Patent Publication Number: US-6220772-B1

Title: Fluid-dispensing and refilling system for a power toothbrush

Description:
This is a continuation-in-part of application Ser. No. 09/229,979, filed on Jan. 13, 1999. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to fluid-dispensing power toothbrushes, and more specifically concerns such a toothbrush which has an on-board reservoir and refilling arrangement and a fluid path arrangement which includes a pump element located in the brushhead portion of the toothbrush. The pump element uses the action of the moving brushhead to move fluid from the on-board reservoir to the bristles on the brushhead. 
     BACKGROUND OF THE INVENTION 
     The effective delivery of an oral dentifrice and/or medication capable of inhibiting or killing bacteria responsible for dental disease has long been desirable and has been the subject of a substantial amount of research effort. A wide variety of devices, both active and passive, have been developed to accomplish the delivery of dentifrice or medication to the bristles. Such devices have been developed for both manual and power toothbrushes. Manual toothbrushes typically use a hand-operated pump, such as shown in U.S. Pat. No. 4,221,492 to Boscardin et al and 4,013,370 to Gingras, while power toothbrushes use a variety of approaches, including on-board and external active pumping devices, which include various mechanical, pneumatic and hydraulic elements. 
     Some power toothbrush fluid-dispensing systems use the action of the toothbrush itself to draw a dentifrice from the reservoir to the bristles, such as shown in U.S. Pat. No. 5,309,590 to Giuliani et al. Some representative examples of fluid-dispensing systems for manual and power toothbrushes include U.S. Pat. Nos. 3,547,110 to Balamuth; 5,066,155 to English et al; 5,208,933 to Lustig and 5,062,728 to Kuo. 
     The reservoir for the dentifrice is typically located either in the handle portion of the toothbrush, such as shown in the &#39;590 patent, or in a separate device, such as shown in the &#39;110 patent. In some cases, the reservoir is disposable, so that when the fluid in the reservoir is depleted, the reservoir itself is discarded and a replacement reservoir is inserted. Such a system is shown in the &#39;370 patent. In other systems, the reservoir is refillable. Typically, the reservoir contains sufficient fluid for a substantial number of individual uses of the fluid dentifrice or medication. 
     Various systems for dispensing the fluid from the brushhead are also known. In some cases, the fluid is dispensed from a plurality of openings in the brushhead itself, such as shown in the &#39;492 patent, while in other cases, the fluid is dispensed through the bristles themselves, such as shown in U.S. Pat. No. 4,039,261 to Evans. 
     Fluid-dispensing systems in general, however, have often been difficult to operate, unreliable and expensive. Many such systems are too complex for reliable operation and/or are incapable of working properly, while other systems fail due to clogging of the fluid lines or exit openings, or poor pumping action, among other reasons. Also, it is difficult to design a system with a pump small enough to fit within a typical toothbrush structure. External pumps are often used, which are bulky and expensive. The pump element, whether on-board or external, is typically too complex for sustained, reliable operation, or too expensive to be practical. For all of these reasons, fluid-dispensing systems for both manual and power toothbrushes have not been particularly successful. 
     Because of the potential benefits, it is desirable to have a fluid-dispensing system in a power toothbrush which is reliable and yet sufficiently simple in design that it is practical to manufacture and maintain. 
     DISCLOSURE OF THE INVENTION 
     Accordingly, the present invention includes a fluid delivery system for a power toothbrush, comprising: a reservoir which is located within a toothbrush head portion of a power toothbrush, wherein the head portion is removable from the handle portion of the toothbrush; a pump member and associated fluid line for moving fluid from the reservoir to a brushhead part of the head portion of the toothbrush; and a dispensing member located in the brushhead, connected to the fluid line, for receiving fluid from the pump member and permitting exit of fluid therefrom to the vicinity of the bristles, under pressure provided by the pump member. 
     The invention also includes a pump for use in the fluid delivery system for a power toothbrush, comprising: a pump member for moving fluid from a reservoir to a dispensing member located in a brushhead portion of a toothbrush, wherein the pump member includes a chamber and a ball which moves within the chamber in response to movement of the brushhead during operation of the toothbrush, wherein movement of the ball in the chamber results in fluid moving from the reservoir into the pump member and then out of the pump member with sufficient pressure to move the fluid to the dispensing member and then outwardly therefrom. 
     The invention also includes a refilling system for a power toothbrush for use with a power toothbrush having an internal reservoir located therein from which fluid in operation is moved to the bristles in the brushhead, the internal reservoir having a small volume, at least one unit of use, the refilling system comprising: an external refilling assembly which is separate from the power toothbrush, the refilling assembly having a fluid reservoir which contains a substantial volume of fluid, at least a plurality of unit-of-use volumes of fluid; means associated with the refilling assembly and the power toothbrush for producing a fluid path from the refilling assembly to the power toothbrush; and means for moving fluid from the refilling assembly to the internal reservoir in the power toothbrush. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view showing a toothbrush which incorporates the fluid-dispensing system of the present invention. 
     FIG. 2 is a partially exploded view of the head portion of the toothbrush of FIG.  1 . 
     FIG. 3 is a schematic view showing a portion of the fluid-dispensing system of the present invention. 
     FIGS. 4A and 4B rare cross-sectional views of a refill valve of the fluid-dispensing system of the present invention, with and without a refilling needle therein. 
     FIG. 5 is a partially exploded view showing the pump member and the brushhead. 
     FIGS. 6 and 7 are cross-sectional views showing the movement of fluid between the reservoir and the brushhead, including the pump element which moves the fluid. 
     FIG. 8 is a cross-sectional view showing the dispensing valve of the fluid delivery system. 
     FIGS. 9 through 13 are diagrams showing the refilling assembly of the present invention and the process of refilling the on-board reservoir of the toothbrush of FIG.  1 . 
     FIG. 14 is a top plan view of the refilling assembly. 
     FIG. 15 is a partially exploded view of an alternative embodiment, of the pump member of FIGS. 5-8. 
     FIG. 16 is a cross-sectional view of the pump member of FIG.  15 . 
     FIG. 17 is another cross-sectional view of the pump member of FIG.  15 . 
     FIG. 18 is a cross-sectional view of the pump chamber portion of the pump member of FIG.  15 . 
     FIG. 19 is a schematic view of a top portion of the pump member of FIG.  15 . 
     FIG. 20 is another cross-sectional view showing the pump chamber portion of the pump member of FIG.  15 . 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     FIG. 1 shows a typical power toothbrush in which the fluid-dispensing and refilling system of the present invention is used. It should be emphasized, however, that the present invention is not limited to the particular power toothbrush shown and described or a particular brushhead movement. Rather, the principles of the present invention can be used with a variety of power toothbrush configurations and structural arrangements, with some aspects of the invention even being usable in a manual toothbrush. 
     The power toothbrush of FIG. 1, shown generally at  10 , comprises a handle portion  12  and a removable head portion  14 . In the handle portion is a power unit, including an electromagnetic driver and a battery for moving a brushhead  18 , which is mounted on a pivoting arm, in a side-to-side manner, as discussed in more detail below. Toothbrush  10  is controlled by a pushbutton on/off switch  19 . 
     FIG. 2 is an exploded view showing the principal parts of the head portion  14  of the toothbrush of FIG.  1 . The head portion includes two mating body parts  22  and  24 , which are fitted together about a support member  32 . Body part  24  includes an extended shield  26  for brushhead  18 . Brushhead  18  is mounted on a pivot arm  30 , which in turn is mounted for pivoting action about a torsion pin pivot member  33 , which extends between opposing sides of support member  32 . Pivot arm  30  is driven by a electromagnetic driver (not shown) in handle portion  12  of the toothbrush, operating on magnetic elements  36  at the end of pivot arm  30 . The structure and operation of such a toothbrush is described in more detail in U.S. Pat. No. 5,378,153 to Giuliani et al, owned by the same assignee as the present invention. 
     Rubber seal  38  and plastic ring  40  seal arm  30  to the body parts  22  and  24 , preventing moisture from moving back into head portion  14 . A nut portion  15  connects head portion  14  to handle portion  12  through a threaded connection. Positioned in an internal cavity  46  formed by the two mated body portions  22  and  24  is an on-board reservoir  50 . On-board reservoir  50  is generally arrow-shaped in configuration, approximately 2 inches long, having front and rear similar flexible plastic panels joined together along the peripheral edges thereof. On-board reservoir  50  in the embodiment shown typically holds sufficient fluid for one brushing use, i.e. one unit of use. This relatively small on-board reservoir volume is significant, in that it permits a fluid reservoir to be positioned in the removable head portion  14  of the toothbrush structure of FIG.  1 . This arrangement has a number of advantages, including a relatively short fluid travel path and an overall simplicity of structure. Accordingly, when head portion  14  is replaced, such as when the bristles of brushhead  18  are worn, reservoir  50  as well as the associated fluid delivery system is part of the replacement unit. 
     Referring to FIGS. 2 and 3, extending from reservoir  50  is a short tube section  52  which fits into a lower end of a refilling valve  56 , which is explained in more detail below. Extending from the side of refilling valve  56 , above the entry point of tube section  52 , is a flexible fluid line  60  which in the embodiment shown is flexible plastic material approximately 0.10 inches in diameter and approximately 1 inch long. Fluid line  60  connects to a fluid inlet tube  62 , which has a diameter of approximately 0.05 inches, and extends into brushhead  18  at a proximal end  64  thereof. 
     FIGS. 5-8 show the fluid delivery structure within brushhead  18 , including a fluid pump  66 , a fluid-delivery cavity  68  which extends from pump  66  in a base element  76 , and a fluid-dispensing valve  70  which extends upwardly from delivery cavity  68 , through brushhead  18  above surface  71  of the brushhead, into the bristle region  72  of the toothbrush. 
     Fluid inlet tube  62  extends into brushhead  18  to where it contacts the entry region  83  (FIG. 7) of fluid pump  66 . Fluid pump  66  is an irregular block of material having a cylindrical opening  75  which extends laterally thereof. Fluid pump  66  is positioned at one end of the elongated base element  76 . Elongated base element  76  is approximately 0.03 inches thick and has a cutout or cavity portion  68  which extends from pump  66  to approximately the other end  80  of base element  76 . Cavity portion  68  in the embodiment shown is approximately 0.015 inches deep. 
     As shown in FIG. 5, fluid pump  66  and base element  76  in the embodiment shown form a unitary member, which fits into a matching cavity  77  in the lower surface of the brushhead. Cavity  77  is configured to provide a solid seal for the ends of cylindrical opening  75  in pump  66  when the unitary member is correctly positioned in cavity  77 . Fluid delivery cavity  68  connects exit portion  85  of pump  66  and the lower end of dispensing valve  70 . A lip  84  surrounding cavity  68  in base element  76  contacts a mating surface  87  in the brushhead when the unitary pump and base element are in place, providing a fluid-tight seal around cavity  68 . Cavity  68  thus serves as a fluid-delivery means connecting pump  66  with dispensing valve  70 . 
     Pump  66  is configured with opposing corners being relieved, the relieved portions extending, respectively, from the opposing open ends of cylindrical opening  75 , around adjacent corners of the block, to a point approximately half-way along the adjacent side of the pump  66 . This configuration is shown most clearly in FIGS. 6 and 7. A spherical ball  63 , which functions as a piston, rides in cylindrical opening  75 . 
     Entry region  83  overlaps one end of opening  75 , while exit region  85  overlaps the other end of opening  75 . Exit region  85  connects to fluid delivery cavity  68  in the base element. Hence, there is a complete fluid path from tube  62  to cavity  68 . The ball  63  moves within cylindrical opening  75 , producing a pumping action for the fluid which enters opening  75 , as the brushhead moves from side to side in operation. 
     Proper clearance between ball  63  and the interior surface of cylindrical opening  75  is important for correct pumping operation, with adequate fluid pressure to valve  70 . In the embodiment shown, the clearance is approximately 0.0015 inches. 
     In operation, during the outlet stroke, as the ball moves toward the exit or outlet region  85  for opening  75 , fluid is moved both toward the outlet region and also around the piston toward the inlet region  83  for opening  75 . On the return stroke of the piston (toward the inlet region  83 ), the closed dispensing valve forces fluid to pass around the ball toward the outlet region, in preparation for the next outlet stroke. The flow rate is partially dependent on the amplitude of the brushhead movement and hence is a function of the loading of the toothbrush. When the brushhead system is a resonant system, such as described in the &#39;153 patent, the flow rate increases when the bristles are in contact with the teeth. The pumping action will occur with or without a dispensing valve at the end of the fluid path and is self-priming in operation, i.e. it can pump air. 
     The action of the piston ball  63  moving back and forth in the opening due to the back and forth action of the brushhead forces fluid out of the outlet region  85  of the pump and allows fluid to enter inlet region  83  from fluid tube  62 . In the outlet region  85 , fluid moves around the corner of the pump block and along the adjacent side, bound by the walls of the brushhead cavity into which the pump and base element fits. The fluid moves into cavity  68  in base element  76 , around a small diverting member  92  near the end of cavity  68  into internal opening  94  of base portion  96  of the dispensing valve  70 . 
     The dispensing valve  70  is shown in FIG.  8 . Internal opening  94  is approximately 0.07 inches in diameter. Valve  70  in the embodiment shown is 0.34 inches high. Valve  70  is known as a “duck bill” valve because it has two converging lip portions  98  and  100  at the free end  101  thereof. The two lip portions  98  and  100  are normally closed, i.e. pressed together, to prevent leakage and/or backflow of fluid. Fluid is moved by the back and forth action of the brushhead and the action of the pump, into valve  70 , with sufficient pressure to force apart the two lips  98  and  100 , dispensing the fluid into the area of the bristles in spurts on each “outlet” stroke of the piston. The valve shown not only prevents backflow of fluid, which is a potential source of contamination, but also assists in making the pump self-priming as well as determining the output flow speed and velocity. 
     The “duck bill” valve  70  is conventional, made out of a flexible plastic material to facilitate opening and closure of the lip portions  98  and  100 . In the embodiment shown, the free end of valve  70  extends above the base of the brushhead approximately 0.18 inches. It is located approximately in the middle of the bristles both longitudinally and laterally, although this is not necessary to proper operation of the system. 
     In operation, as brushhead  18  moves from side to side, such that piston ball  63  moves back and forth between the inlet and outlet ends of the cylindrical opening  75 , small volumes (approximately 0.00013 cc) of fluid will be successively moved from the reservoir through the pump  66  and then to the dispensing valve  70 . The lips  98 ,  100  of valve  70  part slightly with each small surge of fluid, but close again after the surge has passed. The successive amounts of fluid are forced out into the bristle area and are delivered to the desired region of the teeth by the action of the moving bristles. 
     Hence, there is a continuous (in small successive spurts) delivery of fluid to the area of the bristles during bristle action. This system has several advantages over existing systems. First, the continuous (in the form of successive spurts or pulses) nature of the fluid delivery prevents the effect of the fluid from becoming diluted over the brushing time, which is the case when the fluid, be it conventional dentifrice or oral medication, is administered at the start of brushing. Second, the effect of the fluid is enhanced with the present invention because the fluid can be provided directly to the area of bristle action. 
     In the case of the particular action of the toothbrush shown, in the manner and with the operating characteristics, including frequency and amplitude, set forth in the &#39;590 patent, the effect of the fluid, dentifrice or medication, is frequently enhanced due to the cavitation and other action of the fluid created by the bristle action. This is in addition to the precise delivery of the fluid to specific regions of interest in the mouth, including the gingival areas in the gum line and between the teeth. 
     Hence, the fluid-dispensing system of the present invention is not only practical and reliable, but it has a significant therapeutic effect when used under selected operating conditions, such as those produced by the action of the toothbrush in the &#39;590 patent. 
     As indicated above, reservoir  50  in the embodiment shown has a unit-of-use volume, i.e. the volume is sufficient for one brushing of typical length, i.e. two minutes or so. The system of the present invention also includes a refilling system for the unit-of-use reservoir. The refilling system is shown in FIGS. 9-14. 
     FIG. 9 shows the refiller apparatus  102  in general, for use with the toothbrush of FIG.  1 . To refill the unit-of-use reservoir  50  in the head portion of the toothbrush, the refiller apparatus  102  fits down over the top of the toothbrush, with the head portion and the brushhead portion of the toothbrush extending up into the interior of the refiller apparatus  102 . The refiller apparatus includes a housing  104 , with a viewing window  106  which shows a portion of the interior of the refiller apparatus so that the user can ascertain proper insertion of the toothbrush. 
     FIG. 10 shows the various portions of the refiller apparatus. It includes housing  104  and an interior core element  110 . Core element  110  includes a lower portion  112  which is configured to receive and mate with an upper part of the head portion of the toothbrush. Brushhead  18  extends upwardly through an opening  114  in core element  110 . Core element  110  has opposing side tracks  116  and  118  which extend from a lower edge  117  of the core element upwardly thereof, on the exterior surface  119  thereof. Tracks  116  and  118  mate with corresponding mating channels (not shown) on interior surface  120  of housing  104 . 
     This arrangement permits the core element  110  to move up and down a selected distance within housing  104  in a reliable fashion, without rotation or side-to-side movement. Extending upwardly from the top of lower portion  112  of core element  110  is a narrow extending member  122 , with a horizontal lip  124  at the upper end thereof and two spaced wing elements  126  and  128  at the base thereof, adjacent the top of the lower portion. Lower portion  112  of core element  110  also includes a flat surface portion  130  at the upper end thereof, adjacent wing element  128 . Extending through this flat surface portion  130  is a small opening  132 . opening  132  conveniently and readily accommodates a refilling needle from the refilling apparatus. 
     Positioned above core element  110  is a pump assembly  140 , which includes therein a refilling reservoir  111 . Positioned within pump assembly  140  is a fill needle  142 , which is oriented vertically with a base portion  141  of the needle mounted to a seal assembly  144 , which fits into a pump chamber portion  145  of the pump assembly  140  in a sealing relationship to the interior peripheral surface of the pump chamber. In the top of the pump assembly  140  is an opening  150  which connects with refilling reservoir  111  within the pump assembly. A top element  154  snaps onto an upper lip  156  of pump assembly  140 . At the center of top element  154  is a cavity-like portion  158 , at the bottom of which is an opening  160  (shown partially in FIG.  10 ), which can be either in or out of registry with opening  150  in the pump assembly, depending upon the rotational position of the top element. The refiller reservoir  111  may be filled through these two openings  160  and  150  when the top element is in the correct position such that the two openings are in registry. 
     FIGS. 11-13 are cross-sectional diagrams showing the sequence of steps in the refilling process for the unit-of-use reservoir  50  in the toothbrush. In FIG. 11, the toothbrush has been just positioned within the refiller apparatus, with the core element  110  being at its lowermost position. In this position, lip  124  of extending member  122  remains in a receiving slot  170  within the refiller apparatus, as is the case when there is no toothbrush within the refiller. 
     In this position, the lower end  164  of fill needle  142  just penetrates through opening  132  in surface  130  of the core element. The needle base  141  and seal assembly  144  are in their lowermost position within pump chamber  145 . A spring  174  within pump chamber  145  tends to maintain the needle base and seal assembly in their lowermost position. Chamber inlet valve  176  at the lower end of pump chamber  144  is in its closed (lowered) position, as shown. The body of needle  142  is sealed to the lower edge member  149  of chamber  145  by seal  178 . 
     As the toothbrush is inserted further into core element  110  by a user, the particularly configured curved shoulders of the head portion of the toothbrush push against the wing elements  126 ,  128  at the base of extending member  122  (FIG.  10 ). This action forces the extending member  122  backwardly sufficiently that lip  124  at the top of the extending member moves out of receiving slot  170 , allowing the core member to move further up within the refiller apparatus. Further upward pressure on the toothbrush by the user results in further upward movement of the core element  110 , with fill needle  142  penetrating further through opening  132  in the core element and into refiller valve  56  of the head portion  14  of the toothbrush (shown in FIG.  2 ). 
     FIG. 12 shows a mid-position of the movement of the core element where the upper surface of the core element  110  abuts a shoulder portion  180  of fill needle  142 . To achieve this mid-position, the core element has moved upwardly within the refilling apparatus, but neither the needle itself nor the seal assembly  144  to which base  141  of fill needle  142  is attached has moved within pump chamber  145 . Inlet valve  176  remains closed. 
     Referring now to FIG. 13, further upward movement of the toothbrush will result in further upward movement of core element  110  within the refilling assembly, the core element pushing upwardly against the shoulder portion  180  of fill needle  142 . The needle  142 , its base section  141  and the seal assembly  144  move upwardly within pump chamber  145 , against the action of spring  174 , producing a volume  187  between the needle base  141  and the lower end of pump chamber  145 . Fluid from the refilling reservoir is drawn into volume  187  by vacuum action through inlet valve  176 , which moves upwardly. Volume  187  fills with fluid as needle base  141  and seal assembly  144  move upwardly against the action of spring  174  in pump chamber  145 . 
     Fill needle  142  has spaced openings around its periphery where it joins base portion  141 . More particularly, needle  142  joins base portion  141  through a “cross-hair” structure, with the space between the adjacent portions of the cross-hair structure being open to the hollow interior of the needle. When the core element reaches its highest position within the refiller assembly, volume  187  has a capacity of approximately 4 ml, and is completely filled with fluid from the refilling reservoir  111 . 
     At this point, the brushhead is withdrawn slightly. When the brush is withdrawn, the action of spring  174  forces the seal assembly  144 , the base portion  141  of the needle and the fill needle  142  itself downwardly with pump chamber  145 , decreasing the volume  187 . The fluid in volume  187  is forced through the cross-hair openings at the base of the fill needle down into and through the hollow interior of fill needle  142  and out opening  188  at the lower end of the needle. 
     Opening  188  in needle  142  at this point is within the refilling valve in the toothbrush, as explained above. Referring to FIGS. 4A and 4B, needle  142  extends down through a top seal element  189  in the valve  56  to approximately the lower end  190  thereof. The valve  56  seals around the needle  142  in region  193 , preventing any backflow of fluid from the needle through outlet port  194 , which connects with fluid line  60 . Fluid coming out opening  188  in the needle moves through port  192  into fluid line  52  (FIG.  3 ), which leads to the on-board reservoir  50 . 
     The amount of fluid moved from the refilling apparatus into reservoir  50  is approximately 4 milliliters in the embodiment shown, which is the amount of fluid appropriate for one unit-of-use. Other amounts, however, could be dispensed to the on-board reservoir, if desired, depending on the capacity of the reservoir. When the toothbrush is sufficiently withdrawn from the refilling assembly, the needle, its base portion and the seal assembly are back to their original position in the refilling apparatus, as shown in FIG.  12 . The toothbrush is then removed from the refiller apparatus, ready for a single use of fluid, i.e. a single brushing event. The refilling of the on-board reservoir  50  occurs prior to each brushing. 
     While the embodiment shown includes a single unit-of-use reservoir, with the reservoir being filled for each brushing, it is possible to modify the reservoir so as to have fluid for more than one use. The external refilling assembly, however, will still be useful for convenient refilling of the reservoir, permitting use of a relatively small fluid reservoir on board the toothbrush, thus saving space and pumping requirements. 
     Hence, a new fluid-dispensing and refilling system for power toothbrushes has been described. The system includes a small unit-of-use reservoir in a removable head portion of the toothbrush. A fluid line extends from the reservoir to a small pump element located in the brushhead. The pump element, with the back and forth action of the brushhead, provides movement of the fluid from the reservoir to a dispensing valve in the head of the toothbrush, through which fluid moves to the bristles. 
     The on-board reservoir is refilled before each use by a separate refilling apparatus, into which the toothbrush is inserted. Movement of the brushhead relative to the refilling apparatus in a particular sequence results in fluid in the refiller reservoir moving through a fill needle and refiller valve in the head portion of the toothbrush into the on-board unit-of-use reservoir. 
     An alternative embodiment to the pump structure of FIGS. 5-8 is shown in FIGS. 15-20. The complete pump, referred to generally at  202 , is partially formed within base portion  203  of brushhead  204 . A cover member  214  is also part of the complete pump  202 . Fluid, such as a dentifrice, is provided to pump  202  through an inlet tube  206 . A part of the portion of pump  202  formed in base  203  is a cylindrical pump bore  208 . Movable within pump bore  208  is a spherical piston element  210 , also referred to as a piston ball. 
     Positioned at a discharge end  226  of pump bore  208  is a plug element  212 , which has a particular configuration within pump bore  208 . A shallow fluid exit section  215  extends from the discharge end  226  of pump bore  208  to a check valve  216 , which directs fluid to the bristles. The alternative embodiment of FIGS. 15-20 is generally more efficient and produces higher pressure than the embodiment previously described. 
     Referring now in particular to FIGS. 15-18, inlet tube  206  provides fluid, such as a dentifrice, through the proximal end  219  of brushhead  204  to a short channel  220  which is molded into the brushhead (FIG. 16) and which connects distal end  222  of tube  206  to an inlet connection  224  to pump bore  208  at an inlet end  227 . In the embodiment shown, inlet connection  224  is located at the top of pump bore  208 . 
     Pump bore  208  in the embodiment shown has a diameter slightly greater than the diameter of the spherical piston element  210 , which in the embodiment shown is 2 mm. It is desirable to have the diameter of the pump bore only slightly greater than the diameter of the piston element  210  so as to maintain pressure within the pump bore and to have very little leakage of fluid past the piston element when the piston element moves within the bore to discharge fluid from the pump bore. In the embodiment shown, the pump bore has a diameter of approximately 2.1 mm and is approximately 4.5 mm long. 
     Positioned at discharge end  226  of pump bore  208  is plug  212 . Plug  212  has an interior surface  232  (facing the pump bore), which is concavely curved, i.e. disc-shaped, as shown most clearly in FIG.  20 . In the embodiment shown, the curve is slightly greater than the curvature of the spherical piston element. In the embodiment shown, the plug is made from elastomeric material. 
     In its movement within pump bore  208 , the spherical piston element contacts surface  232  at the end of the fluid discharge stroke, during which fluid is pushed from the inlet end of the pump bore to the discharge end by the action of the piston element. In the embodiment shown, the piston element is made from tungsten carbide material. The increased density of tungsten carbide appears to increase the pressure and performance of the pump relative to steel, for instance. 
     The pump variables affecting performance include the diameter of the spherical piston element, the cross-section area of the spherical piston and the mass of the spherical piston. The clearance between the piston element and the bore also affects performance. The fluid in the pump bore is discharged through outlet  234 , located at the top of the discharge end of the pump bore (FIG.  20 ). 
     Fluid discharged from pump bore  208  moves directly into fluid exit section  215 , which in the embodiment shown is approximately 0.25 inches long by 0.10 inches wide and 0.02 inches high, defined in the brushhead and the lower surface  214   a  of cover element  214 . Cover element  214  extends from a point at the start of channel  220  at tube  206  to a point past end  229  of the fluid exit channel  215 . 
     Referring now to FIG. 19, the portion of the fluid exit section defined by the lower surface  214   a  of cover  214  includes two wing extensions  236  and  238  which extend from the longitudinal side edges of the fluid exit channel toward each other, narrowing the exit channel at that point. The two extensions  236  and  238  are generally triangular in shape and narrow the channel from a width of approximately 0.10 inches to a width of approximately 0.04 inches over a distance of approximately 0.08 inches. The two extensions  236  and  238  in channeling the fluid discharged from the pump bore  208  toward the exit opening in the brushhead act as a fluid diode, providing less resistance to fluid flow in the discharge direction than in the opposing direction. Beyond extensions  236  and  238  is a small element  240  which is located centrally between the two sides of the exit channel and which depends down into the exit channel from the lower surface  214   a  of the cover. The exit channel terminates with the sides thereof angling inwardly and then meeting in a curved portion. 
     Molded into base portion  203  of the brushhead directly beneath element  240  is a circular opening  244 , which in the embodiment shown is approximately 0.10 inches in diameter. Opening  244  extends through the brushhead, opening onto the surface from which the bristles extend. Positioned in the opening  244  such that it extends away from the brushhead surface, among the bristles, is the exit check valve  216 . In the embodiment shown, check valve  216  is wedge-shaped in configuration, as opposed to the duck-bill configuration of FIGS. 5-8. Overall, as indicated above, the pump embodiment of FIGS. 15-20 is generally more efficient and produces better pressure than the pump previously disclosed. 
     Although a preferred embodiment of the invention has been disclosed herein for illustration, it should be understood that various changes, modifications and substitutions may be incorporated in such embodiment without departing from the spirit of the invention, which is defined by the claims as follows.