JPH0457378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric pipette device that sucks and discharges a test liquid or the like using a piston that reciprocates within a cylinder chamber, and a titration method using the same.

[Prior Art] A conventional electric pipetting device of this type is disclosed in Japanese Patent Application Laid-open No. 193549/1983.

This electric pipetting device consists of a pipetting drive and a plurality of ejection assemblies. The pipette drive includes a digital linear actuator and a control circuit for controlling it, while the evacuation assembly has pistons and cylinder chambers each having a different evacuation volume.

A digital linear actuator includes a linear shaft that is drivingly connected to a piston during assembly;
It has a step motor that linearly drives the linear shaft back and forth. This step motor is
When the piston comes into contact with the bottom of the cylinder chamber, it slips and stops the piston from descending. The control circuit then reverses the step motor and raises the piston to a starting point called the home position. There is a sampling mode in which the test liquid is sucked in and the entire amount is discharged, an equal volume dispensing mode in which the test liquid is sucked in, distributed in equal amounts and then discharged, and a predetermined amount of the test liquid is sucked and then a predetermined amount of the diluted liquid is injected. The start of each inhalation in the dilution mode in which the test liquid is diluted by inhalation is controlled starting from this home position.

[Problems to be Solved by the Invention] The conventional electric pipetting device described above causes the piston to slip when it comes into contact with the bottom of the cylinder chamber to stop the piston from descending, and then reverses the motor to return the piston to the home position. Since the piston is raised to the home position, it has the disadvantage that it takes time to detect the home position of the piston. Furthermore, since it is necessary to cause the piston to slip when it comes into contact with the bottom of the cylinder chamber, the structure of the motor is complicated and expensive.

[Means for Solving the Problems] An object of the present invention is to solve the problems of the prior art described above and to provide an electric pipette device that can quickly and inexpensively detect the home position of a piston, and an electric pipette device using the same. An object of the present invention is to provide a titration method.

A first aspect of the present invention is an electric pipetting device that sucks and discharges a test liquid, etc. using a piston that reciprocates in a cylinder chamber. A rotary motion/linear reciprocating motion conversion mechanism that converts rotary motion into linear reciprocating motion,
A rotary motion/linear reciprocating motion conversion mechanism is drivingly connected to a linear shaft provided protruding from a piston that reciprocates within the cylinder chamber, and a rotary motion/linear reciprocating motion conversion mechanism is provided in connection with the linear shaft for detecting the home position of the piston. The apparatus is characterized by comprising a home position detection means, and a control means for driving a step motor to move the piston to various positions within the cylinder chamber, starting from the home position of the piston.

A second aspect of the present invention is a titration method for an electric pipetting device in which a test liquid, etc. is drawn in and discharged by a piston reciprocating in a cylinder chamber, and the titration method is performed by driving a step motor while precisely controlling its rotation angle. The home position of the piston is detected by converting the rotational motion of the rotary shaft into linear reciprocating motion to cause the piston to reciprocate within the cylinder chamber, and by the position of the linear shifter provided protruding from the piston. , a step of stopping the rotation of the step motor, a step of driving the step motor in the direction of increasing the volume inside the cylinder chamber to suck in the test liquid, and a step of driving the step motor in the direction of decreasing the volume inside the cylinder chamber. The method is characterized by comprising a step for discharging the test liquid and the like.

[Operation] The step motor is driven by the control means, and its rotating shaft is rotated while being precisely controlled. The rotational motion of the rotary shaft is converted into linear reciprocating motion by a rotary motion/linear reciprocating motion conversion mechanism. This linear motion is transmitted to the piston within the cylinder chamber. When the piston reaches the home position in the cylinder chamber, the home position detection means detects this and stops driving the step motor. As a result, the electric pipette device becomes ready to aspirate the test liquid and the like. Next, the tip of the electric pipetting device is immersed in the test liquid or the like, and the control means is again energized. As a result, the control means drives the step motor to increase the volume inside the cylinder chamber,
Inhale the test liquid, etc. Next, depending on the setting mode of the electric pipetting device, the step motor is driven to increase or decrease the volume within the cylinder chamber. That is, in the case of sampling mode, the entire amount of the aspirated test liquid is discharged as it is, and in the case of equal volume dispensing mode, the aspirated test liquid is distributed in equal amounts and discharged.
In the dilution mode, a predetermined amount of diluent is further inhaled into the inhaled test liquid, and then the entire amount is expelled.

[Example] Next, an electric pipette device of the present invention and a titration method using the same will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of an electric pipetting device according to the present invention.

2 is a plan view of the electric pipetting device of FIG. 1; FIG.

The electric pipetting device 10 according to the present invention generally comprises an upper body 11 and a lower body 12 screwed to the upper body 11 by a fixing cap 13. In addition, the lower body 1
2 consists of an inner sleeve 14 and a cylinder member 28 which is snapped onto the underside of the inner sleeve 14.

The upper body 11 can be divided into two parts, and is assembled and fixed using a required number of screws.
Space 11 formed inside the upper body 11
A step motor 15 that can precisely control the rotation angle is installed inside the motor. A gear 1 is attached to the lower end of the rotating shaft 15a of the step motor 15.
6 is fixed. In the space 11a of the upper body 11, a battery 17 is also housed, and a control panel 18 is provided.

An ejector shaft 19 is installed along the inner side surface of the upper body 11 so as to be able to reciprocate in the vertical direction. An ejector button 19a is fixed to the upper end of the ejector shaft 19. control panel 18
A control circuit 20 that can precisely control the rotation of the step motor 15 is provided on the back side.

As shown in FIG. 3, the control panel 18 includes a liquid crystal display 18a for displaying the set capacity and executed operations, and an on/off switch 18.
b, an input switch 18c, button switches 18d and 18e for changing the set capacity, a switch 18f for mode switching, a switch 18g for answering a call, a switch 18h for locking keyboard operation, and a process switch 18i are provided. . The functions of each switch will be described later along with the operation of the electric pipetting device.

In the liquid crystal display 18a shown in FIG. 3, "D" is a sampling mode, and "R-D" is a sampling mode.
represents the equal volume dispensing mode, and "DL" represents the dilution mode. Moreover, when the mode is sampling mode, "V1" is the amount of inhalation of the test liquid. If the mode is equal volume dispensing mode, “V1”
and “V2” are the inhalation volume and the equal volume dispensing volume of the test liquid, respectively. When the mode is dilution mode, "V1" and "V2" are the inhalation amount of the test liquid and the inhalation amount of the diluent, respectively. "LOCK" is
This is to display the locked state of the keyboard operation, and "▲REAG" and "▼DISP" indicate that the device is in the suction operation state and the discharge operation state. "UL" represents the unit of capacity, ie, microliter, and "〓" indicates the answerback status. Each symbol indicates that state when the backlight illuminates the symbol.

A rotating shaft 15a of a step motor 15 is provided in a space 14a formed inside the inner sleeve 14.
A shaft 21 is rotatably mounted in parallel with. A male thread is cut on the outer periphery of the shaft 21. Axis 21
A gear 22 that meshes with the gear 16 of the rotating shaft 15a when the upper body 11 and the lower body 12 are assembled is also fixed to the upper part of the rotary shaft 15a.

The block 23 is formed with a female thread 23a that threadably engages with the male thread of the shaft 21. Block 23
is also fixed to a linear shaft 25 that projects upward from the piston 24 and is fixed. A groove is cut in the linear shaft 25 in the longitudinal direction, and this groove engages with a projection 14b provided at the lower end of the inner sleeve 14.

When the step motor 15 is rotated with the upper body 11 and lower body 12 combined, the shaft 21 is rotated via the gears 16 and 22. axis 2
1 rotation is converted by the block 23 into a linear reciprocating motion in the vertical direction.

The inner wall of the inner sleeve 14 has the upper body 11
A conductive plate 26 is attached which is adapted to be connected to a power supply circuit when the lower body 12 and the lower body 12 are combined. On the other hand, a conductive plate 27 connected to the power supply circuit is also attached to the block 23. As will be described later, due to the contact between the conductive plate 26 and the conductive plate 27, the piston 24
Detect home position A _O. In the illustrated embodiment, a contact type electric switch is used as the home position detecting means, but any non-contact type sensor, such as an optical sensor or a magnetic sensor, which is well known in the art, may be used.

The cylinder member 28 is made up of four sleeve-shaped parts 28a, 28b, 28c and 28d having different diameters connected by shoulders 28e, 28f and 28g, respectively. Inside the sleeve-like portion 28d of the smallest diameter of the cylinder member 28 is a deflection insert 2.
9 has been inserted. In addition, the sleeve-shaped portion 28
A chip 30 having a chamber 30a for storing a test liquid, etc. is attached around d. The inner side of the sleeve-shaped portion 28c having the second smallest diameter of the cylinder member 28 has a cylinder chamber 28h that receives the piston 24.
and passes through the sleeve-shaped portion 28d.
It is fluidly connected to the receiving chamber 30a of the chip 30.

Inside the sleeve-shaped portion 28b having the second largest diameter in the cylinder member 29, a retaining sleeve 31 is provided.
is installed. An O-ring 31 is installed between the lower surface of the holding sleeve 31 and the inner wall surface of the shoulder portion 28f. A compression spring 33 is installed between the upper surface of the holding sleeve 31 and the lowermost surface of the inner sleeve 14. Therefore, the inner sleeve 1
4 and the cylinder member 28, the retaining sleeve 31 holds the O-ring 32 against the shoulder 2.
8f against the inner wall surface of the piston 2.
4 and the cylinder chamber 28h.

The upper end of the cylinder member 28 extends outward in a brim shape to form a flange portion 28i. An opening is formed in the inner sleeve 14 and the flange portion 28i of the cylinder member 28, and the lower part of the ejector shaft 19 passes through this opening.

An ejector pipe 34 is attached to the outer periphery of the cylinder member 28 so as to be able to reciprocate in the axial direction with respect to the cylinder member 28 . The upper end of the ejector pipe 34 extends outward in a brim shape to form a flange portion 3.
4a, and the lower end surface of the ejector shaft 19 is in contact with this flange portion 34a.

The fixed cap 13 is attached to the upper outer periphery of the cylinder member 28 and the ejector pipe 34. The lower body 12 is assembled to the upper body 11 by threadingly engaging the female threaded portion formed on the upper inner wall surface of the fixed cap 13 with the male threaded portion formed on the lower outer wall surface of the upper body 11. Fix it. A compression spring 35 is installed between the shoulder portion 13a of the fixed cap 13 and the flange portion 34a of the ejector pipe 34. As a result, the ejector shaft 19 and the ejector pipe 34 are pushed upward.

The stroke of the piston 24, that is, the length from the home position A _O to the maximum suction position A ₁ is preferably about 20 mm, thereby improving the resolution of the electric pipetting device. In addition, in order to completely discharge the inhaled test liquid, etc., the stroke required to move the piston 24 beyond the home position A _O to the predetermined second stage discharge position A ₂ is preferably about 2 mm. .

Next, the operation of the electric pipetting device 10 according to the present invention will be explained.

The electric pipetting device 10 has a cylinder chamber 28h.
depending on the cross-sectional area of, e.g. in the range 0.01 to 10,
Range of 0.05~50, Range of 0.2~200 and 1.0~
Titration specifications can range from 1000 to 1000.

The operating modes of the electric pipetting device 10 include a sampling mode in which the test liquid is sucked in and the entire amount is discharged, an equal volume dispensing mode in which the test liquid is sucked in, the same amount is distributed and then discharged, and a test liquid mode is selected. There is a dilution mode in which the test liquid is diluted by inhaling a predetermined amount and then inhaling a predetermined amount of diluent.

Therefore, an example will be described in which 29 samples are performed using an electric pipette device 10 with a titration specification in the range of 1.0 to 1000.

In the electric pipetting device 10 according to the present invention, the tip 30 is of a disposable type, so when using the tip 30, the tip 30 is attached to the electric pipetting device 10.
not installed. Therefore, first, the tip 30 is attached to the lower end of the electric pipetting device 10. At this time, the upper end surface of the chip 30 is
Insert it fully until it makes contact with the lower end surface of 4, making sure that there is no air leakage.

Press the on/off switch 18b on the control panel 18 to energize the electric pipetting device 10.

While looking at the liquid crystal display 18a of the control panel 18, press the mode changeover switch 18f to select the desired mode. For example, the sampling mode is when the backlight is at position "D".

Next, the input switch 18c is pressed and the capacity to be sampled, in this case 29, is input using the button switches 18d and 18e. The sampling capacity is displayed in a number frame on the liquid crystal display 18a.

After completing the necessary inputs, press lock switch 18.
Press h to lock keyboard operations. As a result, the electric pipetting device 10 becomes operational in the sampling mode.

Next, when the process switch 18i is pressed, the control circuit 20 drives the step motor 15 to move the piston 24 toward the home position _AO . When the piston 24 reaches the home position A _O , the conductive plates 26 and 27 come into contact. When the control circuit 20 senses this, it stops the rotation of the step motor 15, and at the same time, the piston 24 reaches the home position _AO , and the electric pipetting device 20 is in a state where it can suck the test liquid. The operator is notified by a buzzer.

The operator dips the tip of the tip 30 into the test liquid and presses the process switch 18i. Control circuit 2
0 then reverses the step motor 15 and raises the piston 24 to a position corresponding to the sampling capacity (between the maximum stroke position _A1 and the home position _A0 ). When the suction of the test liquid is finished, the electric pipetting device 10 again notifies the operator with a buzzer sound.

The operator pulls up the tip of the tip 30 from the test liquid, moves it to a place where the test liquid is to be dropped, and presses the process switch 18i. The control circuit 20 is
Reverse the step motor 15 and return the piston 24 to the home position A _O
5 is stopped. This performs a rough discharge of the test liquid. The control circuit 20 includes a piston 24
After a predetermined time has elapsed since the chip 30 returned to the home position A _O , the step motor 15 is driven again to move the piston beyond the home position A _O to the predetermined second stage ejection position A ₂ . Completely drain the test liquid remaining on the inner wall. When the two-stage discharge is completed, the control circuit 20 returns the piston 24 to the home position A _O , and then notifies the operator again with a buzzer to complete the sampling mode.

If equal volume dispensing mode is selected, enter the equal volume to be dispensed in addition to the test solution inhalation volume; if dilution mode is selected, enter the diluent inhalation volume in addition to the test solution inhalation volume. Also enter the amount.

It is preferable that the rotational speed of the motor is set in two stages so that when the equal volume dispensing mode is selected, dispensing can be performed at a slow speed.

[Effects of the Invention] As described above, the electric pipetting device of the present invention includes a step motor that can precisely control the rotation angle, and a rotary motion that converts the rotary motion of the rotary shaft of the step motor into linear reciprocating motion. /A linear reciprocating motion converting mechanism, which detects the home position of the rotary motion/linear reciprocating motion converting mechanism, which is drivingly connected to a linear shaft protruding from a piston reciprocating within a cylinder chamber. A home position detection means provided in connection with the linear shaft, and a control means for driving a step motor to move the piston to various positions within the cylinder chamber, starting from the home position of the piston. Therefore, the home position of the piston can be detected quickly and inexpensively.

There is a sampling mode in which the test liquid is sucked in and the entire amount is discharged, an equal volume dispensing mode in which the test liquid is sucked in and then dispensed in equal amounts, and a predetermined amount of the test liquid is inhaled and then a predetermined amount of the diluted liquid is inhaled. Since all dilution modes, in which the test liquid is diluted, start from the home position of the piston, rapid detection of the home position of the piston greatly contributes to speeding up the titration work.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an electric pipetting device according to the present invention. Figure 2 shows the first
FIG. 2 is a plan view of the electric pipetting device shown in the figure. FIG. 3 is a front view of the control panel illustrated in FIG. 1. 10...Electric pipetting device, 11...Upper body, 11a...Space, 12...Lower body, 13...Fixed cap, 14...Inner sleeve, 14a...Space, 14b...Protrusion, 15
...Step motor, 15a...Rotating shaft, 16...
...Gear, 17...Battery, 18...Control panel, 1
8a...Liquid crystal display, 18b...On/off switch, 18c...Input switch, 18d...
Button switch, 18e... Button switch, 1
8f...Mode changeover switch, 18g...Answer switch, 18h...Lock switch, 1
8i...Process switch, 19...Ejector shaft, 19a...Ejector button, 20...Control circuit, 21...Shaft, 22...Gear, 23...Block, 23a...Female screw, 24...Piston, 2
5... Linear shaft, 26, 27... Conductive plate, 28... Cylinder member, 28a to 28d
... Sleeve-shaped part, 28e to 28g ... Shoulder part,
28h...Cylinder chamber, 28i...Flange part,
29... Deflection insert, 30... Chip, 30
a... Containment chamber, 31... Holding sleeve, 32...
O-ring, 34... Ejector pipe, 33,3
5... Compression spring.

Claims (1)

[Scope of Claims] 1. An electric pipette device that sucks and discharges a test liquid, etc. using a piston that reciprocates within a cylinder chamber, comprising: a step motor whose rotation angle can be precisely controlled; and rotation of a rotation shaft of the step motor. A rotary motion/linear reciprocating motion conversion mechanism for converting motion into linear reciprocating motion, the rotary motion/linear reciprocating motion being drivingly connected to a linear shaft provided protruding from the piston that reciprocates within the cylinder chamber. a conversion mechanism; a home position detection means provided in association with the linear shaft for detecting the home position of the piston; and a home position detection means for detecting the home position of the piston;
An electric pipetting device comprising: control means for driving the step motor to variously move the position of the piston within the cylinder chamber. 2. The electric pipetting device according to claim 1 further includes a sampling mode in which the test liquid is sucked and the entire amount is discharged, an equal volume dispensing mode in which the test liquid is sucked, distributed in equal amounts and discharged, and a test. 1. An electric pipetting device comprising input means for selecting and setting a dilution mode in which a predetermined amount of a liquid is inhaled and then a predetermined amount of a diluent is inhaled to dilute a test liquid. 3. The electric pipetting device according to claim 2, wherein the control means is configured to move the piston beyond the home position to a predetermined two-stage discharge position in order to completely discharge the aspirated test liquid, etc. An electric pipetting device that drives the step motor. 4. The electric pipette device according to claim 1, further comprising: a disposable tip fluidly connected to the cylinder chamber and having a storage chamber for storing inhaled test liquid, etc. Electric pipetting device. 5. The electric pipetting device according to claim 4, further comprising ejector means for removing the tip from the electric pipetting device with a single touch. 6. The electric pipetting device according to claim 1, wherein the home position detection means comprises a contact type switch. 7. The electric pipetting device according to claim 1, wherein the home position detection means is a non-contact sensor. 8 A titration method for an electric pipette device in which a test liquid, etc. is sucked in and discharged by a piston that moves reciprocatingly in a cylinder chamber, and is driven while precisely controlling the rotation angle of a step motor, and the rotational movement of its rotating shaft is linearly reciprocated. a step of causing the piston to reciprocate within the cylinder chamber by converting the piston into a motion; and a step of directly detecting the home position of the piston by the position of a linear shaft provided protruding from the piston; a step of stopping rotation of the motor; a step of driving the step motor in a direction to increase the volume inside the cylinder chamber to suck in a test liquid, and a step of driving the step motor in a direction to decrease the volume inside the cylinder chamber. A titration method comprising: a step of driving a test liquid, etc. to discharge a test liquid, etc.; 9. In the titration method according to claim 8, the step of discharging the test liquid, etc. includes a step of returning the piston to the home position and temporarily stopping it, and a step of electrically discharging the residual test liquid, etc. held on a wall surface, etc. A titration characterized by comprising the following steps: a step of dropping a drop onto the tip of a type pipetting device; and a step of moving the piston beyond the home position to a predetermined two-stage discharge position to push out the residual test liquid, etc. Method.