Pipette device

There is provided a pipette device capable of adjusting a collection amount in a short time. A pipette device 1 adjusting a volume of a cylinder portion “a” by the axial-direction movement of a plunger 3 caused by the rotation of a push rod 5 includes a speed increasing mechanism 35 provided between a pipette main body 2 and the push rod 5 and increasing a speed of input rotation to transmit the input rotation with the increased speed to the push rod 5.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pipette device for collecting a predetermined amount of a sample (liquid) used for inspection, analysis, experiments, and the like.

2. Description of the Related Art

A pipette device of this type includes a collection amount adjusting mechanism capable of finely adjusting a collection amount of a liquid. For example, Japanese Patent Application Laid-open No. Hei 6-210188 discloses the following. In a cylinder portion of a pipette main body, a plunger changing a cylinder volume is reciprocatably disposed, a push rod reciprocating the plunger is inserted in the pipette main body to be rotatable and movable in an axial direction, and a nut member engaged with the push rod is unrotatably supported in the pipette main body. The axial-direction movement of the push rod is caused by the rotation of an adjustment knob fixed to the push rod, whereby a stroke amount of the plunger is adjusted.

SUMMARY OF THE INVENTION

In the above-described conventional pipette device, since a stroke amount per rotation of the adjustment knob is small, the collection amount cannot be adjusted to a desired amount unless the push rod is rotated a considerably large number of times, which involves a problem that the adjustment takes a lot of time. In particular, when the collection amount frequently changes, the adjustment takes a lot of trouble and workability lowers. Therefore, there is a demand for improvement in this point.

The present invention has been developed in consideration of the above conventional circumstances, and has an object to provide a pipette device capable of adjusting a collection amount in a short time.

The present invention is a pipette device which includes: a pipette main body having a cylinder portion; a plunger disposed in an inserted state in the cylinder portion to be movable in an axial direction and changing a cylinder volume; a push rod which is inserted in the pipette main body to be rotatable and movable in the axial direction and to which the plunger is connected; and a nut supported in the pipette main body to be unrotatable and movable in the axial direction and converting the rotation of the push rod to the axial-direction movement of the push rod, and which adjusts the cylinder volume by the axial-direction movement of the plunger caused by the rotation of the push rod, the pipette device including a speed increasing mechanism provided between the pipette main body and the push rod and increasing a speed of input rotation to transmit the input rotation with the increased speed to the push rod.

According to the present invention, since the speed increasing mechanism increasing the speed of the input rotation to transmit the input rotation with the increased speed to the push rod is provided, it is possible to adjust a collection amount in a short time, which can improve workability.

In a preferable embodiment of the present invention, the speed increasing mechanism is of a planetary gear type that includes: a sun gear provided to be coaxial with the push rod; a planetary gear rotating on an own axis while rotating around an outer periphery of the sun gear; a carrier rotatably supported by the pipette main body and supporting the planetary gear so as to allow the planetary gear to rotate; and an outer ring which is unrotatably supported by the pipette main body and on whose inner peripheral surface an internal gear engaged with the planetary gear is formed, and the speed increasing mechanism increases a speed of rotation input to the carrier to transmit the rotation with the increased speed to the push rod.

According to the above preferable embodiment, since the speed increasing mechanism is the planetary gear mechanism, it is possible to obtain a large speed increase ratio with a compact structure, and the speed increasing mechanism can be disposed between the pipette main body and the push rod without any size increase of the pipette main body.

In another preferable embodiment of the present invention, the speed increasing mechanism outputs rotation inputted to the push rod, from the push rod without any change.

According to the above another preferable embodiment, the speed increasing mechanism is structured to output the rotation inputted to the push rod, from the push rod without any change. Therefore, in adjusting a collection amount, rough adjustment can be made in a short time by the speed increasing mechanism, and by subsequently rotating the push rod, fine adjustment can be made, which can enhance accuracy in adjusting the collection amount.

In still another preferable embodiment of the present invention, the carrier has a holding portion in a bottomed cylindrical shape supporting the planetary gear so as to allow the planetary gear to rotate; and a bearing plate fitted in an opening of the holding portion, the planetary gear is disposed in an opening portion formed in the holding portion, and shaft portions at both ends of the planetary gear are rotatably supported by a bottom wall of the holding portion and the bearing plate.

According to the above still another embodiment, the carrier houses the planetary gear in the opening portion formed in its holding portion in the bottomed cylindrical shape and supports the shaft portions at the both ends of the planetary gear by the bottom wall of its holding portion and its bearing plate so as to allow the shaft portions to rotate. Therefore, the planetary gear part can be downsized, which makes it possible to dispose the speed increasing mechanism without any size increase of the pipette main body.

In yet another preferable embodiment of the present invention, the carrier has a projecting portion integrally formed with the holding portion and projecting out in the axial direction from the pipette main body, and an input member is fitted to the projecting portion.

According to the above yet another embodiment, since the input member is fitted to the projecting portion integrally formed with the holding portion of the carrier and projecting out in the axial direction from the pipette main body, it is possible to easily rotate the carrier by rotating the input member.

According to yet another preferable embodiment of the present invention, the carrier is rotatably supported by the outer ring.

According to the above yet another preferable embodiment, since the carrier is rotatably supported by the outer ring fixed to the pipette main body, it is possible to realize the structure in which the carrier is rotatably supported by the pipette main body, without any complication of the structure and without any increase in the number of components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an embodiment of the present invention will be described based on the attached drawings.

FIG. 1toFIG. 10are views for explaining a pipette device according to an embodiment 1 of the present invention.

In the drawings,1denotes the pipette device for collecting a predetermined amount of a sample (liquid) used for inspection, analysis, experiments, and the like.

The pipette device1includes: a pipette main body2having a cylinder portion “a”; a plunger3disposed in the cylinder portion “a” to be movable in an axial direction and changing a cylinder volume of the cylinder portion “a”; a push rod5inserted in the pipette main body2to be rotatable and movable in the axial direction and moving the plunger3in the axial direction; and a nut6unrotatably supported in the pipette main body2and converting the rotation of the push rod5to the axial-direction movement of the push rod5. Note that the cylinder volume means an axial-direction movable distance (stroke) of the plunger3.

The pipette main body2has: an outer housing9in a cylindrical shape having a grip portion9a; an inner housing disposed in the outer housing9; and a nozzle cone11extending downward from the inner housing10.

The nozzle cone11has: a lager-diameter portion11a; a small-diameter portion11bcontinuously formed from the large-diameter portion11aand forming the cylinder portion “a”; and a nozzle portion11cformed in a tapered shape at a tip portion of the small-diameter portion11b. A pipette tip12is attachably/detachably fitted to the nozzle portion11c.

The plunger3is disposed so as to extend from the nozzle cone11to the inside of a lower portion of the inner housing10, and the push rod5is disposed so that most part thereof is located in the inner housing10. An upper end portion of the plunger3is fittingly inserted in a lower end portion of the push rod5. Further, an upper portion of the push rod5protrudes upward from the pipette main body2, and a push button7is fixed to an upper end portion of the push rod5.

A spring4is disposed between a spring bearing washer13and a spring bearing washer14a, the former washer13being fixedly disposed at a boundary portion between the large-diameter portion11aand the small-diameter portion11bof the nozzle cone11, and the latter washer14abeing disposed in an upper portion of the nozzle cone11. Further, at the boundary portion, an O-ring15is disposed to airtightly seal a gap between the small-diameter portion11band the plunger3. The O-ring15is pressed by the spring bearing washer13due to a biasing force of the spring4, which ensures the sealing.

The nut6is screwed to a screw portion5aformed in the lower end portion of the push rod5so as to be relatively rotatable and is spline-connected to an inner surface of the inner housing10so as to be movable in the axial direction and so as to be unrotatable. Furthermore, a spring bearing washer14bis disposed on a stepped portion11dformed in the upper portion of the nozzle cone11, and between the spring bearing washer14band the nut6screwed to the lower portion of the push rod5, a spring member17is disposed. The spring bearing washer14bprevents the spring bearing washer14afrom moving upward.

The pipette device1includes a pipette detaching mechanism20detaching the pipette tip12that has been used, from the nozzle cone11.

The detaching mechanism20has: an eject cone23fitted around an outer peripheral portion of the nozzle cone11; an eject rod21coupled to the eject cone23; and a return spring22biasing the eject rod21in a return direction (upward inFIG. 1). An upper end portion of the eject cone23is inserted in a lower end portion of the outer housing9. Further, an eject button21ais attached to an upper end portion of the eject rod21, and a lower end of the eject cone23faces and abuts on the pipette tip12.

When the eject button21ais pressed down by a finger, the eject rod21moves down the eject cone23, so that the used pipette tip12is pressed down to fall from the nozzle cone11. When the finger is detached from the eject button21a, the eject rod21is returned to the original position by the return spring22, followed by the returning of the eject cone23.

First to third calibrated dials25to27are fitted to the push rod5. The first calibrated dial25is connected to the push rod5so as to rotate with the push rod5and so as to be relatively movable in the axial direction, and the second and third calibrated dials26,27are fitted to the push rod5so as to be relatively rotatable. Further, the first to third calibrated dials25to27are coupled to one another by a gear shaft28.

When the push rod5rotates, the first calibrated dial25rotates by one graduation and its indication increases, and when the indication of the first calibrated dial25increases by 10 graduations, the indication of the second calibrated dial26increases by one graduation, and further, when the indication of the second calibrated dial26increases by 10 graduations, the indication of the third calibrated dial27increases by one graduation. In this manner, the graduations of the calibrated dials25to27change according to the number of rotations of the push rod5, and it is confirmed that the cylinder volume has been adjusted so that a collection amount becomes an amount corresponding to the graduations.

It should be noted that the number of rotations of the push rod5and the change in the graduations of the calibrated dials25to27are not limited to the above example. For example, when the indication of the first calibrated dial25increases by five or two graduations, the indication of the second calibrated dial26may increase by one graduation.

In the inner housing10, a restricting mechanism30is disposed to restrict the improper rotation of the push rod5. The restricting mechanism30has: a fixed plate31aunrotatably fixed to the inner housing10; a movable plate31bfitted to the push rod5so as to rotate with the push rod5; a plurality of balls33held by the movable plate31b; a spring washer32awhich and the fixed plate31asandwich the balls33; and a biasing spring34pressing and biasing the spring washer32atoward the fixed plate31a. A concave portion in which the balls33are caught is formed in the fixed plate31a.

Between the inner housing10and the push rod5, a speed increasing mechanism35of a planetary gear type is disposed to transmit input rotation to the push rod5, after increasing its speed or without any change.

The speed increasing mechanism35has: a sun gear5bformed in an upper portion of the push rod5integrally and coaxially with the push rod5; three planetary gears36rotating on own axes while rotating around an outer periphery of the sun gear5b; a carrier37supporting the planetary gears36so as to allow the planetary gears36to rotate; and an outer ring38which has an internal gear38bengaged with the planetary gears36and is unrotatably supported by the outer housing9of the pipette main body2.

The outer ring38is in a cylindrical shape, and on its outer peripheral surface, a fitting portion38afitted to the outer housing9is formed, and in an axial-direction upper half portion of its inner peripheral surface, the internal gear38bis formed. Further, in a lower half portion of the inner peripheral surface, the spring washer32bis disposed, and the spring34is in pressure contact with the spring washer32b.

The carrier37has: a holding portion37ain a cylindrical shape having a bottom wall37a′; and a bearing plate37bfitted to an axial-direction lower end portion of the holding portion37a. A through hole37gthrough which the push rod5passes is formed in the bottom wall37a′. Further, the bearing plate37bis fixed owing to press-fitting of boss portions37fintegrally formed with the holding portion37a. Further, in an axial-direction upper end portion of the holding portion37a, a hexagonal projecting portion37cto which a speed increasing dial39is fitted is integrally formed so as to project from the pipette main body2.

Further, in the holding portion37a, opening portions37dhousing the planetary gears36are formed in a slit shape. The planetary gears36are disposed in the opening portions37d.

In the bottom wall37a′ of the holding portion37aand the bearing plate37b, shaft holes37esupporting shaft portions36aof the planetary gears36so as to allow the shaft portions36ato rotate are formed. The planetary gears36are disposed in the opening portions37dto be engaged with the internal gear38band the sun gear5b.

In the speed increasing mechanism35of this embodiment, the number of teeth of each of the gears, an input member, and an output member are set so that one rotation of the speed increasing dial39causes about 3.5 rotations of the push rod5. Concretely, for example, the number of teeth of the sun gear5bis set to 12, the number of teeth of each of the planetary gears36is set to 9, and the number of teeth of the internal gear38bis set to 30, and the speed increasing dial39, that is, the carrier37serves as the input member and the push rod5serves as the output member.

It goes without saying that the speed increase ratio is not limited to the above example.

To collect the sample by the pipette device1of this embodiment, the speed increasing dial39is rotated by a finger until the graduations of the first to third calibrated dials25to27indicate a value substantially corresponding to a necessary collection amount, and subsequently the push rod5is rotated for fine adjustment. In this case, as described above, the rotation of the speed increasing dial39is transmitted to the push rod5after its speed is tripled, and when the push rod5is rotated, the push rod5rotates as it is to move the plunger3in the axial direction, so that a stroke amount of the plunger3and as a result, a volume of the cylinder portion “a” is set.

The pipette tip12is fitted to the nozzle portion11cof the nozzle cone11, and the push button7is pressed down by the finger to move the plunger3to a lower end position in a cylinder volume reducing direction. In this state, the pipette tip12is immersed in the sample and the finger is detached from the push button7. Then, the plunger3moves up in a volume increasing direction by the biasing force of the spring17, a pressure in the pipette tip12becomes negative, and the indicated amount of the sample is collected. In order to inject the collected sample into a device for inspection, analysis, or the like, it is only necessary to push the push button7again, and consequently, the plunger3moves down and the sample is jetted from the pipette tip12. Thereafter, the eject button21ais pressed down to eject the used pipette tip12.

According to this embodiment, since there is provided the speed increasing mechanism35transmitting the input rotation input to the speed increasing dial39to the push rod5after increasing its speed, it is possible to adjust the collection amount of the sample in a short time. This makes it possible to improve collection workability even when the setting of the collection amount is frequently changed, which enables a quick collection work.

In this embodiment, the speed increasing mechanism35is the planetary gear mechanism including: the sun gear5bintegrally formed with the push rod5; the three planetary gears36rotating on their own axes while rotating around the outer periphery of the sun gear5b; the carrier37supporting the planetary gears36so as to allow the planetary gears36to rotate; and the internal gear38bengaged with the planetary gears36. This structure makes it possible to obtain a large speed increase ratio with a compact structure.

Further, since the speed increasing mechanism35is the mechanism of the planetary gear type, it is possible to obtain a large speed increase ratio with a compact structure, which makes it possible to dispose the speed increasing mechanism35between the pipette main body2and the push rod5without any size increase of the pipette main body2.

Further, the speed increasing mechanism35is structured to output the rotation inputted to the push rod5, from the push rod5without any change. Therefore, in adjusting the collection amount, the rough adjustment can be made in a short time by the speed increasing mechanism35, and by subsequently rotating the push rod5, the fine adjustment can be made, which can enhance accuracy of the collection amount adjustment.

Further, the carrier37houses the planetary gears36in the opening portions37dformed in the holding portion37ain the bottomed cylindrical shape and supports the shaft portions36aat the both ends of the planetary gears36by the bottom wall37a′ of the holding portion37aand the bearing plate37bso as to allow the shaft portions36ato rotate. Therefore, it is possible to downsize a part corresponding to the planetary gears36, which makes it possible to dispose the speed increasing mechanism35without any size increase of the pipette main body2.

Further, the speed increasing dial (input member)39is fitted to the projecting portion37cintegrally formed with the holding portion37aof the carrier37and projecting out in the axial-direction from the pipette main body2. This makes it possible to easily rotate the carrier37by rotating the speed increasing dial39.

Furthermore, since the carrier37is rotatably supported by the outer ring38fixed to the pipette main body2, it is possible to realize the structure in which the carrier37is rotatably supported by the pipette main body2, without causing any complication of the structure or any increase in the number of components.

The above embodiment describes the case where the speed increasing mechanism35is of the planetary gear type, but it should be noted that the speed increasing mechanism of the present invention is not limited to this. For example, the speed increasing mechanism can be formed by the combination of spur gears or by a harmonic gear.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.