JPH08215585A - Pipetter - Google Patents

Abstract

PURPOSE: To provide a pipetter composed to execute dispensing and discharging of liquid, such as blood, by utilizing the rotating force of an electric motor. CONSTITUTION: This pipetter has a shaft 4 for feeding which is rotationally driven by the electric motor, is formed with feed screw threads on its outer periphery and is held inserted into a hollow part 5A formed at a piston 5 and a cylinder member 2 formed with a hollow part 2A in which the piston 5 is moved back and forth. Further, the pipetter has an O-ring 6 which hermetically seals the hollow part 2A of the cylinder member 2 and consists of an elastic material and a recessed part 2B for positioning which is formed at the cylinder member 2 and is formed with a curved part complying with the shape of this O-ring 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipettor configured to dispense and discharge a liquid such as blood by utilizing the rotational force of an electric motor.

[0002]

2. Description of the Related Art Conventionally, an instrument called a pipettor has been used as an instrument for dispensing or discharging a liquid such as a test solution for a chemical reaction or an immune reaction. Such pipettors include simple ones that are manually operated by an operator and high-performance pipettors that use the rotational force of an electric motor to dispense and discharge liquid. In addition, recently, many devices have been developed that automatically perform an inspection operation of a liquid such as a solution to be inspected, and the pipettor used in such a device also dispenses and discharges the liquid by utilizing the rotational force of an electric motor. Many high-performance ones are used. An example of a high-performance pipettor that dispenses and discharges a liquid by utilizing the rotational force of such an electric motor is disclosed in Japanese Patent Laid-Open No. 6-134323.

[0003]

As the function of the pipettor, not only the basic function of dispensing and discharging the liquid but also the ability to accurately measure the amount is required. The aforementioned publication discloses a technique in which the connecting member is moved by a screw shaft driven by the rotation of the electric motor, and the piston is reciprocally moved by the moving operation of the connecting member. However, in such a technique, It is necessary to accurately perform the sealing operation by the shield member that seals the gap between the hollow portion formed in the cylinder member and the piston. In the conventional technology, the sealing action is reduced due to the deformation of the shield member. And the load on the piston changes.

The present invention is intended to provide a pipettor which solves the above problems.

[0005]

A pipettor according to the present invention includes a feed shaft which is driven to rotate by an electric motor, has a feed screw formed on the outer periphery thereof, and is inserted in a hollow portion formed in a piston. A cylinder member in which a hollow portion for reciprocating the piston is formed; an O-ring that seals the hollow portion of the cylinder member and is made of an elastic body; and an O-ring formed in the cylinder member and The positioning recess is formed with a curved portion conforming to the shape.

[0006]

According to the present invention, the cylinder member is provided with a positioning recess for positioning the O-ring for sealing the hollow portion formed in the cylinder member, and the positioning recess is provided with a curved portion conforming to the shape of the O-ring. By doing so, the O-ring is accurately positioned.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an essential part showing an embodiment of the pipettor of the present invention, and FIGS. 2 and 3 are enlarged sectional views of the essential part.

In FIG. 1, reference numeral 1 is a casing which constitutes a pipettor, and 2 is a cylinder member which is attached and fixed to the lower portion of the casing 1, and a hollow portion 2A extending from the upper end to the lower end is formed therein. Has been done. Reference numeral 3 is a pipette tip fitted and fixed to the tip of the cylinder member 2 and configured so that the liquid L such as blood is sucked into the hollow portion 3A.

Reference numeral 4 denotes a feed shaft that is rotationally driven by an electric motor (not shown) that rotates during the suction operation and the discharge operation of the liquid L. As shown in FIG. 3, a feed screw 4A is formed on the outer periphery of the feed shaft. Has been done. Reference numeral 5 denotes a cylindrical piston provided so as to reciprocate in a hollow portion 2A formed in the cylinder member 2, and the feed shaft 4 is provided in the hollow portion 5A formed in the piston 5. Is configured to be inserted. Further, as shown in FIG. 3, an inner wall forming the hollow portion 5A of the piston 5 is formed with a female screw 5B for feeding which engages with a screw 4A formed on the shaft 4 for feeding.

An O-ring 6 seals a gap between the hollow portion 2A of the cylinder member 2 and the piston 5, and is made of elastic rubber. Reference numeral 7 is a fixing member that is attached to the cylinder member 2 by screwing, and 8 is a substrate that fixes the electric motor and the like, and is fixed by tightening by the fixing member 7. Reference numeral 9 denotes a ring-shaped pressing member, which is arranged so as to contact the O-ring 6. A spring 10 is provided between the fixing member 7 and the pressing member 9, and is configured to press and press the pressing member 9 toward the O-ring 6.

In FIG. 2, 2B is the cylinder member 2.
It is a positioning recess formed in a circular shape matching the ring shape of the O-ring 6. In such a configuration, the positioning recess 2B has
A curved portion 2C that matches the shape of the cross section of the O-ring 6 is formed.

The pipetter of the present invention is constructed as described above. Next, the operation of the pipette of such a construction will be described. When an operation for suction is performed in a state where the tip end of the pipette tip 3 fitted and fixed to the tip end of the cylinder member 2 is immersed in a liquid contained in a test tube or the like, a switch (not shown) The switching operation is performed and the drive signal is supplied to the electric motor.

When the electric motor rotates in the direction for sucking the liquid, the rotation operation causes the feed shaft 4 to rotate in that direction. When the feed shaft 4 rotates, a piston 5 having a feed female screw 5B engaged with a feed screw 4A formed on the feed shaft 4 is formed.
Is moved upwards. When the piston 5 moves upward, the liquid contained in the test tube or the like is sucked, and the liquid L is sucked into the hollow portion 3A of the pipetter tip 3 as shown in FIG.

In this way, the sucking operation of the liquid L into the hollow portion 3A of the pipettor tip 3 is performed, but when the rotating direction of the electric motor is opposite to the above-mentioned direction, the liquid L is rotated.
Can be discharged from the inside of the hollow portion 3A of the pipettor tip 3 to the outside. That is, when the electric motor is rotated in the reverse direction, the piston 5 formed with the female screw for feeding 5B engaged with the screw 4A formed on the shaft for feeding 4 is moved downward. Thus, the liquid L can be discharged from the hollow portion 3A of the pipetter tip 3 to the outside.

As described above, the piston 5 is reciprocally moved in the vertical direction by the rotation operation of the feed shaft 4,
By the reciprocating movement of the piston 5, the sucking operation of the liquid L into the hollow portion 3A of the pipette tip 3 and the hollow portion 3 are performed.
A discharge operation from A can be performed, but when such an operation is performed, the supporting operation of the piston 5 is performed by the O-ring 6. Further, when the above-described operation is performed, the O-ring 6 is formed on the cylinder member 2 because it is pressed and biased by the pressing member 9 that is biased by the elastic force of the spring 10. The sealing operation of the hollow portion 2A can be reliably performed.

As described above, the sealing operation of the hollow portion 2A by the O-ring 6 is performed.
Is positioned by a positioning recess 2B formed in the cylinder member 2, so that the piston 5
The position of the piston 5 is not displaced by the reciprocating movement of the piston 5, and the supporting operation of the piston 5 can be favorably performed. Further, since the reciprocating movement of the piston 5 is performed while being supported by the O-ring 6 provided to perform the sealing operation of the hollow portion 2A formed in the cylinder member 2, that is, a special supporting member is used. Since it is not necessary, the configuration is simple.

[0017]

According to the present invention, a positioning recess for positioning an O-ring for sealing a hollow portion formed in a cylinder member is formed in the cylinder member, and a curved portion conforming to the shape of the O-ring is formed in the positioning recess. Since the O-ring is formed, the O-ring can be accurately positioned, and as a result, the hollow part formed in the cylinder member can be reliably sealed.

Further, according to the present invention, since the O-ring is pressed and urged in the direction of sealing the hollow portion formed in the cylinder member, the sealing operation of the hollow portion can be performed accurately. Since the pressing member for pressing the O-ring is provided, the biasing force of the spring acts uniformly on the O-ring, and the O-ring can be uniformly deformed.

Further, according to the present invention, since the reciprocating movement of the piston is performed by the O-ring provided to seal the gap between the cylinder member and the piston, when the special support member is provided. It has the advantage that the configuration is simpler than that of the conventional method.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a pipettor of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part showing a pipettor of the present invention.

FIG. 3 is an enlarged cross-sectional view of a main part showing a pipettor of the present invention.

[Explanation of symbols]

 1 Case 2 Cylinder Member 2B Positioning Recess 3 Pipette Tip 4 Feed Shaft 4A Feed Screw 5 Piston 5B Feed Female Thread 6 O-ring 7 Fixing Member 9 Pressing Member 10 Spring

Claims (4)

[Claims] 1. A pipette configured to discharge liquid from the inside of a pipetter tip and suck liquid into the inside of the pipetter tip by reciprocating movement of a cylindrical piston, which is driven to rotate by an electric motor and has a feed screw on the outer periphery. A feed shaft that is formed and inserted into a hollow portion formed in the piston, a cylinder member in which a hollow portion in which the piston reciprocates is formed, and a hollow portion of the cylinder member. A pipettor comprising an O-ring which is hermetically sealed and made of an elastic body, and a positioning recess formed in the cylinder member and having a curved portion conforming to the shape of the O-ring. 2. The pipettor according to claim 1, further comprising a spring for biasing the O-ring in a direction for sealing the hollow portion formed in the cylinder member. 3. The O-ring is pressed and biased in a direction for sealing the hollow portion formed in the cylinder member through a pressing member that comes into contact with the O-ring. Pipette. 4. The pipettor according to claim 1, wherein the piston is supported by an O-ring.