JP2002340915A - Dispenser and dispensing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the formation of a liquid ball at the point of time of completion of discharge while improving liquid drainage in a dispenser. SOLUTION: The leading end surface 16 of a dispensing nozzle 12 is set to the height separated from a liquid surface 14 by an offset distance Δh at the point of time of completion of discharge. The offset distance Δh is set so as to be not more than the maximum value of the size of the liquid ball formed on the leading end surface 16 of the dispensing nozzle 12. The level of the liquid surface 14 is calculated on the basis of the shape data or the like of a container or actually measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispensing apparatus and a dispensing method, and more particularly to a positioning control of a dispensing nozzle at the time of discharge.

[0002]

2. Description of the Related Art As a conventional discharge method in a dispensing apparatus, a submerged discharge method and an air discharge method are known. In the former submerged discharge method, the tip of the dispensing nozzle is placed in the first
Immersed (entered) below the surface of the liquid (eg, blood)
And performs the discharging of the liquid (e.g., reagents). The latter air discharge method discharges the second liquid by sufficiently separating the tip of the dispensing nozzle from the liquid surface of the first liquid in the container.

[0003]

According to the above-mentioned submerged discharge method, since the dispensing nozzle touches the first liquid in the container,
Contamination occurs. That is,
When the second liquid is sequentially discharged to a plurality of containers, there is a problem that the first liquid is mixed between the containers. For this reason, it is possible to configure the dispensing nozzle as a disposable type and to replace the dispensing nozzle for each dispensing (each discharge), but it is uneconomical.

On the other hand, according to the aerial discharge method, such a problem of contamination can be prevented because the discharge is performed at a position sufficiently distant from the liquid surface. There is a problem that a liquid ball is easily formed at the tip, and the dispensing accuracy is reduced due to the formation of the liquid ball, and the liquid ball falls or scatters while the dispensing nozzle is moving. In order to cope with this, it is conceivable to control the operation of the dispensing pump to be reversed at the time of the completion of the discharge so that a part of the liquid is sucked back to prevent the formation of liquid droplets. It is difficult to perform the control, and particularly when the viscosity is high, such control may cause a liquid ball.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to improve liquid shortage at the time of ejection.

Another object of the present invention is to prevent contamination and to prevent the formation of liquid droplets.

[0007]

(1) In order to achieve the above object, the present invention provides a dispensing nozzle for sucking and discharging a liquid, a dispensing pump connected to the dispensing nozzle, A transport mechanism that positions the height of the dispensing nozzle, and a control unit that controls the dispensing pump and the transport mechanism, wherein the control unit is at least at the time of discharge completion,
The tip surface level of the dispensing nozzle is higher than the liquid level of the discharge destination container, and the offset distance from the tip surface level to the liquid level is smaller than the liquid ball size that can occur at the tip of the dispensing nozzle. The height of the dispensing nozzle is positioned so as to be smaller.

According to the above arrangement, when the liquid is sucked into the dispensing nozzle and the liquid is discharged into the container, the distance from the liquid level in the container to the tip surface of the nozzle at least at the completion of the discharge. (Offset distance) is set so that it is smaller than the size of the liquid droplet, preventing the nozzle from entering the liquid in the container and preventing the liquid droplet from being finally formed. it can. That is, at the time of completion of the discharge, the nozzle end face is closely opposed to the liquid surface, so that the last liquid discharge is improved. Therefore, it is possible to obtain an advantage that the ejection accuracy can be improved, and that the liquid ball can be prevented from dropping and scattering during transport of the dispensing nozzle. In the case where the ejection is performed in a state where the nozzle tip is inserted below the liquid level, bubbles are easily generated by air ejection after the entire amount is ejected. However, the above configuration has an advantage that such bubbles can be prevented from being generated. .

Here, the size of the liquid droplet corresponds to the vertical length of the (maximum) liquid droplet that can be generated on the distal end surface of the dispensing nozzle. Surface shape, etc.), the material of the dispensing nozzle, the physical properties of the liquid (especially the viscosity), etc. In the dispensing device, a dispensing nozzle having known characteristics (form and material) is used,
Further, since the liquid to be dispensed is also substantially uniform, the maximum size of the liquid droplet formed on each dispensing nozzle can be regarded as substantially constant. Therefore, such a liquid droplet size is predetermined as a discharge control parameter for each dispensing nozzle by an execution test or the like, and discharge control is performed using the predetermined size.

Preferably, the control section includes a liquid level estimating means for estimating the liquid level from the discharge amount, and a tip level determining means for determining the tip level based on the estimated liquid level. Means. Preferably, the control unit includes a liquid level measuring unit that measures the liquid level, and the control unit includes a tip surface level determining unit that determines the front surface level based on the measured liquid level.

Liquid level (particularly liquid level at the end of discharge)
Can be specified by calculation from the discharge amount up to that time using the container shape data, or can be actually measured using a liquid level sensor. In the case of the former method, if another liquid has already been injected before ejection, it is necessary to grasp the liquid level or the liquid amount of the liquid in advance. In contrast, when discharging liquid to an empty container,
The liquid level can be specified from the shape and discharge amount of the container.

Preferably, the offset distance is 0.1
It is set in a range of 1.0 mm. The maximum size of the liquid droplet may be 1.0 mm, but there is a fluctuation due to various conditions.
It is desirable to set it to 0 mm or less, particularly to 0.5 mm or less. The lower limit of the offset distance is set to such an extent that non-contact can be ensured, though it depends on the positioning accuracy of the device.

[0013] Preferably, the control unit is configured such that, from a discharge start to a discharge end, the tip surface level is higher than the liquid level, and a distance from the tip surface level to the liquid level is the dispensing nozzle. The height of the dispensing nozzle is increased in accordance with the rise in the liquid level so as to be smaller than the liquid ball size that can be generated at the tip of the nozzle.

(2) Further, according to the present invention, in a dispensing method for discharging a liquid from a dispensing nozzle to a discharge destination container, an offset distance smaller than a maximum liquid ball size that can be generated on a tip end surface of the dispensing nozzle is set. It is characterized in that at least at the time of completion of the discharge, the offset distance is added to the liquid surface level of the discharge destination container to determine the tip end surface level of the dispensing nozzle.

The offset distance is specified in advance by an experiment or the like, and for example, is stored in a memory or the like in the apparatus, and is used for ejection control. That is, when determining the height position of the dispensing nozzle at the time of completion of ejection, the height of the nozzle tip surface level is determined as the level obtained by adding the offset distance to the expected or measured liquid level. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing the overall configuration of a dispensing apparatus to which the ejection method according to the present invention is applied.

In FIG. 1, a container 10 is formed of, for example, a transparent test tube, into which a liquid 11 such as a reagent or a sample is discharged. FIG. 1 shows a state at the time of completion of the discharge.

The dispensing nozzle 12 is, for example, a disposable tip constituted by a metal pipe or the like or a member such as a transparent resin. Using the dispensing nozzle 12, liquid can be sucked and discharged.

The dispensing pump 22 is connected to the dispensing nozzle 12 via a pipe 21 such as an air tube, and the operation of the dispensing pump 22 can generate a suction force and a discharge force for the liquid. The transfer mechanism 20 includes the dispensing nozzle 1
2 is transported three-dimensionally. In particular, the height of the dispensing nozzle 12 (tip surface 1
(Level 6). The control unit 24 controls the entire operation of the dispensing apparatus. In the present embodiment, a tip level calculation unit 28 is shown as a function of the control unit 24. In the memory 26, shape data relating to the container 10 is stored, and an offset distance Δh described later in detail is stored. Advanced level calculator 2
8 is based on the shape data and the offset distance Δh,
In the ejection step, the level of the tip surface of the dispensing nozzle 12 is determined. Here, the shape data is data indicating the relationship between the ejection amount and the liquid level. That is, the dispensing nozzle 12
This is data for calculating the level of the liquid surface 14 of the liquid 11 from the discharge amount when performing discharge. The offset distance Δh is, for example, determined in advance by an experiment or the like, and is smaller than the maximum liquid droplet size that can occur on the tip end surface 16 of the dispensing nozzle 12 for the liquid to be dispensed in the dispensing nozzle 12. It is set to the value. Desirably, the offset distance Δh is set to 0.
The value is set within a range of 1 mm to 1.0 mm. Of course, the offset distance Δh may be changed according to the form of the dispensing nozzle 12 or the like, or may be changed according to the physical properties of the liquid to be dispensed.

In the dispensing apparatus of the present embodiment, the liquid to be dispensed is biological blood (particularly serum), and an offset distance Δh corresponding to the sample is set in advance.

In the configuration example shown in FIG. 1, the liquid level of the liquid 11 is obtained by calculation, but it is needless to say that the liquid level is actually measured, and the discharge control may be performed based on the measured liquid level.

FIG. 2 conceptually shows the liquid ball 29 described above. When the ejection of the nozzle 12 is completed, a liquid ball 29 is formed on the tip end surface 16 of the nozzle 12 according to various conditions. In a state where the liquid ball 29 is formed, when the nozzle 12 is lifted upward and conveyed, the liquid ball 29
This causes the problem of falling and scattering. Therefore, in the present embodiment, the offset distance Δh is set to be equal to or less than the maximum size S of the liquid ball 29, and the tip level is determined as the height obtained by adding the offset distance Δh to the calculated or measured liquid level. At the time of completion of discharge, the liquid ball 29 can be sucked to the liquid surface side.

This is shown in FIGS. 3 and 4.
At the time of completion of the ejection, even if a liquid ball is to be formed by causing the front end face 16 to face the liquid surface 14 with the above-described offset distance Δh, the portion adheres to the liquid surface 14 side. , It is taken into the liquid level 14 by surface tension. Therefore, the dispensing nozzle 12
The liquid is completely cut off from the tip surface 16 of the dispensing nozzle 1
2 can be raised, so that the above-described problems such as dropping or scattering of the liquid ball 29 can be solved.

By the way, if the tip of the dispensing nozzle 12 is immersed in the liquid surface 14 and discharge is performed, the nozzle 12
The liquid easily adheres to the outer surface of the liquid crystal, and as a result, a problem such as the formation of a liquid ball and the above-described contamination occurs. In the present embodiment, however, such a problem also occurs because the offset distance Δh is determined. Can be prevented.

FIG. 5 is a graph showing the discharge control performed by the control unit 24 during discharge. In this graph, the horizontal axis is the time axis, and the vertical axis is the relative height h with the origin at the bottom of the inner surface of the container. In the figure, reference numeral 104 indicates a change in liquid level from the start of discharge to the end of discharge. Reference numeral 100 indicates a change in the tip level when the follow-up control is performed by gradually raising the tip level from the start of ejection in relation to the ejection amount. According to such discharge control, the tip level is always positioned above the offset distance Δh in relation to the liquid level. Then, at or immediately after the completion of the ejection, the dispensing nozzle 12
Is raised upward.

Reference numeral 102 denotes another discharge control example. According to this control example, the tip level at the time of completion of discharge is determined in advance, and the dispensing nozzle 1 is set there.
A series of ejections are performed in a state where the front end face of the dispensing nozzle 2 is positioned, and finally, the dispensing nozzle 12 is pulled upward at the time of completion of ejection or immediately thereafter. In any case, the offset distance is set at the time when the ejection of the liquid droplet is completed, that is, the tip surface of the nozzle is opposed to the liquid surface with a small space therebetween. This has the advantage that the formation of can be prevented. Incidentally, the discharge amount in one discharge step is set in advance by a program or the like, and the dispensing speed is also known. Therefore, the liquid level at each point in the discharge process can be calculated by calculation.

In the above embodiment, the liquid level was obtained by calculation, but it is also possible to actually measure the liquid level of the liquid. This is shown in FIGS. In the example shown in FIG. 6, a light-emitting device 30 and a light-receiving device 32 are provided on both sides of the container 10, and by transmitting and receiving the measuring light 34 between them,
Is scanned in the vertical direction, the height of the liquid surface 14 can be determined based on the changing point of the transmitted light amount. Although the transmitted light method is shown in FIG. 6, the liquid level may be measured from the side using the reflected light method.

FIG. 7 shows an example in which the liquid level is measured from above. In this example, the block 3 provided on the base end side of the dispensing nozzle 12 is shown.
6 is provided with an ultrasonic distance sensor 38, which emits an ultrasonic wave 40 downward from the ultrasonic distance sensor 38 and receives the reflected ultrasonic wave 40 by the ultrasonic distance sensor 38, thereby transmitting and receiving the ultrasonic wave. The height of the liquid surface 14 is measured from the time according to the above. Of course, the level of the liquid surface 14 may be optically measured instead of the ultrasonic method shown in FIG. Performing such a non-contact type liquid level measurement has the advantage that the liquid level is measured with high precision without causing contamination and the like, so that the above-described discharge control can be performed with higher precision.

Incidentally, in each of the above embodiments,
Although the case of discharging liquid to an empty container has been described,
Of course, the same method as described above can be applied to the case where another liquid is ejected in advance while another liquid is ejected in advance. In this case, the total liquid level can be easily calculated from the shape and the discharge amount of the container by grasping the amount of the liquid injected first. Further, if the liquid level is actually measured, the above-described ejection method can be applied without necessarily grasping the liquid amount of the liquid previously injected.

[0031]

As described above, according to the present invention,
It is possible to make the liquid shortage at the time of discharge favorable. As a result, dispensing accuracy and dispensing reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a dispensing apparatus to which a discharge method according to the present invention is applied.

FIG. 2 is a diagram for explaining formation of a liquid ball.

FIG. 3 is a diagram for explaining the adsorption of a liquid ball to a liquid surface.

FIG. 4 is a diagram for explaining adsorption of a liquid ball to a liquid surface.

FIG. 5 is a diagram for explaining operating conditions during ejection control.

FIG. 6 is a diagram showing a method for measuring a liquid level.

FIG. 7 is a diagram showing another method of measuring the liquid level.

[Explanation of symbols]

Reference Signs List 10 container, 11 liquid, 12 dispensing nozzle, 14 liquid level, 16 tip surface, 20 transport mechanism, 21 piping, 22
Dispensing pump, 24 control unit, 26 memory, 28 tip level calculation unit.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 2G052 AD06 AD26 BA14 CA04 CA11 CA28 CA31 CA32 HA08 HA12 HA13 HA19 HC02 HC07 HC32 JA09 2G058 EA02 ED21 ED25 ED31 GB03 GB06 GE02

Claims (6)

[Claims] A dispensing nozzle for sucking and discharging a liquid; a dispensing pump connected to the dispensing nozzle; a transport mechanism for positioning a height of the dispensing nozzle; A control unit that controls a transport mechanism, wherein at least at the time of completion of the discharge, the tip surface level of the dispensing nozzle is higher than the liquid level of the discharge destination container, and from the tip surface level. A dispensing device, wherein the height of the dispensing nozzle is positioned so that an offset distance to the liquid level is smaller than a liquid ball size that can be generated at the tip of the dispensing nozzle. 2. The apparatus according to claim 1, wherein the control unit includes: a liquid level estimating unit configured to estimate the liquid level from the discharge amount; and the tip level based on the estimated liquid level. And a tip surface level determining means for determining the tip surface level. 3. The apparatus according to claim 1, further comprising a liquid level measuring unit for measuring the liquid level, wherein the control unit determines the tip level based on the measured liquid level. A dispensing device comprising tip level determining means. 4. The dispensing device according to claim 2, wherein the offset distance is set within a range of 0.1 to 1.0 mm. 5. The apparatus according to claim 1, wherein the control section is configured such that, from a discharge start to a discharge end, the tip surface level is higher than the liquid level, and from the tip surface level to the liquid level. So that the distance is smaller than the liquid droplet size that can occur at the tip of the dispensing nozzle,
A dispensing apparatus characterized by increasing the height of the dispensing nozzle following the rise in the liquid level. 6. A dispensing method for discharging a liquid from a dispensing nozzle to a discharge destination container, wherein an offset distance smaller than a maximum liquid ball size that can occur on a tip end surface of the dispensing nozzle is determined, and at least the discharge is completed. A dispensing method, wherein at the time point, the tip surface level of the dispensing nozzle is determined by adding the offset distance to the liquid level of the discharge destination container.