Patent Description:
As would be understood by one of skill in the art, a pipette is a device that is normally used in conjunction with a pipette tip to transfer or distribute a measured volume of liquid from one location to another. Manually-operated air-displacement pipettes, which are of the most interest with respect to this application, operate generally by creating a vacuum via the retraction of a piston located in the pipette body. Thus, when the open end of an associated pipette tip is submersed in a liquid, the resulting vacuum draws air from the pipette tip and an amount of the liquid is consequently drawn into the tip to replace the evacuated air. Movement of the pipette piston is regulated such that a desired measured amount of liquid is drawn into the tip during the aspiration phase of the pipetting operation.

Manually-operated air-displacement pipettes are available in a wide volume range of between about <NUM>. 2µL to several thousand µL. Because a user may need to pipette a multitude of different liquid volumes, such pipettes are frequently offered with different volume ranges (e.g., <NUM>-<NUM>µL, <NUM>-<NUM>µL, <NUM>-<NUM>,<NUM>µL) and with volume adjustability within the selected volume range. Volume adjustability is commonly accomplished, for example, by manually rotating a provided volume setting shaft or manually rotating the plunger button and associated plunger of the pipette which, through one of various possible associated mechanisms, results in a change in the volume setting of the pipette.

A common drawback to known volume-adjustable pipettes has been the time and effort required to make volume adjustments - particularly when the difference between the current volume setting and a desired volume setting is large. For example, in the case of known volume-adjustable pipettes, a full rotation of the pipette volume adjusting device may result in a volume change of only <NUM>%-<NUM>% of the total volume of the pipette. Thus, making a large change in volume may require significant and time consuming effort on the part of a user.

Volume adjustable pipettes with speed-increased volume adjustment functionality are known. However, these know pipettes suffer from various deficiencies including, but not limited to, complex and/or inaccurate volume adjustment mechanisms, the need to employ separate volume adjustment inputs for low speed and high speed volume adjustment; and/or the need to provide a volume adjustment input that is separate from the pipette plunger rod or plunger button.

As would also be understood by one of skill in the art, calibration of the dispensed fluid volume is required for accurate pipetting. Consequently, pipettes are typically calibrated at the factory and may also be calibrated during servicing operations.

In one known pipette design, calibration is accomplished by disconnecting a volume display from an associated volume screw, and volume offset is separately accomplished by moving a bottom stop. In another known pipette design, calibration is accomplished by disengaging a volume display from an associated volume screw using a spline-type coupling located within the counter wheels of the volume display, and subsequently adjusting the position of the volume screw. In yet another known pipette design, calibration and volume offset are accomplished by moving an upper stop of the pipette without changing the pipette volume display (see e.g. <CIT>).

It is evident from the foregoing description that adjustable volume pipettes and pipettes that permit user calibration or volume offset are known. However, when the identified drawbacks of known volume-adjustable pipettes are considered in the context of the numerous pipetting operations and associated volume adjustments made by many pipette users over the course of a typical work day, the benefits of providing an improved design that facilitates more efficient pipette volume adjustment should be readily apparent. Similarly, while mechanisms and techniques for pipette calibration and volume offset are known, it would nonetheless be desirable to provide a simplified and compact pipette calibration/volume offset mechanism that may be used in conjunction with an improved pipette volume adjustment mechanism in a new manually operated pipette.

The invention is a pipette calibration and volume offset mechanism as defined in claim <NUM>.

Exemplary embodiments described herein are directed to a quickset mechanism for easily and rapidly adjusting the liquid volume of a manually-operated (manual) volume-adjustable pipette. The exemplary quickset mechanisms described in the present specification do not fall under the scope of the claims.

Other exemplary embodiments described herein are directed to a combined pipette calibration and volume offset mechanism that may be used in a manual pipette, such as but not limited to a volume-adjustable manual pipette having quickset volume adjustability. Still other exemplary embodiments described herein are directed to a volume-adjustable manual pipette that employs a quickset mechanism for rapid volume adjustment, and to such a quickset pipette with a combined pipette calibration and volume offset mechanism.

An exemplary pipette quickset volume adjustment mechanism (quickset mechanism) allows a user to rapidly and accurately adjust the volume of a pipette. Generally speaking, volume adjustments are made by adjusting the position of a volume screw of the pipette through rotation of the pipette plunger button - which rotates the plunger rod to which the plunger button is affixed. The quickset mechanism includes a specialized planetary gearbox that is selectively rotationally coupled to the plunger rod and adapted to alter the rotation speed-ratio between the plunger rod and the volume screw.

In one exemplary embodiment, the quickset mechanism may provide a user with three input modes: a direct drive mode, a speed multiplying mode, and a lock mode that prohibits volume adjustment. In the direct drive mode, the volume screw of the pipette is directly driven (i.e., in a <NUM>:<NUM> ratio) by rotation of the plunger button. In the speed multiplying mode, rotation of the plunger button drives the planetary gearbox which, in turn, rotates the volume screw. The planetary gearbox may have a wide range of possible speed ratios (e.g., <NUM>:<NUM>). Consequently, a single rotation of the plunger button will result in multiple (e.g., four) rotations of the volume screw when the quickset mechanism is set to the speed multiplying mode. This allows a user to make large volume changes quickly and accurately. After using the speed multiplying mode, the quickset mechanism may be set to the direct drive mode to make the final, fine volume adjustment. The lock mode may be used to prevent inadvertent volume changes or drift once a desired pipette volume is set.

One exemplary embodiment of a volume-adjustable manual pipette with quickset volume adjustment (quickset pipette) is similar to a traditional manual pipette in that the quickset pipette may include a body portion, a tip mounting shaft attached to the body portion at the distal end thereof, and a piston assembly including a piston, a stroke spring, and a plunger button attached to a plunger rod, which is coupled to the piston. A user may axially displace the piston by way of the plunger button and associated plunger rod to aspirate and dispense a liquid of interest. The quickset pipette further includes a quickset mechanism, such as the exemplary quickset mechanism described above. Thus, an exemplary quickset pipette affords a user with the ability to aspirate and dispense liquids of different volumes, while easily and rapidly making precise volume changes.

An exemplary quickset pipette may also include a combined calibration and volume offset mechanism by which the pipette may be calibrated and/or a volume offset may be applied. Generally speaking, this exemplary calibration/offset mechanism includes among other components a mode selection mechanism, a follower element, an offset counter, a user rotatable input mechanism, a (calibration) housing, and a coupling for coupling the offset counter to a threaded element that is axially displaceable to adjust the home position of a pipette to which the calibration/offset mechanism is installed, thereby increasing or decreasing the aspiratable liquid volume of the pipette.

An exemplary calibration/offset mechanism may be installed in a volume-adjustable manual pipette, such as but not limited to an exemplary quickset pipette. In any case, the pipette may again have traditional manual pipette components such as those mentioned above. When the pipette is a quickset pipette the calibration/offset mechanism is installed in the pipette body along with the quickset mechanism.

A calibration adjustment is effected by first rotating the user rotatable input mechanism of the calibration/offset mechanism so that the offset counter displays a "zero" offset. Next, the mode selection mechanism is placed in the calibration mode, which disengages the offset counter from the coupling. The pipette may then be calibrated by turning the user rotatable input mechanism, which adjusts the axial location of the home position (and volume) of the pipette by axially displacing the threaded element. The volume may be adjusted in this manner, for example, until the gravimetric reading of the aspirated liquid dispensed by the pipette matches the set point of the pipette that is displayed by the counter wheels of the volume display.

To effect a volume offset, a user first ensures that the mode selection mechanism is in the offset mode - which is the default mode in this exemplary embodiment. This engages the offset counter, which is nominally set to zero. The desired volume offset may then be entered by turning the user rotatable input mechanism, which again adjusts the axial location of the home position and volume of the pipette by axially displacing the threaded element. In the offset mode, the amount of offset entered is tracked and indicated by the offset counter.

Other aspects and features of the general inventive concept will become apparent to those skilled in the art upon review of the following detailed description of exemplary embodiments along with the accompanying drawing figures.

In the following descriptions of the drawings and exemplary embodiments, like reference numerals across the several views refer to identical or equivalent features, and:.

As used herein "constrained" is intended to mean that the macro motion of a given component in a defined direction is permitted, but is limited in some fashion.

As used herein "restrained" is intended to mean that the macro motion of a given component in a defined direction is not permitted.

As used herein "macro motion" is intended to mean motion beyond what is allowed by slip-fit type clearances. For example, a rotating shaft is considered to have no macro motion in the direction perpendicular to its axis of rotation even if a clearance is provided to allow free rotation.

One exemplary manually-operated, quickset volume-adjustable pipette (quickset pipette) <NUM> is depicted in cross section in <FIG>. The quickset pipette <NUM> generally includes a body <NUM> for gripping by a user. The pipette body <NUM> includes a tip mounting portion <NUM> at a distal end 10b thereof. The tip mounting portion <NUM> is adapted to receive and retain a pipette tip (not shown). A plunger assembly of the quickset pipette <NUM> comprises a piston <NUM> that is located for reciprocating movement within the body portion <NUM>, a plunger rod <NUM> that extends proximally upward from the piston, and a plunger button <NUM> that is located outside the body portion <NUM> and is affixed to a proximal end of the plunger rod for manipulation by user. A stroke spring <NUM> resides within the body portion <NUM> to drive the piston <NUM> proximally during a liquid aspiration phase of a pipetting operation. A blowout spring <NUM> of a blowout assembly <NUM> (see <FIG>) also resides within the body portion <NUM> and, as would be understood by one of skill in the art, acts to return the piston <NUM> from a blowout operation that may be performed subsequent to dispensing aspirated liquid from the pipette. A tip ejector <NUM> may also be provided to eject pipette tips from the tip mounting shaft <NUM> when desired.

Because the quickset pipette <NUM> is a volume-adjustable pipette, a volume adjustment assembly is also provided for effectuating desired volume changes. The volume adjustment assembly includes, among other components, the plunger rod <NUM>, the plunger button <NUM>, and a substantially hollow volume screw <NUM> through which the plunger rod passes. The bottom face of the volume screw <NUM> defines the upper stop position of the plunger assembly in this exemplary embodiment, such as by contact with a flange <NUM> on the plunger rod <NUM>.

A volume setting display assembly <NUM> providing a volume setting display <NUM> that is visible through an opening <NUM> in the body <NUM> of the quickset pipette <NUM> may also be included for indicating the current pipette volume setting. As will be described in far greater detail below, the volume adjustment assembly of the quickset pipette <NUM> further includes a non-claimed quickset volume adjustment mechanism (quickset mechanism) <NUM> that facilitates a rapid adjustment of the pipette volume when desired.

As will also be described in further detail below, this exemplary quickset pipette <NUM> additionally includes a calibration/offset mechanism <NUM>. The calibration/offset mechanism <NUM> permits a user, service technician, etc., to factory calibrate or recalibrate the pipette, and/or to set a volume offset.

Setting aside for a moment the unique functionality imparted to the quickset pipette <NUM> by the quickset mechanism <NUM> and the calibration/offset mechanism <NUM>, the quickset pipette otherwise operates generally as would be familiar to one of skill in the art. That is, during a liquid aspiration phase of pipette operation, a user depresses the plunger button <NUM> to axially move the piston <NUM>, against the biasing force of the stroke spring <NUM>, from the upper stop position to a lower stop (home) position. The open end of the pipette tip (not shown) is then placed into a liquid of interest, and the plunger button <NUM> is released, allowing the stroke spring <NUM> to return the piston <NUM> to the upper stop position while simultaneously aspirating a volume of the liquid of interest. To dispense the aspirated liquid, the user places the pipette tip over a desired receptacle, and once again depresses the plunger button <NUM> to move the piston <NUM> from the upper stop position to the home position. Once the aspirated liquid is dispensed, the user may also perform a blowout operation by further depressing the plunger button <NUM> so as to cause an additional axial movement of the piston <NUM> and a compression of the blowout spring <NUM>. Upon completion of a blowout operation, releasing the plunger button <NUM> will once again result in a return of the piston <NUM> to the upper stop position, this time by the combined biasing forces of the blowout spring <NUM> and the stroke spring <NUM>.

Because volume changes between consecutive aspiration/dispensing operations may be significant, as explained above, the volume adjustment assembly includes the exemplary quickset mechanism <NUM>, which permits a selective multiplication in the speed by which the pipette volume may be adjusted. A more detailed depiction of the exemplary quickset mechanism <NUM> appears in <FIG>. As best shown in <FIG>, the exemplary quickset mechanism <NUM> includes a transmission input <NUM>, one or more cam follower pins <NUM> that are mounted to a distal portion of the transmission input, a first (direct drive) barrel cam <NUM>, a gearbox input <NUM>, a second (speed multiplying) barrel cam <NUM>, a planetary gearbox <NUM>, a gearbox output shaft <NUM>, and a direct drive lock plate <NUM>. The first barrel cam <NUM> and a majority of the remaining quickset mechanism components are retained in a frame <NUM> when the quickset mechanism <NUM> is in an assembled state, as shown in <FIG>. The plunger rod <NUM> passes axially through the entirety of the quickset mechanism <NUM>.

The transmission input <NUM> of the quickset mechanism <NUM> acts as a mode selector through which a user can opt to adjust the pipette volume using a fine (direct drive) or coarse (speed multiplying) mode. In some embodiments, the transmission input <NUM> may also be used to lock the quickset mechanism, thereby prohibiting user volume adjustments and preventing inadvertent changes or drift in selected pipette volume. The transmission input <NUM> is located at the proximal end 10a of the pipette body <NUM>, and will typically include a lever <NUM> or another appropriate actuator that protrudes through an opening in the pipette body to facilitate user rotation of the transmission input. In this exemplary quickset pipette <NUM>, the transmission input <NUM> also includes detented mode positions that correspond to each of the selectable direct drive, speed-multiplied and locked quickset mechanism modes. The transmission input <NUM> may also include one or more indicating elements <NUM> that may correspondingly point to a mode number, symbol or other graphic mode identifier located on the pipette body <NUM>. The indicating element(s) <NUM> will indicate the volume adjustment mode selected by a user via rotation of the transmission input <NUM>.

The direct drive barrel cam <NUM> and the speed multiplying barrel cam <NUM> each include one or more arcuate or sloped cam slots 80a, 90a, while the frame <NUM> includes one or more linear retention slots 110a. The cam slots 80a, 90a and the retention slots 110a substantially correspond in location to the one another when the quickset mechanism <NUM> is assembled, however, the cam slots 80a, 90a may be of somewhat different shape or orientation to produce a desired individual movement of the direct drive barrel cam <NUM> and the speed multiplying barrel cam <NUM>. The one or more cam follower pins <NUM> likewise extend through or into the one or more cam slots 80a, 90a and the one or more retention slots 110a in the assembled direct drive barrel cam <NUM>, speed multiplying barrel cam <NUM>, and frame <NUM> respectively. Thus, the direct drive barrel cam <NUM> is rotationally restrained by the frame <NUM>, and is axially constrained by the movement of the one or more cam follower pins <NUM> of the transmission input <NUM> that reside in the cam slots 80a of the direct drive barrel cam. During rotation of the transmission mechanism lever <NUM>, the one or more cam follower pins <NUM> rotate in the slots 110a in the frame, which causes the direct drive barrel cam <NUM> and the speed multiplying barrel cam <NUM> to move upward or downward due to corresponding interaction of the cam slots 80a, 90a located therein with the one or more cam follower pins <NUM>.

In this exemplary embodiment, three cam follower pins <NUM>, three corresponding cam slots 80a, 90a, and three corresponding retention slots 110a are used for force balancing purposes. Other numbers of cam follower pins, cam slots and retention slots may be used in other embodiments.

The planetary gearbox <NUM> shown in partially exploded form in <FIG>, is shown further exploded in <FIG>. This exemplary planetary gearbox <NUM> is comprised of planet gear carrier <NUM>, a plurality of planet gears <NUM>, a cap <NUM> (only as part of the gearbox housing), a sun gear <NUM>, a ring gear <NUM>, and the gearbox output shaft <NUM>. As shown, the planet gear carrier <NUM> may be an integral part of the gearbox input <NUM>, or the planet gear carrier may otherwise be affixed to a distal end thereof. Similarly, the sun gear <NUM> may be an integral part of or may otherwise be affixed to a proximal end of the gearbox output shaft <NUM>. The various components of the planetary gearbox <NUM> are contained in a gearbox housing. In this exemplary embodiment, the housing is comprised of the ring gear <NUM> and the cap <NUM>, which are adapted to snap together or to be otherwise joined so as to form a substantially monolithic structure.

In this exemplary embodiment, the planetary gearbox <NUM> is a single-stage planetary gearbox. Consequently, and generally speaking, when the planetary gearbox <NUM> is selectively engaged, the speed by which the volume of the quickset pipette <NUM> may be adjusted is multiplied by the speed ratio provided by the planetary gearbox <NUM>. A wide range of planetary gearbox speed ratios may be selected in different exemplary embodiments. For purposes of illustration only, the speed ratio provided by the planetary gearbox <NUM> of this exemplary quickset pipette <NUM> is <NUM>:<NUM>.

The plunger button <NUM> and plunger rod <NUM> of the quickset pipette <NUM> also play a role in the operation of the quickset mechanism <NUM>. More particularly, the plunger rod <NUM> passes through but is rotationally coupled to the gearbox input <NUM> of the planetary gearbox <NUM> of the quickset mechanism <NUM>, and the plunger button <NUM> is affixed to the proximal end of the plunger rod such that rotation of the plunger button will also rotate the plunger rod. In this exemplary embodiment, rotational affixation of the plunger rod <NUM> to the gearbox input <NUM> is accomplished by way of a hex-shaped (or other non-circular shaped) protrusion <NUM> on the plunger rod and a correspondingly shaped recess <NUM> in the proximal end of the gearbox input that is dimensioned to securely receive and retain the hex-shaped protrusion. Other rotational coupling techniques may be employed in other embodiments. Consequently, a rotation of the plunger button <NUM> will produce a rotation of the plunger rod <NUM>, and rotation of the plunger rod will produce a rotation of the gearbox input <NUM>.

As briefly suggested above, when the exemplary quickset mechanism <NUM> is assembled, the speed multiplying barrel cam <NUM> is concentrically located within the direct drive barrel cam <NUM> such that the distal portion of the transmission input <NUM> is received therein, and the one or more cam follower pins <NUM> that protrude from the transmission input <NUM> simultaneously extend through the one or more cam slots 80a in the direct drive barrel cam <NUM>, the one or more cam slots 90a in the speed multiplying barrel cam <NUM>, and the one or more cam slots 110a in the frame <NUM>. The axial motion of the one or more cam follower pins <NUM> is restrained by slots 110a in the frame <NUM>, while the rotational motion of the one or more cam follower pins is constrained by the slots in the frame. The transmission input <NUM> is axially restrained and is rotationally constrained by engagement of the one or more cam follower pins <NUM> with the slots 110a in the frame <NUM>. Consequently, rotation of the transmission input <NUM> within permitted limits via the lever <NUM> will cause the one or more cam follower pins <NUM> to move within the arcuate or sloped cam slots 80a, 90a, 110a which produces an axial displacement of the barrel cams <NUM>, <NUM>.

The gearbox input <NUM> may be of various designs, including but not limited to the elongated and substantially hollow shaft shown in the drawings. The gearbox input <NUM> transmits rotation of the plunger rod <NUM> (see above) to the planet gear carrier <NUM> of the planetary gear box <NUM>. The gearbox input <NUM> is axially restrained by the gearbox housing <NUM>, and is unconstrained rotationally.

As previously described, the gearbox housing <NUM> is an assembly comprising the ring gear <NUM> and the cap <NUM>. The cap <NUM> may be affixed to the ring gear <NUM> by a variety of techniques, such as but not limited to, by a spline and snaps. Since the ring gear <NUM> forms a part of the gearbox housing <NUM> in this exemplary planetary gearbox <NUM> embodiment, the ring gear is restrained from rotation whenever the gearbox housing is restrained from rotation.

The ring gear <NUM> is the internally-toothed <NUM> gear of the planetary gear box <NUM>. In this exemplary embodiment, the ring gear <NUM> also has gear teeth <NUM> formed in or otherwise affixed to a bottom face thereof. These gear teeth <NUM> form a gearbox housing lower face gear <NUM>. Similarly, the cap <NUM> has gear teeth <NUM> formed in or otherwise affixed to a top face thereof. These gear teeth <NUM> form a gearbox housing upper face gear <NUM>. Thus, in addition to the internal gearing (i.e., teeth <NUM>) of the ring gear <NUM>, the gearbox housing <NUM> also presents a lower face gear <NUM> and an upper face gear <NUM>.

The speed multiplying barrel cam <NUM> includes gear teeth 90b that extend from the bottom thereof to form a speed multiplying barrel cam lower face gear <NUM>. The speed multiplying barrel cam lower face gear <NUM> is designed to engage with the matching teeth of the upper face gear <NUM> of the gearbox housing <NUM> when the quickset mechanism <NUM> is placed in the direct drive or locked mode. The speed multiplying barrel cam is rotationally restrained by the direct drive barrel cam <NUM>, inside of which the speed multiplying barrel cam <NUM> is nested in this exemplary quickset mechanism <NUM>. The speed multiplying barrel cam <NUM> is also axially constrained by movement of the one or more cam follower pins <NUM>.

As noted above, the speed multiplying barrel cam <NUM> nests inside the direct drive barrel cam <NUM> in the exemplary quickset mechanism <NUM> shown and described herein. However, in other exemplary quickset mechanism embodiments, the relationship of the direct drive barrel cam <NUM> and speed multiplying barrel cam <NUM> may be reversed or both barrel cams could be sequentially arranged in the axial direction.

The direct drive lock plate <NUM> of the quickset mechanism <NUM> includes an axial opening <NUM> that allows the gearbox output shaft <NUM> to pass therethrough. The opening <NUM> and the gearbox output shaft <NUM> may have a corresponding, non-circular shape, or the direct drive lock plate <NUM> may be keyed or otherwise affixed to the gearbox output shaft, such that the direct drive lock plate and the gearbox output shaft are rotationally coupled (i.e., the lock plate may not rotate on the gearbox output shaft). Although rotationally unconstrained, the direct drive lock plate <NUM> is axially constrained by arms 80b of the direct drive barrel cam <NUM>. Consequently, the direct drive barrel cam <NUM> controls the axial position of the direct drive lock plate <NUM>.

The direct drive lock plate <NUM> also includes gear teeth <NUM> formed in or otherwise affixed to a top face thereof. These gear teeth <NUM> form a direct drive lock plate upper face gear <NUM>. The direct drive lock plate upper face gear <NUM> is designed to engage with matching gear teeth <NUM> of the gearbox housing lower face gear <NUM>.

Because the direct drive lock plate <NUM> is rotationally coupled to the gearbox output shaft <NUM>, engagement of the direct drive lock plate upper face gear <NUM> with the lower face gear <NUM> of the gearbox housing <NUM> will fix the ring gear <NUM> to the gearbox output shaft when the quickset mechanism <NUM> (and direct drive lock plate <NUM>) is placed in the direct drive mode. When not in the direct drive mode, the direct drive lock plate <NUM> is idle, and freely rotates with the gearbox output shaft <NUM>.

In addition to being rotationally constrained by the direct drive lock plate <NUM> when the direct drive lock plate is engaged with the gearbox housing <NUM>, the gearbox output shaft <NUM> is also axially restrained by the gearbox housing, such as by a flange or similar feature that is located distally of the sun gear <NUM>. The gearbox output shaft <NUM> may be affixed to or may be an extension of the sun gear <NUM>.

The gearbox output shaft <NUM> transmits direct or speed-multiplied user rotation of the plunger button <NUM> to the volume screw <NUM>. The volume screw <NUM> is in threaded engagement with a correspondingly-threaded retention element that is located within and fixed to the pipette body <NUM>, such that rotation of the volume screw will result in an axial displacement of the volume screw relative to the pipette body. Since the lower face of the volume screw <NUM> serves as the upper stop for the plunger assembly in this exemplary quickset pipette <NUM>, axial displacement of the volume screw <NUM> adjusts the volume of the pipette by altering the overall plunger stroke.

The frame <NUM> houses a number of quickset mechanism components, restrains the rotation of the direct drive barrel cam <NUM>, serves as a rotational bushing for the planetary gearbox <NUM>, rotationally constrains the one or more cam follower pins <NUM>, and axially restrains the one or more cam follower pins. The frame <NUM> is fixed both axially and rotationally to the pipette body <NUM>.

Mode selection using the transmission input <NUM> of the quickset mechanism <NUM> operates to change the restraints of the planetary gearbox <NUM> between a locked state and an unlocked state. In the speed multiplying mode, the planetary gearbox is in an unlocked (operational) state because the ring gear <NUM> (which also functions as part of the housing of the planetary gearbox) is fixed to the frame <NUM> and the gearbox output shaft <NUM> is unconstrained, thereby permitting rotation of the internal planetary gearbox components. Since the input to the planetary gearbox <NUM> in this exemplary embodiment is the planet gear carrier <NUM>, the output is the sun gear <NUM>, and the ring gear <NUM> is fixed to the frame <NUM>, the planetary gear box <NUM> functions as a speed multiplier when unlocked. More specifically, the carrier <NUM> and the planet gears <NUM> (which are rotationally mounted on the carrier) will rotate within the fixed ring gear <NUM>. Rotation of the planet gears <NUM> in this manner causes a rotation of the sun gear <NUM>, but at a multiplied speed - in this exemplary embodiment, at a rotational speed that is four times greater than the rotational speed of the gearbox input <NUM> and the planet gear carrier <NUM>. The rotational speed of the planet gear carrier <NUM> (input) resulting from user rotation of the plunger button <NUM> and the plunger rod <NUM> is, therefore, multiplied by the planetary gearbox <NUM>, and subsequently transmitted to the volume screw <NUM> by the sun gear <NUM> and the gearbox output shaft <NUM>. Thus, the volume screw <NUM> will rotate faster than the speed at which the user rotates the plunger button <NUM>.

In contrast, when any two of the planetary gearbox input, ring gear <NUM> and output are fixed to each other, the planetary gearbox <NUM> is locked (non-operational) - meaning there can be no relative motion between any of the components in the planetary gearbox (neglecting backlash). In this exemplary embodiment, a locked state of the planetary gearbox <NUM> results both from the ring gear <NUM> being fixed to the frame <NUM> and the gearbox output shaft <NUM> being fixed to the ring gear.

In the direct drive mode, the gearbox output shaft <NUM> is fixed to the ring gear <NUM>, and the ring gear is uncoupled from the frame <NUM>. Consequently, the entire planetary gearbox <NUM> will rotate with the plunger button <NUM> and plunger rod <NUM> in the direct drive mode.

Movement and interaction of the various components of the exemplary quickset mechanism <NUM> when placed in each mode of operation may be better understood by reference to <FIG>, where the frame <NUM> has been omitted for clarity. In <FIG>, <FIG> represents the exemplary quickset mechanism <NUM> in a locked mode that prevents pipette volume adjustments, <FIG> represents the quickset mechanism in a direct drive (<NUM>:<NUM> speed ratio) mode, and <FIG> represents the quickset mechanism in a speed multiplying (e.g., <NUM>:<NUM> speed ratio) mode.

The exemplary quickset mechanism <NUM> is represented in a locked mode in <FIG>. When the transmission input <NUM> is placed in the locked mode, movement of the one or more cam follower pins <NUM> in the one or more cam follower slots 80a of the direct drive barrel cam <NUM> causes the direct drive barrel cam to be moved upward, which simultaneously causes the direct drive lock plate <NUM> to also move upward and for the direct drive lock plate upper face gear <NUM> to engage the gearbox housing lower face gear <NUM>. Because the direct drive lock plate <NUM> and the gearbox output shaft <NUM> are rotationally coupled, engagement of the direct drive lock plate upper face gear <NUM> and the gearbox housing lower face gear <NUM> causes the gearbox output shaft <NUM> to be fixed to the gearbox housing <NUM>, which prevents rotation of the internal planetary gearbox components.

While movement of the one or more cam follower pins <NUM> when the transmission input <NUM> is placed in the locked mode causes the direct drive barrel cam to be moved upward, the same pin movement simultaneously causes the speed multiplying barrel cam <NUM>, which is nested inside of the direct drive barrel cam <NUM>, to be moved downward. This downward movement of the speed multiplying barrel cam <NUM> results in an engagement of the speed multiplying barrel cam lower face gear <NUM> with the gearbox housing upper face gear <NUM>, thus effectively fixing the planetary gearbox <NUM> to the frame <NUM>. The simultaneous engagement of the lock plate upper face gear <NUM> with the gearbox housing lower face gear <NUM> and the speed multiplying barrel cam lower face gear <NUM> with the gearbox housing upper face gear <NUM>, prevents any rotation of the plunger button <NUM>, the plunger rod <NUM> and the volume screw <NUM>, thereby locking the quickset pipette <NUM>.

Referring now to <FIG>, the quickset mechanism <NUM> has been placed in the direct drive mode by accordingly rotating the transmission input <NUM> to the proper position using the lever <NUM>. When the transmission input <NUM> is rotated to the direct drive mode, resulting movement of the one or more cam follower pins <NUM> in the one or more cam follower slots 80a of the direct drive barrel cam <NUM> causes the direct drive barrel cam to be moved upward, which simultaneously causes the direct drive lock plate <NUM> to also move upward and for the lock plate upper face gear <NUM> to engage the gearbox housing lower face gear <NUM>. Because the direct drive lock plate <NUM> and the gearbox output shaft <NUM> are rotationally coupled, engagement of the direct drive lock plate upper face gear <NUM> and the gearbox housing lower face gear <NUM> causes the gearbox output shaft <NUM> to be fixed to the gearbox housing <NUM>, thereby preventing rotation of the internal planetary gearbox components.

The aforementioned rotation of the transmission input <NUM> and resulting movement of the one or more cam follower pins <NUM> also causes the speed multiplying barrel cam <NUM>, which is nested inside the direct drive barrel cam <NUM>, to be moved upward. This upward movement of the speed multiplying barrel cam <NUM> results in a disengagement of the speed multiplying barrel cam lower face gear <NUM> from the gearbox housing upper face gear <NUM>. The disengaged speed multiplying barrel cam <NUM> is thus idle in the direct drive mode, while the planetary gearbox <NUM> is essentially a rigid coupling between the plunger rod <NUM> and the gearbox output shaft <NUM> and rotates freely with the plunger rod. As a result, a rotation of the plunger button <NUM> and affixed plunger rod <NUM> will result in a like (<NUM>:<NUM>) rotation of the volume screw <NUM>.

Referring now to <FIG>, the quickset mechanism <NUM> has been placed in the speed multiplying mode by accordingly rotating the transmission input <NUM> to the proper position using the lever <NUM>. When the transmission input <NUM> is rotated to the speed multiplying mode, resulting movement of the one or more cam follower pins <NUM> in the one or more cam follower slots 80a of the direct drive barrel cam <NUM> causes the direct drive barrel cam to be moved downward, which simultaneously causes the direct drive lock plate <NUM> to also move downward and for the lock plate upper face gear <NUM> to disengage from the gearbox housing lower face gear <NUM>. This causes the lock plate to idle.

The aforementioned rotation of the transmission input <NUM> and resulting movement of the one or more cam follower pins <NUM> also causes the speed multiplying barrel cam <NUM>, which is nested inside the direct drive barrel cam <NUM>, to be moved downward. This downward movement of the speed multiplying barrel cam <NUM> results in an engagement of the speed multiplying barrel cam lower face gear <NUM> with the gearbox housing upper face gear <NUM>, thus effectively fixing the ring gear <NUM> to the frame <NUM> and enabling rotation of the planetary gear components. As a result, a rotation of the plunger button <NUM> and affixed plunger rod <NUM> will result in rotation of the volume screw <NUM> at a multiplied (e.g., <NUM>:<NUM>) rotational speed.

A user is not required to engage the speed multiplying mode of the quickset pipette <NUM> when making a volume adjustment. However, in the case where a user desires to use the speed multiplying mode to hasten a volume adjustment, the user first engages the speed multiplying mode by placing the lever <NUM> of the quickset mechanism transmission unit <NUM> in the speed multiplying position. The speed multiplying position (as well as the direct drive and locked positions) may each be defined by a detent that provides tactile feedback to the user, and/or by a graphical representation on the pipette body <NUM>. Subsequent rotation of the plunger button <NUM> thereafter produces a speed-multiplied rotation of the volume screw <NUM> and a corresponding coarse volume adjustment. When the desired quickset pipette <NUM> volume is neared, the user may switch the quickset mechanism <NUM> to the direct drive mode by placing the lever <NUM> of the transmission unit <NUM> in the direct drive position. A subsequent rotation of the plunger button <NUM> will then produce a <NUM>:<NUM> rotation of the volume screw <NUM> and a corresponding fine volume adjustment. Using both the speed multiplying mode and the direct drive mode allows for both rapid and precise pipette volume setting. Once the desired pipette volume has been set, the user may prevent an inadvertent adjustment or drift of the volume setting by placing the lever <NUM> of the transmission unit <NUM> in the locked position.

To further facilitate volume setting, the quickset pipette <NUM> is provided with an exemplary volume setting display assembly <NUM>. The volume setting display assembly <NUM> of this exemplary quickset pipette <NUM> is comprised of a series of numbered counter wheels <NUM> that are coupled to the volume adjustment assembly of the pipette. More particularly, the counter wheels <NUM> are rotationally coupled via gearing to the volume screw <NUM>. Rotation of the plunger button <NUM> and volume screw <NUM> thus results in a corresponding rotation of the counter wheels <NUM> such that the numerical readout presented by the counter wheels is representative of the current volume setting of the pipette. As described earlier, the counter wheels <NUM> are visible through the opening <NUM> in the pipette body <NUM>. Other pipette embodiments may substitute an electronic volume setting display and corresponding volume detection sensors, etc., for the counter wheel-based volume setting display assembly <NUM> of the quickset pipette <NUM>.

The quickset pipette <NUM> of <FIG> is depicted again in <FIG> after a volume adjustment has been made thereto. In this case, the volume of the quickset pipette <NUM> as shown in <FIG> has been reduced in comparison to the volume of the quickset pipette <NUM> as shown in <FIG>. Consequently, it may be observed that the plunger button <NUM>, plunger rod <NUM> and associated flange <NUM>, piston <NUM>, and volume screw <NUM> have all moved distally within the pipette body <NUM>, and the stroke spring <NUM> has been compressed. The distally-displaced position of the bottom face of the volume screw <NUM> defines a new plunger unit upper stop position.

As described previously, calibration of the dispensed fluid volume is required for accurate pipetting. Consequently, pipettes are typically calibrated at the factory and may also be re-calibrated thereafter, such as during servicing operations.

Pipette calibration is typically performed using distilled water. As a result, pipette users may desire to input a factory volume offset when pipetting fluids with densities that differ from the density of distilled water. Likewise, it may be desirable to input a factory volume offset when pipetting at atmospheric conditions that differ from standard temperature and pressure (STP) - at high altitudes, for example.

To this end, the exemplary quickset pipette <NUM> also includes a calibration/offset mechanism <NUM>. One exemplary embodiment of such a calibration/offset mechanism is shown in detail in <FIG>.

As shown in <FIG>, the exemplary calibration/offset mechanism <NUM> includes - proximally-to-distally in general order of appearance - a mode selection mechanism in the form of a mode selector barrel cam (i.e., a barrel cam input) <NUM>; a follower element in the form of a follower barrel cam (i.e., a barrel cam follower) <NUM>, which is coupled to the barrel cam input <NUM> so as to be axially displaceable in response to movement of the barrel cam input; an offset counter <NUM>; a user rotatable input mechanism in the form of a pinion gear <NUM>; and a coupling <NUM> for coupling the offset counter <NUM> to an axially displaceable threaded element <NUM> (a housing of a blowout assembly <NUM> in this example) that may be selectively axially displaced to adjust the home position of a pipette to which the calibration/offset mechanism <NUM> is installed, thereby increasing or decreasing the liquid volume of the pipette. The above-listed components of the calibration/offset mechanism <NUM> are substantially retained in a (calibration) housing <NUM> when the calibration/offset mechanism <NUM> is in an assembled state, as is shown in <FIG>.

In addition to the calibration/offset mechanism <NUM>, <FIG> and <FIG> also show various components of the volume setting display assembly <NUM>. This exemplary volume setting display assembly <NUM> is shown to include the aforementioned volume screw <NUM>, and the counter wheels <NUM> that present a numerical representation of the set pipette volume. The volume setting display assembly <NUM> further includes a mounting plate <NUM> having an opening through which the volume screw <NUM> passes, and which is adapted to receive and support the assembly of counter wheels <NUM> and associated gearing. The mounting plate <NUM> may be a component of the volume setting display assembly <NUM> or may be a component of the calibration/offset mechanism <NUM>, but is nonetheless affixed to the calibration housing <NUM> (such as by a press fit) and serves as an upper axial constraint for the barrel cam input <NUM> of the calibration/offset mechanism.

The volume screw <NUM> also passes through a transfer gear <NUM> that rotates on the top face of the mounting plate <NUM>. The transfer gear <NUM> includes tabs <NUM> that engage corresponding slots on the volume screw <NUM>, such that rotation of the volume screw produces a rotation of the transfer gear. A cluster gear <NUM> is interposed between the transfer gear <NUM> and the counter wheel gearing, such that rotation of the volume screw <NUM> will cause a volume-indicating rotation of the counter wheels <NUM>.

The barrel cam input <NUM> of the calibration/offset mechanism <NUM> is partially nested in but extends upward some distance from the barrel cam follower <NUM>. The barrel cam input <NUM> includes a mode selector element such as a selection lever <NUM> or similar actuator that is accessible through a calibration/offset aperture <NUM> in the pipette body <NUM>. The mode selection lever is usable to select either a calibration mode or an offset mode of the calibration/offset mechanism <NUM> by rotating the barrel cam input <NUM>, as explained in more detail below.

As mentioned above, the follower element (barrel cam follower) <NUM> of the exemplary calibration/offset mechanism <NUM> is axially displaceable in response to movement of the mode selection mechanism (barrel cam input <NUM>). To that end, one or more arcuate or sloped cam slots <NUM> are present on the exterior of the barrel cam input <NUM> in this particular example, and are located and designed to engage with one or more cam follower pins <NUM> that extend inward from an interior surface of the barrel cam follower <NUM>. As a result, rotation of the barrel cam input <NUM> via the selection lever <NUM> will produce an axial displacement of the barrel cam follower. The design of the mode selection mechanism and follower element may be different in other embodiments, such that the follower element may be axially displaced by an action of the mode selection mechanism that is other than rotation.

The barrel cam input <NUM> of this exemplary embodiment is rotationally constrained (within some angle). The barrel cam input <NUM> is also axially constrained by the calibration housing <NUM> and the mounting plate <NUM>.

The barrel cam follower <NUM> is interposed between the barrel cam input <NUM> and the calibration housing <NUM>, and includes downwardly extending arms <NUM> designed to engage with slot features <NUM> in the calibration housing <NUM>. An offset counter rotation groove <NUM> may be present on interior surfaces of the barrel cam follower arms <NUM>. The one or more cam follower pins <NUM> can be seen to extend inwardly from the barrel cam follower <NUM>, as described above.

The offset counter <NUM> displays the magnitude and direction of any volume offset input by a user, such as through a series of positive and negative numerals printed along the circumference thereof. When the calibration/offset mechanism <NUM> is assembled, the offset counter <NUM> is retained in and freely rotates within the calibration housing <NUM>, such as within the offset counter rotation groove <NUM> of the barrel cam follower <NUM>. In this manner, the offset counter <NUM> is axially constrained by (i.e., moves axially with) the barrel cam follower <NUM>, but is not rotationally constrained by the barrel cam follower.

The offset counter <NUM> fits over an upper section of the coupling <NUM>, and is selectively rotationally coupled to or rotationally decoupled therefrom as explained further below. The offset counter <NUM> may have slots 265a, recesses or other similar features in a top surface thereof that are selectively engageable with corresponding male features of another offset counter component. For example, the underside of a top surface of the calibration housing <NUM> may include such features. The male features will block upward movement of the offset counter <NUM> when the offset counter slots 265a are not aligned with the male features, but will permit upward movement when there is an alignment via entry of the male features into the slots. Alignment of the male features and the slots 265a in the offset counter <NUM> is configured to occur only if the offset counter is set to a "zero" position - thereby preventing decoupling of the offset counter and performance of a calibration operation if the current pipette calibration setting is in an offset condition.

To rotationally couple the offset counter <NUM> to the coupling <NUM>, the offset counter may include inner gear teeth or splines <NUM> that are designed to engage with mating gear teeth or splines <NUM> on the exterior of the coupling. In other embodiments, the offset counter <NUM> and the coupling <NUM> may have corresponding tapers or may be provided with some other features to ensure that the offset counter and the coupling will rotate together when the calibration/offset mechanism <NUM> is set to the offset mode.

The coupling <NUM> rotationally couples the offset counter <NUM> to the blowout assembly <NUM> when the calibration/offset mechanism <NUM> is set to the offset mode (which is the normal calibration/offset mechanism mode), and transfers rotational motion of the pinion gear <NUM> to a blowout assembly housing <NUM> of the blowout assembly <NUM>. The offset counter may be decoupled from the blowout assembly to permit factory calibration (in the calibration mode). Positional adjustments to the blowout assembly <NUM> will thus be transmitted to and indicated by the offset counter during user offset input, but not during factory calibration (or recalibration). The coupling <NUM> includes vertical slots <NUM> in a lower section thereof for receiving alignment and engagement arms <NUM> of the blowout assembly housing <NUM>.

The rotationally unconstrained pinion gear <NUM> is provided to convert user input into rotation of the coupling <NUM>. More specifically, the pinion gear <NUM> converts rotation around an axis that is perpendicular to the offset counter <NUM> and coupling <NUM> into rotation around the central axis of the offset counter and coupling. This allows a user to conveniently rotate the coupling <NUM> by engaging the pinion gear <NUM> using a hex key or other suitable tool. Rotation of the coupling <NUM> by the pinion gear <NUM> is produced by engagement of the pinion gear with a corresponding miter gear <NUM> located on the coupling.

The calibration housing <NUM> of this exemplary calibration/offset mechanism <NUM> is a substantially hollow cylinder. The calibration housing <NUM> includes an axial opening <NUM> in a proximal end 280a thereof to permit passage of the plunger rod <NUM>; the aforementioned slots <NUM> at the proximal end for receiving the downwardly extending arms <NUM> of the barrel cam follower <NUM>; a calibration viewport <NUM> for observing the numerals printed on the offset counter <NUM>; and a pinion gear access opening <NUM> for allowing engagement and rotation of the pinion gear <NUM> through the calibration housing. The calibration housing <NUM> may also include one or more slots <NUM> or similar apertures through which corresponding clips <NUM> or equivalent retention elements may be inserted for retention of one or more calibration/offset mechanism <NUM> components. For example, the clips <NUM> may be inserted into the slots <NUM> in the calibration housing <NUM> to engage a retention grove <NUM> in the coupling <NUM>, thereby causing the coupling to be axially restrained within the calibration housing.

The calibration housing <NUM> further includes internal threads <NUM> (see <FIG>). The internal threads <NUM> are provided to mate with external threads <NUM> at a proximal end of the threaded element (blowout assembly housing <NUM>) of the blowout assembly <NUM>, such that the blowout assembly housing and the calibration housing may be assembled in threaded engagement. The calibration housing <NUM> also serves as the positional reference point for calibration, and is fixed for all degrees of freedom to the pipette body <NUM>.

The blowout assembly <NUM> includes a blowout piston <NUM>, which is located in the blowout assembly housing <NUM> along with the blowout spring <NUM>. The blowout spring <NUM> is located below the blowout piston <NUM> such that the blowout piston is biased toward the proximal end of the quickset pipette <NUM> and the upper stop position thereof.

External threads <NUM> are present at the proximal end 510a of the blowout assembly housing <NUM>. The external threads <NUM> on the blowout assembly housing <NUM> are provided to engage with the corresponding internal threads <NUM> in the calibration housing <NUM>, as described above. Thus, when the calibration/offset mechanism <NUM> is assembled, the blowout assembly housing <NUM> may be axially displaced relative to the calibration housing <NUM> by threading the blowout assembly housing into or out of the calibration housing.

The blowout assembly housing <NUM> further includes upwardly extending alignment arms <NUM> that are dimensioned and located to fit into the slots <NUM> in the lower portion of the coupling <NUM> in an interdigitating manner. This interdigitating assembly rotationally couples the blowout assembly housing <NUM> to the coupling <NUM> such that the blowout assembly housing will be caused to correspondingly rotate when the coupling is rotated by the pinion gear <NUM>, while also allowing axial movement of the blowout assembly housing relative to the coupling.

The home position of the quickset pipette <NUM> may be defined as the position where the pipette piston <NUM> has fully compressed the stroke spring <NUM> and the aspirated liquid volume has been fully dispensed, but where a blowout stroke and any compression of the blowout spring <NUM> has not yet commenced. In this exemplary embodiment, the plunger rod <NUM> also includes a flange <NUM> that will contact a top surface of the blowout piston <NUM> of the blowout assembly <NUM> when the plunger rod is in the home position (and will also contact the bottom face of the volume screw <NUM> when the plunger rod is in the upper stop position). Calibrating the pipette volume or inputting a volume offset may be accomplished by moving the axial position of the blowout assembly <NUM> (including the blowout spring <NUM>), which has the effect of increasing or decreasing the liquid volume of the pipette.

When the calibration/offset mechanism <NUM> is fully assembled, the barrel cam input <NUM> is both rotationally and axially constrained; the barrel cam follower <NUM> is rotationally restrained by the calibration housing <NUM> and axially constrained by movement of the one or more cam follower pins <NUM>; the coupling <NUM> is axially restrained in the calibration housing, but is free to rotate; the offset counter <NUM> is axially restrained relative to the barrel cam follower <NUM> but movable therewith, and is rotationally coupled to the coupling <NUM> when the calibration/offset mechanism <NUM> is set to the offset mode and rotationally decoupled from the coupling when the calibration/offset mechanism is set to the calibration mode; the pinion gear <NUM> is axially restrained by the calibration housing <NUM> but is rotationally unconstrained; and the blowout assembly <NUM> is rotationally constrained by the coupling but free to move axially relative thereto, and also axially constrained (but not restrained) by engagement of the external threads <NUM> on the blowout assembly housing <NUM> and the corresponding internal threads <NUM> in the calibration housing <NUM>.

The mode selection lever <NUM> of the barrel cam input <NUM> is used to select either the calibration mode or the offset mode of the calibration/offset mechanism <NUM>. Typically, the default calibration/offset mechanism <NUM> will be the offset mode, such that any user adjustment of the pinion gear <NUM> will be indicated by offset counter <NUM>.

To input a volume offset, a user first ensures that the calibration/offset mechanism <NUM> is already set to the offset mode, or manipulates the mode selection lever <NUM> of the barrel cam input <NUM> to select the offset mode. When the mode selection lever <NUM> of the barrel cam input <NUM> is placed in the offset mode, the barrel cam follower <NUM> is moved downward by movement of the one or more cam follower pins <NUM> of the rotating barrel cam follower in the one or more cam slots <NUM> on the exterior of the barrel cam input <NUM>. This downward movement of the barrel cam follower <NUM> causes a like downward movement of the offset counter <NUM>, which is axially restrained relative to the barrel cam follower <NUM> by offset counter rotation groove <NUM> in the barrel cam follower arms <NUM>. The offset counter <NUM> is thereby rotationally coupled to the coupling <NUM>.

A volume offset of the quickset pipette <NUM> is then accomplished by extending a hex key or other appropriate tool through the calibration/offset aperture <NUM> in the pipette body <NUM> and through the pinion gear access opening <NUM> in the calibration housing <NUM>, to engage and rotate the pinion gear <NUM> in one direction or the other so as to input a desired negative or positive volume offset. Rotation of the pinion gear <NUM> produces a rotation of the coupling <NUM>, which correspondingly causes rotation of the blowout assembly housing <NUM> that is rotationally coupled thereto. Rotation of the blowout assembly housing <NUM> results in an upward (threading) or downward (unthreading) axial displacement of the blowout assembly <NUM> relative to the calibration housing <NUM> and the pipette body <NUM> - moving the home position of the pipette and causing a change in the volume of liquid that can be aspirated by the pipette.

Because the offset counter <NUM> is rotationally coupled to the coupling <NUM>, the offset counter will rotate along with the coupling when the user rotates the pinion gear <NUM> in the offset mode. Consequently, the amount of inputted offset is indicated by the offset counter <NUM> and is observable by the user through the calibration viewport <NUM> in the calibration housing, which is viewable through the calibration/offset aperture <NUM> in the pipette body <NUM>.

To perform a factory calibration or a recalibration, a user manipulates the mode selection lever <NUM> of the barrel cam input <NUM> to select the calibration mode. When the mode selection lever <NUM> of the barrel cam input <NUM> is placed in the calibration mode, the barrel cam follower <NUM> is moved upward by movement of the one or more cam follower pins <NUM> of the rotating barrel cam follower in the one or more cam slots <NUM> on the exterior of the barrel cam input <NUM>. This upward movement of the barrel cam follower <NUM> causes a like upward movement of the offset counter <NUM>, which is axially restrained relative to the barrel cam follower <NUM> by offset counter rotation groove <NUM> in the barrel cam follower arms <NUM>. The offset counter <NUM> is thereby rotationally decoupled from the coupling <NUM>. As mentioned previously, the calibration/offset mechanism may include a feature that prevents the calibration mode from being selected (and the offset counter <NUM> from being decoupled from the coupling <NUM>) unless the offset counter <NUM> is set to the "zero" position. This ensures that a calibration operation is not inadvertently performed with a volume offset already input to the pipette <NUM>.

A calibration or recalibration of the quickset pipette <NUM> is then effectuated by extending a hex key or other appropriate tool through the calibration/offset aperture <NUM> in the pipette body <NUM> and through the pinion gear access opening <NUM> in the calibration housing <NUM>, to engage and rotate the pinion gear <NUM> in one direction or the other. Rotation of the pinion gear <NUM> again produces a rotation of the coupling <NUM>, which causes a corresponding rotation of the blowout assembly housing <NUM> and an upward (threading) or downward (unthreading) axial displacement of the blowout assembly <NUM> relative to the calibration housing <NUM> and the pipette body <NUM> - moving the home position and causing a desired change in the liquid volume of the pipette.

Because the offset counter <NUM> is rotationally decoupled from the coupling <NUM> in the calibration mode, the offset counter may not be observable through the calibration viewport <NUM> and will not rotate with the coupling when the user rotates the pinion gear <NUM>. Consequently, the offset counter <NUM> will not reflect any change in the pipette volume that occurs during a calibration or recalibration operation.

An alternative exemplary embodiment of a non-claimed pipette quickset volume adjustment mechanism <NUM> is represented in <FIG>. As with the previously described exemplary quickset volume adjustment mechanism, this quickset volume adjustment mechanism <NUM> is designed to be installed in the body <NUM> of a pipette. To that end, the quickset volume adjustment mechanism <NUM> includes a pair of upper and lower mounting elements <NUM>, <NUM> that may be shaped and dimensioned to correspond to the interior walls of the given pipette body <NUM> to which the quickset mechanism will be installed. In other embodiments, a greater or lesser number of such mounting elements may be employed, and said mounting element(s) may have different shapes and or dimensions from those shown in <FIG>.

The pipette into which the exemplary quickset volume adjustment mechanism <NUM> is installed may be similar to an exemplary pipette described above. That is, the pipette may include, for example, a body portion <NUM> for gripping by a user, a distal tip mounting portion that is adapted to receive and retain a pipette tip, a plunger assembly having a piston that is reciprocatable within the body portion, a plunger rod that extends proximally upward from the piston, and a plunger button that is located outside the body portion and is affixed to a proximal end of the plunger rod for manipulation by user. A stroke spring may again reside within the body portion to drive the piston proximally during a liquid aspiration phase of a pipetting operation, and a blowout spring may reside within the body portion to return the piston from a blowout operation that may be performed subsequent to dispensing aspirated liquid from the pipette. The pipette may also include other features such as but not limited to, a tip ejector a volume adjustment assembly, a volume setting display assembly, and a calibration/offset mechanism. Consequently, the pipette may operate in a typical fashion (as explained above) to aspirate and dispense a volume of a liquid of interest.

Because volume changes between consecutive aspiration/dispensing operations may be significant, as previously described, the exemplary quickset volume adjustment mechanism <NUM> may be used to selectively multiply the speed by which the aspiratable pipette volume may be adjusted. Broadly speaking, the quickset volume adjustment mechanism <NUM> is shown in <FIG> to include a rotatable user input element <NUM> that is usable to adjust the pipette volume, a gear train <NUM> (described in more detail below) that includes a number of selectively interacting individual gears, an input shaft <NUM> that transmits rotation of the user input element <NUM> to the gear train, an output shaft <NUM> that transmits rotation of the gear train <NUM> to a volume screw (not shown) of the pipette to which the volume adjustment mechanism is installed, and a pair of linkage elements <NUM>, <NUM> that that are operative to manipulate the gear train <NUM> so as to permit selection between at least a (direct) <NUM>:<NUM> and a speed multiplying volume setting mode. The interaction of these components to provide either a direct or a speed multiplying mode is described in detail below.

As should be apparent to one of skill in the art, a plunger button or similar pipette actuator would reside proximally of the user input element <NUM> when the quickset volume adjustment mechanism <NUM> is installed to the pipette body. To this end, the quickset volume adjustment mechanism <NUM> includes an axial bore <NUM> in the user input element <NUM> through which may pass the plunger rod to which the plunger button is attached. Referring to <FIG>, it may also be observed that similar and cooperating axial bores <NUM>, <NUM>, <NUM>, <NUM> also pass respectively through the input shaft <NUM>, an input gear <NUM> of the gear train <NUM>, an output gear <NUM> of the gear train, and the output shaft <NUM>. As such, the plunger rod acts as an alignment element for various components of the quickset volume adjustment mechanism <NUM>, while depression of the plunger rod via the plunger button is still operable to linearly displace the piston of the pipette plunger assembly in typical fashion.

The gear train <NUM> of this exemplary quickset volume adjustment mechanism <NUM> includes four gears, the selection and engagement of which determines whether the quickset volume adjustment mechanism operates in a <NUM>:<NUM> or a speed multiplying mode. In at least some embodiments, the gear train <NUM> may also be alternatively set to a free spinning and/or locked state by which the quickset volume adjustment mechanism <NUM> is resultantly placed in a non-functional or locked mode.

Referring primarily to <FIG> and <FIG>, it may be observed that the gear train includes the input gear <NUM>, a transfer gear <NUM>, a speed-multiplying gear <NUM>, and the output gear <NUM>. The transfer gear <NUM> meshes with the input gear <NUM>, and the speed-multiplying gear <NUM> meshes with the output gear <NUM>. The transfer gear <NUM> and speed-multiplying gear <NUM> of this exemplary embodiment rotate on a separate shaft <NUM> that extends between the mounting elements <NUM>, <NUM>.

The speed-multiplying gear <NUM> includes an integral splined coupling element 710a at the proximal end thereof. Similarly, the input gear <NUM>, includes an integral splined coupling element 700a at the distal end thereof. The splined coupling element 710a allows the associated speed-multiplying gear <NUM> to be selectively engaged with the transfer gear <NUM> when it is desired to perform a volume adjustment at a multiplied speed. The splined coupling element 700b allows the associated input gear <NUM> to be selectively engaged with the output gear <NUM> when it is desired to perform a volume adjustment at a <NUM>:<NUM> speed.

As shown in <FIG>, a portion of each of the input shaft <NUM> and the input gear <NUM> passes through a bore <NUM> in the upper mounting element <NUM>. The proximal end of the input gear <NUM> is rotationally coupled to the distal end of the input shaft <NUM>, such as through the use of corresponding hexagonal or other non-circular shapes, or by another means that would be familiar to one of skill in the art. Although rotationally coupled thereto, the input gear <NUM> is axially displaceable by some distance along the input shaft <NUM>. The input gear <NUM> may thus be moved upward and downward relative to the pipette body <NUM> so as to be selectively engaged with or disengaged from the output gear <NUM>. Assuming the gear train is not placed in an optional locked state (as described below), rotation of the user input element <NUM> causes a like rotation of the input gear <NUM>.

In a manner similar to that of the input gear <NUM>, the speed-multiplying gear <NUM> is axially displaceable by some distance along the shaft <NUM>. The speed-multiplying gear <NUM> may thus be moved upward and downward relative to the pipette body <NUM> so as to be selectively engaged with or disengaged from the transfer gear <NUM>.

As can be further observed in <FIG>, a portion of the output shaft <NUM> passes through a bore <NUM> in the lower mounting element <NUM>. The output shaft <NUM> is rotationally coupled at its proximal end to the distal end of the output gear <NUM>, such that rotation of the output gear <NUM> will cause a rotation of the output shaft <NUM>. A distal end of the output gear <NUM> is shown to be adapted for connection to a volume screw of the pipette which, as explained above, alters the aspiratable liquid volume of the pipette when rotated.

As mentioned above, this exemplary quickset volume adjustment mechanism <NUM> includes a pair of linkage elements <NUM>, <NUM> that are operable to set the state of the gear train <NUM>. In at least some other embodiments, a single linkage element that is coupled to appropriate gears of the gear train <NUM> may be substituted for the separate linkage elements <NUM>, <NUM> shown and described herein.

In any case, it should be understood by one of skill in the art that a single linkage element or the pair of linkage elements <NUM>, <NUM> would be connected to a mode selection component or components (not shown) located exterior of an associated pipette so as to be accessible and operable by a user. In some exemplary embodiments, the mode selection component may be designed to produce a like (coupled) upward or downward movement of a single linkage element or of the pair of linkage elements <NUM>, <NUM>, so as to provide selection between only a direct or speed multiplying volume setting mode by accordingly setting the appropriate state of the gear train <NUM>. In other exemplary embodiments, where such as here there are separate linkage elements <NUM>,<NUM>, a mode selection component(s) may be designed to permit selective and independent movement of the linkage elements in both an upward and downward direction. Such a design permits the setting of additional locked and free-spinning gear train <NUM> states and allows the quickset volume adjustment mechanism <NUM> to be placed in a locked mode or a non-functional mode in addition to a direct and a speed multiplying volume setting mode. Mode selection along with associated linkage element movement and gear train states is discussed in more detail below.

In the drawing figures, both of the linkage elements <NUM>, <NUM> are depicted in the down position for purposes of illustration, which manipulates the gear train <NUM> such that the quickset volume adjustment mechanism <NUM> is set to the direct drive (<NUM>:<NUM>) mode. More specifically, placement of the first linkage element <NUM> in the down position causes the spline connector 700a of the input gear <NUM> to engage with the output gear <NUM>, while placement of the second linkage element <NUM> in the down position causes the spline connector 710a of the speed-multiplying gear <NUM> to disengage from the transfer gear <NUM>. Consequently, in the direct drive mode, rotation of the user input element <NUM> will cause a rotation of both the transfer gear <NUM> and the output gear <NUM>. However, because the transfer gear <NUM> is disengaged from the speed multiplying gear <NUM>, the transfer gear will rotate idly while rotation of the output gear <NUM> is caused directly by the input gear <NUM> in a <NUM>:<NUM> ratio with rotation of the user input element <NUM>.

Oppositely, placement of both linkage elements <NUM>, <NUM> in the up position manipulates the gear train <NUM> such that the quickset volume adjustment mechanism <NUM> is set to the speed multiplying mode. More specifically, placement of the first linkage element <NUM> in the up position causes the spline connector 700a of the input gear <NUM> to disengage from the output gear <NUM>, while placement of the second linkage element <NUM> in the up position causes the spline connector 710a of the speed-multiplying gear <NUM> to engage with the transfer gear <NUM>. Disengagement of the input gear <NUM> from the output gear <NUM> prevents any direct rotation of the output gear by the input gear (and the user input element <NUM>). Consequently, in the speed multiplying mode, rotation of the user input element <NUM> will cause a rotation of the input gear <NUM>, rotation of the input gear will cause a rotation of the transfer gear <NUM> and the speed-multiplying gear <NUM> engaged therewith, and rotation of the speed-multiplying gear will cause a rotation of the output gear <NUM>. In this exemplary embodiment, the pitch diameters of the various gears <NUM>, <NUM>, <NUM>, <NUM> are selected such that the output gear <NUM> and output shaft <NUM> will rotate at twice the speed of the user input element <NUM> when the quickset volume adjustment mechanism <NUM> is set to the speed multiplying mode - i.e., the speed ratio of the gear train <NUM> in the speed-multiplied mode is <NUM>:<NUM>. Other speed ratios are possible in other embodiments.

Placement of the first linkage element <NUM> in the up position and the second linkage element <NUM> in the down position, places the gear train <NUM> in a free spinning state and sets the quickset volume adjustment mechanism <NUM> to a non-functional mode. More specifically, placement of the first linkage element <NUM> in the up position causes the spline connector 700a of the input gear <NUM> to disengage from the output gear <NUM>, while placement of the second linkage element <NUM> in the down position causes the spline connector 710a of the speed-multiplying gear <NUM> to disengage from the transfer gear <NUM>. Consequently, in the free spinning state of the gear train <NUM>, rotation of the user input element <NUM> will cause the input gear <NUM> and the transfer gear <NUM> to rotate idly. The speed-multiplying gear <NUM> and the output gear <NUM> will not rotate due to their disengaged conditions and, therefore, no rotation of the output shaft <NUM> nor any volume setting change of the pipette will occur upon rotation of the user input element <NUM>.

Lastly, placement of the first linkage element <NUM> in the down position and the second linkage element <NUM> in the up position, locks the gear train <NUM> and sets the quickset volume adjustment mechanism <NUM> to a locked mode. More specifically, placement of the first linkage element <NUM> in the down position causes the spline connector 700a of the input gear <NUM> to engage with the output gear <NUM>, while placement of the second linkage element <NUM> in the up position causes the spline connector 710a of the speed-multiplying gear <NUM> to engage with the transfer gear <NUM>. Consequently, with all of the gears <NUM>, <NUM>, <NUM>, <NUM> of the gear train <NUM> engaged, any rotation of the user input element <NUM>, the gear train, or the output shaft <NUM>, is prohibited. In the locked mode, the quickset volume adjustment mechanism <NUM> is thus locked against a change in the aspiratable liquid volume of the pipette through rotation of the user input element <NUM>.

Other gear train configurations are possible in other similar exemplary quickset volume adjustment mechanism embodiments. For example, the total number of gears in the gear train may be different than the four gears shown in <FIG>. The gear ratios of the gears used may also be different to thereby produce a multiplied speed ratio of more or less than <NUM>:<NUM>. Other gear train modifications are also possible.

The aforementioned mode selection component or components on or associated with the outside of the pipette body for operating the linkage elements <NUM>, <NUM> may take many forms. For example, a mode selection component(s) may be provided in a form such as but not limited to, a pivotable collar, separate sliding or pivoting collars, one or more tabs or buttons, or any other element or elements that may be connected to a linkage element or to multiple linkage elements <NUM>, <NUM> to facilitate the upward and downward movement thereof.

As used herein, the term "distal" is intended to refer to the end of the pipette where the pipette tip normally resides, and the term "proximal" is intended to refer to the end of the pipette where the plunger button normally resides.

As used herein, the terms "axial" or "axially" are intended to refer to a direction that is parallel to the length-wise axis of the plunger rod when installed to the pipette.

As used herein, the term "central axis" is intended to refer to the symmetrical axis of a component or the pipette.

As used herein, the term "downward" is intended to refer to a proximal-to-distal direction relative to the pipette, and the term "upward" is intended to refer to a distal-to-proximal direction relative to the pipette.

As used herein "first" and "second" are intended only to differentiate between two elements or components for purposes of description, and not to indicate an order, a preference, or superiority or inferiority, of any kind.

Claim 1:
A pipette calibration and volume offset mechanism (<NUM>) for a pipette (<NUM>) to which the mechanism (<NUM>) is to be installed, the pipette (<NUM>) being configured to aspirate a volume of a liquid of interest simultaneous to an axial return motion of a piston (<NUM>) of the pipette (<NUM>) from a lower stop position being a home position to an upper stop position along an upward direction which is a distal-to-proximal direction, the mechanism (<NUM>) comprising:
a housing (<NUM>);
a mode selection mechanism (<NUM>) having a mode selector element (<NUM>) movable between a first and second position, the mode selection mechanism (<NUM>) being axially and rotationally constrained at a proximal end of the housing (<NUM>);
an axially displaceable follower element (<NUM>) interposed between the mode selection mechanism (<NUM>) and the housing (<NUM>) and coupled to the mode selection mechanism (<NUM>) characterized in that the pipette calibration and volume offset mechanism further comprises:
an offset counter (<NUM>) located within the housing (<NUM>) and axially movable with the follower element (<NUM>);
a threaded element (<NUM>) located within the housing (<NUM>) and having an axial position that is adjustable to define the home position of a pipette to which the calibration and volume offset mechanism (<NUM>) is installed;
a coupling (<NUM>) located within the housing (<NUM>), the coupling (<NUM>) rotationally coupled to the threaded element (<NUM>) and operative to selectively rotationally couple the offset counter (<NUM>) to or decouple the offset counter (<NUM>) from the threaded element (<NUM>); and
a user rotatable input mechanism (<NUM>) that is rotationally coupled to the coupling (<NUM>);
wherein, the offset counter (<NUM>) will not rotate with the input mechanism (<NUM>) and the coupling (<NUM>) when the mode selector element (<NUM>) of the mode selection mechanism (<NUM>) is in the first position; and
wherein, the offset counter (<NUM>) will rotate with the input mechanism (<NUM>) and the coupling (<NUM>) when the mode selector element (<NUM>) of the mode selection mechanism (<NUM>) is in the second position.