponentially as shown by the broken line in FIG. However, normally, in the process of the rise, the internal pressure of the piping system reaches the peak pressure Pmax at which liquid dripping occurs, and liquid dripping occurs. In the illustrated example, the internal pressure of the piping system reaches the peak pressure Pmax at time t1. In this case, the liquid is pushed out by the internal pressure, and liquid dripping occurs from the tip of the nozzle tip 30. After the occurrence of dripping, as shown in FIG. 3, the internal pressure of the piping system rapidly decreases. As described above, the internal pressure of the piping system usually increases exponentially, in other words, the rate of increase in internal pressure gradually decreases with the passage of time since liquid suction. This is presumably because, as time passes, the vicinity of the liquid level in the nozzle tip approaches a saturated state, and the evaporation rate becomes slower.

  In this embodiment, in order to prevent or reduce such dripping, the gas in the nozzle tip is discharged by the dispensing pump 16 in order to offset the above-described increase in internal pressure due to liquid evaporation from the completion of liquid suction to liquid discharge. Air suction is performed. This air suction is performed at an extremely low speed so that an air gap does not occur at the tip of the nozzle tip 30. By performing such an air suction operation, dripping can be prevented or reduced. However, the present invention, unlike the prior art, performs this air suction based on the air suction setting information stored in the storage unit 25 in advance.

  That is, conventionally, a technique has been proposed in which the piping system internal pressure after liquid suction is monitored by a pressure sensor, and air is sucked by the dispensing pump 16 so as to offset the increase in the internal pressure. However, in order to prevent dripping by such a method, a pressure sensor with high accuracy and excellent responsiveness is required, which causes an increase in cost. Further, the detected pressure value immediately after the completion of liquid suction may not show a correct value due to mechanical vibration or leakage of the piping system 14. Furthermore, there is a problem that the peak pressure at which liquid dripping occurs is not always constant depending on the liquid property and the state of the chip. For this reason, the conventional technology for sucking air in the piping system internal pressure according to the monitoring result cannot effectively prevent or reduce the dripping.

  On the other hand, in this embodiment, this air suction is performed based on air suction setting information stored in the storage unit 25 in advance. The air suction setting information includes air suction conditions defined in advance for each of various dispensing conditions (the shape of the nozzle tip 30, the type of liquid, the target suction amount, etc.), more specifically, the air suction speed va, the air amount upper limit. A value Va or the like is recorded, and is defined based on a prior experimental result or the like. And by carrying out air suction based on such pre-defined air suction conditions, dripping can be prevented or reduced more reliably.

  Here, prior to detailed description of the air suction setting information, various parameters related to the occurrence of dripping will be briefly described. First, the peak pressure, which is the internal pressure of the piping system 14 where dripping occurs, will be examined. The peak pressure Pmax at which liquid dripping occurs based on immediately after liquid suction can be estimated as Pmax = 2 × σ / (d / 2). Here, σ is the surface tension of the liquid, and d is the tip inner diameter of the nozzle tip 30. As is clear from this equation, it can be seen that the peak pressure depends on the type of liquid to be sucked (surface tension) and the type of nozzle tip 30 (inner diameter at the tip).

Further, when the amount of vapor at the time of dripping, that is, the limit vapor amount E is examined, the amount of evaporation E at that time is estimated as E = Pmax / P ₀ × V ₀ from the pressure immediately before the occurrence of dripping. it can. Here, V ₀ is a dead volume (a space volume in which no liquid exists) of the piping system 14 including the nozzle tip 30, and P ₀ is an atmospheric pressure. When the amount of steam generated in the nozzle tip reaches this limit steam amount E, dripping occurs.

  Here, the elapsed time (hereinafter referred to as “limit elapsed time Tmax”) until the dripping occurs (that is, the generated steam amount reaches the limit steam amount E) after the liquid suction is completed is around the nozzle tip 30. Depending on the environmental conditions such as temperature and humidity, the amount of liquid sucked into the nozzle tip also varies.

  FIG. 4 is a graph showing the difference in the limit elapsed time Tmax depending on the amount of liquid sucked into the nozzle tip. More specifically, FIG. 4 shows an experiment in which the limit elapsed time Tmax when distilled water is sucked using each nozzle tip 30 with the same shape and temperature is kept constant for each liquid suction amount. It is a graph which shows a result. In FIG. 4, the horizontal axis indicates the liquid suction amount, and the vertical axis indicates the limit elapsed time Tmax. The liquid suction amount is indicated as a percentage with respect to the capacity of the nozzle tip 30. For example, when the specified capacity of the nozzle tip 30 used in the experiment is 1000 μL, the amount of liquid suction when 200 μL of liquid is sucked is indicated as “20%”.

  As apparent from FIG. 4, when the liquid suction amount is less than 20% of the nozzle tip capacity, the liquid can be held in the nozzle tip for 90 seconds or more without causing dripping. On the other hand, when the liquid suction amount becomes 20% or more of the nozzle tip capacity, the limit elapsed time Tmax decreases, and it can be seen that dripping occurs in a relatively short time. However, when the liquid suction amount becomes 70% of the nozzle tip capacity, the limit elapsed time Tmax becomes slightly longer. When the liquid suction amount becomes 80% or more of the nozzle tip capacity, the limit elapsed time Tmax is greatly increased so that the liquid can be held in the nozzle tip for 180 seconds or more without causing dripping. Become.

  That is, when a small amount and a large amount of liquid are sucked, the limit elapsed time Tmax tends to be long, but when an intermediate amount of liquid is sucked, the limit elapsed time Tmax tends to be short. The reason for this tendency can be considered as follows. When the liquid suction amount is large, the air volume (dead volume) inside the nozzle tip is small. Therefore, the saturated state is approached at a relatively early stage, and further evaporation hardly occurs. As a result, the amount of evaporation generated is reduced, and it is considered that dripping does not easily occur. When the liquid suction amount is small, the air volume (dead volume) inside the nozzle tip increases, but the liquid surface area to be evaporated decreases. For this reason, it is considered that the evaporation rate becomes slow and liquid dripping hardly occurs.

  The air suction setting information is defined based on various experimental results performed in advance in consideration of various conditions related to the occurrence of dripping as described above. FIG. 5 is a diagram illustrating an example of air suction setting information used in the present embodiment. In FIG. 5, the value of each item is illustrated as “***”, but actually, specific numerical values are stored.

  As shown in FIG. 5, the air suction setting information defines air suction conditions (specifically, air suction speed va and air amount upper limit value Va) for each liquid suction amount (that is, target liquid suction amount). is doing. Moreover, this air suction condition is prepared for each type (shape) of the nozzle tip 30.

  Such air suction conditions are defined based on experiments conducted in advance. For example, for each liquid suction amount, the amount of increase in the internal pressure of the piping system after 5 seconds from the completion of liquid suction is measured. The liquid evaporation rate is estimated from the pressure increase. Then, an air suction speed va that can cancel this evaporation is obtained. Then, the obtained air suction speed va is compiled into a format as shown in the table of FIG. 5 and stored in the storage unit 25 as air suction setting information.

  Further, as described with reference to FIG. 3, when the vicinity of the liquid surface in the nozzle tip is saturated, the liquid hardly evaporates and the internal pressure does not increase. If air suction is continued in such a saturated state, an air gap may occur. Therefore, in the present embodiment, an upper limit value of the air suction amount Va is also set, and the air suction is stopped when the air suction amount reaches the upper limit value Va.

  Here, the air amount upper limit value Va is calculated and stored by an experiment performed in advance. That is, when the air amount upper limit value Va is defined, a change in internal pressure after liquid suction as shown in the graph of FIG. 3 is obtained in advance by experiments or the like. Then, from the change in the internal pressure, the internal pressure when the vicinity of the liquid surface in the nozzle tip becomes saturated, that is, when the change in the internal pressure almost disappears, is estimated. Then, based on the internal pressure at the time of saturation, the amount of steam at the time of saturation may be calculated, and the calculated amount of steam may be defined as the air amount upper limit value Va.

  The air suction setting information illustrated in FIG. 5 is an example, and other types of air suction setting information may naturally be used. For example, in this example, the amount of increase in internal pressure and the amount of evaporation after the elapse of 5 seconds are also stored, but these numerical values may not be used because they are not used for actual air suction operation control. Further, as long as at least the air suction speed va is stored, the air amount upper limit value Va may also be omitted.

  Further, in this example, the air suction speed va and the like are defined for each liquid suction amount and the type of the nozzle tip 30. However, even if air suction conditions are created for each environmental condition (temperature and humidity). Good. On the contrary, rather than prescribing air suction conditions corresponding to various dispensing conditions, only one air suction condition corresponding to a specific dispensing condition is prescribed, and when actually dispensing An air suction parameter may be obtained by multiplying the one air suction condition by a correction count corresponding to the dispensing condition. For example, only the air suction speed va and the air amount upper limit value Va when 100 μL of distilled water is sucked by the 1000 μL nozzle tip 30 are stored in the storage unit 25 as air suction conditions. When 100 μL of serum is actually sucked with 1000 μL nozzle tip 30 instead of distilled water, the stored air suction speed va and the air amount upper limit value Va are multiplied by a prescribed correction count to be suitable for serum. The air suction speed va and the air amount upper limit value Va may be corrected and used. In addition, other conditions, the amount of liquid suction, the type of nozzle tip 30, temperature, humidity, and the like may be similarly corrected by multiplying the correction coefficient as appropriate.

  Further, in this example, air suction setting information in a matrix format is illustrated, but the air suction speed va and the air amount upper limit value Va are set to the shape of the nozzle tip 30, the liquid suction amount, temperature, humidity, liquid type, and the like. What is expressed as a function of the above may be stored as air suction setting information.

  In the above description, only the case where the dispensing conditions (nozzle tip 30 types, liquid suction amount, temperature, humidity, liquid type) are constant and the air suction speed is also constant is illustrated. The air suction speed va may be varied evenly. For example, the air suction speed va may be varied in accordance with the elapsed time after the liquid suction with the nozzle tip 30 is completed.

  FIG. 6 is a diagram illustrating an example of an air suction speed va that can be employed in this case. In FIG. 6, the horizontal axis indicates the elapsed time since the completion of liquid suction, and the vertical axis indicates the air suction amount. A thick solid line in FIG. 6 indicates a change in the air suction amount when the air suction setting information illustrated in FIG. 5 is followed.

  Although the air suction speed may be constant as shown by the bold solid line, air suction is intermittently performed as shown by the broken line in FIG. 6 (in other words, the air suction speed va is set to zero and a constant value). It is also possible to change it repeatedly. Thus, by intermittently performing air suction, formation of an air gap can be effectively prevented or reduced.

  As another aspect, the air suction speed va may be changed in a plurality of stages (two stages in the illustrated example) as shown by a thin solid line in FIG. Thus, when changing to a several step | paragraph, it is desirable to make air suction speed va small, so that elapsed time becomes long. This is because as the elapsed time becomes longer, the liquid surface periphery in the nozzle tip approaches a saturated state, the evaporation rate becomes slower, and consequently the pressure increase rate becomes slower.

  In addition, the air suction speed va may be continuously changed as shown by a one-dot chain line in FIG. When continuously changing in this way, it is desirable to set the air suction speed so that the waveform of the air suction amount corresponds to the rising waveform of the piping system internal pressure shown by the broken line in FIG.

  In any case, as described above, an air suction speed va or the like that can prevent dripping is experimentally determined and stored in advance, and at the time of actual dispensing processing, the stored air suction speed va is used. By performing air suction, the rate of dripping and air gap can be greatly reduced.

  Next, the flow of the dispensing process in the dispensing apparatus 10 will be described in detail. Various modes of the dispensing process performed in the dispensing device 10 are conceivable. Here, the following three modes will be described. One is a one-to-one type in which a target liquid discharge amount of liquid is sucked once from the suction source container 100, the liquid is discharged once to the discharge destination container 102, and then the nozzle chip 30 is discarded and replaced. Note. The other is that the amount of liquid corresponding to the target liquid discharge amount × N is sucked from the suction source container 100 at a time, and the liquid is sequentially discharged to the N discharge destination containers 102. This is a 1-to-N dispensing system that is discarded and replaced. The last one is to suck the target liquid discharge amount from the suction source container 100 once and repeat the operation of discharging the liquid once to the discharge destination container 102 a plurality of times with the same nozzle tip 30, This is a re-suction type dispensing in which the nozzle tip 30 is discarded and replaced. Hereinafter, the flow of each dispensing process will be described in detail with reference to the drawings.

  7 and 8 are flowcharts showing the flow of the one-to-one type dispensing process. When performing one-to-one dispensing, the control unit 24 first sets a target liquid suction amount Vs based on various dispensing conditions input via the input unit 26 (S10). The target suction amount Vs is a value obtained by adding the excess amount e to the target liquid discharge amount Vdis. In FIG. 7 and FIG. 8, “N” means the discharge number command value, and N = 1 is always set in the case of one-to-one type dispensing.

  Subsequently, the control unit 24 stores various dispensing conditions (target suction amount, nozzle tip 30 type, liquid type, temperature, humidity, etc.) input via the input unit 26 and the storage unit 25. An air suction parameter is set based on the current air suction setting information (S12). That is, the control unit 24 determines the air suction speed va and the air amount upper limit value Va corresponding to the input dispensing conditions, and temporarily stores them in the memory.

  Subsequently, the control unit 24 drives the moving mechanism 20 to move the nozzle unit 12 to the suction source container 100 (S14). More specifically, first, the nozzle portion 12 is moved horizontally to be positioned immediately above the suction source container 100. Subsequently, the nozzle unit 12 is lowered, and the tip of the nozzle tip 30 is lowered to the vicinity of the liquid level of the suction source container 100.

  If the tip of the nozzle tip 30 is located near the liquid level, the control unit 24 then drives the dispensing pump 16 to start liquid suction by the nozzle tip 30 (S16). This liquid suction is performed until the suction amount reaches the target liquid suction amount Vs calculated in step S10. When the liquid suction is completed, the control unit 24 then drives the moving mechanism 20 to raise the nozzle unit 12 and separate the tip of the nozzle tip 30 from the liquid level (S18).

  After that, the nozzle unit 12 is moved to the discharge destination container 102 (S20). That is, after raising the nozzle part 12 to the uppermost point of the nozzle axis, it is horizontally moved to a position directly above the discharge destination container 102, and finally the nozzle part 12 is lowered to the discharge height.

  In parallel with the movement of the nozzle unit 12, the control unit 24 drives the dispensing pump 16 to execute air suction (S22). That is, the dispensing pump 16 sucks air in the nozzle tip at the air suction speed va calculated in step S12. As described above, the air suction speed is a speed that can offset the increase in internal pressure accompanying the evaporation of the liquid in the nozzle tip. Therefore, by performing this air suction, it is possible to prevent an increase in the internal pressure of the nozzle tip 30, and as a result, it is possible to prevent liquid dripping accompanying an increase in the internal pressure. Further, since the air suction speed va is set at a very low speed so as not to suck air more than necessary, the occurrence of an air gap is prevented or reduced.

  Here, such air suction is particularly effective when the movement of the nozzle portion 12 is temporarily stopped due to some error. That is, normally, when any error occurs during the movement of the nozzle unit 12, the control unit 24 responds appropriately to the error according to the message presented via the output unit 28. Until the movement of the nozzle portion 12 is temporarily stopped. This pause time may range from several minutes to several tens of minutes. When such a long stop occurs, liquid evaporation in the nozzle tip increases, and the possibility of dripping increases. However, as in this embodiment, by taking air suction in consideration of liquid evaporation, even if the nozzle unit 12 is stopped during the movement for a long time, dripping or the like can be effectively prevented. it can.

  If the nozzle unit 12 reaches the discharge destination container 102 (Yes in S24), the control unit 24 stops driving the dispensing pump 16 and ends the air suction operation (S26). Although not shown in the flowchart of FIG. 8, prior to the nozzle unit 12 reaching the discharge destination container 102, the air suction amount Vkn (n means the number of discharges. In this case, air suction is also stopped when n = 1) always reaches a predetermined upper limit value Va (when Vkn> Va). This is because when the upper limit value Va is reached, the vicinity of the liquid surface in the nozzle tip approaches a saturated state, and it is considered that further liquid evaporation does not occur. Then, by stopping air suction when the upper limit value Va is reached in this way, it is possible to effectively prevent the occurrence of an air gap due to excessive air suction.

  Next, the control unit 24 drives the dispensing pump 16 to discharge the liquid held in the nozzle tip to the discharge destination container 102 (S28). Here, the liquid discharge amount (movement amount of the plunger 42 of the syringe pump) is set to the target liquid discharge amount Vdis specified by the user or the air suction amount Vkn up to the present time is added to the target liquid discharge amount Vdis. The optimum value may be selected as appropriate according to the characteristics of the dispensing pump 16 or the like.

  If the specified amount of liquid can be discharged, the moving mechanism 20 is driven to raise the nozzle unit 12 and move the nozzle tip 30 away from the liquid surface of the discharge destination container 102 (S30). As a result, one ejection process is completed once.

  When the discharge process is completed, the control unit 24 determines whether or not the designated dispensing operation has been completed (S32). In the case of the one-to-one type dispensing in which the nozzle tip 30 is discarded and replaced after being discharged once into one discharge destination container 102, the determination in this step S32 is always Yes. Therefore, if the liquid ejection is completed once, the process proceeds to steps S34 and S36.

  When the discharge process is completed, the control unit 24 drives the moving mechanism 20 to move the nozzle unit 12 to the chip disposal position (S34). More specifically, the nozzle unit 12 is raised to the uppermost point of the nozzle axis, horizontally moved to a position just above the tip discarding position, and then lowered to the tip discarding position. Even in the movement process to the tip disposal position, the liquid remaining in the nozzle tip may be dripped. Therefore, in the present embodiment, the air suction operation is executed even in the movement process to the chip disposal position (S36). However, the amount of liquid remaining in the nozzle tip after liquid ejection is often a relatively small amount (theoretically, only the excess amount e), and the evaporation amount is also very small. Therefore, in some cases, this air suction operation (S36) may be omitted when moving to the tip disposal position. If the tip disposal position is reached, the nozzle tip 30 is detached from the tip mounting portion 32 and discarded (S38). Then, the one-to-one type dispensing process is completed.

  Next, the liquid corresponding to the target liquid discharge amount × N is sucked from the suction source container 100 at a time, and the liquid is sequentially discharged to the N discharge destination containers 102, and then the nozzle chip 30 is discarded. The flow of 1-to-N dispensing to be exchanged will be described with reference to the same FIGS.

  Even in the case of 1 to N dispensing, the rough flow is almost the same as in the 1 to 1 dispensing. However, in the case of one-to-N dispensing, steps S20 to S32 are repeated until the designated number N of discharge processes is completed, which is slightly different from the case of one-to-one dispensing.

  That is, if the liquid ejection process is completed in step S30, the control unit 24 determines whether or not the designated dispensing operation has been completed (S32). At this time, if the number n of discharges so far has not reached the designated discharge number command value N, the process proceeds to step S12a. In step S12a, the air suction parameter is reset.

  That is, immediately after the completion of the liquid ejection, it is expected that the liquid remaining on the inner wall of the nozzle chip 30 evaporates instantaneously. Further, the vicinity of the liquid level after the liquid discharge is separated from the liquid level before the discharge that has approached the saturated state, and is often in a non-saturated state. Therefore, it is conceivable that the evaporation rate that has gradually decreased after the liquid is sucked is greatly increased after the liquid is discharged.

  Therefore, in the case of one-to-N dispensing that repeats liquid discharge a plurality of times, each time liquid is discharged, air suction parameters are reset based on the amount of remaining liquid in the nozzle tip after the liquid is discharged. I am doing so.

  Various resetting methods are conceivable. In the simplest method, the liquid remaining amount Vsn in the nozzle tip at the time of completion of ejection is assumed to be the target liquid suction amount Vs (Vs = Vsn), and the air amount upper limit value Va = Va1 in the same procedure as step S12. (Vsn) and calculating the air suction speed va = va1 (Vsn). However, even when the liquid remaining amount is 100 μL immediately after the suction (at the time of S18) and when the liquid remaining amount after the first liquid discharge (S30) is 100 μL, the liquid remaining amount is the same. It can be inferred that the evaporation rate is slightly different. For example, since the liquid remains attached to the inner wall of the nozzle chip 30 after the liquid is discharged, the contact area between the liquid and air is larger when 100 μL remains after the liquid is discharged than when 100 μL remains immediately after the suction. It is likely that the evaporation rate will temporarily increase. Further, even after the same liquid is discharged, the vapor amount in the nozzle tip tends to be larger in the second time than in the first time and in the third time than the second time, and the evaporation speed may be slow. When the difference in evaporation rate or the like can be grasped to some extent by experiments or the like according to the progress of dispensing, the air suction speed or the like may be varied according to the progress. In the present embodiment, the air suction speed va is determined based on the discharge amount Vdis and the remaining liquid amount Vsn immediately after the discharge. Further, the air amount upper limit value Va is determined based on the discharge amount Vdis, the remaining liquid amount Vsn immediately after the discharge, and the total air suction amount ΣVkn sucked so far.

  If the air suction parameter can be reset, steps S20 to S32 are executed again. At this time, the air suction in step S22 is performed using the reset air suction parameter. Finally, when the discharge processing for the designated number N is completed (Yes in S32), the control unit 24 moves the nozzle unit 12 to the chip disposal position while performing air suction (S34, S36), The nozzle tip 30 is discarded. Then, the 1-to-N dispensing process is completed.

  Next, the flow of the re-suction dispensing process in which the liquid suction / discharge process is repeated N times with the same nozzle tip 30 will be described with reference to FIGS.

  Also in the case of re-suction dispensing, the flow (S10 to S30) until the first liquid discharge is completed is substantially the same as the above-described 1 to N dispensing. On the other hand, after the completion of the first liquid discharge, when the determination of whether or not the dispensing is completed (S32) is No, processing slightly different from the one-to-N dispensing is performed.

  That is, when the dispensing operation is not completed, the control unit 24 resets the air suction parameter (S12b). In this embodiment, the air suction speed va is determined based on the discharge amount Vdis and the residual liquid amount Vsn immediately after discharge (theoretically, only the excess amount e). Further, the air amount upper limit value Va is determined based on the discharge amount Vdis, the residual liquid amount Vsn immediately after discharge (theoretically, only the excess amount e), and the total air suction amount (ΣVkn + ΣVjn) sucked so far. Yes.

  Then, based on the set value obtained by the resetting, the nozzle portion 12 is moved so that the tip of the nozzle tip 30 is positioned in the vicinity of the liquid surface of the suction source container 100 while performing air suction (S40 to S44). . When the movement of the nozzle unit 12 is completed (Yes in S44), the air suction is finished (S46), and the liquid remaining in the nozzle tip 30 is discharged to the suction source container 100 (S48). Thereafter, the air suction setting parameters used for the next liquid suction / discharge are reset (S12c). If the air suction setting parameter can be reset, steps S16 to S32 are repeated again. Finally, when N times of liquid suction / discharge, which is the number of times designated by the user, are completed, the nozzle portion 12 is moved to the tip discarding position while performing air suction, and the nozzle tip 30 is discarded ( S34-S38). This completes the re-suction dispensing process.

  As is apparent from the above description, according to the present embodiment, after the liquid suction, an air suction parameter that can cancel the increase in internal pressure accompanying the evaporation of the liquid in the nozzle tip is determined in advance, and the nozzle is determined according to the air suction parameter. Air suction inside the chip is performed. Thereby, even if it does not provide a highly accurate pressure sensor etc., generation | occurrence | production of a liquid dripping and an air gap can be prevented or reduced effectively. In addition, as is clear from the above description, in the present embodiment, if the processing progress status is viewed from another viewpoint, the air flow is appropriately changed according to the change in the remaining liquid amount in the nozzle tip accompanying the liquid suction / discharge. The suction parameter value is reset. As a result, an increase in the internal pressure in the nozzle tip can be prevented more accurately, and as a result, dripping and occurrence of an air gap can be more effectively prevented or reduced.

  10 dispensing device, 12 nozzle section, 14 piping system, 16 dispensing pump, 18 pump drive section, 20 moving mechanism, 22 pressure sensor, 24 control section, 25 storage section, 26 input section, 28 output section, 30 nozzle tip , 32 Chip mounting part, 34 piping, 40 cylinder, 42 plunger, 50 rack, 100 suction source container, 102 discharge destination container.

Claims (6)

A dispensing device for sucking and discharging liquid,
A nozzle in which the liquid is held,
A moving mechanism for moving the nozzle;
A pump for performing liquid suction and discharge at the nozzle by changing the internal pressure of the piping system including the nozzle;
At least air suction conditions including an air suction speed in the nozzle that can offset an increase in internal pressure due to liquid evaporation occurring in the nozzle between the completion of liquid suction at the nozzle and the start of liquid discharge are preliminarily set as air suction setting information. Memorized storage means;
Control means for controlling driving of the moving mechanism and the pump, wherein the pump performs air suction under an air suction condition defined in the air suction setting information between completion of liquid suction at the nozzle and start of liquid discharge. Control means for instructing
A dispensing device comprising: The dispensing device according to claim 1,
The air suction condition further includes an upper limit value of the amount of air to be sucked,
The control means stops the air suction even before the liquid discharge is started when the air suction amount sucked by the air suction reaches the upper limit value.
A dispensing device characterized by that. The dispensing apparatus according to claim 1 or 2,
The air suction setting information stores a plurality of different air suction conditions for each liquid suction condition at the nozzle,
The control unit selects air suction conditions suitable for the actually performed liquid suction based on the conditions of the actually performed liquid suction.
A dispensing device characterized by that. A dispensing device according to claim 3, wherein
The liquid dispensing condition includes at least one of a liquid suction amount, a liquid type, a nozzle type, temperature, and humidity. A dispensing device according to any one of claims 1 to 4, wherein
The dispensing device according to claim 1, wherein the air suction speed is a variable value that changes in accordance with an elapsed time from the completion of the liquid suction. A dispensing device according to any one of claims 1 to 5,
The said control part resets the said air suction conditions, when the liquid quantity in the said nozzle changes with progress of a dispensing process, The dispensing apparatus characterized by the above-mentioned.

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