JP2004245697A - Dispensing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispensing apparatus for determining whether a gas is leaked from a junction between a nozzle tip and a tip mount without sucking a liquid into the nozzle tip. <P>SOLUTION: In the dispensing apparatus, a control means 13 delivers the gas from a pump 7 while a tip opening of the nozzle tip is immersed in the liquid before the liquid is sucked into the nozzle tip, and controls operation of the pump 7 and a nozzle movement means 15 for implementing a process for pressurizing the nozzle tip within a range in which bubbles do not generate from the tip opening. A leakage determination means 17 determines whether the gas is leaked from the junction between the nozzle tip and the tip mount based on air pressure detected by a pressure sensor 16 for detecting the air pressure within the nozzle tip after the process for pressurizing the nozzle tip. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dispensing device.
[0002]
[Prior art]
2. Description of the Related Art A dispensing apparatus which is mounted with a disposable nozzle tip and inhales and discharges a liquid from an opening at the tip (opening at a lower end) of the nozzle tip is widely used. The nozzle tip is mounted by inserting and fitting the tip mounting portion of the dispensing device into the base end opening (upper end opening). The joint between the nozzle tip and the tip mounting part needs to be fitted airtight so as not to cause air leakage. This is because if air leaks at this joint, the amount of liquid suction and the amount of discharge will be incorrect.
[0003]
However, since the nozzle tip is composed of a molded product made of a resin material, the shape of the base end opening may be inappropriate due to molding failure or the like. In some cases, air leakage may occur at the joint between the nozzle tip and the tip mounting portion. Therefore, the dispensing device detects the presence or absence of the air leak, and when the air leak occurs, discards the nozzle tip and replaces it with another nozzle tip.
[0004]
In the conventional dispensing apparatus, the detection of the presence or absence of the air leak is performed by detecting a change in pressure in the nozzle tip after sucking the liquid into the nozzle tip (for example, see Patent Document 1). . Then, when it is detected that there is an air leak, the sucked liquid is discharged back to the container, and then the nozzle tip is discarded and replaced with a new nozzle tip. In this case, the sucked liquid slightly adheres to the discarded nozzle tip and remains, so that the liquid is wasted. As a result, when the liquid is a specimen collected from a patient, there is a problem that the number of specimens is insufficient for necessary test items, and when the liquid is an expensive reagent, the cost increases. .
[0005]
[Patent Document 1]
JP-A-8-334516
[0006]
[Problems to be solved by the invention]
It is an object of the present invention to provide a dispensing apparatus capable of determining whether gas leaks from a joint between a nozzle tip and a tip mounting portion without sucking a liquid into the nozzle tip. .
[0007]
[Means for Solving the Problems]
Such an object is achieved by the present invention described in the following (1) to (5). Further, the following (6) to (10) are preferable.
[0008]
(1) A dispensing device for sucking / discharging a liquid from a tip opening of a removably mounted disposable nozzle tip,
A pump for sucking and discharging gas,
A tip mounting portion having an opening through which gas flows in and out by operation of the pump, and to which the nozzle tip is detachably mounted;
Moving means for moving at least the vertical direction of the chip mounting portion,
Control means for controlling the operation of the pump and the moving means,
Pressure detection means for detecting the air pressure in the nozzle tip mounted on the tip mounting portion,
Leak determining means for determining the presence or absence of gas leakage from the joint between the nozzle tip and the tip mounting portion,
The control means discharges gas from the pump in a state where the tip opening of the nozzle tip is immersed below the liquid surface before sucking the liquid into the nozzle tip, and does not generate bubbles from the tip opening. Controlling the operation of the pump and the moving means to perform a nozzle tip pressurizing step of pressurizing the nozzle tip in a range,
The dispensing apparatus according to claim 1, wherein the leak determining means determines whether or not gas has leaked from the joint based on the pressure detected by the pressure detecting means after the pressurizing step in the nozzle tip.
[0009]
(2) The leak judging means, when the air pressure detected by the pressure detecting means drops to a predetermined judgment value within a predetermined time after the pressurizing step in the nozzle tip, the gas leaking from the joint. The dispensing apparatus according to the above (1), wherein it is determined that there is a dispenser.
[0010]
(3) When the pressure detected by the pressure detecting means does not increase to a predetermined determination value during the pressurizing step in the nozzle tip, the leak determining means determines whether or not the gas from the joining portion has been discharged. The dispensing device according to (1) or (2), wherein it is determined that there is a leak.
[0011]
And (4) further comprising an exchange means for exchanging the nozzle tip mounted on the tip mounting portion, wherein when the leakage determination device determines that there is a gas leak from the joint portion, the nozzle mounting portion is mounted on the tip mounting portion. The dispensing device according to any one of the above (1) to (3), which operates to replace the nozzle tip.
[0012]
(5) further comprising a liquid level detecting means for detecting the liquid level of the liquid to be sucked based on the atmospheric pressure detected by the pressure detecting means,
A liquid level detecting step of, when discharging the gas from the pump, lowering a tip end opening of the nozzle tip toward a liquid level of the liquid to be sucked when trying to suck the liquid into the nozzle chip; Controlling the operation of the pump and the moving means to perform
The liquid level detecting means determines that the tip end opening of the nozzle tip is submerged below the liquid level when the pressure detected by the pressure detecting means increases in the liquid level detecting step. Detect the surface,
The leak determining means according to any one of (1) to (4), wherein the liquid level detecting step is used as the pressurizing step in the nozzle tip to determine whether or not gas leaks from the joint. Dispensing device.
[0013]
(6) A dispensing method in which a liquid is sucked and discharged from a tip opening of a disposable nozzle tip which is detachably mounted on a chip mounting portion having an opening through which gas flows in and out by operation of a pump for sucking and discharging gas. hand,
Prior to inhaling a liquid into the nozzle tip, the pump discharges gas from the pump in a state where the tip opening of the nozzle tip is submerged below the liquid level, and the nozzle tip is in a range that does not generate bubbles from the tip opening. Having a nozzle tip pressurizing step to pressurize the inside,
After the step of pressurizing the inside of the nozzle tip, the joining of the nozzle tip and the tip mounting portion is performed based on the pressure detected by the pressure detecting means for detecting the pressure inside the nozzle tip mounted on the chip mounting portion. Dispensing method characterized by determining the presence or absence of gas leakage from a part.
[0014]
(7) After the step of pressurizing the inside of the nozzle tip, when the air pressure detected by the pressure detecting means drops to a predetermined determination value within a predetermined time, it is determined that there is gas leakage from the joint. The dispensing method according to (6).
[0015]
(8) If the air pressure detected by the pressure detecting means does not rise to a predetermined determination value during the pressurizing step in the nozzle tip, it is determined that there is gas leakage from the joint. The dispensing method according to the above (6) or (7).
[0016]
(9) The dispensing method according to any one of (6) to (8), wherein when it is determined that gas leaks from the joint, the nozzle tip mounted on the tip mounting portion is replaced.
[0017]
(10) When a liquid is to be sucked into the nozzle tip, there is provided a liquid level detecting step of lowering the tip opening of the nozzle tip toward the liquid level of the liquid to be sucked while discharging gas from the pump. And
In the liquid level detection step, the liquid level is detected by determining that the tip end opening of the nozzle tip is submerged below the liquid level when the air pressure detected by the pressure detecting means rises, The dispensing method according to any one of (6) to (9), wherein a liquid level detecting step is used as the pressurizing step in the nozzle tip to determine whether or not gas leaks from the joint.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a dispensing device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
[0019]
1 is a perspective view showing an embodiment of the dispensing device of the present invention, FIG. 2 is a perspective view showing an x-axis direction moving means in the dispensing device shown in FIG. 1, and FIG. 3 is a dispensing device shown in FIG. FIG. 4 is a perspective view showing a y-axis direction moving unit, a z-axis direction moving unit, and a dispensing head in the apparatus. FIG. 4 is a longitudinal sectional view showing a pump, a tip mounting unit, and a nozzle tip in the dispensing apparatus shown in FIG.
[0020]
In the following description, for convenience of description, one horizontal direction (lateral direction of the apparatus) is an x-axis direction, a direction perpendicular and horizontal to the x-axis direction (front-back direction of the apparatus) is a y-axis direction, and a vertical direction (up-down direction). Direction) is called the z-axis direction. Further, in FIG. 1, details such as a dispensing head and an arm are omitted.
[0021]
As shown in FIG. 1, the dispensing device 1 includes a device main body 2 and a dispensing head 3 movably installed with respect to the device main body 2. This dispensing apparatus 1 dispenses a liquid parent sample (original sample) such as blood or serum collected from a patient, urine or the like, and subdivides (separates) it into a test child. This is a device that creates a specimen.
[0022]
The apparatus main body 2 includes a work table 21, a device storage unit 22 erected behind the work table 21, a second device storage unit 23 provided above the device storage unit 22, and a second device And a protruding portion 24 protruding forward from one side of the storage portion 23.
[0023]
On the work table 21, a plurality of containers, such as test tubes, for storing samples (liquids) are arranged (placed) side by side. In the present embodiment, a plurality of test tube racks 100 that hold a plurality of test tubes in an upright state in a matrix can be placed on the work table 21. The test tubes storing the parent sample and the test tubes storing the child sample are held in these test tube racks 100, respectively.
[0024]
A chip rack 200 can be placed behind the test tube rack 100 on the work table 21. The tip rack 200 can hold a plurality of disposable (disposable) nozzle tips 300 arranged in a matrix with the nozzle tips 300 standing upright.
[0025]
An arm 11 that supports the dispensing head 3 is installed on the apparatus main body 2. The arm 11 is disposed so that its longitudinal direction is in the y-axis direction, and its rear end is supported by the device housing 22. The device housing section 22 is provided with an x-axis direction moving means 4 described later, and by this operation, the arm 11 moves in the x-axis direction with respect to the apparatus main body 2.
[0026]
The dispensing head 3 is movably supported in the longitudinal direction of the arm 11, that is, in the y-axis direction. The dispensing head 3 moves in the y-axis direction with respect to the apparatus main body 2 by the operation of the y-axis direction moving means 5 described later.
[0027]
The dispensing head 3 can be moved in the xy plane in a space (work space) above the work table 21 by a combination of operations of the x-axis direction movement means 4 and the y-axis direction movement means 5.
[0028]
On the front surface of the protruding portion 24, a display means 25 constituted by, for example, a touch panel is provided. The display unit 25 displays, for example, an input screen for setting various conditions, and the operator touches the display unit 25 with a finger to set various conditions. The display unit 25 also displays information such as the state of the dispensing device 1 and occurrence of an error.
[0029]
As shown in FIG. 2, the x-axis direction moving means 4 includes a slide block (moving body) 41 movably installed along the x-axis direction by the guide of the guide rail 12 installed in the equipment storage unit 22. A drive pulley (belt wheel) 42 and a driven pulley (belt wheel) 43 installed near both ends of the guide rail 12, a pulse motor (stepping motor) 44 for rotating and driving the drive pulley 42, a drive pulley 42 and a driven pulley And a belt 45 looped around 43.
[0030]
The slide block 41 is fixed to a part of the belt 45 by a fixing portion 411 formed to project. The rear end of the arm 11 is fixed to the slide block 41.
[0031]
When the pulse motor 44 drives the drive pulley 42 to rotate, the belt 45 rotates, and the slide block 41 is moved by the belt 45 in the x-axis direction. Accordingly, the arm 11 also moves in the x-axis direction. The slide block 41 and the arm 11 move rightward or leftward with respect to the apparatus main body 2 by switching between forward rotation and reverse rotation of the pulse motor 44.
[0032]
The belt 45 is formed of a toothed belt having teeth that mesh with teeth formed on the outer peripheral surfaces of the driving pulley 42 and the driven pulley 43, and does not slip on the driving pulley 42 and the driven pulley 43. I have.
[0033]
As shown in FIG. 3, the y-axis direction moving means 5 includes a slide block (moving body) 51 movably installed along the longitudinal direction of the arm 11 by a guide rail (not shown), and a rear end of the arm 11. A drive pulley (belt wheel) 52 installed in the vicinity, a driven pulley (belt wheel) 53 installed near the front end of the arm 11, and a pulse installed near the rear end of the arm 11 to rotationally drive the drive pulley 52 It has a motor (stepping motor) 54 and a belt 55 wound around a driving pulley 52 and a driven pulley 53.
[0034]
The slide block 51 is fixed to a part of the belt 55. The frame 31 of the dispensing head 3 is fixed to the slide block 51.
[0035]
When the pulse motor 54 drives the drive pulley 52 to rotate, the belt 55 rotates, and the slide block 51 is pulled by the belt 55 to move in the longitudinal direction of the arm 11, that is, in the y-axis direction. Along with this, the dispensing head 3 also moves in the y-axis direction. The slide block 51 and the dispensing head 3 move forward or backward with respect to the apparatus main body 2 by switching the pulse motor 54 between normal rotation and reverse rotation.
[0036]
The belt 55 is formed of a toothed belt having teeth that mesh with teeth formed on the outer peripheral surfaces of the driving pulley 52 and the driven pulley 53, so that the belt 55 does not slip on the driving pulley 52 and the driven pulley 53. I have.
[0037]
The dispensing head 3 has a frame 31, which is a skeleton constituted by members elongated in the z-axis direction, and a tip mounting portion 32 on which the nozzle tip 300 can be mounted.
[0038]
As shown in FIG. 4, the chip mounting section 32 is formed of a substantially tubular member having a ventilation flow path 321 formed therein. The constituent material of the tip mounting portion 32 is preferably various metal materials such as stainless steel, aluminum or aluminum alloy, copper or copper-based alloy.
[0039]
The nozzle tip 300 is a tubular member (molded article) made of a synthetic resin material, and preferably has at least a tip (lower end) portion tapered. The nozzle tip 300 is removably mounted on the tip mounting section 32 by inserting and fitting the lower end of the tip mounting section 32 into its base opening (upper opening) 302. Further, it is preferable that the nozzle tip 300 is translucent or transparent (has a light transmitting property).
[0040]
As shown in FIG. 3, a pump 7 for sucking / discharging air (gas) is provided on a frame 31 of the dispensing head 3. In the present embodiment, the pump 7 is configured by a syringe pump (piston pump) having a cylinder 71 and a plunger (piston) 72. As shown in FIG. 4, the pump 7 and the upper end opening of the tip mounting portion 32 are connected by a flexible piping tube 33, and their internal spaces communicate with each other. When the pump 7 operates, air (gas) passes through the pipe tube 33, and air (gas) flows in and out of the lower end opening 322 of the tip mounting portion 32, thereby increasing and decreasing the pressure in the nozzle tip 300, The liquid can be sucked and discharged from the tip opening 301 of the nozzle tip 300.
[0041]
Pump driving means 14 for moving the plunger 72 of the pump 7 is provided on the frame 31 of the dispensing head 3. Although not shown, the pump driving means 14 is configured to move the plunger 72 with respect to the cylinder 71 by, for example, a ball screw (feed screw) mechanism and a pulse motor (not shown) for driving the mechanism. I have. The operation of the pump 7 is controlled by a control unit 13 described later via the pump driving unit 14.
[0042]
As shown in FIG. 4, the dispensing apparatus 1 is provided with a pressure sensor (pressure detecting means) 16 for detecting the air pressure inside the nozzle tip 300 mounted on the tip mounting section 32. In the present embodiment, the pressure sensor 16 detects the pressure in the nozzle tip 300 by detecting the air pressure in the pipe tube 33 communicating with the nozzle tip 300 attached to the tip attachment portion 32. I have. The pressure sensor 16 may be installed at any position as long as it communicates with the inside of the nozzle chip 300 mounted on the chip mounting section 32.
[0043]
The chip mounting portion 32 is installed so as to be movable in the z-axis direction with respect to the frame 31, and is moved (elevated and lowered) in the z-axis direction with respect to the apparatus main body 2 by the operation of the z-axis direction moving means 6.
[0044]
As shown in FIG. 3, the z-axis direction moving means 6 includes a slide block (moving body) 61 movably installed along the z-axis direction by a guide rail (not shown) with respect to the frame 31. It has driven pulleys (belt wheels) 62 and 63 installed near the upper end and the lower end, respectively, and a belt 64.
[0045]
The slide block 61 is fixed to a part of the belt 64 via a fixing member 67. The chip mounting section 32 is fixed to the slide block 61 via a support section 68.
[0046]
A drive pulley (not shown) for driving a belt 64 is provided inside the slide block 51. The belt 64 is wound around driven pulleys 62 and 63, and a slide block 51 is provided at an intermediate portion therebetween. It is drawn inside and is also hung around this drive pulley.
[0047]
The drive pulley in the slide block 51 is driven to rotate by a pulse motor (stepping motor) 65 installed near the rear end of the arm 11. That is, as shown in FIG. 3, a propeller shaft 66 extending along the longitudinal direction of the arm 11 is rotatably installed on the arm 11, and an output shaft of the pulse motor 65 is connected to the propeller shaft 66. ing. The propeller shaft 66 penetrates the slide block 51 and a drive pulley therein, and the slide block 51 moves in the y-axis direction with the propeller shaft 66 inserted. The drive pulley in the slide block 51 rotates with the propeller shaft 66 regardless of the position of the slide block 51 with respect to the propeller shaft 66.
[0048]
When the pulse motor 65 rotationally drives the drive pulley in the slide block 51 via the propeller shaft 66, the belt 64 rotates and is pulled by the belt 64, and the slide block 61 moves in the z-axis direction, that is, in the vertical direction. Along with this, the tip mounting section 32 and the nozzle tip 300 also move (up and down) in the z-axis direction. The tip mounting section 32 and the nozzle tip 300 move up or down by switching the pulse motor 65 between normal rotation and reverse rotation.
[0049]
In the following description, the x-axis direction moving unit 4, the y-axis direction moving unit 5, and the z-axis direction moving unit 6 are collectively referred to as a nozzle moving unit 15 for moving the chip mounting unit 32 in a three-dimensional direction. There is.
[0050]
The basic operation of such a dispensing device 1 is as follows. First, the nozzle moving means 15 is operated to move the dispensing head 3 above the container of the suction destination, and then the tip mounting section 32 and the mounted nozzle chip 300 are lowered to place the nozzle chip 300 in the container. insert. In this state, the pump 7 is operated to reduce the pressure in the nozzle tip 300, thereby sucking the liquid into the nozzle tip 300.
[0051]
Next, after raising the nozzle tip 300, the dispensing head 3 is moved to the position of the discharge destination container. Next, the nozzle chip 300 is lowered into the discharge destination container, and the pump 7 is operated to increase the pressure in the nozzle chip 300, thereby discharging the sucked liquid.
[0052]
Subsequently, when dispensing a different sample, the nozzle tip 300 is replaced as follows in order to prevent contamination. Removal of the used nozzle tip 300 is performed by moving the dispensing head 3 to the position of the tip remover 26 (see FIG. 3) installed in the apparatus main body 2. The chip remover 26 is a plate-shaped member having a notch 261 having a width into which the chip mounting portion 32 can be inserted with almost no gap. The chip mounting portion 32 is inserted into the notch 261 to raise the chip mounting portion 32. Then, the upper end of the nozzle tip 300 comes into contact with the lower surface of the tip remover 26, so that the nozzle tip 300 is detached from the tip mounting portion 32. Next, the dispensing head 3 is moved above the chip rack 200, and the tip mounting portion 32 is lowered toward the new nozzle chip 300 that is held upright, whereby the nozzle chip 300 is mounted on the chip mounting portion 32. As described above, the dispensing apparatus 1 includes the exchange means for exchanging the nozzle tip 300 mounted on the tip mounting section 32.
[0053]
FIG. 5 is a schematic block diagram of the dispensing apparatus shown in FIG. 1, FIG. 6 is a diagram showing a circuit configuration of the leak determination means, and FIG. 7 is a view showing a state in which the tip opening of the nozzle tip is submerged below the liquid level. FIG. 8 is an enlarged cross-sectional view, and FIG. 8 is a graph showing the air pressure in the nozzle tip when the in-nozzle tip pressurizing step is performed on the vertical axis and the time on the horizontal axis.
[0054]
As shown in FIG. 5, the dispensing apparatus 1 includes control means 13 for controlling the operation of each unit. The control unit 13 has a CPU (Central Processing Unit) 131 and a storage unit (storage unit) 132.
[0055]
The storage unit 132 has a storage medium (recording medium) that stores (records) programs, data, and the like, and is readable by the CPU 131. This storage medium is, for example, a RAM (Random Access Memory: including both volatile and nonvolatile), an FD (Floppy Disk (“Floppy” is a registered trademark)), an HD (Hard Disk), and a CD-ROM (Compact). It is composed of a magnetic or optical recording medium such as a disc read-only memory or a semiconductor memory. The storage medium is fixedly provided in the storage unit 132 or is detachably mounted. The storage medium includes various application programs corresponding to each unit of the dispensing apparatus 1, Various programs such as a program for performing a control operation and various data are stored in advance, and data processed by each program, input data from each unit connected to the control unit 13, and the like are stored.
[0056]
The control unit 13 is connected to a pump driving unit 14, a nozzle moving unit 15, and a display unit 25. The control unit 13 reads out various programs and data stored in the storage unit 132 as necessary, and controls the operations of these units based on the programs and data. Note that the control of the control unit 13 for the pump driving unit 14 and the nozzle moving unit 15 may be open loop control or closed loop control.
[0057]
Further, the control means 13 includes a leak determination means 17 for determining whether or not air (gas) leaks from a joining portion (fitting portion) J between the nozzle tip 300 and the tip mounting portion 32, and a detection by the pressure sensor 16. The liquid level detecting means 18 for detecting the liquid level S (the height of the liquid level S) of the liquid to be sucked in based on the obtained pressure is connected to each.
[0058]
Hereinafter, the liquid level detection process performed by the dispensing apparatus 1 will be described.
When a liquid is to be sucked into the nozzle tip 300, the dispensing apparatus 1 performs a liquid level detection step. In the liquid level detecting step, the control means 13 lowers the tip opening 301 of the nozzle chip 300 toward the liquid level S of the liquid to be sucked while discharging gas from the pump 7 from the state shown in FIG. Next, the operation of the pump 7 and the nozzle moving means 15 is controlled. That is, the nozzle tip 300 descends toward the liquid surface S while discharging air from the distal end opening 301.
[0059]
When the nozzle tip 300 descends and the tip opening 301 sinks below the liquid level S, the air in the nozzle tip 300 loses its escape place and is compressed by the pump 7 to increase the air pressure. Therefore, when the pressure detected by the pressure sensor 16 in the liquid level detecting step rises, the liquid level detecting means 18 can determine that the tip opening 301 of the nozzle tip 300 has submerged below the liquid level S, Thus, the liquid level S (the height of the liquid level S) is detected. The liquid level detecting means 18 is configured to make this determination by comparing the atmospheric pressure detected by the pressure sensor 16 or its time derivative with a predetermined determination value (reference value).
[0060]
When detecting the liquid level S, the liquid level detecting means 18 outputs a detection signal to the control means 13. The control unit 13 stops the lowering of the nozzle tip 300 based on the detection signal input from the liquid level detection unit 18 and starts the liquid suction operation. During the liquid suction operation, the position of the nozzle tip 300 may be kept stopped, or the tip opening 301 may be controlled so as to follow the lowering of the liquid level S.
[0061]
In the liquid level detection process as described above, the control means 13 pressurizes the inside of the nozzle chip 300 within a range in which no air bubbles are generated from the front end opening 301 after the tip opening 301 of the nozzle tip 300 is sunk below the liquid level S. The operation of the pump 7 is controlled and stopped as described above. This control can be performed as follows.
[0062]
As shown in FIG. 7, when the inside of the nozzle tip 300 is pressurized in a state where the tip opening 301 of the nozzle tip 300 is submerged below the liquid surface S, air protrudes outward from the tip opening 301 and the vicinity of the tip opening 301 , A substantially spherical liquid surface Q is formed. In this state, the air pressure inside the nozzle tip 300 becomes larger than the pressure outside the liquid surface Q due to the surface tension acting on the liquid surface Q. The pressure increment ΔP due to the surface tension of the liquid surface Q is obtained as 2σ / r, where σ is the surface tension of the liquid and r is the radius of curvature of the liquid surface Q. That is, ΔP increases as the radius of curvature of the liquid surface Q decreases.
[0063]
The radius of curvature of the liquid surface Q is smallest when the liquid surface Q projects hemispherically from the distal end opening 301 as shown in FIG. Assuming that the inner diameter of the distal end opening 301 is d, the radius of curvature r of the liquid surface Q at this time is d / 2. Therefore, the pressure increment ΔP due to the surface tension of the liquid surface Q is maximum when r = d / 2, and the maximum value is 4σ / d. Therefore, the pressure outside the liquid surface Q becomes the atmospheric pressure P ₀ In the state shown in FIG. 7, the pressure in the nozzle tip 300 becomes P ₀ + 4σ / d.
[0064]
In order to generate bubbles from the distal end opening 301, it is necessary to pressurize the inside of the nozzle tip 300 beyond the state shown in FIG. Therefore, conversely, after the tip end opening 301 of the nozzle tip 300 has sunk below the liquid level S, the pressure inside the nozzle tip 300 becomes P ₀ If the operation of the pump 7 is stopped before reaching + 4σ / d, it is possible to control so that bubbles are not generated from the tip opening 301.
[0065]
By the way, in such a dispensing apparatus 1, the control means 13 sends the liquid from the pump 7 in a state where the tip opening 301 of the nozzle chip 300 is immersed below the liquid surface S prior to sucking the liquid into the nozzle chip 300. An in-nozzle chip pressurizing step of discharging air and pressurizing the inside of the nozzle chip 300 within a range in which no bubbles are generated from the tip opening 301 is performed. Then, based on the air pressure detected by the pressure sensor 16 after the pressurizing step in the nozzle tip (when the pressurizing step in the nozzle tip is performed), the leak determining means 17 determines the nozzle tip 300 and the chip mounting section 32. It is determined whether or not air leaks from the joint J.
[0066]
In the present embodiment, the leak determination means 17 uses the liquid level detection step as a nozzle tip pressurizing step. Thereby, the liquid level detection and the determination of the presence or absence of air leakage from the joint J can be performed at the same time, the operation of the dispensing apparatus 1 can be rationalized, and the sample processing efficiency can be improved.
[0067]
The pressure in the nozzle tip 300 becomes P by the pressurizing step (liquid level detecting step) in the nozzle tip. ₁ When there is no air leak at the joint J when the air pressure rises, the air pressure in the nozzle tip 300 becomes P as shown by (1) in FIG. ₁ To maintain.
[0068]
On the other hand, when there is an air leak at the joint J, the air pressure inside the nozzle tip 300 becomes P 2 as shown by (2) in FIG. ₁ Should rise and then descend. Therefore, after the pressurizing step in the nozzle tip, the leak determining means 17 determines that the air pressure detected by the pressure sensor 16 is within a predetermined time within a predetermined determination value (reference value) P. _T If it has descended, it is determined that there is air leakage from the joint J (judgment method 1). The determination value P _T Is P ₀ <P _T <P ₁ Is satisfied, and a suitable value can be obtained and set empirically (experimentally).
[0069]
Further, the leak determination means 17 determines that the air pressure detected by the pressure sensor 16 when the in-nozzle chip pressurizing step is performed is equal to a predetermined determination value P. _T Even if it does not rise from the beginning (indicated by (3) in FIG. 8), it is determined that there is leakage of air from the joint J (determination method 2).
[0070]
In the present embodiment, the same determination value is used in the determination method 1 and the determination method 2, but different determination values may be used.
[0071]
When the leak determining means 17 determines that there is air leakage from the joint J, it is preferable that the control means 13 displays the fact on the display means 25 and notifies the operator of the fact.
[0072]
In the present invention, in the pressurizing step in the nozzle tip, as described above, the tip opening 301 of the nozzle tip 300 is immersed below the liquid surface S in the nozzle tip 300 within a range in which no bubbles are generated from the tip opening 301. Before the step of pressurizing the inside of the nozzle tip, air bubbles may be generated once or more than once from the tip opening 301 (one or more air bubbles may be generated). That is, after the tip opening 301 of the nozzle tip 300 is immersed below the liquid surface S, once or more (one or more) bubbles are generated from the tip opening 301, the in-nozzle tip pressurizing step is performed. You may.
[0073]
Next, a circuit configuration of the leak determination unit 17 will be described with reference to FIG.
In the present embodiment, the leak determination unit 17 uses the pressure sensor 16 also as a unit for measuring the atmospheric pressure. That is, the current signal representing the atmospheric pressure output from the pressure sensor 16 before the tip opening 301 of the nozzle tip 300 comes into contact with the liquid surface S is converted into a voltage signal by the current-voltage conversion circuit 171, and then the atmospheric pressure measurement is performed. ADC (Analog / Digital Converter) 172.
[0074]
The judgment value setting memory 174 stores the judgment value P _T Is stored in advance. A digital signal representing the set value data stored in the decision value setting memory 174 and a digital signal representing the atmospheric pressure data output from the ADC 172 for atmospheric pressure measurement are input to the determination value calculation unit 173. The determination value calculation unit 173 performs an arithmetic operation on the two to determine the determination value P. _T Is calculated.
[0075]
The calculated judgment value P _T Is converted into an analog signal (voltage signal) by a DAC (digital / analog converter) 175 and then input to a comparator 176. The current signal output from the pressure sensor 16 and representing the atmospheric pressure in the nozzle chip 300 is converted into a voltage signal by the current-voltage conversion circuit 171 and then input to the comparator 176.
[0076]
The comparator 176 compares the levels of the voltages of the above two input signals, and outputs a High level signal or a Low level signal to the determination unit 177 as a result. Based on the signal input from the comparator 176, the determination unit 177 determines the presence or absence of air leakage from the joint J according to the above-described determination methods 1 and 2, and sends a signal representing the determination result to the control unit 13. Output.
[0077]
When the leak determining means 17 determines that there is air leakage from the joint J, the control means 13 controls the dispensing apparatus 1 so that the nozzle tip 300 mounted on the tip mounting section 32 is replaced by the above-described method. Activate. As a result, the defective nozzle tip 300 that caused the air leak is discarded and a new nozzle tip 300 is mounted, so that the air leak from the joint J can be eliminated. Therefore, in the dispensing device 1, the liquid can be dispensed while always accurately controlling the suction amount and the discharge amount, and it is possible to prevent the dispensing amount from being disordered.
[0078]
In the present invention, the presence or absence of air leakage from the joint J is detected by the above-described method without sucking the liquid into the nozzle tip 300. Even if 300 is discarded, the amount of liquid remaining on the discarded nozzle tip 300 is substantially zero. Therefore, wasteful consumption of the liquid can be prevented. As a result, it is possible to prevent an inconvenience such as a shortage of samples for a required test item when the liquid is a sample collected from a patient, and when the liquid is an expensive reagent. In addition, it is possible to prevent the processing cost from increasing due to the large consumption of the reagent.
[0079]
Furthermore, according to the present invention, when air leaks from the joint J, it is not necessary to perform an operation of returning the liquid sucked into the nozzle tip 300, so that there is no loss of processing time and the processing can be performed quickly. You can also.
[0080]
Further, as described above, the leak determination unit 17 of the present embodiment takes the determination value P into consideration in consideration of the fluctuation of the atmospheric pressure. _T Is calculated, the determination can be made more accurately. In the present invention, the determination value may not be based on the atmospheric pressure.
[0081]
Further, in the present invention, the leak determination unit 17 may be configured to make a determination by comparing a time differential value (first differential or secondary differential) of the atmospheric pressure in the nozzle tip 300 with a determination value. . Further, in the present invention, the leak determination unit 17 is not limited to a hardware configuration as in the present embodiment, but may be a software configuration.
[0082]
In the present invention, the dispensing apparatus 1 performs the liquid level detection process when the height of the liquid level S of the liquid to be aspirated is known in advance, or when the depth of the container is extremely shallow. Need not be performed. In that case, the dispensing apparatus 1 lowers the tip opening 301 of the nozzle tip 300 to a predetermined position to be positioned slightly below the liquid surface S, and then, before sucking the liquid into the nozzle tip 300, Then, air is discharged from the pump 7 and the inside of the nozzle chip 300 is pressurized within a range in which air bubbles are not generated from the distal end opening 301. Thereafter, the presence or absence of air leakage from the joint J is detected in the same manner as described above.
[0083]
As described above, the dispensing apparatus of the present invention has been described with respect to the illustrated embodiment, but the present invention is not limited to this. Each part constituting the dispensing apparatus of the present invention can be replaced with an arbitrary component capable of exhibiting the same function, and an arbitrary component may be added.
[0084]
In the present invention, the liquid to be dispensed is not limited to the sample, but may be any liquid such as a reagent (chemical solution).
[0085]
The moving means of the x-axis, the y-axis, and the z-axis are not limited to those using a belt, but may use any structure, for example, a feed screw such as a ball screw, a rack and pinion gear. And any configuration using a linear motor or the like.
[0086]
The moving means for moving the chip mounting portion moves the chip mounting portion in the three-dimensional direction in the above-described embodiment. However, any moving device for moving the chip mounting portion at least in the vertical direction may be used.
[0087]
【The invention's effect】
As described above, according to the present invention, it is possible to determine whether or not gas has leaked from the junction between the nozzle tip and the tip mounting portion without sucking the liquid into the nozzle tip. Therefore, even when gas leakage occurs and the nozzle tip is replaced, there is almost no liquid remaining in the nozzle tip, so that waste (loss) of the liquid can be eliminated.
In addition, when gas leakage occurs, it is not necessary to discharge the liquid once sucked in, which contributes to a reduction in processing time.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a dispensing device of the present invention.
FIG. 2 is a perspective view showing an x-axis direction moving means in the dispensing apparatus shown in FIG.
FIG. 3 is a perspective view showing a y-axis direction moving unit, a z-axis direction moving unit, and a dispensing head in the dispensing apparatus shown in FIG.
FIG. 4 is a longitudinal sectional view showing a pump, a tip mounting portion, and a nozzle tip in the dispensing apparatus shown in FIG.
FIG. 5 is a schematic block diagram of the dispensing device shown in FIG.
FIG. 6 is a diagram illustrating a circuit configuration of a leak determination unit.
FIG. 7 is an enlarged cross-sectional view showing a state in which the tip opening of the nozzle tip is submerged below the liquid level.
FIG. 8 is a graph showing the air pressure in the nozzle tip when the in-nozzle tip pressurizing step is performed on the vertical axis, and the time on the horizontal axis.
[Explanation of symbols]
1 Dispensing device
11 arms
12 Guide rail
13 control means
131 CPU
132 storage
14 Pump driving means
15 Nozzle moving means
16 Pressure sensor
17 Leak determination means
171 Current-voltage conversion circuit
172 ADC for atmospheric pressure measurement
173 Judgment value calculation unit
174 Judgment value setting memory
175 DAC
176 Comparator
177 Judgment unit
18 Liquid level detection means
2 Main unit
21 Workbench
22 Equipment storage
23 Second device storage unit
24 Projection
25 Display means
26 Chip Remover
261 Notch
3 Dispensing head
31 frames
32 Chip mounting part
321 ventilation channel
322 lower end opening
33 Piping tube
4 x-axis moving means
41 slide block
411 Fixed part
42 drive pulley
43 driven pulley
44 pulse motor
45 belt
5 Y-axis direction moving means
51 slide blocks
52 drive pulley
53 driven pulley
54 pulse motor
55 belt
6 z axis direction moving means
61 slide block
62, 63 driven pulley
64 belt
65 pulse motor
66 propeller shaft
67 Fixing member
68 Support
7 pump
71 cylinder
72 plunger
100 test tube rack
200 chip rack
300 nozzle tip
301 Tip opening
302 proximal opening
J joint
S, Q liquid level

Claims (5)

A dispensing device that sucks and discharges liquid from a distal end opening of a disposable nozzle tip that is detachably mounted,
A pump for sucking and discharging gas,
A tip mounting portion having an opening through which gas flows in and out by operation of the pump, and to which the nozzle tip is detachably mounted;
Moving means for moving at least the vertical direction of the chip mounting portion,
Control means for controlling the operation of the pump and the moving means,
Pressure detection means for detecting the air pressure in the nozzle tip mounted on the tip mounting portion,
Leak determining means for determining the presence or absence of gas leakage from the joint between the nozzle tip and the tip mounting portion,
The control means discharges gas from the pump in a state where the tip opening of the nozzle tip is immersed below the liquid surface before sucking the liquid into the nozzle tip, and does not generate bubbles from the tip opening. Controlling the operation of the pump and the moving means to perform a nozzle tip pressurizing step of pressurizing the nozzle tip in a range,
The dispensing apparatus according to claim 1, wherein the leak determining means determines whether or not gas has leaked from the joint based on the pressure detected by the pressure detecting means after the pressurizing step in the nozzle tip. The leak determination unit is configured to determine that, after the pressurizing step in the nozzle tip, when the air pressure detected by the pressure detection unit drops to a predetermined determination value within a predetermined time, there is a gas leak from the joint. The dispensing device according to claim 1, wherein the determination is performed. The leak determining means may leak gas from the joint if the pressure detected by the pressure detecting means does not rise to a predetermined determination value when performing the in-nozzle tip pressurizing step. The dispensing device according to claim 1 or 2, wherein The nozzle mounted on the tip mounting portion, further comprising an exchange means for exchanging the nozzle tip mounted on the tip mounting portion, wherein the leak determination portion determines that there is gas leakage from the joint portion. 4. The dispensing device according to claim 1, wherein the dispensing device operates to change tips. Liquid level detection means for detecting the liquid level of the liquid to be inhaled based on the atmospheric pressure detected by the pressure detection means,
A liquid level detecting step of, when discharging the gas from the pump, lowering a tip end opening of the nozzle tip toward a liquid level of the liquid to be sucked when trying to suck the liquid into the nozzle chip; Controlling the operation of the pump and the moving means to perform
The liquid level detecting means determines that the tip end opening of the nozzle tip is submerged below the liquid level when the pressure detected by the pressure detecting means increases in the liquid level detecting step. Detect the surface,
The dispensing according to any one of claims 1 to 4, wherein the leak determining unit determines whether or not gas leaks from the joint by using the liquid level detecting process as the pressurizing process in the nozzle tip. apparatus.

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