Abstract:
A dentifrice dispensing electrical toothbrush using a replaceable dual-channel brush head. The dual-channel brush head has a first channel for housing a drive shaft for bristle oscillation and a second channel for dispensing the dentifrice material. The brush head is mounted on the dual-channel connector of the brush handle which contains a drive mechanism and a pumping mechanism that dispenses dentifrice material from a cartridge in the handle. A manual dispensing configuration uses an external rubber button and an electrical dispensing configuration uses a rotary solenoid for actuating an internal rubber button that applies pumping pressure to the dentifrice material. The latter benefits arthritis sufferers, as no external squeezing action is required.

Description:
BACKGROUND OF THE INVENTION 
   It has been recognized that an electrical toothbrush is more effective in removing plaque and preventing gum disease than a conventional manual toothbrush. It is also well known that squeezing on a toothpaste tube for dispensing toothpaste presents a significant challenge to severe arthritis suffers as well as the visually impaired. Thus an electrical toothbrush integrated with a toothpaste dispensing pump is a necessity for the physically challenged and also desirable for the convenience of general consumers. For long service life, all wearable parts need to be included in one replacement unit. For the ease of replacement, it is desirable to have a failure-free single-step in the mounting of the replaceable brush head on the toothbrush handle which contains driving components and a pumping mechanism. For the ease of operation for the physically challenged, it is desirable simply to press on an electrical switch for automatic dispensing of dentifrice material to the top of the bristles. It is the objective of the present invention to achieve the above desirable features in one dentifrice-dispensing electrical toothbrush. 
   (1) Field of the Invention 
   The present invention relates to an dentifrice dispensing electrical toothbrush using a replaceable brush head having dual channels for housing a drive shaft for bristle oscillation and a flow path for dispensing toothpaste. 
   (2) Related Art 
   U.S. Pat. No. 5,640,735 provides a water-flow powered toothbrush using a gear train assembly to accomplish controlled rotation of a plurality of gear driven bristle tufts. Separated from the water-flow drive, the toothbrush mechanism incorporates a flushing water supply passage for the circulation of clean water through a gear system thereby accomplish continuous cleaning of the gear train during tooth brushing activity. The brush head and housing structure define flushing water inlet and outlet passages which are in communication with the internal gear chamber of the brush head. The brush head is also provided with a water outlet valve that is forced to open by excessive water pressure when a user covers the water outlet port by a finger. Although its replaceable brush head contains a drive shaft and flow channels, its flow passage mechanism is for the circulation of cleaning water only. It is not applicable to the one-way dispensing of toothpaste, which requires a single outlet flow channel and one-way check valve to block any returning flow of toothpaste into a pumping chamber. 
   For low cost replacement of brush unit of a dentifrice dispensing electrical toothbrush, U.S. Pat. No. 6,434,773 by Kuo uses a replaceable brush cradle unit containing two bristle elements with no drive shafts. The replaceable brush cradle unit is detachably fastened to the drive head of a neck containing a drive shaft and a flow channel which are integrally attached to the toothbrush handle. The dentifrice material is pumped from the cartridge in the handle to the spout opening at the base of one of the bristle elements. The two bristle elements are engaged with the posts of the drive head in a manner that allows them to free to oscillate by a snap-on retention cradle. They are easily detached and replaced without replacing the drive shaft. Rotary motion from a motor is converted to oscillatory motion with either a cam assembly or an off-center shaft extension for engaging the drive notches of the bristle elements. The replacement method has disadvantages. Although only the bristle elements and the retention cradle are replaced, the posts supporting the free rotation of the brush elements are wearable but they remain on the permanent drive head. A worn post can cause wobbling of oscillating bristle element and excessive noise that results in reduced service life of the toothbrush. Furthermore, the mounting of the replaceable cradle unit on the drive head requires manual insertion of the notches of the bristle elements on top of the drive tab in the drive head. As the drive tab stops at a random position, aligning the two notches against the drive tab presents a significant challenge for the user. 
   To achieve a compact brush head profile, U.S. Pat. No. 6,735,803 by Kuo utilizes a linkage for converting a rotary motion of the drive motor to a planar motion in imparting the oscillation of a rotary bristle unit in an electrical dentifrice-dispensing toothbrush. Similar to the above U.S. Pat. No. 6,434,773, the replaceable bristle unit does not contain a drive shaft. The drive shaft is included in a non-detachable neck which is integrally connected to the handle. The replaceable bristle unit consists of a rotary bristle element and a stationary bristle element. The latter has an opening for the flow of dentifrice material through the drive head. The bristle unit is snap-on latched to the side walls of the drive head. The linkage is used to convert the rotation of the drive shaft to a planar oscillation that enables a compact drive head configuration. The dentifrice dispensing is accomplished by using a rotary solenoid for actuating an internal elastic compressible button that applies pumping pressure to the dentifrice material. The mechanism of the replaceable bristle unit as describes has the same disadvantage of requiring a special effort in aiming at the position of the linkage arm for the insertion of the notch of the rotary bristle unit. As the mounting of the rotary bristle unit is one-way and non-detachable, any misalignments of the notch on the linkage arm can cause damage to the drive mechanism. 
   SUMMARY OF THE INVENTION 
   The present invention provides a dentifrice dispensing electrical toothbrush that uses a replaceable brush head having dual channels for housing a drive shaft for bristle oscillation and a flow path for dispensing toothpaste. A manual dispensing configuration utilizes an external rubber button for applying a pumping force for dispensing the toothpaste while an electrical-mechanical dispensing configuration uses an internal rubber button and an electrical actuator means for doing the same. 
   In the dual-channel brush head, one channel houses the first drive shaft and a separate channel functions as part of the flow path of the pumped dentifrice material. The electrical dispensing mechanism includes a switch, a rotary solenoid, and a plunger in contact with a resilient rubber button. The activation of the switch causes the rotary solenoid to lift the plunger to press on the rubber button to force dentifrice material to flow to the top of the bristles. Through a control mechanism, de-activation of the switch causes these components back to their original home positions and accordingly the follower inside the cartridge advances to keep the dentifrice material in a packed condition for next pumping action. 
   The essential components of the dentifrice dispensing electrical toothbrush include 1) a handle which serves as a housing for a motor, batteries and a toothpaste cartridge; 2) a replaceable dual-channel brush head having a rotary bristle element and a stationary dispensing bristle element with a spout opening; 3) a dual-channel connector on the handle; 4) a drive coupling mechanism; 5) an electrical actuation mechanism including a switch, a rotary solenoid, and a plunger. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1   a  is a cross section view of a drive mechanism for a dentifrice dispensing electrical toothbrush having a replaceable dual-channel brush head. 
       FIG. 1   b  is an enlarged cross section side view of the drive mechanism and the spout opening in the brush head of  FIG. 1   a.    
       FIG. 2  is an illustration of the engagement between two drive shafts, bristle elements and an oscillation linkage shown in  FIG. 1   a.    
       FIG. 3   a  is a cross section view of the handle of dentifrice dispensing electrical toothbrush showing exposed dual-channel connector. 
       FIG. 3   b  is a cross section view of a replaceable dual-channel brush head detached from the dual-channel connector. 
       FIG. 4   a  is a cross section view of an electrical dentifrice dispensing toothbrush with the plunger in the non-dispensing position. 
       FIG. 4   b  is a cross section view of an electrical dentifrice dispensing toothbrush with the plunger in the dispensing position. 
       FIG. 5  is a cross section view of a dentifrice dispensing electrical toothbrush with a cover and a plug attached. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. 
   A dentifrice dispensing electrical toothbrush of the present invention has a replaceable dual-channel brush head and a handle having a dual-channel connector. The dual-channel brush head has a channel for housing a drive shaft for the oscillation of the first rotary bristle unit and a separate channel for the flow of dentifrice material to the top of the second bristle unit. The dual-channel brush head is detachably mounted on the dual-channel connector, which contains a drive shaft driven by a motor and a flow channel in communication with the pumping chamber for dispensing the dentifrice material to the second bristle unit from a cartridge inserted in the handle serving as reservoir for the dentifrice material. 
   Referring to  FIG. 1   a , a dentifrice-dispensing electrical toothbrush  2  has handle  4  with dual-channel connector and replaceable brush head  20 . The latter is shown separately in  FIG. 3   b  and also partially shown in an enlarged view in  FIG. 1   b . First bristle unit  8  is mounted on post  86  and second bristle unit  9  has spout opening  114 . The first bristle unit  8  is driven by cam linkage  242  attached to the top end of first drive shaft  216  in the replaceable brush head  20 , which is detachably engaged with second drive shaft  236  driven by motor  212  powered by the battery in the handle  4 . 
   Dentifrice cartridge  124  having follower  126  is also housed within handle  4 . Dentifrice material (not shown) is pumped from pump chamber  94 , through first flow channel  102  and spout opening  114 , to bristle unit  9 . A pumping force is supplied to chamber  94  by depression of elastic compressible button  96  that closes the one-way valve  122 . As the elastic compressive button  96  is released to restore to its original free position the follower  126  in the cartridge moves forward under a vacuum force to compact the dentifrice material. 
   The structure and function of the dentifrice dispensing electrical toothbrush of the present invention are described in details as follows. 
   Further shown in  FIG. 1   a  and  FIG. 1   b , a plurality of bristles  76  are attached to the top surface of base  84  of first bristle unit  8 . Drive notch  90  is appended to side wall  88  of bristle base  84 . The underside of bristle base  84  has split bushing walls  85  which are shaped to mate with post  86  of platform  72 . Drive notches  90  of first bristle unit  8  accommodates drive rod  34  such that when drive rod  34  is positioned in drive notch  90 , the oscillating motion of drive rod  34  causes first bristle unit to freely oscillate on post  86 . The mechanism for the oscillation motion will be described in later sections. The mounting of a rotary bristle unit on a stationary post for free rotation and its one-way engagement for preventing detachment of the rotary bristle unit from the post has been described in prior art. A preferred embodiment as disclosed in U.S. Pat. No. 6,735,803 by Kuo is briefly described below. 
   The one-way engagement of bristle base  84  of bristle unit  8  on post  86  is enabled by the mounting of two half-circle-shaped split bushing walls  85  on the underside of bristle base  84  on two half-circle-shaped split shaft walls  91  of post  86 . Gaps (not shown) between split walls  85  allow wall deflections apart from each other while gaps  97  of post  86  allow for deflections of adjacent split walls  91  toward each other. All the split walls are of cantilever configuration for flexibility for the mounting of bristle unit  8  on post  86 . For preventing disengagement, post  86  has retention rim  100  and the flexible bushing has annular groove  101  at corresponding mating positions. The diameter of retention rim  100  of post  86  is smaller than the diameter of annular groove  101  engaged therein but is larger than the inner diameter of bushing walls  85 . Also, the nominal inside diameter of bushing walls  85  is slightly larger than corresponding outer diameter of post  86  for establishing a clearance between the post and the bushing for the free rotation of bristle unit  8 . This configuration prevents the bristle unit dislodged from the post. During brushing, the brushing pressure pushes bristle unit  8  against the post  86 , therefore, the rotary bristle unit cannot detach from the post under the brushing condition. For the oscillation of the rotary bristle unit  8 , as shown in  FIG. 1   a ,  FIG. 1   b  and  FIG. 2 , a U-shaped pivotal cam linkage  242  having stud shaft  230  and L-shaped cylindrical rod  34  is engaged with the offset cylindrical rod  234  of the cap  226  which is attached to the end of first drive shaft  216 . The cam linkage  242  is pivotal against stud shaft  230  which is rotationally supported by the platform  72 . The cylindrical rod  34  is engaged with the notch  88  such that the pivoting motion of the cam linkage  242  imparts the oscillation of the cylindrical rod  34  and bristle unit  8  when the cam linkage is driven by the offset cylindrical rod of cap  226 , which is mounted on the top end of first drive shaft  216 . The first drive shaft  216  is engaged with second drive shaft  236  which is driven by motor  212 . The bottom end of first drive shaft  216  has a non-circular prong-adapter  62  inserted onto the drive-socket receptacle end  64  of second drive shaft  236 . In one embodiment both prong-adapter  62  and receptacle-end  64  have square-shaped cross-section. When the motor is energized, the engagement of drive shafts  236  and  216  imparts the oscillating motion of the first bristle unit  8 . 
   The communication and engagement of the first drive shaft  216  with second drive shaft  236  is enabled by the mounting of the replaceable dual-channel brush head on the dual-channel connector  151  of the handle  4 .  FIG. 3   a  and  FIG. 3   b  show views of detached replaceable brush head  20  and exposed connector  151 . The replaceable dual-channel brush head  20  consists of platform  72  having post  86  and a spout opening  114 , dual-channel neck  19  having first drive shaft  216  in first drive channel  104  and first flow channel  102  which extends to spout opening  114 . The top end of dual-channel neck  19  is connected to platform  84  and the bottom end is for detachably mounting on dual-channel connector  151  of handle  4 . Connector  151  has second drive shaft  236  in second drive channel  202  for coupling with first drive shaft  216 , and second flow channel  204  for detachably connecting to first flow channel  102  of brush head  20 . 
   For preventing leaking of dentifrice material, the inner attachment walls  153  of first flow channel  102  and the inner attachment wall  155  of first drive shaft channel  104  at the bottom of the brush head  20  are in intimate sliding contact with the outer wall  159  of the connector  151  when the brush head  20  is fully mounted on the connector  151 . The precision of the mounting ensures the insertion of the prong-adapter  62  onto the mating receptacle end  64  of second drive shaft  236 . 
   Referring to  FIG. 1   a , for dispensing dentifrice material, the flow path from the cartridge  124 , which as a reservoir stores dentifrice material, through the pump chamber  94  and the flow channel  102  to the spout opening  114  and to the top of bristles in the second bristle unit  9  is full of dentifrice material (not shown). A detailed description of the pump mechanism using an elastic compressible button is given in U.S. Pat. No. 6,434,773. Here a brief description is given below. When the elastic compressible button  96  is depressed, the dentifrice material is forced to move from pump chamber  94 , through flow channel  102  and spout opening  114 , to the top of the second bristle unit  9 . The vacuum created in chamber  94  when the pumping force is released and elastic compressible button  96  being restored to its original free position, causes dentifrice material to flow from cartridge  124  through one-way check valve  122  and into chamber  94  to replace the quantity of dentifrice material removed from the chamber by the application of the pumping force. The flow of dentifrice material from cartridge  124  causes corresponding advancement of follower  126  at the base of the cartridge. When all of the dentifrice material is depleted from cartridge  124 , the cartridge is removed from the handle and replaced by a full cartridge. Cartridge  124  is fastened by threads at the base of the one-way check valve  122 . 
   Another embodiment of the present invention is a dentifrice-dispensing electrical toothbrush using an electrical means to dispense the dentifrice material from the handle to the top of bristles. As shown in  FIG. 4   a  and  FIG. 4   b , dentifrice-dispensing electrical toothbrush  402  has handle  404 , connector  406  and replaceable dual-channel brush head  20 . The structures and functions of the dual-channel brush head, the connector and the coupling of the brush-head drive shaft to the motor drive shaft are the same as shown in  FIG. 1   a  and described previously. 
   However, the delivery of dentifrice material is achieved by using an electrical-mechanical means that has been disclosed in details in U.S. Pat. No. 6,735,803 by Kuo. Here the electrical-mechanical means is briefly described as follows. The electrical-mechanical means consists of rotary solenoid  456 , cam  454 , and plunger  452  for contacting on resilient compressible button  496  as shown in  FIG. 4   a , which shows these components at the non-dispensing home positions. Upon activating rotary solenoid  456  by pushing on electrical button switch  460  positioned on the external surface  468  of handle  404 , cam  454  on the shaft of the rotary solenoid  456  rotates 180 degree from the non-dispensing home position to move plunger  452  forward to depress on compressible button  496  to the fully compressed dispensing position, which is shown in  FIG. 4   b . The compression of the resilient compressible button provides the pumping force to dispense the dentifrice material.  FIG. 4   b  shows cam  454 , plunger  452  and resilient compressible button  496  at the dispensing positions. Then upon the release of button switch  460 , through a control circuitry (not shown) rotary solenoid  456  is energized to cause cam  454  to return to the home position. On the way to the home position the compressible button restores to its original shape together with the movement of the dentifrice material from the cartridge to replenish the pump chamber. Although the use of a rotary solenoid is preferred, the actuation of the plunger for compressing on the elastic button can be achieved by linear solenoid or a clutch connected to motor  412 . 
   Additionally, the spout opening  114  in the dual-channel brush head  20  needs to be plugged for preventing drying of the dentifrice material. Sealing of spout opening  114  of the dentifrice dispensing electrical toothbrush is similar to that described in U.S. Pat. No. 6,434,773 by Kuo.  FIG. 5  shows sealing plug  132  being inserted into spout opening  114 . The positioning of the plug for sealing is facilitated by guides (not shown) on cover  130  when the cover is at its fully closed and locked position on the shoulder of the handle. 
   The invention has been described in detail with reference to preferred embodiments thereof. However, it is understood that variations and modifications can be effected within the spirit and scope of the invention.