Abstract:
A pin support assembly includes a pin support frame having a plurality of apertures for supporting an array of pins for dispensing fluids. The pins are supported for longitudinal or “floating” movement to prevent damage to the pins. An actuation assembly engages an end of each of the pins to ensure that the pins are properly seated in the support frame in a planar fashion. The actuation assembly engages the pins as the pins move relatively toward a head block and disengages the pins as the pins move relatively away from the head block.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention is generally related to apparatus for dispensing controlled amounts of fluid.  
           [0003]    2. Description of the Related Art  
           [0004]    Many research and/or manufacturing settings require the delivery of a precise amount of fluid. Precisely controlling the delivery of fluid can be important to producing accurate test results or to producing high quality products, as well as being important in lowering costs associated with such operations. Often, these applications require a large number of repetitive operations. For example, biological or chemical assays may employ hundreds, thousands, or more of individual testing steps. Efficiency, accuracy and repeatability require that these operations be automated. One method of automating is to perform multiple tests at discrete locations on a single plate (i.e., plate, slide, or array). This requires the delivery of very precise amounts of fluids, for example agents or reagents, to hundreds or even thousands of locations on the plate. Other automated methods are of course possible. The cost of high precision automated equipment is typically substantial.  
           [0005]    One approach to delivery of a controlled amount of fluid employs pipette tips. The pipette tip relies on capillary action to draw a precise amount of fluid from a reservoir into an internal passage of the pipette tip, for delivery to the desired location. Pipette tips may be particularly suitable for dispensing fluids in the micro-liter range.  
           [0006]    U.S. Pat. No. 5,497,670 issued Mar. 12, 1996 discloses a dispensing apparatus including means for loading pipette tips carried by a pipette plate onto dispensing cylinders such that a loading force is maintained during the operation to ensure a hermetic seal. The pipette tips are manually placed on the pipette tip plate, the pipette tip plate being slidingly received within the dispensing apparatus.  
           [0007]    U.S. patent application Ser. No. 08/751,859 filed Nov. 18, 1996 discloses a dispensing apparatus. The dispensing apparatus is similar to that disclosed in the aforementioned patent, but substitutes a more conventional pipette tip carrier for the pipette tip plate, which is less expensive, less likely to be contaminated, and easily adapted for robotic operation or automation.  
           [0008]    U.S. application Ser. No. 10/027,448 filed Dec. 20, 2001 discloses a dispensing apparatus that employs a modified pipette tip box tray carrier to furnish pipette tips carried in a standard pipette tip box to the apparatus, and includes engagement means to engage pipette tip box tray carrier such that the pipette tips are loaded into corresponding internal cylinders formed in a dispense block head of the dispensing apparatus. The dispense block head comprises a solid block of material having a plurality of internal cylinders to engage the pipette tips in a sealing engagement.  
           [0009]    A distinctly different approach to precisely dispensing fluids employs one or more pins to retrieve a desired amount of fluid from a reservoir, and to dispense the retrieved fluid to a desired location. In contrast to pipette tips, these pins do not include an internal passage, but rather retrieve a small sample of the fluid as the pin is removed from a reservoir, the fluid forming a droplet on the outer surface at the end of the pin. The amount of fluid retrieved by the pin is a function of a number of parameters including the size, shape and material of the pin and the viscosity of the fluid, all of which affect surface tension. The pin based approach may be particularly suitable for dispensing fluids in the nano-liter range.  
           [0010]    Automating the pin based approach would be highly desirable, as would be the taking advantage of the substantial investment made in existing automated equipment such as pipette based dispensing apparatus.  
         BRIEF SUMMARY OF THE INVENTION  
         [0011]    In one aspect, a pin support assembly includes a pin support frame having a plurality of apertures for supporting an array of pins for dispensing fluids. An actuation assembly engages an end of each of the pins to ensure that the pins are properly seated in the support frame in a planar fashion. Interchangeability of the pin support frame with a pipette box tray carrier allows a single drive mechanism to be employed for different operations, for example dispensing very small amounts of fluid versus dispensing very large amounts of fluid, reducing costs.  
           [0012]    In another aspect, a pin support assembly for use with a dispense head apparatus having a movable piston plate includes a pin engagement actuation member selectively positionable with respect to the dispense head apparatus to be moved by the piston plate of the dispense head apparatus, a pin engagement member opposed to the pin engagement actuation member and mounted for movement with respect thereto, a biasing member coupled to bias the pin engagement member and the first pin engagement actuation member away from one another, and a linkage coupling the pin engagement actuation member and the pin engagement member to selectively move the pin engagement member and the first pin engagement actuation member towards one another. The pins are supported for longitudinal or “floating” movement to prevent damage to the pins.  
           [0013]    In another aspect, a pin support assembly for supporting pins for use with a dispense head apparatus having a movable piston plate and a carrier plate includes a first pin support surface having a first plurality of apertures of a first diameter, a second pin support surface having a second plurality of apertures of a second diameter, the second diameter smaller than the first diameter, the second pin support surface spaced from and coupled to the first pin support surface to form a pin support frame, a pin engagement member opposed to the first pin support surface and mounted for movement with respect thereto between an engaged position where the pin engagement member contacts a respective end of each of a number of pins received in the first and the second apertures of the first and the second pin support surfaces of the pin support frame, if any, and an unengaged position spaced from the engaged position to disengage the respective ends of the pins received in the first and the second apertures of the first and the second pin support surfaces of the pin support frame, if any; a movable pin engagement actuation member opposed to and spaced across the pin engagement member from the pin support frame, a scissors linkage coupling the pin engagement actuation member and the pin engagement member to selectively move the pin engagement member and the first pin engagement actuation member towards and away from one another, a biasing member coupled to bias the pin engagement member toward the disengaged position, and a set of mounting members sized to receive a set of loading pins on the carrier plate of the dispense head apparatus to selectively position the pin support assembly with respect to the dispense head apparatus such that the pin engagement actuation member is movable by the piston plate of the dispense head apparatus.  
           [0014]    In yet another aspect, a dispensing apparatus includes a pin support frame having a plurality of pin receiving apertures, a pin engagement member having a substantially planar pin engagement surface, the pin engagement member selectively movable between an engaged position and a disengaged position spaced from the engaged position, the pin engagement surface being proximate the pin support frame when the pin engagement member is in the engaged position and the pin engagement surface being distal to the pin support frame when pin engagement member is in the disengaged position, a pin engagement actuation member spaced across the pin engagement member from the pin support frame and movable between a first position spaced relatively from the pin support frame and a second position spaced relatively toward the pin support frame, a linkage coupling the pin engagement actuation member and the pin engagement member to selectively move the pin engagement member towards the pin engagement actuation member as the pin engagement member moves toward the disengaged position and to move the pin engagement member away from the pin engagement actuation member as the pin engagement member moves towards the engaged position, and a drive member couplable to selectively move the pin engagement actuation member between the first position and the second position.  
           [0015]    In yet a further aspect, a dispensing apparatus includes a pin support frame having a first plurality of pin receiving apertures of a first diameter and a second plurality of pin receiving apertures of a second diameter smaller than the first diameter, each of the pin receiving apertures of the first plurality aligned with a respective one of the pin receiving apertures of the second plurality for supportingly receiving a respective pin for axial movement with respect thereto, and a pin engagement member having a substantially planar pin engagement surface, the pin engagement member selectively positionable between an engaged position to contact the pins received in the pin receiving apertures if any, and a disengaged position spaced from the engaged position.  
           [0016]    In yet a further aspect a dispensing apparatus includes a drive assembly including a drive assembly frame, a drive member mounted to the drive assembly frame for axial movement with respect thereto, and a pin support assembly including a pin support frame having a number of apertures for slidingly receiving a plurality of pins, a pin engagement member mounted for movement with respect to the pin support frame between an engaged position and a disengaged position, and a linkage coupled to move the pin engagement member toward the disengaged position when the drive member moves towards the pin support frame and to move the pin engagement member toward the engaged position when the drive member moves away from the pin support frame, wherein the pin support assembly is selectively attachable and detachable to the drive assembly.  
           [0017]    In yet an even further aspect, a dispensing apparatus includes pin support means for supporting each of a plurality of pins, a pin engagement member selectively positionable between an engaged position simultaneously engaging in a single plane a respective end of each of a plurality of pins and a disengaged position spaced from the engaged position, and actuating means for moving the pin engagement member between the engaged and the disengaged positions. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0018]    In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrary enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements, as drawn are not intended to convey any information regarding an actual shape of the particular elements, and are solely selected for ease of recognition in the drawings.  
         [0019]    [0019]FIG. 1 is a front elevational view of a fluid dispensing apparatus with a pipette tip box tray carrier in a disengaged position to load a pipette tip box holding a plurality of pipette tips.  
         [0020]    [0020]FIG. 2 is a partial front elevational view of the fluid dispensing apparatus of FIG. 1 with the pipette tip box tray carrier in an engaged position to engage the pipette tips in the pipette tip box with respective ones of internal cylinders formed in a dispense block head of the fluid dispensing apparatus.  
         [0021]    [0021]FIG. 3 is a partially exploded top, front, right isometric view of a pin support assembly having a pin support frame and an actuation assembly for use with the fluid dispensing apparatus of FIGS. 1 and 2, for example, as a substitute for the pipette tip box and pipette tip box tray carrier thereof.  
         [0022]    [0022]FIG. 4 is a further exploded top, front, right isometric view of a pin support assembly of FIG. 3.  
         [0023]    [0023]FIG. 5 is a view of an alternative embodiment of the pin support frame of the pin support frame of FIGS. 3 and 4.  
         [0024]    [0024]FIG. 6 is a top, front, right isometric view of the actuation assembly of the pin support assembly of FIG. 3.  
         [0025]    [0025]FIG. 7 is a front elevational view of the actuation assembly of FIG. 6 in a pin engaged position.  
         [0026]    [0026]FIG. 8 is a front elevational view of the actuation assembly of FIG. 6 in a pin disengaged position.  
         [0027]    [0027]FIG. 9 is a right side elevational view of the actuation assembly of FIGS. 7 and 8 showing the pin engaged (broken line) and disengaged positions (solid line).  
         [0028]    [0028]FIG. 10 is an top, front, right isometric view of an alternative block of the fluid dispensing apparatus of FIG. 1.  
         [0029]    [0029]FIG. 11 is a partial, cross-sectional view along section  11  of FIG. 6, illustrating complementary mating portions of the coupling members on the pin support assembly and the carrier plate.  
         [0030]    [0030]FIG. 12 is a partial, cross-sectional view along section line  12  of FIG. 6, further illustrating the complementary mating portions of the coupling members on the pin support assembly and the carrier plate. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]    In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, one skilled in the art will understand that the invention may be practiced without these details. In other instances, well-known structures associated with dispensing apparatus, actuators, motors, motor controllers, and automated systems and devices have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments of the invention.  
         [0032]    Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.” 
         [0033]    The headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed invention.  
         [0034]    [0034]FIGS. 1 and 2 show a fluid dispensing apparatus  10  that includes a piston plate  12 , a horseshoe plate  14 , and a carrier plate  16 . The fluid dispensing apparatus  10  may employ a pipette tip box  18  that holds a number of pipette tips  20  for retrieving and dispensing defined amounts of fluids. The pipette tip box  18  is detachably coupled to the carrier plate  16  by way of a pipette box tray carrier  22 . In the illustrated example, the pipette box tray carrier  22  includes a pair of L-shaped ears or lugs for engaging and disengaging a set of loading pins  24  of the moveable carrier plate  16 .  
         [0035]    In operation, a pipette tip box  18  loaded with a plurality of pipette tips  20  is loaded onto the pipette box tray carrier  22 . The pipette box tray carrier  22  is coupled to the carrier plate  16 . The pipette box tray carrier  22  moves relative to a dispense block head  26  to selectively engage the ends of the pipette tips  20  with respective ones of a number of internal cylinders formed in the dispense block head  26 . The structure and operation of the fluid dispensing apparatus  10  of FIGS. 1 and 2 is further described in U.S. patent application Ser. No. 08/751,859, filed Nov. 18, 1996, and in U.S. patent application Ser. No. 09/442,500, filed Dec. 20, 2001, and thus will not be repeated herein in the interest of brevity and clarity.  
         [0036]    [0036]FIGS. 3 and 4 show a pin support assembly  30  for use with dispensing apparatus, such as the dispensing apparatus  10  of FIG. 1. The pin support assembly  30  includes a frame  31 , a pin support frame  32  for supporting a plurality of pins  34  and an actuation assembly  36  for selectively engaging ends  38  of the pins  34 . The frame  31  may support the pin support frame  32  and protect the pins  34  from damage.  
         [0037]    Each of the pins  34  has a first portion  40  of a first diameter and a second portion  42  of a second diameter less than the first diameter. The amount of fluid drawn by the pin  34  will in part be a function of the second diameter. In the embodiment illustrated in FIGS. 3 and 4, the pin support frame  32  includes a first frame member  44  having a plurality of apertures  46  having diameters slightly greater than the first diameter of the first portion  40  of the pin  34 . The pin support frame  32  also includes a second frame member  48  having a plurality of apertures  50  having diameters slightly greater than the second diameter of the second portion  42  of the pin  34 . The apertures  50  of the second frame member  48  are aligned or in registration with a respective one of the apertures  46  of the first frame member  44 . Each of the pins  34  is received in a respective pair of the apertures  46 ,  50  for axial movement with respect thereto. The second support frame  48  serves as a stop, engaging an edge formed between the first and second portions  40 ,  42  of the pins  34  to limit the axial travel of the pins  34 .  
         [0038]    [0038]FIG. 5 shows an alternative embodiment of the pin support frame  32  employing a single frame member  52  having apertures  46  formed in an upper surface  54  and apertures  50  formed in a lower surface  56 . The pins  34  are again supported for axial movement, the difference in the diameters of the first aperture  46  and the second aperture  50  forming a stop to limit the axial travel of the pins  34 .  
         [0039]    As illustrated in FIGS. 4, 6,  7 ,  8  and  9 , the actuation assembly  36  includes a pin engagement member  60  mounted for movement with respect to the pin support frame  32  between an engaged position contacting the ends  38  of the pins  34  and a disengaged position spaced from the engaged position. The engaged position is best illustrated in FIG. 8, and in broken line in FIG. 9. The disengaged position is best illustrated in FIG. 7, and in solid line in FIG. 9. The pin engagement member  60  may include a plate  62  having an engagement surface  63  and a resilient member or pad  64  attached to the engagement surface  63  of the plate  62 .  
         [0040]    The actuation assembly  36  includes a linkage  66  coupled to move the pin engagement member  60  toward the disengaged position when a drive member such as the dispense head  26  of the dispensing apparatus  10  moves toward the pin support frame  32 , and to move the pin engagement member  60  toward the engaged position when the drive member moves away from the pin support frame  32 . The linkage  66  may, for example, take the form of a scissor linkage, as illustrated in FIGS. 4 and 9. The linkage  66  may include two pairs of linkage members, pivotally coupled by a pivot pin  67 , to provide balance and even force across the pin engagement member  60 . The linkage  66  may also includes rollers or bushings  69  at the extremities thereof.  
         [0041]    The actuation assembly  36  may also include a pin engagement actuation member  68 , opposed across the pin engagement member  60  from the pin support frame  36 . The pin engagement actuation member  68  may include a plate  70  and resilient member or pad  72 , the resilient pad  72  attached to a surface of the plate  70  which is engaged by the drive member, such as the dispense head  26 . Thus, the linkage  66  couples the pin engagement actuation member  68  and the pin engagement member  60  to move the pin engagement member  60  toward the disengaged position as the pin engagement actuation member  68  moves toward the pin engagement member and the pin support frame  32 , and to move the pin engagement member toward the engaged position as the pin engagement actuation member  68  moves away from the pin engagement member  60  and the pin support frame  32 . The actuation assembly  36  may also include biasing members such as leaf springs or coil springs  71  to bias the pin engagement member  60  toward the disengaged position. The actuation assembly  36  may also include additional biasing members such as leaf springs or coil springs  74  biasing the arms of the linkage  66  into engagement with the plates  62 ,  70  in order to prevent unintended “chatter” or movement of the parts. Proper dimensioning of the various holes  75  and fasteners  77  received through the holes  75 , also helps to reduce or eliminate chatter. (Only a small number of the fasteners  77  are illustrated for sake of clarity of the drawings.) As indicated in the Figures, many of the holes  75  may be countersunk, particularly where the holes  75  must accommodate springs  71 .  
         [0042]    Thus, the pin engagement member  60  engages the ends  38  of the pins  34  in a single plane in response to movement by a drive member such as the dispense head block  26 , or a pin head block  76  illustrated in FIG. 10. With reference to FIG. 10, the pin head block  76  is similar to the dispense head block  26 , however, the pin head block eliminates the internal cylinders  13  found in the dispense head block  26 .  
         [0043]    With continuing reference to FIGS. 4 and 6- 9 , the actuation assembly  36  may include an actuation assembly frame member  78  having a pair of slots  79  through which the linkage  66  is received and mounted via the pivot pins  67 . The actuation assembly  36  also includes coupling members  80  which may have L-shaped ears or lugs  82  or other attachable/detachable coupling structures for selectively coupling the pin support assembly  30  to the carrier plate  16  (FIG. 1) of the fluid dispensing apparatus  10 .  
         [0044]    As best illustrated in FIGS. 3, 4 and  6 , the pin support assembly  30  may include coupling members  80  for selectively engaging and disengaging the loading pins  24  of the movable carrier plate  16  (FIG. 1). The coupling members  80  may take the form of two pairs of generally L-shaped ears or lugs. The pin support assembly  30  may include a mating portion having a complementary shape to mate with the loading pins  24 . For example the ears or lugs may include a lip formed at a distal end, defining an interior diameter sized and dimensioned to matingly receive a respective one of the loading pins  24 .  
         [0045]    The pin support assembly  30  may further include a mating portion having a complementary shape to mate with a mating potion of the dispense head apparatus  10 . For example, as illustrated in FIGS. 11 and 12, the coupling members  80  may form all or a part of a mating portion for mating with a portion of the carrier plate  16 . For instance, the coupling members  80  may, as illustrated, be tapered or curved in a first direction parallel to a direction of movement of the pin engagement actuation member  68  and may be tapered or curved in a second direction perpendicular to the direction of movement of the pin engagement actuation member  68 . This ensures precise positioning of the pins  34  with respect to a target such as locations on a plate, slide or array.  
         [0046]    Although specific embodiments of an examples for the dispensing apparatus are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the invention, as will be recognized by those skilled in the relevant art. The teachings provided herein of the invention can be applied to other dispensing apparatus, not necessarily the pin dispensing apparatus generally described above.  
         [0047]    The various embodiments described above can be combined to provide further embodiments. All of the above U.S. patents, U.S. patent applications and publications referred to in this specification are incorporated herein by reference, in their entirety. Aspects of the invention can be modified, if necessary, to employ systems, circuits and concepts of the various patents, applications and publications to provide yet further embodiments of the invention. These and other changes can be made to the invention in light of the above detailed description. In general, in the following claims, the terms used should not be construed to limits the invention to the specific embodiments disclosed in the specification and the claims, which should be construed to include all dispensing apparatus that operate in accordance with the claims. Accordingly, the invention is not limited by the disclosure, but instead its scope is to be determined entirely by the following claims.