JPH075013A - Repetitively dispensing pipet - Google Patents

Abstract

PURPOSE:To set a one-time dispense quantity without steps, and make it possible to perform a highly precise repetitive dispeuse. CONSTITUTION:When a push button 51 is pushed and a first rack 8 is moved forward against a coil spring 12, rotation of a drive gear 5 engaged with the first rack 8 is transmitted to a pinion through a one way clutch, and a second rack 9 engaged with the pinion pushes down a piston 34 in a cylinder by a specified distance. As the result, the piston 34 is moved only when the first rack 8 is moved forward a specified quantity of liquid is discharged, the displacement of the first rack 9 is transmitted only in one direction, and dispensing is repeated at and after the next time because the second rack 9 stops at forward movement position just before by the action of the one way clutch even if the first rack 8 is moved backward by spring force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an object to provide a repetitive dispensing pipette in which one dispensing amount can be set steplessly and can be displayed digitally.

[0002]

2. Description of the Related Art A repetitive dispensing pipette, which is convenient for subdividing an equal amount of a drug solution in a reagent bottle, can repeatedly discharge a predetermined amount of the drug solution by a single inhalation operation, so that a chemical analysis or Useful for drug testing. A first conventional example of this type of repetitive dispensing pipette is, for example, Japanese Patent Publication No. 59-4.
No. 649 (JP-A-57-77916) "Repeating dispenser"
Have been disclosed in. This one uses a piston unit that applies a piston / cylinder mechanism as a chemical liquid suction / exhaust pump, attaches a nozzle 78 to be inserted into a reagent bottle at the tip of the cylinder, and installs a claw feed mechanism on the piston 73 that enables a stepwise discharge operation. It is assembled and configured. In use, first, the tip of the nozzle is inserted into the reagent bottle, and the drug solution is sucked into the cylinder while pushing up the suction button 47 connected to the piston 73. Next, when the nozzle 78 is applied to the test tube of the dispensing destination and the operating cylinder 20 is pushed down with a finger, the claw 53 that moves downward together with the operating cylinder 20 causes the rack shaft 45 to move.
Mesh with the teeth 46 of the. At this time, the rack shaft 45 is pushed downward by a predetermined amount, and a predetermined amount of chemical liquid is discharged from the cylinder 71. After completion of the first discharge, the operating cylinder 20
When the claw 53 is released, the operating cylinder 20 and the claw 53 return upward by the force of the spring 51, but the claw 53 during the returning operation simply slides with respect to the rack shaft 45 and is not locked. Stops at the discharge position. Therefore, by repeatedly depressing and releasing the push button, a predetermined amount of drug solution is repeatedly dispensed.

As a second conventional example of the repeated dispensing pipette, there is a commercially available repeated dispensing pipette.
When a push button is pushed down after the liquid medicine is sucked into the cylinder, this commercially available repeated dispensing pipette engages a claw integrated with the push button with the pinion to rotate the pinion by a predetermined angle, thereby causing the pinion to move. A rack that constantly meshes and a piston integrated with the rack move downward by a predetermined amount, and a certain amount of the chemical liquid is discharged. When the pressing force of the push button is released and the push button moves upward, the claw is released from the engagement with the pinion and slips with respect to the pinion, so that the downward movement position of the piston is maintained. Repeated dispensing is performed by repeating this operation.

[0004]

In the repeat dispensing pipette of the first conventional example, an inner cylinder 30 for restricting the lower limit of movement of the operation cylinder is rotatably fitted in the operation cylinder 20. When the operation cylinder is pushed down, the lower end of the inner cylinder is brought into contact with and locked by the stopper surface 42, and the downward movement is stopped to complete one dispensing. Specifically, several step portions 33 to 37 having different heights are formed at the lower end of the inner cylinder, and by rotating the inner cylinder 30 with respect to the operation cylinder while rotating the operation ring 31 with a fingertip, Although the step portions 33 to 37 that come into contact with and engage with the stopper surface can be switched, there are the following drawbacks.

When changing the dispensing amount, it suffices to change the distance between the step portion and the stopper surface.
0 Since there is a physically fixed limit to the number of steps that can be formed with steps in the circumferential direction at the lower end, it is possible to set the dispensing amount only in steps and within a certain range. There was a drawback that it became a thing.

Further, in order to set the dispensing amount steplessly, the inner cylinder 30 or the claw 53 is connected to a mechanism of a screw and a nut so that at least the downward movement start position of the claw 53 (that is, upward movement). Even if the position can be variably positioned in the vertical direction infinitely, the position at which the claw moves slightly downward and the first engagement with the rack teeth is always determined by the pitch of the rack teeth. That is, in principle, the variable minimum unit of the dispensing amount cannot improve the resolution below the pitch of the rack teeth formed on the rack shaft.
That is, there is a drawback that the dispensing amount cannot actually be set steplessly and the application range is limited.

[0007] Therefore, even if other conventional examples are included, there is no one in which one dispensing amount can be variably set steplessly. Therefore, it is necessary to digitally display the one dispensing amount variable. There was no such thing.

The second conventional example also has the same drawbacks as the first conventional example.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional example, and has the structure of a body (1).
And a shaft unit (51, 25, 15, 11, 8) which has at least a pressing portion (51) and a first rack (8) and which is attached to the body so as to be vertically reciprocally movable.
A spring (12) for urging the shaft unit in the upward return direction, a second rack (9) and a piston (34) fitted in the cylinder (38), and with respect to the body (1). And a piston unit (8, 33, 34) that is reciprocally movable in the vertical direction and a shaft (3
A), at least a first gear (5) that meshes with the first rack (8), a second gear (3B) that meshes with the second rack (9), and the first and second gears. Gear (5, 3
A gear unit (3) provided with a one-way clutch (4) for transmitting rotational power between B) only in one rotation direction.
A, 5, 3B, 4).

Further, the shaft unit further includes a screw shaft portion (15) and a screw stopper portion (14) which is screwed onto the screw shaft portion so as to be vertically movable.
And a nut (16) capable of abutting against each other, and by adjusting the movement of the nut, the stroke of one dispensing amount can be set steplessly.

[0011]

According to the above construction, when the pressing portion (51) of the shaft unit is pushed to move the first rack (8) forward against the spring (12), the first rack (8) meshes with the first rack (8). The rotation of the first gear (5) is transmitted to the second gear (3B) via the one-way clutch (4), and the second gear (3B)
A second rack (9) that meshes with pushes down the piston (34) in the cylinder (38) by a predetermined distance. For this reason,
The piston (34) is displaced only when the first rack (8) is moved forward to discharge a predetermined amount of liquid, and even if the first rack (8) is moved back by the spring force, the one-way clutch (4) By this action, the second rack (9) stops at the previous forward movement position, so that the displacement of the first rack (9) is transmitted only in one direction and the dispensing is repeated from the next time onward by the same repetition.

The first gear (5) and the second gear (3B)
The second rack relative to the displacement of the first rack (8) according to the gear ratio of
Although the displacement ratio of the rack (9) is determined, the slipping function of the one-way clutch allows the variable minimum unit of the dispensing amount for one time to be zero, that is, the dispensing amount can be set continuously variable.

[0013]

1 and 2 are a front view and a side view of an embodiment of a repeat pipette according to the present invention, and FIGS.
A vertical sectional front view of the above-mentioned repeated dispensing pipette and 4-4 in FIG.
FIG. 5 is an enlarged sectional view taken along line 5-5 in FIG. 4, and FIGS. 6 to 10 are longitudinal side views showing a sequential operation of the above repetitive dispensing pipette.

The repetitive dispensing pipette shown in FIGS. 1 and 2 is constructed by incorporating a main unit inside a resin cylindrical body 1 which can be held by one hand. A counter window 24 for a digital display mechanism is formed in the front portion of the body 1, and an ejector button 31 used for inhaling a chemical liquid and discharging a tip is vertically provided on a rear portion opposite to the counter window 24. A rectangular hole (not shown) for guiding is provided. The upper surface opening of the body 1 is covered with a cap 30 in which the capacity of each model is described as, for example, 20 to 100 microliters (μl).
A push button 51 for pushing from above with a thumb is coupled to the tip of a button shaft 25 made of an aluminum prismatic member through which a lock screw 29 screwed into a central screw hole of a presser 26 housed in 0 is inserted loosely. I am allowed. In addition, the lower surface opening of the body 1 is closed by an ejector cap 45 with a resin lower body portion 35 interposed therebetween, and a transparent resin is attached to the tip of a cylinder 38 that is inserted through an ejector pipe 43 that penetrates the ejector cap 45. The disposable chip 52 made of metal is removably inserted. The tip 52 is basically discarded without being reused or is reused after cleaning in order to prevent the possibility that the chemicals are mixed by mistake.

Inside the body 1, as shown in FIGS. 3 and 4, the shaft unit with a digital display mechanism for axially transmitting the movement of the push button 51 and the displacement of the first rack 8 driven by the shaft unit. , A piston unit for transmitting the displacement of the second rack 9 driven by the gear unit to the piston 34, the tip 5
Ejector units and the like for disengaging 2 are arranged in the axial direction in order from the top. After the piston unit and the ejector unit are assembled to the body 1, the shaft unit and the gear unit are integrally mounted inside the body 1 through the upper opening of the body 1, and at that time, the second rack 9 meshes with the gear unit.

The shaft unit includes a push button 51, a button shaft 25, a variable screw 15, a first rack holder 11, and a first rack holder.
It is composed of a rack 8 and the like. This shaft unit is
When the lock screw 29 is loosened and the push button 51 and the button shaft 25 are rotated in the forward and reverse directions, the dispensing amount is variably set. On the other hand, in conjunction with the forward and reverse rotation of the button shaft 25, the digital display mechanism is operated. The display can also be switched. Specifically, a presser 26 is housed inside the cap 30 by closing the upper surface opening of the body 1, and between the presser 26 and the base 14 facing the presser 26 with a certain distance therebetween via the pinion shaft 19. , Shaft unit and digital display mechanism are incorporated. As will be described later, the digital display mechanism comprises a well-known counter mechanism for displaying a three-digit numerical value, and a pinion shaft 19 whose both ends are fixed to the retainer 26 and the base 14 by set screws 26A and 14A is used for displaying the numerical value. Carry pinion 22
A and 22B are rotatably fitted.

The button shaft 25 is inserted into a presser 26 covered with a cap 30 to reach the inside of the body 1, but more specifically, a lock screw 29 is screwed into a recess formed in the presser 26.
Then, the Teflon washer 28 and the lock plate 27, which are pressed against the bottom surface of the recess by the lock screw 29, are inserted through the cap 30 to reach the inside of the body 1. The button shaft 25 inserted into the body 1 has a counter drive adjustment ring 23 whose upper surface abuts on the cap 30 inserted through the button shaft 25.
Is integrally rotatably connected to. The variable screw 16 is screwed with a variable nut 16 whose dispensing amount is set according to the screwing position, and the upper and lower displacement limits of the variable nut 16 are stopped by the screw 18 and the base 14. . The base 14 is
The pinion shaft 19 is engaged with the step portion of the inner wall of the body 1 and is connected to the presser 26 by the pinion shaft 19 described above.
Further, a cylindrical portion 14B for accommodating the variable screw 15 and guiding the variable nut 16 in a non-rotatable manner in the axial direction is provided at a substantially central portion of the base 14, and the stopper is provided at an opening portion of the cylindrical portion 14B. The screw 18 is screwed.

The digital display has 0-9 indicating the smallest digit.
The drive drum 21 in which the numbers up to are engraved on the outer periphery, and the upper two digit digit number arrangement drums 20A and 20B in which the numbers 0 to 9 are engraved on the outer periphery are also included in the cylindrical portion of the base 14. 14B is rotatably fitted and configured. The adjustment ring 23 having a square hole that is rotatably integrally engaged with the button shaft 25 is spline-fitted to the drive drum 21, and the drive teeth formed at only one place on the drive drum 21 are provided via the carry pinion 22A. Second digit digit arrangement drum button 20
It meshes with A. This second digit digit arrangement drum 20
In A, the teeth formed on the entire circumference mesh with the carry pinion 22A, but only the teeth formed at only one place mesh with the carry pinion 22B. Engages with the digit / numeral arrangement drum 20B of the third digit via the carry pinion 22B. Therefore, the drive drum 2
The second digit digit arrangement drum 20A when 1 rotates once
Is rotated 1/10 and the second digit digit arrangement drum 20A makes one rotation, the third digit digit arrangement drum 20B is made 1
/ 10 turn.

The variable screw 15 rotatably connected to the lower end of the button shaft 25 is simply in contact with the upper surface of the first rack holder 11 which is abutted and locked by the base 14 by the urging force of the spring 12. It functions to push down the first rack 8 held by the first rack holder 11. A guide shaft 13 having a lower end fitted and fixed to the case 2 of the gear unit is inserted into two axially symmetrical positions in the first rack holder 11, and the guide function causes the first rack holder 11 to move in the axial direction. The displacement is guided. Further, a coil spring 12 is fitted between the first rack holder 11 and the gear case 2, and always biases the first rack holder 11 upward.

The gear case 2 is locked to the step portion of the inner wall of the body 1 and, as shown in FIG. 5, the pinion shaft 3A.
On the other hand, the one-way clutch 4 which is retained inside the large-diameter drive gear 5 by the clutch retainer 6 to prevent it from coming off and the small-diameter pinion 3B are coaxially fixed. Both ends of the pinion shaft 3A are held by the gear case 2 and the lid 10 fixed to the gear case 2 by the set screw 10A, and the drive gear 5 is mounted on the pinion shaft 3A via the bearing 7.
It is assembled to be freely rotatable. The one-way clutch may be provided between the shaft 3A and the pinion 3B instead of being provided between the shaft 3A and the drive gear 5.

In FIG. 5, the drive gear 5 is in mesh with the first rack 8 and the pinion 3B is in mesh with the second rack 9. Therefore, the displacement transmission ratio from the first rack 8 to the second rack 9 is determined by the gear ratio between the drive gear 5 and the pinion 3B. The one-way clutch 4 may be a known rotary one-way clutch in which a coil spring and a ball are inserted between an inner race fitted and fixed to the pinion shaft 3A and an outer race fitted and fixed to the inner circumference of the drive gear 5, for example. Origin type OWC4-9-6-
IN is used.

In this one-way clutch 4, when the first rack 8 moves downward and the drive gear 5 rotates in the clockwise direction in FIG. 4 (hereinafter referred to as the forward rotation direction), the balls engage with the inner wall of the outer race. 4 contributes to the power transmission to the pinion shaft 3A, but the first rack 8 moves upward and the drive gear 5 moves to the position shown in FIG.
When rotating in the counterclockwise direction (hereinafter referred to as the reverse rotation direction), the ball escapes from the inner wall of the outer race, so that power is not transmitted to the pinion shaft 3A. However, when viewed from the side of the pinion 3B, when the ejector button 31 is operated and the second rack 9 is moved upward, for example, when inhaling a chemical solution, rotation of the pinion 3B in the reverse direction is driven via the one-way clutch 4. Since the power is transmitted to the gear 5, it is necessary to consider the design of the meshing relationship between the drive gear 5 and the first rack 8 as described below.

That is, the first rack 8 has the piston 34.
To allow the drive gear 5 to rotate during the upward return movement of
At the normal position for returning to the upper position, a certain length from the lower end side is defined as a toothless portion 8a having no rack teeth so as to be disengaged from the drive gear 5. Therefore, when the ejector button 31 is operated and the second rack 9 is moved upward to inhale the chemical liquid, the rotation of the pinion 3B in the reverse direction is transmitted to the first rack 8 via the one-way clutch 4 and the drive gear 5. There is no such thing.

From the viewpoint different from the above, the toothless portion 9a is also formed on the second rack 9. That is, when the piston 34 has finished dispensing the last time and moved to the vicinity of the lowermost part, the second rack 9 has a piston holder 33, which will be described later.
So that it stops before or just before the ejector pin 42,
A certain length from the upper end side is a toothless portion 9a without rack teeth. Therefore, after the final dispensing is completed, push button 5
The second rack 9 and the piston 34 will not move downward no matter how many times the button 1 is pressed, and the tip 52 of the cylinder 38 will not move from the tip of the cylinder 38 only when the ejector button 31 is pressed downward.
The chip 52 cannot be ejected even if the push button 51 is pressed.

The lower end of the second rack 9 is fixed to the piston holder 33 with a screw 9A, and the upper end of the second rack 9 is inserted through the gear case 2. The piston holder 33 also holds the upper end of the piston 34, and the lower end of the ejector shaft 32 is fixed by a set screw 32A. Therefore, if the ejector button 31 attached to the upper end of the ejector shaft 32 is slid up and down,
The piston 34 can be integrally moved up and down. The piston 34 is slidably fitted in a cylinder 38 fixedly held in the lower portion 35 of the body, and constitutes a piston unit together with the second rack 9 and the cylinder 38. The O-ring 39 that seals the sliding contact portion of the piston 34 in a liquid-tight manner is fitted on the inner circumference of the upper end opening of the cylinder 38, and the wall of the tubular portion 35A of the lower body 35 is sandwiched between the seal ring 40 and the O-ring retainer 36. Is axially pressed against. In this case, set the cylinder holder 37 to the cylinder 3
By holding the cylinder holder 37 fitted to 8 in the tubular portion 35A by screwing it, the cylinder 38 is held to the lower portion 35 of the body.

An ejector pin receiver 41, which holds the lower end of an ejector pin 42 slidably inserted in the cylinder holder 37, is slidably fitted to the outer periphery of the cylinder holder 37, and the piston holder 33 moves downward. When it is displaced to the limit, it moves downward together with the ejector pin 42. Further, an ejector spring 44 is fitted around the outer circumference of the ejector pipe 43, and the ejector cap 45 is screwed into the cylinder holder 37. Ejector pipe 4
3 is slidable with respect to the cylinder holder 37.
Further, the tip 52 is mounted on the outer periphery of the cylinder 38 whose tip extends from the ejector pipe 43.

The ejector unit for ejecting the tip 52 includes an ejector button 31, an ejector shaft 32, an ejector pin 42, and an ejector pin receiver 4
1, an ejector pipe 43, an ejector spring 44 and the like.

Next, the operation of the above repeated dispensing pipette will be described with reference to FIGS. 6 to 12. First, in FIG.
The state where the cylinder 38 is filled with the liquid medicine is shown, but the liquid medicine is sucked by inserting the tip 52 at the tip of the cylinder 38 into the liquid medicine bottle and pulling the ejector button 31 back to the uppermost end. Therefore, when the body 1 of the repetitive pipette is grasped with one hand and the push button 51 is pushed down by the thumb, the button shaft 25 and the variable screw 15 are integrally moved downward, and the first rack holder 11 is resisted against the coil spring 12. And push down. As shown in FIG. 7, the downward movement of the button shaft 25 is performed until the lower end surface of the variable nut 16 is brought into contact with and locked to the upper end surface of the base 14, and during this time, the first rack holder 1
The first rack 8 held at 1 drives the drive gear 5 in the normal direction. The normal rotation of the drive gear 5 is transmitted to the pinion 3B that is a driven gear via the one-way clutch 4, and the second rack 9 is driven downward by the normal rotation pinion 3B. Therefore, the piston 34 integrated with the second rack 9 moves downward by the same distance as the second rack 9, and discharges the chemical liquid in the cylinder 38 into the sample.

In this case, the stroke (downward movement distance) of the piston 34 becomes a stroke b (see FIG. 7) obtained by multiplying the stroke a of the button shaft 25 (see FIG. 7) by the gear ratio of the drive gear 5 and the pinion 3B. Since the gear ratio is fixed depending on the model, it is substantially determined by the stroke of the button shaft 25, that is, the distance between the variable nut 16 and the base 14.

On the other hand, when the pressing force of the push button 51 is released,
The button shaft 25 is pushed back by the force of the coil spring 12, and the push button 51, the variable nut 16, the variable screw 15, the first rack holder 11, the first rack 8 and the like are shown in FIG.
As shown in, all of them move up to the first position all at once.
Therefore, the drive gear 5 is driven in the reverse direction as the first rack 8 returns to the upward direction, but the reverse rotation of the drive gear 5 is blocked by the one-way clutch 4 and is not transmitted to the piston 34.
The drive gear 5 only idles. Therefore, the second rack 9 does not move upward following the first rack 8, and the piston 34 also stops at the first stage discharge position.

Thus, every time the first dispensing is completed and the push button 51 is pushed down several times, the first rack 8 and the second rack 8
A predetermined amount of liquid medicine is dispensed by the piston 34 in accordance with the downward movement of the rack 9.

Thus, for example, when the twelfth final dispensing is performed, as shown in FIG.
Immediately after the uppermost end of the toothed portion of the second rack 9 is disengaged from the pinion 3B by moving downward by 2b, that is, the toothless portion 9a corresponds to the pinion 3B. Therefore, even if the push button 12 is pushed down again from the ascending return position shown in FIG.
4 never moves down.

When the final dispensing is completed, the piston holder 3
The lower surface of 3 abuts on the ejector pin 42. Therefore, in FIG. 10, when it is desired to eject the tip 52, the ejector button 31 is depressed by the remaining stroke.
As a result, the piston holder 33 moves the ejector pin 42
Is pushed down, and the ejector pin receiver 41 pushes down the ejector pipe 43 against the ejector spring 44. The ejector pipe 43 slides on the outer wall of the cylinder 38 and pushes the tip 52 covering the tip of the cylinder 38, and removes it from the cylinder 38. Therefore, the chip 52
Is released by the ejector button 31 instead of the push button 51, and the tip 52 is not released unnecessarily in connection with the final dispensing operation.

By the way, the amount of the chemical solution discharged in one operation, that is, the dispensed amount is displayed as a three-digit numerical value on the digital display mechanism. However, regarding the numerical value at the end, an integer value may not be clicked. Instead, for example, the value below the decimal point, such as the value between "3" and "4" or the value near "3", can in principle be continuously variably adjusted. The resolution below the decimal point of this digital display mechanism is determined by the minimum rotation angle of the push button 51 that can be operated with the feeling of a human fingertip, but in practice, for example, 20 to 100 microliters (μ
In the range up to l), it is possible to make fine adjustments not only in units of 1 microliter but also in finer increments.

When adjusting the dispensing amount, refer to FIG. 3 and FIG.
First, the lock screw 29 is loosened, and the lock plate 27 is released from the regulation so that it can rotate together with the button shaft 25. next,
When increasing the dispensed amount for one time, the button shaft 25 is rotated clockwise together with the push button 51. As a result, the variable screw 15 also rotates in conjunction with the button shaft 25, and the variable nut 16 screwed onto the variable screw 15 is screwed upward in accordance with the amount of rotation of the button shaft 25. As a result, the distance between the lower end surface of the variable nut 16 and the upper end surface of the base 14 is increased, and the downward movement amount of the button shaft 25 that can be moved downward by one operation is also increased. On the contrary to the above, in order to decrease the dispensing amount for one time, the button shaft 25 together with the push button 51 may be rotated counterclockwise. After setting the required dispensing amount, tighten the lock screw 29 to lock the lock plate 27.
At the same time, the button shaft 25 is non-rotatably locked. By the rotation of the button shaft 25, the display of the digital display mechanism is increased or decreased, and the set dispensing amount is accurately displayed. Further, since the number of repetitions at the time of dispensing is a value obtained by dividing the cylinder volume by the amount of one dispensing, the number of repetitions decreases as the amount of one dispensing becomes larger.

[0036]

As described above, according to the present invention, the body (1), and at least the pressing portion (51) and the first rack (8), are reciprocally movable in the vertical direction with respect to the body (1). Mounted on the shaft unit (51, 25, 1
5, 11, 8), a spring (12) for urging the shaft unit in an upward return direction, a second rack (9) and a piston (34) fitted in the cylinder (38),
A piston unit (9, 33, 34) provided so as to be reciprocally movable in the vertical direction with respect to the body (1), and at least the first rack (8) with respect to the shaft (3A) arranged on the body. A first gear (5) meshing with the second rack (9), a second gear (3B) meshing with the second rack (9), and the first and second gears.
Since the gear unit (3A, 5, 3B, 4) provided with the one-way clutch (4) for transmitting the rotational power between the gears (5, 3B) only in one rotation direction is provided, To work.

That is, the shaft units (51, 25, 1
Press the pressing part (51) of (5, 11, 8) to press the spring (12).
When the first rack (8) is moved forward against the rotation of the first rack (8), the rotation of the first gear (5) meshing with the first rack (8) is changed to the second gear (3B) via the one-way clutch (4). And the second rack (9) meshing with the second gear (3B) pushes down the piston (34) in the cylinder (38) by a predetermined distance, so that the piston (34) moves the first rack (8). The one-way clutch (4) works when the first rack (8) is moved back by the spring force when it is displaced to discharge a predetermined amount of liquid only when it is moved forward, and the second rack (9) is moved immediately before. Therefore, the displacement of the first rack (8) is transmitted in only one direction and the dispensing is continued by the same repetition from the next time onward. Therefore, there are the following advantages.

Regarding the variable minimum unit of one dispensing amount, since the meshing pitch of the pinion and the rack tooth is absorbed by the slip function of the one-way clutch (4), the variable minimum unit is originally the rack unit. Without being limited to the tooth pitch or the above-mentioned meshing pitch, it can be practically zero or stepless, which is very convenient in practice.

Further, as means for realizing the above-mentioned stepless variable, the shaft unit further includes a screw shaft portion (1
5) and a nut (1) screwed onto the screw shaft portion so as to be vertically movable and capable of abutting on the stopper portion (14) of the body.
6) and, by adjusting the movement of the nut,
Since the stroke of the dispensing amount can be set steplessly, the dispensing amount is set steplessly with extremely high accuracy according to the screwing position of the nut (16) screw-fed by the screw shaft portion (15). can do.

The basic configuration is a first rack that moves integrally with a push button, both gears, a rotary one-way clutch,
The basic structure is simple as long as there is a piston and a second rack that moves integrally, and the one-way clutch is a rotary type and does not take up space, so the product can be downsized.

By changing the meshing ratio of the first and second gears, the stroke of the piston can be easily changed, and the range of application is widened.

Since the minimum unit for varying the dispensing amount is cell, that is, stepless variable, it is very convenient to mount a known digital display mechanism to perform digital stepless display of the dispensing amount.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of a repeat dispensing pipette according to the present invention.

FIG. 2 is a side view of the repeat dispensing pipette.

FIG. 3 is a vertical cross-sectional front view of the above repeated dispensing pipette.

FIG. 4 is a sectional view taken along line 4-4 in FIG.

5 is an enlarged sectional view taken along line 5-5 in FIG.

FIG. 6 is a vertical sectional side view of the repeated dispensing pipette before being pressed.

FIG. 7 is a vertical cross-sectional side view of the repeated dispensing pipette in a one-step pressed state.

FIG. 8 is a vertical cross-sectional side view of the repeated dispensing pipette in a state after returning to the one-step pressing state.

FIG. 9 is a vertical sectional side view of the repeated dispensing pipette in a pressed state at the final stage.

FIG. 10 is a vertical cross-sectional side view of the repeated dispensing pipette in a state after returning to the final-stage pressure.

[Explanation of symbols]

 1 Rotation 2 Gear Case 3A Pinion Shaft 3B Pinion 4 One Way Clutch 5 Drive Gear 8 1st Rack 9 2nd Rack 11 1st Rack Holder 12 Coil Spring 14 Base 15 Variable Screw 16 Variable Nut 25 Button Shaft 31 Ejector Button 33 Piston Holder 34 Piston 38 Cylinder 51 Push Button 52 Chip

Claims (7)

[Claims] 1. A shaft unit (51, 25) having a body (1), at least a pressing portion (51) and a first rack (8), and which is attached to the body (1) so as to be vertically reciprocally movable. , 15, 11,
8), a spring (12) for urging the shaft unit in an upward returning direction, a second rack (9) and a piston (34) fitted in a cylinder (38), and a body (1) A piston unit (9, 33,
34) and disposed on the body, at least with respect to the shaft (3A),
Between a first gear (5) meshing with the first rack (8), a second gear (3B) meshing with the second rack (9), and between the first and second gears (5, 3B). A repetitive dispensing pipette, comprising: a gear unit (3A, 5, 3B, 4) provided with a one-way clutch (4) for transmitting rotational power only in one rotation direction. 2. The repeat pipette according to claim 1, wherein the one-way clutch (4) is housed in a first gear (5) and the second gear (3B) is attached to a shaft (3A). Repeated dispensing pipette, characterized in that the one-way clutch is fixed and performs a one-way clutch function between the first gear (5) and the shaft (3A). 3. The repeated pipette according to claim 1 or 2, wherein the first rack (8) returns upward so as to allow rotation of the first gear (5) during upward movement of the piston unit. The repetitive dispensing pipette, which is provided with a toothless portion (8a) which can be meshed and disengaged from the first gear (5) in the normal position. 4. The repeated dispensing pipette according to any one of claims 1 to 3, wherein the piston unit (9, 33, 34) is further provided with an ejector pressing portion (3).
1) is integrally provided, and the ejector pressing portion (3
By pressing 1) downward, the cylinder (3
Repeated dispensing pipette characterized in that the tip (52) attached to the tip of 8) is ejected. 5. The repeated dispensing pipette according to claim 4, wherein the second rack (9) has only the ejector pressing portion (31) when the piston unit finishes the final dispensing. Repeated dispensing pipette, characterized in that a toothless portion (9a) capable of engaging and disengaging from the second gear (3B) is provided so that the two racks (9) can be pushed downward. 6. A shaft unit (51, 25, 15,) which has a body (1), at least a pressing portion (51) and a first rack (8), and is attached to the body so as to be vertically reciprocally movable. 11, 8) and a spring (1 for urging the shaft unit in the vertical return direction).
2), a second rack (9), and a piston (34) fitted in the cylinder (38), and a piston unit (9, 33) that is reciprocally movable in the vertical direction with respect to the body (1). ，
34) and disposed on the body, at least with respect to the shaft (3A),
Between a first gear (5) meshing with the first rack (8), a second gear (3B) meshing with the second rack (9), and between the first and second gears (5, 3B). A gear unit (3A, 5, 3B, 4) provided with a one-way clutch (4) for transmitting rotational power only in one rotation direction, and the shaft unit further includes a screw shaft portion (15).
And a nut (16) screwed onto the screw shaft portion so as to be vertically movable and capable of abutting on the stopper portion (14) of the body.
And a repetitive dispensing pipette, wherein the stroke of one dispensing amount can be variably set by moving and adjusting the nut. 7. The repeated dispensing pipette according to claim 6, wherein the body further has a digital display mechanism for digitally variably displaying one dispensing amount in association with the rotation of the shaft unit. Characteristic repeat dispensing pipette.