Abstract:
A fluid dispenser from which fluid may be dispensed upon passive pressurization of a fluid reservoir therein. Upon exposing a nib of the fluid dispenser to the surroundings, either by disengagement of a cap or extension or contraction of the fluid dispenser, the fluid reservoir is pressurized without requiring the operator to exert manual force on the walls of the fluid dispenser. In certain embodiments, the rate of flow initiated passively may be increased by the operator actively engaging an interface, which increases the pressure within the fluid reservoir.

Description:
FIELD OF THE DISCLOSURE  
       [0001]     This disclosure relates to the field of fluid dispensers generally and, more specifically, to dispensers of correction fluid, ink, paint, and the like which utilize pressurized reservoirs to discharge fluid from the dispenser. 
     
    
     DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0002]      FIG. 1  is a perspective view of a first embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines the position of the cap for the fluid dispenser with the tip in a concealed condition, and showing in broken lines the rotated position of the cap for the fluid dispenser with the tip in an exposed condition and the fluid dispenser pressurized;  
         [0003]      FIG. 2  is a cross-sectional view taken along lines  2 - 2  of  FIG. 1 , but showing in solid lines the rotated position of the cap for the fluid dispenser with the tip in an exposed condition and the fluid dispenser pressurized, and showing in broken lines, broken away, the position of the cap for the fluid dispenser with the tip in a concealed condition;  
         [0004]      FIG. 3  is a cross-sectional view taken along lines  3 - 3  of  FIG. 1 ;  
         [0005]      FIG. 4  is an exploded view of the fluid dispenser shown in  FIG. 1 ;  
         [0006]      FIG. 5  is a cross-sectional view of a second embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines the position of the cap for the fluid dispenser with the tip in an exposed condition and the fluid dispenser pressurized, and showing in broken lines the extended position of the cap of the fluid dispenser with the tip in a concealed condition;  
         [0007]      FIG. 6  is a cross-sectional view of a third embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines the position of the cap for the fluid dispenser with the tip in an exposed condition and the fluid dispenser pressurized, and showing in broken lines the extended position of the cap of the fluid dispenser with the tip in a concealed condition;  
         [0008]      FIG. 7  is a cross-sectional view of a fourth embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines a shroud of the fluid dispenser in a retracted position, such that the nib of the fluid dispenser is exposed, and showing in broken lines the shroud in an extended position, wherein the nib is concealed;  
         [0009]      FIG. 8  is a cross-sectional view of a fifth embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines a shroud of the fluid dispenser in a retracted position, such that the nib of the fluid dispenser is exposed, and showing in broken lines the shroud in an extended position, wherein the nib is concealed;  
         [0010]      FIG. 9  is a cross-sectional view of a sixth embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines a substantially rigid tip portion in an extended position, such that the nib of the fluid dispenser is exposed, and showing in broken lines an outer casing of the fluid dispenser while the tip holder is in a retracted position, wherein the nib is concealed;  
         [0011]      FIG. 10  is a perspective view of a seventh embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines a spring associated with the exterior of the fluid dispenser while the fluid dispenser is in an uncapped condition, and showing in broken lines the spring while the fluid dispenser is in a capped condition; and  
         [0012]      FIG. 11  is a perspective and partial cross-section view of an eighth embodiment of a fluid dispenser made in accordance with the present disclosure, showing in solid lines the nib of the fluid dispenser in an exposed condition, and showing in broken lines an outer casing of the fluid dispenser while the nib is in a concealed position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     With reference to the drawing figures, various preferred embodiments of a fluid dispenser are herein described. While one particularly advantageous use of the fluid dispensers of the present disclosure is a dispenser for correction fluid, it is appreciated by those ordinarily skilled in the art that the particular fluid to be dispensed may be of many forms. It is desirable, however, that the fluid to be dispensed has a sufficiently high viscosity to facilitate gradual dispensing from the fluid dispenser, i.e. to resist unintentional spillage of fluid, or that a control member, such as a valve, be provided to control lower viscosity fluids.  
         [0014]      FIGS. 1-4  depict a first embodiment of a fluid dispenser  10 . The fluid dispenser  10  includes a cap  12 , a main dispenser body  14 , and a substantially rigid tip portion  16 . The main dispenser body  14  defines a fluid reservoir  18 , and is preferably made of a resilient, semi-rigid, deformable, shape-recoverable material, such as plastic. A suitable material for the main dispenser body  14  exhibiting these desirable characteristics is a blow moldable grade of unfilled nylon 6, for instance Novamid ST110BH available from Mitsubishi Engineering Plastics Corp.  
         [0015]     Fluid from the reservoir  18  is dispensed from a tip  60 . As shown schematically in  FIGS. 2 and 3 , a control member, such as a valve  15 , may be provided between the reservoir  18  and the tip  60  to control flow of fluid to the tip  60 . The valve  15 , however, may be removed without departing from the scope of the present disclosure. For example, the fluid to be dispensed may be sufficiently viscous that it does not flow from the tip  60  during the time period between opening the cap  12  and placing the tip against the surface to be marked. Alternatively, a structure that does not include a valve member, such as a capillary structure, may be provided for less viscous fluids such that the fluid is delayed from reaching the tip  60  for a period of time sufficient to place the tip  60  against the surface.  
         [0016]     The cap  12  rotates, or swings, between a non-dispensing or closed position, as shown in solid lines in  FIG. 1 , and a dispensing or open position, as shown in broken lines in  FIG. 1 . The phrase “dispensing position” as used herein does not necessarily mean that fluid is automatically dispensed when the cap is in that position. Instead, when the cap  12  is in the dispensing position, the dispenser  10  may merely be capable of dispensing fluid, and fluid flow may not begin until a control member such as the valve  15 , if provided, is actuated to an open position. In dispensers having a control member, the cap need only protect the tip  60  in the closed position to prevent inadvertent contact with a surface. For dispensers that do not include a control member, the cap may also completely cover and/or seal the tip  60  to prevent discharge of fluid. The cap  12  is preferably formed of a generally U-shaped profile, with opposing legs  20 ,  22 . As shown in  FIG. 4 , the opposing legs  20 ,  22  may be formed separately, and fastened together via tongue projections  24  provided at the top of at least one of the legs  20 ,  22 , and complementary grooves  26  at the top of the other of the legs  20 ,  22 . Each of the tongue projections  24  may be provided with a hook-like end  28 , to facilitate locking the opposing legs  20 ,  22  of the cap  12  together. The opposing legs  20 ,  22  may be manufactured as identical parts, so as to reduce complexity in manufacturing. For instance, the legs  20 ,  22  may be provided with hermaphroditic tongue  24  and groove  26  connectors, such that the legs  20 ,  22  are interchangeable.  
         [0017]     A force member in the form of a resilient spring clip  30  is provided over the legs  20 ,  22  of the cap  12 . In the embodiment shown in  FIGS. 1-4 , the legs  20 ,  22  are provided with a recessed region  32  extending over a substantial portion of the exterior of each of the legs  20 ,  22 , bounded by a retaining wall  34 . The legs  20 ,  22  are preferably additionally provided with an elongated central ridge  36 . The resilient clip  30  is provided with a centrally-located, complementary, ridge-receiving slit or opening  38 . Once the opposing legs  20 ,  22  are interconnected, the resilient spring clip  30  is placed over the opposing legs  20 ,  22 , and received in the recessed region  32  of the opposing legs  20 ,  22 , with the central ridge  36  projecting through the ridge-receiving slit  38  in the resilient spring clip  30 .  
         [0018]     Each of the opposing legs  20 ,  22  is also preferably provided with an interface, such as a recessed button  40  at the bottom of the central ridge  36 . The recessed button  40  is preferably of a shape to facilitate placement of an operator&#39;s fingertip or thumbtip therein. The resilient spring clip  30  is further provided with interface access openings  42  at either end of the ridge-receiving slit  38 , so that when the spring clip  30  is received in the recessed region  32 , the recessed button  40  is accessible. Each of the opposing legs  20 ,  22  is further provided with an inwardly-directed ring  44  projecting from an interior surface thereof.  
         [0019]     The main dispenser body  14  has opposing recesses  46 ,  48  therein. The opposing recesses  46 ,  48  are preferably round, and receive the inwardly-directed rings  44  projecting from the interior surface of the opposing legs  20 ,  22  of the cap  12 . Once the inwardly-directed rings  44  are received in the opposing recesses  46 ,  48 , the cap  12  is rotatable with respect to the main dispenser body  14 . One or more locking tabs  50 ,  52  may be provided as extensions from the inwardly-directed rings  44 , with complementary locking recesses  54 ,  56  extending from the opposing recesses  46 ,  48 , to retain the cap  12  in either an open position or a closed position. For example, locking tabs  50 ,  52  are selectively received in the complementary recesses  54 ,  56  while the cap  12  is in the closed position, such that the substantially rigid tip portion  16  is not exposed, thereby locking the cap  12  in the closed position.  
         [0020]     An application of a suitable amount of force to the curved end  58  of the cap  12  to overcome the resistance caused by the presence of the locking tabs  50 ,  52  in the locking recesses  54 ,  56 , commensurate with the force necessary to remove of a cap of a conventional writing utensil, causes the locking tabs  50 ,  52  to move out of the complementary locking recesses  54 ,  56 , allowing the cap  12  to swivel or rotate to an open position. When the locking tabs  50 ,  52  again align with the complementary locking recesses  54 ,  56 , the cap  12  is locked in the open position. To re-close the fluid dispenser  10 , the operator need only again apply a suitable amount of force to the curved end  58  of the cap  12  to overcome the resistance, again causing the locking tabs  50 ,  52  to move out of the complementary locking recesses  54 ,  56 , and allowing the cap  12  to swing back to the closed position. The ability of the cap  12  to rotate between open and closed positions is indicated by the double-headed arrow in  FIG. 1 . It is recognized that the cap  12  may have a 180° range of motion, or preferably, a 360° range of motion, such that the cap could be rotated in either direction to change from an open to a closed position and vice-versa.  
         [0021]     The resilient spring clip  30  biases the opposing legs  20 ,  22  toward one another. While the cap  12  is in the closed position, the opposing legs  20 ,  22  engage the substantially rigid tip portion  16 , forcing the opposing legs  20 ,  22  outwardly, to a substantially parallel orientation, thereby causing the opposing legs  20 ,  22  to resist the biasing force of the resilient spring clip  30 . As used herein, it is to be understood that “substantially rigid” describes a tip portion that has sufficient rigidity to overcome the biasing force of a spring member, even after repeated openings and closings of the fluid dispenser. For example, in this embodiment, the substantially rigid tip portion  16  has sufficient rigidity to overcome the biasing force of the resilient spring clip  30 , so as to ensure the opposing legs  20 ,  22  of the cap are pushed apart from one another, into the substantially parallel orientation, when positioned over the substantially rigid tip portion  16 . The tip portion  16  may therefore be somewhat flexible and/or compressible, but still be considered substantially rigid. When the cap  12  is swiveled or rotated toward the open position, the opposing legs  20 ,  22  disengage from the substantially rigid tip portion  16 . Due to the restoring force of the resilient spring clip  30 , the opposing legs  20 ,  22  bend toward one another, thereby compressing the main dispenser body  14 . By compressing the main dispenser body  14 , the fluid reservoir  18  defined by the main dispenser body  14  is likewise compressed, causing fluid f retained in the fluid reservoir  18  to exit the fluid reservoir  18  through a nib  60  provided in the substantially rigid tip portion  16 , so that the fluid f may be applied to a surface, such as a piece of paper.  
         [0022]     Fluid may be passively pressurized within the reservoir  18  upon swiveling the cap  12  to an open position. The valve  15  may then be actuated to an open position to dispense fluid from the tip  60 . Alternatively, if no valve  15  is provided, the fluid may be dispensed immediately or after a delay period upon placing the cap  12  in the open position. Depending on the viscosity of the fluid f, it may be the case that the operator desires the fluid f to be dispensed faster than the rate at which the fluid is passively dispensed due to the compression of the main dispenser body  14  by the cap  12 . The operator may advantageously apply pressure to the recessed buttons  40 , or other similar interface, provided along the opposing legs  20 ,  22 . The interface may alternatively be provided on the main dispenser body  14  itself, rather than on the cap  12 . The recessed buttons  40  are preferably located substantially opposite the inwardly-directed rings  44 , such that pressure applied to the raised buttons  40  while the cap  12  of the fluid dispenser  10  is in an open position increases the compression of the fluid reservoir  18 , causing the fluid f to be dispensed at a faster rate. Because some fluids tend to congeal or separate over time, a mixing slug  62  may also be provided in the reservoir  18 . While the fluid dispenser  10  is shown to have a generally rectangular shape, it is recognized that the fluid dispenser  10  may have other shapes, such as generally cylindrical.  
         [0023]     Various types of known writing tips and valves may be used in the fluid dispenser  10 . For example, the tip  60  may be a ball point having one or more ball members which also provide the control member. Alternatively, the tip  60  may be a conduit formed of metal or plastic. To control fluid flow through the conduit, the valve  15  may be a pin valve that actuates in response to writing pressure, a paint-marker valve that requires a pushing force to open, or other known type of valve, or a combination of any such valves. Alternatively, a non-valved system, such as a capillary structure, may be provided to control or delay flow of fluid to the tip  60 .  
         [0024]     Turning to  FIG. 5 , a second embodiment of the fluid dispenser is shown in cross-section. The fluid dispenser  110  of the second embodiment includes a cap  112 , a main dispenser body  114 , and a substantially rigid tip portion  116 . The cap  112  includes a nib-receiving aperture  118  at a distal end  120  thereof. While the cap  112  is in a retracted position, as indicated in solid lines in  FIG. 5 , a proximal end  122  of the cap  112  engages an interface in the form of an outwardly-projecting button member  124  provided along the main dispenser body  114 . As in the first embodiment, the main dispenser body  114  defines a fluid reservoir  126 . At least in an area of the button member  124 , the main dispenser body  114  is preferably made of a semi-rigid, deform able, shape-recoverable material, such as plastic. A nib  128  extends from the substantially rigid tip portion  116 . While the cap  112  is in the retracted position, the nib  128  is exposed.  
         [0025]     The button member  124  is situated and adapted such that upon engagement with the proximal end  122  of the cap  112 , the button member  124  causes the main dispenser body  114  to compress, thereby pressurizing the fluid f in the fluid reservoir  126 . The cap  112  in conjunction with the button member  124  thereby act together as a force member. Pressurization of the fluid f in the fluid reservoir  126  generates a pressure force sufficient to dispense the fluid f from the fluid dispenser  110  through the nib  128 . Fluid f is thereby passively pressurized by the fluid dispenser  110  upon movement of the cap  112  to the retracted position.  
         [0026]     In order to dispense the fluid f faster than the rate at which the fluid f is dispensed due to the compression of the main dispenser body  114  by the cap  112 , an operator may advantageously apply pressure to the button member  124  in the direction of the arrow indicated in the drawing. Pressure applied to the button member  124  while the cap  112  of the fluid dispenser  110  is in a retracted position increases the compression of the fluid reservoir  126 , causing the fluid f to be dispensed at a faster rate. The button member  124  is preferably provided with tactilely satisfactory topography, such as a plurality of ridges  130 . It will be appreciated by those in the art that the displacement of the button member  124  is exaggerated to some extent in  FIG. 5 , and represents, albeit in a somewhat exaggerated manner, displacement of the button member  124  not only due to engagement with the proximal end  122  of the cap  112 , but also further displacement due to manual application of force by an operator to increase the rate of flow of fluid f. It will be further appreciated that displacement of the button member  124  solely due to engagement with the proximal end  122  of the cap  112  would generally be less pronounced than the displacement of the button member  124  when coupled with the manual application of force by an operator on the button member  124 .  
         [0027]     The cap  112  of the fluid dispenser  110  is preferably movable to an extended position, as shown in broken lines in  FIG. 5 . In the extended position, the proximate end  122  of the cap  112  disengages from the button member  124 , and the nib  128  is concealed by the distal end  120  of the cap  112 . Upon disengagement of the proximate end  122  of the cap  112 , the button member  124 , as well as any additional compressed portion of the main dispenser body  114 , recovers its pre-compressed shape, thereby reducing the pressure on the fluid f.  
         [0028]     The cap  112  is preferably permanently retained on fluid dispenser  10 . For example, the proximate end  122  of the cap  112  may be bounded between the button member  124  and the substantially rigid tip portion  116 . A slide or twist mechanism (not shown), or some combination thereof, may be used to actuate the cap  112  between an extended position and a retracted position.  
         [0029]     In a third embodiment, as shown in  FIG. 6 , the fluid dispenser  210  has a cap  212  threadedly engaged with a main dispenser body  214 . As in the second embodiment, the cap  212  is movable between a retracted position, shown in solid lines in the drawing, and an extended position, represented in broken lines. The fluid dispenser  210  further includes a substantially rigid tip portion  216  in combination with the main dispenser body  214 . The main dispenser body  214  defines a fluid reservoir  218 .  
         [0030]     The cap  212  has a distal end  220  and a proximate end  222 . The distal end  220  has a nib-receiving aperture  224 . The nib-receiving aperture  224  may be of sufficient size to receive the region of the tip portion  216  in which a nib  226  is secured, as shown in  FIG. 6 , or alternatively, may be sized to receive only the nib  226 . When the cap  212  is twisted to its extended position, the nib  226  is concealed by the distal end  220  of the cap  212 . This advantageously prevents residual fluid f on the distal end of the nib  226  from undesirably dripping onto a surface, such as a piece of paper. The dispenser  210  may also include a control member similar to the valve  15  of the first embodiment to further prevent inadvertent fluid flow from the nib  226 . When the cap  212  is twisted to its retracted position, the nib  226  is exposed and the proximate end  222  engages a resilient collapsible portion  228  of the main dispenser body  214  which is preferably made of a semi-rigid, deformable, shape-recoverable material, such as plastic.  
         [0031]     Upon such engagement, the resilient collapsible portion  228  of the main dispenser body  214  is compressed, reducing the volume of the fluid reservoir  218 , thereby pressurizing fluid f contained in the fluid reservoir  218 . If no control member is provided, pressurization of the fluid results in the fluid f being passively dispensed through the nib  226 . Alternatively, if a control member is provided between the reservoir  218  and the nib  226 , an additional step to actuate the control member to the open position may be necessary before fluid will flow to the nib  226 . In either instance, fluid f is passively pressurized in the fluid reservoir  218  upon rotational movement of the cap  212  to the retracted position. When the cap  212  is twisted back to its extended position the resilient collapsible portion  228  returns to its uncompressed shape, thereby equalizing the pressure within the fluid reservoir  218 . While not shown in  FIG. 6 , the fluid dispenser  210  of the third embodiment may be provided with an interface along the main dispenser body  214  in order to allow the operator to selectively increase the rate of flow of the fluid f from the fluid dispenser  210 .  
         [0032]     A fourth embodiment is shown in cross-section in  FIG. 7 , in which a fluid dispenser  310  is provided having a shroud, which for purposes of this disclosure is also considered a cap  312 , a main dispenser body  314 , an internal collapsible bladder  316  defining a fluid reservoir  318 , and a tip portion  320 . The shroud or cap  312  preferably includes an internally threaded region  322  and an externally threaded region  324 .  
         [0033]     The externally threaded region  324  engages an internally threaded portion  326  provided at a first end  328  of the main dispenser body  314 . The internally threaded region  322  engages external threads  330  provided on the tip  320 . The external threads  330  are preferably oriented in the same direction, and with a complementary pitch, to the externally threaded region  324 , such that rotation of the shroud or cap  312  results in movement of the cap  312  relative to both the main dispenser body  314  and the tip  320 .  
         [0034]     A proximate end  332  of the shroud or cap  312  abuts a surface  334  of the internal collapsible bladder  316  at least when the cap  312  is actuated toward its retracted position. Continued rotation of the cap  312  toward its retracted position causes the internal collapsible bladder  316  to compress, pressurizing fluid f within the fluid reservoir  318  defined by the internal collapsible bladder  316 . At least the proximate end  332  of the cap  312  thereby acts as a force member. The cap  312  is provided with a nib-receiving opening  334  in a distal end  336  thereof, as in the second or third embodiments.  
         [0035]     Upon rotating the cap  312  toward its extended position, the collapsible internal bladder  316  returns to substantially its pre-compressed shape, and the pressure within the fluid reservoir  318  equalizes. The internal collapsible bladder  316  preferably has two interconnected chambers, with one of the chambers being a relatively small bellows portion  338  and the other chamber being a relatively large bellows portion  340 . At least some of the large bellows portion  338  is occupied by a gas a, such as air. The volume of the large bellows portion  340  may be significantly greater than the volume of the small bellows portion  338 . Thus, as the shroud or cap  312  is twisted relative to the main dispenser body  314 , fluid and gas occupying the relatively larger volume within the large bellows portion  340  is forced in the direction of the small bellows portion  338 , thereby pressurizing the contents. Fluid f is thereby passively pressurized in the fluid reservoir  318  upon rotational movement of the cap  312  to the retracted position.  
         [0036]     Turning to  FIG. 8 , a fifth embodiment of a fluid dispenser  410  includes a cap  412 , a main dispenser body  414 , and a substantially rigid tip portion  416 . The main dispenser body  414  defines a fluid reservoir  415 . The cap  412  is preferably made primarily of a resilient material such as a spring, with legs  418 ,  420  that are biased toward one another, as represented by the generally upwardly directed and generally downwardly directed arrows in  FIG. 8  in the immediate vicinity of the legs  418 ,  420 . The cap  412  thereby acts as a force member. The walls  422 ,  424  of the main dispenser body  414  are compressible.  
         [0037]     The cap  412  is moveable between an open position, as shown in solid lines in  FIG. 8 , and a closed position, as represented by broken lines in the drawing figure. As the cap  412  is moved to its open position, the legs  418 ,  420  of the cap  412  approach one another, thereby compressing the walls  422 ,  424  between the legs  418 ,  420  and pressurizing the fluid f inside the fluid reservoir  415 . The pressurized fluid f may then be dispensed through a nib  426  provided in the substantially rigid tip portion  416  either directly or through a control member that has been actuated to an open position. Fluid f is thereby passively pressurized in the fluid reservoir  415  upon movement of the cap  412  to the open position. The operator may selectively increase the rate at which the fluid f is dispensed by manually applying pressure to the main dispenser body  414 .  
         [0038]     As the cap  412  is moved from the open position to the closed position, the substantially rigid tip portion  416  forces the legs  418 ,  420  apart, such that the legs  418 ,  420  ride along the outer walls of the substantially rigid tip portion  416  until inwardly-directed stop walls  428 ,  430  provided on the legs  418 ,. 420  of the cap  412  abut complementary proximate ends  432 ,  434  of the substantially rigid tip portion  416 . Once the legs  418 ,  420  of the cap  412  lose contact with the walls  422 ,  424  of the main dispenser body  414 , the walls  422 ,  424  return to their uncompressed shape and the pressure in the fluid reservoir  418  is reduced. Favorably, the cap  412 , when in the closed position, also conceals the nib  426  from view, as in certain of the embodiments described above.  
         [0039]      FIG. 9  shows a sixth embodiment of a fluid dispenser  510 . The fluid dispenser  510  includes a main dispenser body  512 , a substantially rigid tip portion  514 , a compressible fluid-containing bladder  516 , and a spring  518 . A nib  520  extends from a distal end  522  of the substantially rigid tip portion  514 . The substantially rigid tip portion  514 , the nib  520 , and the compressible bladder  516  move as substantially a single unit relative to the main dispenser body  512  and spring  518 , which operate together as a second unit. In  FIG. 9 , the fluid dispenser  510  is shown with the substantially rigid tip portion  514 , the nib  520 , and the compressible bladder  516  in an extended position relative to the main dispenser body  512 , such that the nib  520  extends outside of the main dispenser body  512  through a nib-receiving aperture  524  in a distal end of the main dispenser body  512 .  
         [0040]     In this extended position, the spring  518 , which includes two legs  526  and  528  biased toward one another, compresses the bladder  516 . The spring  518  thereby acts as a force member. By compressing the bladder  516 , the pressure within the bladder  516  increases. The pressurized fluid f contained within the bladder  516  may then be dispensed from the fluid dispenser  510 . Fluid f is thereby passively pressurized in the bladder  516  upon movement of the main dispenser body  512  to the retracted position.  
         [0041]     The substantially rigid tip portion  514 , the nib  520 , and the bladder  516  are also movable to a retracted position, as represented by broken lines in  FIG. 9 , in which the nib  520  is withdrawn into the nib-receiving aperture  524 . Inasmuch as the main dispenser body  512  serves as structure that conceals the nib  520  while the substantially rigid tip portion  514 , the nib  520 , and the bladder  516  are in the retracted position, in this embodiment the main dispenser body  512  is also the cap. As the substantially rigid tip portion  514  moves toward a proximate end  530  of the main dispenser body  512 , the legs  526 ,  528  of the spring  518  are forced apart from one another by the substantially rigid tip portion  514 , thereby removing compressive force from the bladder  516 . The nib  520  is preferably provided with an air hole  532  through which the bladder  516  draws air upon removal of the compressive force therefrom. By drawing air into the bladder  516  through the air hole  532  in the nib  520 , the pressure in the bladder  516  reduces, which may stop the flow of fluid f through the nib  520 .  
         [0042]      FIG. 10  shows a seventh embodiment of a fluid dispenser  610 , including a removable cap  612  (shown in broken lines), a compressible main dispenser body  614 , a substantially rigid tip portion  616 , and a spring  618  associated with the main dispenser body  614 , the spring  618  being on the exterior of the main dispenser body  614 . As indicated in broken lines in  FIG. 10 , when the cap  612  is positioned over the substantially rigid tip portion  616 , a spring-retaining tab  620  of the cap  612  prevents the spring  618  from compressing the compressible main dispenser body  614 . When the cap  612  is removed, as shown in solid lines in the drawing figure, the spring  618  compresses the main dispenser body  614 , thereby pressurizing a fluid retaining reservoir  622  defined by the main dispenser body  614 . The fluid f contained in the reservoir  622  may then be dispensed through a nib  624 . The spring  618  thereby acts as a force member, and the fluid f is passively pressurized in the reservoir  622  upon removal of the cap  612  from the main dispenser body  614 . The operator may selectively increase the rate at which fluid is dispensed by manually applying pressure to the main dispenser body  614 .  
         [0043]     Turning now to  FIG. 11 , an eighth embodiment of a fluid dispenser  710  is shown. The fluid dispenser  710  includes a removable cap  712 , a main dispenser body  714 , a compressible bladder  716 , and a tip portion  718 . The interior of the cap  712  is provided with one or more bladder compression surfaces  720 , arranged such that when the cap  712  is placed on the proximate end  722  of the main dispenser body  714 , the bladder compression surface or surfaces  720  compresses the compressible bladder  716 . At least the portion of the cap  712  defined by the one or more bladder compression surfaces  720  thereby acts as a force member.  
         [0044]     The compressible bladder  716  defines a portion of a fluid reservoir  724 , which extends through the main dispenser body  714 . As the bladder compression surface or surfaces  720  compresses the compressible bladder  716 , the fluid reservoir  724  is pressurized. With the fluid reservoir  724  pressurized, fluid f contained therein may then be dispensed through a nib  726  extending from the tip  718 . The fluid f is thereby passively pressurized in the fluid reservoir  724  upon placement of the cap  712  on the proximate end  722  of the main dispenser body  714 . The nib  726  is preferably provided with an air inlet hole  728 , so that when the cap  712  is removed from the proximate end  722  of the main dispenser body  714 , ambient air is drawn into the compressible bladder  716 , thereby lowering the pressure back to equilibrium and causing the compressible bladder  716  to recover its uncompressed shape. With the pressure in the bladder  716  equalized, fluid flow through the nib  716  may be stopped.  
         [0045]     The degree to which the reservoir is passively pressurized may be quantified by comparing the volume of the reservoir with the cap in the non-dispensing and dispensing positions. Such a comparison was performed on a fluid dispenser similar to that shown in  FIGS. 1-4  by orienting the dispenser vertically, removing the tip  60 , and completely filling the reservoir  18  and tip portion  16  with water while the cap was in the non-dispensing position. The weight of the water added to completely fill the reservoir  18  and tip portion  16  was then recorded. With the dispenser still in the vertical position, the cap was moved to the dispensing position, thereby compressing the reservoir and causing a portion of the water to be displaced. The weight of the water displaced from the reservoir was then recorded. Accordingly, a comparison of the weight of water displaced when the cap is placed in the dispensing position to the total weight of water in the reservoir and tip portion with the cap in the non-dispensing position may be expressed as a fluid displacement percentage. Furthermore, the recorded water weights are directly proportional to reservoir volume, and therefore provide a measure of the uncompressed reservoir volume when the cap is in the non-dispensing position and a compressed reservoir volume when the cap is in the dispensing position. Thus, the fluid displacement percentage quantifies the passive pressurization of the fluid reservoir.  
         [0046]     The fluid displacement percentage described above should be sufficient to generate fluid flow but not too large that the fluid flow is excessive or uncontrollable. Accordingly, the fluid displacement percentage should be at least approximately 1% and no greater than approximately 25%. Preferably, the fluid displacement percentage falls within the range of 3-16%. As will be appreciated by those skilled in the art, the most desirable fluid displacement percentage will depend on the viscosity of the fluid and the resistance to flow caused by the particular tip used for the dispenser.  
         [0047]     While certain preferred embodiments have been described, it will be appreciated that modifications may be made thereto without departing from the scope of the appended claims.