Patent Publication Number: US-2023149140-A1

Title: Oral Care Implement and Refill Head Thereof

Description:
BACKGROUND 
     Toothbrushes generally include a handle for gripping by a user and a head that has cleaning elements thereon that engage the user&#39;s oral cavity surfaces for cleaning. In manual toothbrushes, the cleaning elements become worn after several months of use which requires replacement of the entire toothbrush. In electric toothbrushes, the cleaning elements become worn after several months of use which requires replacement of a refill head that is configured to be coupled to a particular handle. Toothbrush manufacturers generally design such electric toothbrushes with very specific connection mechanisms to ensure that only refill heads that they manufacture can be used with the handle that they manufacture. Moreover, ensuring a tight fit between the handle and the oral care refill head while allowing vibrations generated by a motor to be imparted to the cleaning elements and minimized at the handle are important considerations in the design of such connection mechanisms. Thus, there remains a need to design new connection mechanisms for this purpose. Furthermore, when brushing it is important to make sure that the user does not apply too much pressure onto the teeth and gums because doing so will not only cause the cleaning elements to become worn more quickly, but it can also cause damage to the user&#39;s teeth and gums. Thus, a need also exists for an oral care implement having a pressure detection and indication system to readily inform the user when they are applying too much pressure onto the teeth and gums. 
     BRIEF SUMMARY 
     The present invention may be directed to an oral care implement having an oral care refill head and a handle. The oral care refill head may be detachably coupled to the handle. Specifically, the handle may include a stem that is received within a connection cavity of the oral care refill head. The stem and the connection cavity may have specific geometries and structures to ensure an adequate coupling therebetween. The present invention may also be directed to an oral care implement having a pressure sensing assembly. Specifically, excessive pressure applied onto the oral care refill head will cause the motor and a motor chassis to rock. As the motor chassis rocks, a contact element thereon will actuate a pressure actuator element. In response, a control unit may initiate generation of a user perceptible signal to inform the user of the excess pressure. 
     In one aspect, the invention may be an oral care refill head for detachable coupling to a handle, the oral care refill head comprising: a head portion comprising an oral care treatment tool; an attachment portion extending along a longitudinal axis from a proximal end to a distal end, the head portion located at the distal end of the attachment portion, the attachment portion comprising: a connection cavity defined by an inner sidewall and an inner end wall of the attachment portion, the connection cavity extending along a cavity axis from an opening in the proximal end of the attachment portion to the inner end wall of the attachment portion, the connection cavity configured to receive a stem of the handle; a locking protuberance protruding from the inner sidewall into the connection cavity and configured to engage a locking depression of the stem, the locking protuberance located at a first axial distance from the proximal end of the attachment portion; a first radial shoulder formed in the inner sidewall and located a second axial distance from the proximal end of the attachment portion, the first radial shoulder circumferentially aligned with the locking protuberance and the second axial distance being greater than the first axial distance; and a second radial shoulder formed in the inner sidewall and located on an opposite side of the inner sidewall than the first radial shoulder, the second radial located a third axial distance from the proximal end of the attachment portion that is greater than the second axial distance. 
     In another aspect, the invention may be oral care implement comprising: a handle comprising: a gripping portion having a housing defining an internal chamber and a distal end surface; a rocker unit mounted within the internal chamber so as to be rockable relative to the housing about a fulcrum, the rocker unit comprising: a stem extending from the distal end surface of the gripping portion and configured to be detachably coupled to the oral care refill head; a motor operably coupled to the stem to impart movement to the stem; and a motor chassis supporting the motor and comprising a contact element; and a power source positioned within the internal chamber; a control unit operably coupled to the motor and the power source, the control unit comprising an actuator element, the control unit configured to initiate generation of a user perceptible signal upon the actuator element being actuated; and wherein upon a pressure being applied to the oral care treatment tool that exceeds a pressure threshold, the rocking unit is altered from a normal position to an excessive-pressure position in which the contact element actuates the actuator element. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG.  1    is a front perspective view of an oral care implement in accordance with an embodiment of the present invention; 
         FIG.  2    is a front perspective view of the oral care implement of  FIG.  1    with an oral care refill head detached from a handle; 
         FIG.  3    is a cross-sectional view taken along line III of  FIG.  2   ; 
         FIG.  3 A  is a close-up view of area IIIA of  FIG.  3   ; 
         FIG.  4    is a perspective view of an insert coupler of the oral care refill head of the oral care implement of  FIG.  1   ; 
         FIG.  5    is a front view of the insert coupler of  FIG.  4   ; 
         FIG.  6    is a cross-sectional view taken along line VI-VI of  FIG.  4   ; 
         FIG.  7    is a rear view of the insert coupler of  FIG.  4   ; 
         FIG.  8    is a cross-sectional view taken along line VIII-VIII of  FIG.  7   ; 
         FIGS.  9 A- 9 C  are perspective, side, and front views, respectively, of a stem of the handle of the oral care implement of  FIG.  1   ; 
         FIG.  10    is a cross-sectional view taken along line X-X of  FIG.  1   ; 
         FIG.  11    is a close-up view of area XI of  FIG.  10   ; 
         FIG.  12    is an exploded view of the oral care implement of  FIG.  1   ; 
         FIG.  13    is a cross-sectional view taken along line XIII-XIII of  FIG.  12   ; 
         FIGS.  14 A and  14 B  are perspective and front views, respectively, of a lower portion of a motor chassis of a rocker unit in accordance with an embodiment of the present invention; 
         FIG.  15    is a cross-sectional view taken along line XV-XV of  FIG.  1    with the rocker unit in a normal position; 
         FIG.  16    is a close-up view of area XVI of  FIG.  15   ; 
         FIG.  17    is a cross sectional view taken along line XV-XV of  FIG.  1    with the rocker unit in an excessive-pressure position; and 
         FIG.  18    is a close-up view of area XVIII of  FIG.  17   . 
     
    
    
     DETAILED DESCRIPTION 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     The description of illustrative embodiments according to principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless explicitly indicated as such. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Moreover, the features and benefits of the invention are illustrated by reference to the exemplified embodiments. Accordingly, the invention expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features; the scope of the invention being defined by the claims appended hereto. 
     Referring first to  FIGS.  1  and  2   , an oral care implement  100  will be described in accordance with an embodiment of the present invention. In the exemplified embodiment, the oral care implement  100  is a powered or electric toothbrush. In other embodiments, the oral care implement  100  may be a manual toothbrush. In still other embodiments, the oral care implement  100  may be other hygienic tools for treating the oral cavity such as a tongue scraper, a gum and soft tissue cleanser, a water pick, an interdental device, a tooth polisher, a specially designed ansate implement having tooth engaging elements, or any other type of implement that is commonly used for oral care. In still other embodiments, the oral care implement  100  may be a personal care implement instead of an oral care implement. Examples of such personal care implements include hairbrushes, razors, body scrubbers, skin treatment devices, or the like. The oral care implement  100  generally comprises a handle  200  and an oral care refill head  300 . Thus, it is to be understood that the inventive concepts discussed herein can be applied to any type of oral care implement or personal care implement unless a specific type of implement is specified in the claims. The structural and functional details of the oral care implement  100  will be provided below in accordance with exemplary embodiments of the present invention. 
     The handle  200  is the portion of the oral care implement  100  that is gripped by a user during use. The oral care refill head  300  is the portion of the oral care implement  100  that performs the cleaning or other hygienic function. As shown in  FIG.  2   , the oral care refill head  300  can be detached from the handle  200 , and thus when they are coupled the oral care refill head  300  is detachably coupled to the handle  200 . Thus, the oral care refill head  300  may be detached from the handle  200  and replaced with a new oral care refill head  300  when cleaning elements on the oral care refill head  300  become worn over time. This allows the handle  200  to continue to be used while the oral care refill head  300  is exchanged, which is important because the expensive electronic circuitry is located within the handle  200 . Multiple users can also use the same handle  200  while placing their individual oral care refill heads thereon prior to use. 
     The handle  200  comprises a gripping portion  210  that terminates at a distal end surface  211  and a stem  250  protruding from the distal end surface  211  of the gripping portion  210 . The gripping portion  210  is the part of the handle  200  that is gripped by a user during oral hygiene activities and it may include various buttons, switches, indicators, lights, user controls, or the like to both allow a user to control functionality and operation of the oral care implement  100  and also provide information to the user. For example, the handle  200  may comprise a power button  201  that can power the oral care implement  100  on and off (and provide power to a motor thereof as described in more detail below). The handle  200  may also include an intensity button  202  that allows the user to modify the speed or intensity of the motor or allows the user to change a mode of operation of the motor. The handle  200  may also include various indicators  203  that may be activated (e.g., lights that may be illuminated) to inform a user when the battery is low, when the user is brushing with too much pressure, when the oral care implement  100  is powered on, and various other information that may be helpful to a user. 
     Referring to  FIGS.  2  and  10   , as noted above the handle  200  houses the electronic components associated with the oral care implement  100 . Thus, as shown in  FIG.  10   , the gripping portion  210  of the handle  200  houses a motor  130  and a power source  140  that are operably coupled together. Thus, when a user presses the power button  201 , power is supplied form the power source  140  to the motor  130  and the motor  130  is activated. The stem  250  is operably coupled to the motor  130  and may form a portion of a drive shaft of the motor  130  or the stem  250  may be operably coupled to a drive shaft of the motor  130 . For example, the stem  250  may form a distal portion of the drive shaft of the motor  130 . In some embodiments, the stem  250  may be a plastic housing or the like that surrounds the drive shaft of the motor  130  with the plastic housing that surrounds the drive shaft forming the coupling between the handle  200  and the oral care refill head  300 . In the exemplified embodiment, the stem  250  is operably coupled to the motor  130  and due to that coupling, upon activating the motor  130  by powering on the oral care implement  100 , the motor  130  will impart movement to the stem  250  thereby causing the stem  250  to rotate, oscillate, or the like. Furthermore, when the oral care refill head  300  is coupled to the handle  200  as shown in  FIG.  10   , such movement of the stem  250  will create vibrations on the oral care refill head  300 , or at least the cleaning elements thereof, to optimize the cleaning performance. The stem  250  forms the feature of the handle  200  that couples to the oral care refill head  300  and also imparts movement to the cleaning elements of the oral care refill head  300 . 
     As also seen in  FIG.  10   , there is a control unit  150  in the handle  200 . In the exemplified embodiment, the control unit  150  comprises a printed circuit board  149  and several electronic components thereon in electrical communication with one another. For example, the control unit  150  may comprise a power actuator  151 . The power button  201  may be in operable coupling with the power actuator  151  of the control unit  150  to control the power on and power off function of the motor  140 . Thus, pressing the power button  201  will cause the power button  201  to engage and actuate the power actuator  151 , which will cause the control unit  150  to power the motor  140  on and/or off. The intensity button  202  may be in operable coupling with an intensity actuator  152  of the control unit  150  so that pressing the up or down arrows of the intensity button  202  causes the intensity button  202  to engage and actuate the intensity actuator  152 , and in response the control unit  150  will change the mode of operation or increase or decrease the motor intensity or speed. 
     The indicators  203  may be formed by transparent portions of the handle  200  that are aligned with light sources  153  on the control unit  150  that illuminate when different thresholds are met. For example, when the battery power is below a threshold, a low battery light may illuminate and be seen through a transparent portion of the handle  200  (such as an icon that is readily identifiable as a battery power indicator). Furthermore, when excessive pressure is felt during brushing, a high pressure light may illuminate. Of course, other indicators  203  may be used to provide different indications to a user as desired. The control unit  150  may comprise a controller or processor that receives input from the various actuators and transmits instructions to the power source  130 , motor  140 , and various light sources to activate and deactivate accordingly. However, a processor or controller is not needed in all embodiments and in other embodiments activating and deactivating the various actuators opens and closes a switch which either causes power to be supplied to or prevents power from being supplied to the various components for activation and deactivation thereof. The various actuators described herein as being part of the control unit  150  may be various switches including trigger switches, contact switches, conductive switches, throw switches, push button switches, pressure switches, toggle switches, or other mechanical type switches. In other embodiments electronic switches could be used in place of the mechanical type switches. 
     Turning again to  FIGS.  1  and  2   , the oral care refill head  300  comprises a head portion  310  and an attachment portion  320 . The head portion  310  comprises an oral treatment tool (or head structure)  311  having a front surface  312  and a rear surface  313 . Furthermore, the head portion  310  comprises a plurality of tooth cleaning elements  314  extending from the front surface  312  of the oral treatment tool  311 . The plurality of tooth cleaning elements  314  may comprise bristle tufts, filament bristles, fiber bristles, nylon bristles, polybutylene terephthalate (PBT) bristles, spiral bristles, rubber bristles, elastomeric protrusions, flexible polymer protrusions, lamella, combinations thereof, and/or structures containing such materials or combinations. Thus, any combination of these elements may be used to form one or more of the tooth cleaning elements  314  in some embodiments. Furthermore, where bristles are used for one or more of the tooth cleaning elements  314 , such bristles can be tapered, end-rounded, spiral, or the like. The tooth cleaning elements  314  may be coupled to the head portion  310  using any known techniques such as staples, anchor-free tufting, in-mold tufting, PTT, or the like. In the exemplified embodiment, the tooth cleaning elements  314  comprises a plurality of tufts of bristles arranged in a particular pattern on the head portion  310 . Of course, the particular pattern of the tooth cleaning elements  314  is not to be limiting of the present invention unless specifically claimed as such. 
     Furthermore, in the exemplified embodiment there is a soft tissue cleaner  315  positioned on the rear surface  313  of the head portion  310  of the oral care refill head  300 . The soft tissue cleaner  315  may be an elastomeric material such as thermoplastic elastomer that is injection molded onto the rear surface  313  of the head portion  310 . The soft tissue cleaner  315  may include a pad portion  316  and a plurality of protuberances  317  protruding from the pad portion  316  (see  FIG.  3    for best illustration of pad portion  316  and protuberances  317 ). Alternatively, the soft tissue cleaner  315  may include ridges, depressions, nubs, or any desirable feature for cleaning and/or scraping the tongue and its papillae. 
     Referring to  FIGS.  3  and  3 A , the oral care refill head  300 , and specifically the attachment portion  320  thereof, will be described in greater detail. The attachment portion  320  of the oral care refill head  300  is fixed to the head portion  310  and extends directly from the head portion  310 . The attachment portion  320  comprises a proximal end  321  and a distal end  322 , and the head portion  310  is located at the distal end  322 . The attachment portion  320  of the oral care refill head  300  extends along a longitudinal axis A-A from the proximal end  321  to the distal end  322 . Furthermore, in the exemplified embodiment the attachment portion  320  comprises an outer sleeve portion  323  that comprises a central cavity  324  and an insert coupler  325  that is fixed within the central cavity  324  of the outer sleeve portion  323 . In the exemplified embodiment, the outer sleeve portion  323  is integrally formed with the head portion  210  and the insert coupler  325  is a separate component that is positioned within the central cavity  324  of the outer sleeve portion  323  and fixed thereto. In some alternative embodiments, the insert coupler  325  could be omitted and the features of the insert coupler  325  described herein could be formed integrally with the outer sleeve portion  323 . The features of the insert coupler  325  may be described more generally as being features of the attachment portion  320  of the oral care refill head  300 , and any such features could be formed from the outer sleeve portion  323 , the insert coupler  325 , or a combination of both. 
     The insert coupler  325  comprises and/or defines a connection cavity  326 . Specifically, the insert coupler  325  comprises an inner sidewall  327  and an inner end wall  328  that collectively define the connection cavity  326 . The connection cavity  326  is a blind hole formed into the insert coupler  325  that ends at the inner end wall  328 . The connection cavity  326  is designed and configured to receive the stem  250  of the handle  200  when the oral care refill head  300  is coupled to the handle  200 . The connection cavity  326  extends along a cavity axis B-B that is coaxial with the longitudinal axis A-A of the attachment portion  320  of the oral care refill head  300 . The connection cavity  326  extends along the cavity axis B-B from an opening  329  in the proximal end  321  of the attachment portion  320  to the inner end wall  328 . 
     Referring to  FIGS.  3 - 6   , the insert coupler  325  comprises an annular ring structure  301  that forms an annular proximal end surface  302  of the insert coupler  325  and a body structure  303  extending from an upper surface of the annular ring structure  301  that is opposite the annular proximal end surface  302  of the annular ring structure  301 . The body structure  303  comprises a radially deflectable arm  330  that forms a part of the inner sidewall  327 . Specifically, a through-slot  331  is formed into the body structure  303  to define the radially deflectable arm  330 . The through-slot  331  is a U-shaped opening formed into and through the body structure  303  of the insert coupler  325  to define the radially deflectable arm  330 . The through-slot  331  separates a distal end  332  of the radially deflectable arm  330  from the annular ring structure  301  and then extends upwardly along both opposing side edges of the radially deflectable arm  330 . As a result, the radially deflectable arm  330  is able to deflect radially relative to the remainder of the body structure  303  and relative to the annular ring structure  301 . Thus, the radially deflectable arm  330  is capable of deflecting inward into and towards the cavity axis B-B and outward away from the cavity axis B-B. Specifically, the radially deflectable arm  330  can flex inwardly and outwardly about a living hinge  332  that is located at the same elevation as the distal ends of the U-shaped through-slot  331 . The radially deflectable arm  330  may flex/pivot about the living hinge  332  in the manner described during insertion of the stem  250  of the handle  200  into the connection cavity  326  and removal of the stem  250  of the handle  200  from the connection cavity  326 . 
     As best shown in  FIG.  3 A  and mentioned above, the insert coupler  325  is positioned within the central cavity  324  of the outer sleeve portion  323 . The insert coupler  325  may be fixed to the outer sleeve portion  323  using mechanical interference, tight fit, interference fit, nub and recess, adhesives, ultrasonic welding, or the like in various different embodiments. However, it should be appreciated that the insert coupler  325  is fixed to and therefore non-movable relative to the outer sleeve portion  323  of the attachment portion  320  of the oral care refill head  300 . The outer sleeve portion  323  comprises an annular proximal end surface  304  that is substantially coplanar with and circumscribes the annular proximal end surface  302  of the insert coupler  325 . In the embodiment shown, the annular proximal end surface  302  of the insert coupler  325  is slightly recessed relative to the annular proximal end surface  304  of the outer sleeve portion  323 , but they may be exactly coplanar in other embodiments. However, the slight recess of 1-2 mm is still considered to be substantially coplanar as that phrase is used herein. In the exemplified embodiment, no portion of the insert coupler  325  protrudes beyond the annular proximal end surface  304  of the outer sleeve portion  323 . Rather the annular proximal end surface  302  of the insert coupler  325  is either flush with or slightly recessed relative to the annular proximal end surface  304  of the outer sleeve portion  323 . The insert coupler  325  does not cover or overlie any part of the annular proximal end surface  304  of the outer sleeve portion  323 . Rather, the annular proximal end surface  304  of the outer sleeve portion  323  remains entirely exposed along the proximal end  321  of the attachment portion  320 . The annular proximal end surface  304  of the outer sleeve portion  323  and the annular proximal end surface  302  of the insert coupler  325  collectively form the proximal end  320  of the attachment portion  320 . 
     Furthermore, still referring to  FIG.  3 A , when the insert coupler  325  is located within the central cavity  324  of the outer sleeve portion  323 , a gap  305  exists between an inner surface  306  of the outer sleeve portion  323  and an outer surface  333  of the radially deflectable arm  330 . This gap  305  is needed to allow the radially deflectable arm  330  to deflect outwardly away from the cavity axis B-B during insertion/removal of the stem  250  of the handle  200  from the connection cavity  326  as briefly mentioned above. 
     Referring again to  FIGS.  3  and  3 A , the radially deflectable arm  330  comprises an inner surface  334  that is opposite to the outer surface  333 . The inner surface  334  of the radially deflectable arm  330  forms a portion of the inner sidewall  327  of the connection cavity  326 . Furthermore, the radially deflectable arm  330  comprises a locking protuberance  335  protruding from the inner surface  334  of the radially deflectable arm  330  and into the connection cavity  326 . In the exemplified embodiment, the locking protuberance  335  is a dome-shaped or convex structure that protrudes from the inner surface  334  of the radially deflectable arm  330  at (or immediately adjacent to) the distal end  332  of the radially deflectable arm  330 . However, the locking protuberance  335  could take on other shapes in other embodiments such as being a linear structure or the like. In still other embodiments, the locking protuberance  335  could be a locking groove instead, this structure being dependent on the structure of a locking groove or protuberance of the stem  250  of the handle  200  with which it is intended to engage. Furthermore, the exact location of the locking protuberance  335  along the radially deflectable arm  330  may be modified slightly so that the locking protuberance  335  is spaced a short distance from the distal end  332  of the radially deflectable arm  330  in some embodiments. The locking protuberance  335  is configured to engage a locking depression formed into the stem  250  as described in greater detail below with reference to  FIGS.  10  and  11   . The locking protuberance  335  is located at a first axial distance D 1  from the proximal end  321  of the attachment portion  320 . Although the first axial distance D 1  is marked in  FIG.  3 A  as being located at an axial centerpoint along the locking protuberance  335 , the invention is not limited to this and the first axial distance D 1  could be located at any axial location along the locking protuberance  335 . 
     The inner sidewall  326  of the attachment portion  320  (which is formed by the inner surface of the insert coupler  325  in the exemplified embodiment) comprises a first radial shoulder  336  located a second axial distance D 2  from the proximal end  321  of the attachment portion  320 . The second axial distance D 2  is greater than the first axial distance D 1  such that the first radial shoulder  336  is located further from the proximal end  321  of the attachment portion  320  than the locking protuberance  335 . The first radial shoulder  336  is circumferentially aligned with the locking protuberance  335 . Thus, the first radial shoulder  336  and the locking protuberance  335  are located on the same side of the cavity axis B-B. Although the second axial distance D 2  is marked in  FIG.  3 A  as being located at a proximal-most end of the first radial shoulder  336 , the invention is not to be so limited in all embodiments and the second axial distance D 2  could be positioned at any axial location along the first radial shoulder  336 . 
     It should be understood that the phrase “circumferentially aligned” means that the features, elements, or components mentioned are at the same angular position. This is similar to axially aligned, except that it includes the features, elements, or components being positioned at different radial distances from the relevant axis. Thus, the first radial shoulder  336  and the locking protuberance  335  are at the same angular position relative to the cavity axis B-B. Other features are mentioned below as being circumferentially aligned and they should also be understood to be located at the same angular position. Furthermore, the term “radial” means that the shoulder(s) described herein extend in a radial direction relative to the cavity axis B-B. In the exemplified embodiment, the shoulders described herein (including the first radial shoulder  336  and other radial shoulders described below) do not extend along the entire circumference of the inner sidewall  327 , although they may in alternative embodiments. 
     The first radial shoulder  336  is oriented at a first oblique angle Θ 1  relative to the cavity axis B-B. Furthermore, the first radial shoulder  336  is planar in the exemplified embodiment. The first radial shoulder  336  also has a first radial width W 1  measured from the inner surface  335  of the radially deflectable arm  330  to an end of the first radial shoulder  336  located furthest from the proximal end  321  of the attachment portion  320 . The inner surface  334  of the radially deflectable arm  330  is planar from the locking protuberance  335  to the first radial shoulder  336 . 
     The inner sidewall  327  of the attachment portion  320  (which is formed by the inner surface of the insert coupler  325  in the exemplified embodiment) comprises a second radial shoulder  337  located a third axial distance D 3  from the proximal end  321  of the attachment portion  320 . The third axial distance D 3  is greater than the second axial distance D 2  such that the second radial shoulder  337  is located further from the proximal end  321  of the attachment portion  320  than the first radial shoulder  336  and the locking protuberance  335 . Although the third axial distance D 3  is marked in  FIG.  3 A  as being located at a proximal-most end of the second radial shoulder  337 , the invention is not to be so limited in all embodiments and the third axial distance D 3  could be positioned at any axial location along the first radial shoulder  337 . 
     In the exemplified embodiment, the second radial shoulder  337  is not transversely aligned with the first radial shoulder  336 . That is, there is no transverse axis (transverse to the cavity axis B-B) that intersects both of the first and second radial shoulders  336 ,  337 . This is because the starting point of the second radial shoulder  337  (the end of the second radial shoulder  337  that is closest to the proximal end  321  of the attachment portion  320 ) is located further from the proximal end  321  of the attachment portion  320  than the ending point of the first radial shoulder  336  (the end of the first radial shoulder  336  that is closest to the proximal end  321  of the attachment portion  320 ). 
     The second radial shoulder  337  is located on the opposite side of the inner sidewall  327  than the first radial shoulder  336  and the locking protuberance  330 . Thus, while the first radial shoulder  336  and the locking protuberance  330  are located on a first side of the cavity axis B-B, the second radial shoulder  337  is located on a second side of the cavity axis B-B. The second radial shoulder  337  has a radial width W 2  that is less than the radial width W 1  of the first radial shoulder  336 . Thus, the second radial shoulder  337  is shallower or shorter than the first radial shoulder  336 . The second radial shoulder  337  may be oriented at a second oblique angle Θ 2  relative to the cavity axis B-B, the second oblique angle Θ 2  being different than the first oblique angle Θ 1 . However, in the exemplified embodiment the second radial shoulder  337  is arcuate or curved rather than being planar. The second radial shoulder  337  may be planar in other embodiments. 
     The inner sidewall  327  of the attachment portion  320  also comprises a third radial shoulder  338  located a fifth axial distance D 5  from the proximal end  321  of the attachment portion  320 . The fifth axial distance D 5  is grater than the first, second, and third axial distances D 1 , D 2 , D 3  and thus the third radial shoulder  338  is located further from the proximal end  321  of the attachment portion  320  than each of the locking protuberance  330 , the first radial shoulder  336 , and the second radial shoulder  337 . In the exemplified embodiment, the third radial shoulder  338  is oriented perpendicular to the cavity axis B-B, although the invention is not to be so limited in all embodiments. The third radial shoulder  338  is circumferentially aligned with the first radial shoulder  336  and with the locking protuberance  330 . Thus, the locking protuberance  330 , the first radial shoulder  336 , and the third radial shoulder  338  are located on the same side of the cavity axis B-B and the second radial shoulder  337  is located on the other side of the cavity axis B-B. 
     The inner sidewall  327  comprises several planar sections that are delineated and/or bounded by the various radial shoulders  336 ,  337 ,  338  mentioned herein. Thus, the inner sidewall  327  of the attachment portion  320  comprises a first planar section  339  located between the first radial shoulder  336  and the third radial shoulder  338 , a second planar section  340  located between the second radial shoulder  337  and the inner end wall  328  of the connection cavity  326 , and a third planar section  341  located between the third radial shoulder  338  and the inner end wall  328  of the connection cavity  326 . The first and third planar sections  339 ,  341  are circumferentially aligned with the first and third radial shoulders  336 ,  338 . The second planar section  340  is circumferentially aligned with the second radial shoulder  337 . Thus, the first and third planar sections  339 ,  341  are located on one side of the cavity axis B-B and the second planar section  340  is located on an opposite side of the cavity axis B-B. While the first and third planar sections  339 ,  341  are circumferentially aligned, they are radially offset such that the third planar section  341  is located closer to the cavity axis B-B than the first planar section  339 . The third planar section  341  and possibly also the second planar section  340  are configured to contact a distal stem section of the stem  250  of the handle  200  as described further below. 
     In the exemplified embodiment, the first planar section  339  has a slight curvature as it extends near to the first radial shoulder  336 . However, the invention is not to be so limited in all embodiments and the first planar section  339  may be completely planar in other embodiments. Furthermore, an upper portion of the first planar section  339  is completely planar in the exemplified embodiment. 
     The inner sidewall  327  also has planar sections extending from the first radial shoulder  336  to the locking protuberance  335  and from the second radial shoulder  337  to the proximal end  321  of the attachment portion  320 . The planar section extending from the first radial shoulder  336  to the locking protuberance  335  is circumferentially aligned with the first and third planar sections  339 ,  341  but radially offset such that the first planar section  339  is located closer to the cavity axis B-B than the planar section extending from the first radial shoulder  336  to the locking protuberance. The planar section extending from the second radial shoulder  337  to the proximal end  321  is circumferentially aligned with the second planar section  340  but radially offset such that the second planar section  340  is located closer to the cavity axis B-B than the planar section extending from the second radial shoulder  337  to the proximal end  321  of the attachment portion  320 . 
     The attachment portion  320  of the oral care refill head  300  comprises an engagement protuberance  345  protruding from the inner sidewall  327  and into the connection cavity  326 . In the exemplified embodiment, the engagement protuberance  345  is located along and extends or protrudes from the second planar section  340  of the inner sidewall  327  between the second radial shoulder  337  and the inner end wall  328 . The engagement protuberance  345  is located a fourth axial distance D 4  from the proximal end  321  of the attachment portion  320 . The fourth axial distance D 4  is greater than each of the first, second, and third axial distances D 1 , D 2 , D 3  but less than the fifth axial distance D 5 . Thus, the engagement protuberance  345  is located further from the proximal end  321  of the attachment portion  320  than the locking protuberance  335 , the first radial shoulder  336 , and the second radial shoulder  337 , but the third radial shoulder  338  is located further from the proximal end  321  of the attachment portion  320  than the engagement protuberance  345 . As will be described in greater detail below with reference to  FIG.  11   , the engagement protuberance  345  is configured to engage the stem  250  of the handle  200  via a compression fit to hold the stem  250  in place and maintain the connection between the oral care refill head  300  and the handle  200 . 
     The connection cavity  326  has several axial sections that are delineated by the various radial shoulders described herein. Specifically, the connection cavity  326  comprises a first axial cavity section  350  extending from the proximal end  321  of the attachment portion  320  to the first radial shoulder  336 . The first axial cavity section  350  has a first width W 3 . The connection cavity  326  comprises a second axial section  351  extending from the first radial shoulder  336  to the second radial shoulder  337 . The second axial section  351  has a second width W 4  that is less than the first width W 3 . The connection cavity  326  comprises a third axial section  352  extending from the second radial shoulder  337  to the third radial shoulder  338 . The third axial cavity  352  has a third width W 5  that is less than the second width W 4 . The connection cavity  326  comprises a fourth axial section  353  extending from the third axial shoulder  338  to the inner end wall  328 . The fourth axial section  353  has a fourth width W 6  that is less than the third width W 5 . In the exemplified embodiment, the first axial cavity section  350  has a circular transverse cross-sectional profile. 
     Referring to  FIGS.  7  and  8   , the engagement protuberance  345  is located on a flexible portion  360  of the inner sidewall  327 . Specifically, as best seen in  FIGS.  7  and  8    (but also shown in  FIG.  3 A ), there is a first axially elongated slot  361  and a second axially elongated slot  362  located along the second planar section  340  of the inner sidewall  327 . The first and second axially elongated slots  361 ,  362  are circumferentially spaced apart from one another but transversely aligned with one another. Thus, the circumferential portion of the inner sidewall  327  located between the first and second elongated slots  361 ,  362  is referred to herein as the flexible portion  360  of the inner sidewall  327 . This is because the flexible portion  360  of the inner sidewall  327  is capable of flexing inwardly towards the connection cavity  326  and outwardly away from the connection cavity  326  in response to radial forces being applied thereon. Thus, if a force is applied pushing the flexible portion  360  of the inner sidewall  327  towards the connection cavity  326  then it will flex inwardly and if a force is applied pushing the flexible portion  360  of the inner sidewall  327  away from the connection cavity  326  then it will flex outwardly. As discussed in greater detail below, when the stem  250  of the handle  200  is inserted into the connection cavity  326 , the stem  250  and the engagement protuberance  345  are in forcible contact with one another such that the stem  250  forces the flexible portion  360  of the inner sidewall  327  to flex outwardly while maintaining engagement with the engagement protuberance  345 . This creates a very snug and tight fit to hold the stem  250  in place. 
     Referring to  FIGS.  9 A- 9 C , the stem  250  of the handle  200  will be described in greater detail. The stem  250  is illustrated by itself in  FIGS.  9 A- 9 C  having been removed and separated from the handle  200 . The stem  250  extends along a stem axis C-C from a proximal end  251  of the stem  250  to a distal end  252  of the stem  250 . When the stem  250  is coupled to the handle  200  as shown in  FIG.  2    for example, the stem  250  extends along the stem axis C-C from the distal end surface  211  of the gripping portion  210  of the handle  200  to the distal end  252  of the stem  250 . 
     Referring to  FIGS.  9 A- 9 C,  10 , and  11   , the stem  250  as well as its interaction with various components of the oral care refill head  300  will be described. The stem  250  comprises a proximal stem section  253  that is located within the interior of the gripping section  210  of the handle  200  when the stem  250  is coupled to the handle  200 , a base stem section  254 , and a distal stem section  255 . The proximal stem section  253  may form the drive shaft of the motor  140  in some embodiments. In other embodiments, stem  250  may comprise only the base stem section  254  and the distal stem section  255 , which form a distal portion of a drive shaft of the motor  140  with the remainder of the drive shaft of the motor  140  being formed by the proximal stem section  253 . The base stem section  254  is located between the proximal stem section  253  and the distal stem section  255 . As noted above, the proximal stem section  253  is located within the interior of the handle  200 , the base stem section  254  protrudes from and is adjacent to the gripping portion  210  of the handle  200 , and the distal stem section  255  extends from the base stem section  254  to the distal end  252 . In some embodiments, the stem  250  may comprise only the portions thereof that extend from the distal end surface  211  of the gripping portion  210  of the handle  200  (i.e., the base stem section  254  and the distal stem section  255 ). 
     The stem  250  comprises an annular groove  256  located in the proximal stem section  253 . The annular groove  256  is configured to mate with a locking member  370  of the handle  200  as shown in  FIG.  10   . Specifically, the locking member  370  comprises one or more locking arms  371  that nest within the annular groove  256  in the proximal stem section  253  of the stem  250  to couple the stem  250  to the handle  200 . The locking arms  371  are configured to flex outwardly as the stem  250  is inserted into the gripping section  210  of the handle  200 . However, once the stem  250  is coupled to the handle  200 , the engagement between the locking arms  371  and the annular groove  256  prevents the stem  250  from being removed from the handle  200  by simply pulling axially on the stem  250 . 
     The stem  250  also comprises a locking depression  257  located along the base stem section  254  of the stem  250 . In the exemplified embodiment, the locking depression  257  is an annular depression  257  that extends around the entire circumference of the stem  250 . Thus, the locking depression  257  extends 360 degrees around the stem  250 . However, in other embodiments the locking depression  257  may extend along a part but not the entirety of the circumference of the stem  250 . In the exemplified embodiment, the locking depression  257  has a V-shaped cross-section, although the invention is not to be so limited in all embodiments and the cross-sectional shape of the locking depression  257  could be modified so long as it is configured to matingly engage the locking protuberance  335  of the radially deflectable arm  330 . 
       FIGS.  10  and  11    illustrate the locking protuberance  335  of the radially deflectable arm  330  nesting within the locking depression  257  in the base stem section  254  of the stem  250 . This interaction prevents the oral care refill head  300  from being readily detached from the stem  250  unless a sufficient force is applied onto the oral care refill head  300  relative to the handle  200  to detach the oral care refill head  300  from the handle  200  by removing the locking protuberance  335  from the locking depression  257 . During coupling of the oral care refill head  300  to the handle  200 , the locking protuberance  335  of the oral care refill head  300  snap fits into the locking depression  257  of the stem  250 , thereby achieving the coupling between the oral care refill head  300  and the handle  200 . It should be appreciated that the locking depression  257  could be a protuberance and the locking protuberance  330  could be a depression in alternative embodiments. 
     The distal stem section  255  of the stem  250  comprises a first radial planar shoulder  260  located on a first side of the stem axis C-C and a second radial planar shoulder  261  located on a second side of the stem axis C-C that is opposite the first side of the stem axis C-C. The distal stem section  255  of the stem  250  further comprises a first planar surface  262  extending from the first radial planar shoulder  260  to the distal end  252  and a second planar surface  263  extending from the second radial planar shoulder  261  to the distal end  252 . The first planar surface  262  and the first radial planar shoulder  260  are located on a first side of the stem axis C-C and the second planar surface  263  and the second radial planar shoulder  261  are located on a second side of the stem axis C-C. The first and second planar surfaces  262 ,  263  are oriented substantially parallel to one another and to the stem axis C-C. (the term substantially allowing for a range of plus or minus 5°). In some embodiments, the first and second planar surfaces  262 ,  263  may be exactly parallel to one another and to the stem axis C-C. The first and second planar surfaces  262 ,  263  are flat faces on the stem  250  which is otherwise round. Thus, the portions of the outer surface of the stem  250  between the first and second planar surfaces  262 ,  263  along the distal stem section  255  are round or arcuate. 
     The first and second radial planar shoulders  260 ,  261  are aligned along the stem axis C-C. Thus, there is no transverse axis (oriented perpendicular to the stem axis C-C) that would intersect any part of the first radial planar shoulder  260  and also intersect a part of the second radial planar shoulder  261 . Rather, the first and second radial planar shoulders  260 ,  261  are located at entirely different axial heights along the stem  250 . Stated another way, the first radial planar shoulder  260  extends from a first end  264  to a second end  265 , the first end  264  being closer to the proximal end  251  than the second end  265 . The second radial planar shoulder  261  extends from a first end  266  to a second end  267 , the first end  266  being closer to the proximal end  251  than the second end  267 . The second end  265  of the first radial planar shoulder  260  is located closer to the proximal end  251  of the stem  250  than the first end  266  of the second radial planar shoulder  261  (or, the first end  266  of the second radial planar shoulder  261  is located closer to the distal end  252  of the stem  250  than the second end  265  of the first radial planar shoulder  260 ). 
     Referring to  FIGS.  10  and  11   , the interaction between the handle  200  and the oral care refill head  300  will be further described. As mentioned above, the stem  250  is securely coupled to the handle  200  via engagement between the locking arms  371  of the locking member  370  of the handle  200  and the annular groove  256  of the stem  250 . The base and distal stem sections  254 ,  255  of the stem  250  protrude from the distal end surface  211  of the gripping portion  210  of the handle  200 . When the oral care refill head  300  is placed onto the stem  250  of the handle  200 , the radially deflectable arm  330  deflects outwardly until the locking protuberance  335  nests within the locking depression  257 . The radially deflectable arm  330  then snaps back inward towards the cavity axis B-B and as the locking depression  257  nests within the locking protuberance  335  the oral care refill head  300  becomes locked to the handle  200  via the stem  250 . At this time, the oral care refill head  300  is fully coupled to the handle  200 . 
     In this state, there is a gap  275  between the first planar section  262  of the stem  250  and the first planar section  339  of the inner sidewall  327 . There is also a gap between the first radial shoulder  336  of the oral care refill head  300  and the first radial planar shoulder  260  of the stem  250 . However, the first planar surface  262  of the stem  260  is in direct surface contact with the third planar section  341  of the inner sidewall  327 . That is, the gap  275  exists between a first portion of the first planar surface  262  of the stem  250  and the first planar section  339  of the inner sidewall  327 , but a second portion of the first planar surface  262  of the stem  250  is in contact with the third planar section  341  of the inner sidewall  327 . A portion of the first planar section  339  of the inner sidewall  327  that is located between the first radial shoulder  336  of the inner sidewall  327  and the inner end wall  328  is spaced apart from and not in contact with the stem  250 . This occurs because of the inclusion of the third radial shoulder  341  as discussed above. Specifically, the third radial shoulder  341  creates a pocket-like area along the first planar section  339  of the inner sidewall  327  such that the first planar section  339  cannot contact the first planar surface  262  of the stem  250  when the third planar section  341  of the inner sidewall  327  is in contact with the first planar surface  262  of the stem  250 . 
     Furthermore, the second planar surface  263  of the stem  250  may be in contact with the second planar section  340  of the inner sidewall  327 . However, it is possible that there may not be contact between the second planar surface  263  of the stem  250  and the second planar section  340  of the inner sidewall  327 . Rather, due to the engagement between the engagement protuberance  345  and the second planar surface  263  of the stem  250 , the flexible portion  360  of the inner sidewall  327  may flex outwardly so that there is no direct contact between the second planar surface  263  of the stem  250  and the second planar section  340  of the inner sidewall  327 . However, the engagement protuberance  345  will be pressed forcibly against the second planar surface  263  of the stem  250 , thereby pressing the first planar surface  262  of the stem  250  into contact with the third planar section  341  of the inner sidewall  327 . The engagement protuberance  345  is located on the opposite side of the cavity axis B-B than the locking protuberance  335 . 
     As can be seen in  FIG.  11   , the distal end  252  of the stem  250  is in contact with the inner end wall  328  of the connection cavity  326 . That is, there is no space or gap between the distal end  252  of the stem  250  and the inner end wall  328  of the connection cavity  326  in the exemplified embodiment. This again ensures a tight fit between the stem  250  and the oral care refill head  300  and ensures that vibrations generated by the stem  250  will be transmitted to the oral care refill head  300  and the tooth cleaning elements  314 . 
     The locking member  370  has a top portion  372  and the locking arms  371  extend downwardly from the top portion  372 . An upper surface  373  of the top portion  372  forms a portion of the distal end surface  211  of the gripping portion  210 . The locking arms  371  form an inner annular wall of the locking member  370  and the locking member  370  also includes an outer annular wall  374  that extends downwardly from the top portion  372  and engages the gripping portion  210  of the handle  200 . The handle  200  also comprises a seal member  375  that surrounds a distal portion of the gripping portion  210  of the handle  200  as best shown in  FIG.  11   . As seen in  FIG.  10   , when the oral care refill head  300  is coupled to the handle  200 , the radially deflectable arm  330  is on the same side of the cavity axis B-B and the longitudinal axis A-A of the attachment portion  320  of the oral care refill head  300  as the cleaning portions of the tooth cleaning elements  314  which extend from the front surface  312  of the oral treatment tool  311 . 
     Referring to  FIGS.  12 ,  13 , and  15   , exploded views in perspective and cross-section as well as an assembled cross-sectional view, respectively, are provided and will be described collectively. As discussed above, the oral care implement  100  comprises the oral care refill head  300  which is detachably coupled to the handle  200  by engagement between the insert coupler  325  of the oral care refill head  300  and the stem  250  of the handle  200 . The handle  200  includes the gripping portion  210  which is a plastic housing that houses the remaining components of the handle  200 . Specifically, the gripping portion  210  of the handle  200  comprises a housing  215  having an internal cavity or chamber  213  within which the remaining components of the handle  200  are located. In that regard, the control unit  150 , the power source  130 , and the motor  140  are disposed within the internal chamber  213  of the housing  215  of the gripping portion  210  of the handle  200 . 
     Furthermore, the handle  200  comprises a rocker unit  400  that is at least partially mounted within the internal chamber  213  of the gripping portion  210  of the handle  200 . In the exemplified embodiment, the rocker unit  400  comprises the stem  250 , the motor  140 , and a motor chassis  401  that supports the motor  140 . The motor chassis  401  forms a sleeve around at least a portion of the motor  140  as shown, for example, in  FIGS.  15  and  16    and described in greater detail below. As will be described below, portions of the rocker unit  400 , and specifically the motor  140  and the motor chassis  401 , are mounted within the internal chamber  213  of the gripping portion  210  of the handle  200  so as to be rockable relative to the housing  215  of the gripping portion  210  about a fulcrum. The stem  250  may also rock (or pivot) relative to the housing  215  in response to forces/pressures acting thereon as described more fully herein below. 
     The motor chassis  401  comprises an upper portion  410  and a lower portion  450 . The upper portion  410  of the motor chassis  401  forms an upper sleeve  411  within which a top portion  141  of the motor  140  nests. The lower portion  450  of the motor chassis  401  forms a lower sleeve  451  within which a bottom portion  142  of the motor  140  nests. In the exemplified embodiment, the motor chassis  401  does not cover or surround the entirety of the motor  140 . Rather, a middle portion of the motor  140  located between the top and bottom portions  141 ,  142  of the motor  140  is not surrounded or otherwise covered by the motor chassis  401 . However, in other embodiments the motor chassis  410  could cover or surround the entirety of the motor  140 . Furthermore, rather than having upper and lower portions  410 ,  450  which are separate components, in other embodiments the motor chassis  401  could comprise a singular housing or sleeve that surrounds a portion of or the entirety of the motor  140 . 
     As noted above, the rocker unit  400  is mounted in such a way that it is rockable relative to the housing  215  about a fulcrum and this rocking motion will be described in greater detail below with reference to  FIGS.  15 - 18   . In the exemplified embodiment, the fulcrum is formed by a protrusion  412  extending from the upper portion  410  of the motor chassis  401  (the protrusion  412  can be seen more clearly in  FIG.  16   ). Specifically, the protrusion  412  is an elongated ridge-like protrusion that extends from an outer surface of the upper portion  410  of the motor chassis  401 . Thus, as excessive pressure is applied onto the tooth cleaning elements  314  during use, the oral care refill head  300  causes the stem  250  to pivot, which in turn causes the motor  140  and the upper portion  410  of the motor chassis  401  to pivot/rock about the fulcrum or protrusion  412 . As the upper portion  410  of the motor chassis  401  pivots/rocks about the protrusion  412 , the lower portion  450  of the motor chassis  401  also pivots/rocks so as to actuate a pressure actuator element  155  as described in greater detail below. In response to excessive pressure on the tooth cleaning elements  314 , the upper portion  410  of the motor chassis  401  may rock in a first direction and the lower portion  450  of the motor chassis  401  may rock in a second direction that is opposite the first direction. The first direction may be a direction opposite the direction that the tooth cleaning elements  314  extend from the head and the second direction may be the same direction as that which the tooth cleaning elements  314  extend from the head, or vice versa. 
     In addition to the motor chassis  401 , in the exemplified embodiment the oral care implement  100  comprises a support chassis  402 . The support chassis  402  comprises an upper chamber  403  within which the motor  140  and the motor chassis  401  nest and a lower chamber  404  within which the power source  130  nests. The support chassis  402  is also housed within the internal chamber  213  of the housing  215  of the gripping portion  210  of the handle  200 . The support chassis  402  is fixed within the internal chamber  213  of the housing  210  in the exemplified embodiment. Furthermore, as shown in  FIG.  15    and described in more detail below, the lower portion  450  of the motor chassis  401  is fixedly coupled to the support chassis  402  with a fastener  405 . The lower portion  450  of the motor chassis  401  could alternatively be fixedly coupled directly to the housing  410  with a fastener in other embodiments. 
     As noted above, the oral care implement  100  also comprises a control unit  150  that is located within the internal chamber  213  of the gripping portion  210  of the handle  200 . The control unit  150  comprises the printed circuit board  149  which has a first surface  148  and an opposite second surface  147 . The power actuator  151  and the intensity actuator  152  are located on the first surface  148  of the printed circuit board  149 . Furthermore, the control unit  150  comprises the pressure actuator element  155  located on the second surface  147  of the printed circuit board  149 . The pressure actuator element  155  is actuated when a user is applying too much pressure onto the oral care refill head  300  during use of the oral care implement  100  for tooth cleaning or other oral or personal hygiene activities and the details of this operation will be described in greater detail below. The oral care implement  100  also comprises a pressure actuated light source  380  that is operably coupled to the control unit  150 . Upon actuation of the pressure actuator element  155  as mentioned above and described in greater detail below, the control circuit  150  may be configured to illuminate the pressure actuated light source  380 . 
     Referring briefly to  FIGS.  12  and  16   , the control unit  150  also comprises a second printed circuit board  160  comprising a plurality of light sources  161 . The control unit  150  is configured to illuminate one or more of the light sources  161  to indicate an intensity of the motor  140  to the user. Specifically, as noted above the user can adjust the intensity of the motor using the intensity button  202  which will actuate the intensity actuator  152  on the printed circuit board  149  of the control unit  150 . Furthermore, in response to the intensity actuator  152  being actuated (either upward or downward), the control circuit  150  will either activate or deactivate one or more of the light sources  161  on the second printed circuit board  160 . The light emitted by the light sources  161  may be seen through a transparent window  165  on a rear of the handle  200 . 
     Additional components of the oral care implement  100  are shown in  FIGS.  12 ,  13 , and  15    but not described herein. It should be understood that such additional components may comprise gaskets, end caps, covers, structural parts, elastomeric seals, or the like that may serve a purpose in rendering the housing  210  fluid-tight so that fluid cannot destroy the internal electronic components and in ensuring proper functionality and operation of the oral care implement  100  in accordance with the teachings set forth herein. 
     Referring to  FIGS.  14 A,  14 B, and  16   , the lower portion  450  of the motor chassis  401  will be described in greater detail. The lower portion  450  of the motor chassis  401  comprises a first section  452  and a second section  453  that is coupled to the first section  452 . The first section  452  of the lower portion  450  of the motor chassis  401  comprises the lower sleeve  451  and an actuator arm  455  comprising a contact element  456 . The actuator arm  455  extends downwardly from a bottom end of the lower sleeve  451  and is integral with and fixed to the lower sleeve  451 . The lower sleeve  451  of the first section  452  of the lower portion  450  of the motor chassis  401  defines a cavity  454  within which the bottom portion  142  of the motor  140  nests. The second section  453  of the lower portion  450  of the motor chassis  401  is integrally formed with the first section  452  such that the first and second sections  452 ,  453  form a monolithic component. 
     In the exemplified embodiment, the second section  453  of the lower portion  450  of the motor chassis  401  comprises a first strut  457  and a second strut  458  that are coupled to the actuator arm  455  of the first section  452 . Specifically, each of the first and second struts  457 ,  458  comprises a vertical portion  459 ,  460  that is spaced apart from the actuator arm  455  and a horizontal portion  461 ,  462  that extends from a top end of the vertical portion  459 ,  460  to the actuator arm  455  such that a terminal end of the horizontal portion  461 ,  462  is coupled to the actuator arm  455 . The struts  457 ,  458  form the only connection or coupling between the first and second sections  452 ,  453  of the lower portion  450  of the motor chassis  401 . This connection between the first and second sections  452 ,  453  allows for the first section  452  of the lower portion  450  to pivot relative to the second section  453  of the lower portion  450 . While the first and second struts  457 ,  458  are used to couple the first and second sections  452 ,  453  of the lower portion  450  together in the exemplified embodiment, the invention is not to be so limited in all embodiments. In other embodiments, the first and second sections  452 ,  453  of the lower portion  450  of the motor chassis  401  may be coupled together via one or more flexible struts, a living hinge, a thinned section, or combinations thereof that will still permit the first section  452  to pivot, rock, or otherwise move relative to the second section  453  as described herein. 
     The second section  453  of the lower portion  450  of the motor chassis  401  also comprises a connection portion  470 . Specifically, the connection portion  470  extends from a bottom end of the vertical portion  459  of the first strut  457  to a bottom end of the vertical portion  460  of the second strut  458 . The connection portion  470  is spaced from a distal end of the actuator arm  455  by a gap, which ensures that the actuator arm  455  (along with the lower sleeve  451 ) can pivot relative to the first and second struts  457 ,  458  and the connection portion  470 . Thus, there is a U-shaped gap between the actuator arm  455  of the first section  452  and the second section  453  which enables the actuator arm  455  to flex, pivot, rotate, or the like relative to the second section  453 . The connection portion  470  comprises a connection feature  471  that facilitates connecting the connection portion  470  directly to the support chassis  402  or to the housing  210 . In the exemplified embodiment, the connection feature  471  is an aperture that is configured to receive the fastener  405  mentioned above. However, the invention is not to be so limited and in other embodiments the connection feature  471  could comprise a protrusion that is received in a recess of the support chassis  402  or the housing  210  to couple the second section  453  of the lower portion  450  of the motor chassis  401  to the support chassis  402  or to the housing  210 . 
     As shown in  FIGS.  15  and  16    and as discussed above, in the exemplified embodiment the connection portion  470  of the second section  453  of the lower portion  450  of the motor chassis  401  is coupled directly to the support chassis  402 . Specifically, the fastener  405  extends through the connection feature  471  (i.e., aperture) in the connection portion  470  of the second section  453  of the lower portion  450  of the motor chassis  401  and into an aperture or recess in the support chassis  402 . As a result, the second section  453  is fixedly secured to the support chassis  402 . Of course, in other embodiments the second section  453  could be fixedly secured directly to the housing  215  of the gripping portion  210  of the handle  200  by having the fastener  405  extend into an aperture in the housing  215  rather than an aperture in the support chassis  402 . However, the same result is achieved which is that the second section  453  of the lower portion  450  of the motor chassis  401  is fixedly coupled to the housing  210  such that the second section  453  of the lower portion  450  of the motor chassis  401  does not move relative to the housing  210 . Fastening the second section  453  of the lower portion  450  of the motor chassis  401  to the support chassis  402  or to the housing  215  stabilizes the motor, and the structure of the lower portion  450  of the motor chassis  401  still enables the rocking/pivoting motion needed to actuate the pressure actuator element  155  as described herein. 
     However, the first section  452  of the lower section  450  of the motor chassis  402  is configured to pivot or otherwise move or bend relative to the second section  453  of the motor chassis  402  and relative to the housing  210 . Specifically, because the second section  453  is only coupled to the first section  452  via the struts  457 ,  458 , there is some degree of flexibility in the connection between the first and second sections  452 ,  453 . Furthermore, the first section  452  is not directly coupled to the housing  210  or to the support chassis  402 , but is only coupled thereto indirectly via the second section  453 . Thus, a force being applied onto the first section  452  will permit the first section  452  to pivot or rock relative to the second section  453  and relative to the support chassis  402  and to the handle  200 , and this may be done to actuate the pressure actuator element  155  as described in greater detail below. 
       FIGS.  15  and  16    illustrate the oral care implement  100  with the rocker unit  400  in a normal position. The normal position is a position whereby either no pressure is being applied onto the tooth cleaning elements  314  or a pressure that is below a threshold required to cause the rocker unit  400  to rock relative to the housing  210  about the fulcrum is being applied onto the tooth cleaning elements  314 . Thus, the rocker unit  400  is only configured to rock about the fulcrum when an excessive pressure is being used during brushing or otherwise when a force greater than a threshold is being applied onto the tooth cleaning elements  314  in the direction of the arrow labeled F in  FIG.  15   . Thus, the normal state includes a non-use state and a state of use whereby excessive brushing pressure is not being used and an excessive force above a threshold is not being applied onto the tooth cleaning elements  314 . The rocker unit  400  is therefore biased into the normal position. 
     In the exemplified embodiment, when the rocker unit  400  is in the normal position, the contact element  456  of the rocker unit  400  (located on the actuator arm  455  of the first section  452  of the lower portion  450  of the motor chassis  401 ) is spaced apart from the pressure actuator element  155  of the control unit  150  such that the contact element  456  is not actuating the pressure actuator element  155 . Of course, the invention is not to be limited to this configuration in all embodiments. For example, in some embodiments the pressure actuator element  155  may be a trigger switch or a depressible switch. In such embodiments, in the normal position the contact element  456  may be in contact with the pressure actuator element  155  of the control unit  150  without depressing or otherwise actuating the pressure actuator element  155 . Thus, there need not be a gap between the contact element  456  of the rocker unit  400  and the pressure actuator element  155  of the control unit  150  for the pressure actuator element  155  to be in a non-activated state. Either way, in the exemplified embodiment when the rocker unit  400  is in the normal position, the contact element  456  of the rocker unit  400  does not actuate the pressure actuator element  155 . Thus, unless an excessive force beyond a predetermined threshold (an excessive brushing pressure or the like) is being applied onto the tooth cleaning elements  314 , the pressure actuator element  155  is not actuated. 
     Referring to  FIGS.  17  and  18   , the force F is being applied onto the tooth cleaning elements  314  with a pressure that exceeds a threshold. As a result, the rocker unit  400  has been altered from the normal position that was shown in  FIGS.  15  and  16    to an excessive-pressure position. A description of how the force F is imparted onto the rocker unit  400  is described here. First, the force F is applied onto the tooth cleaning elements  314 , which causes the oral care refill head  300  to pivot rearward in the directly of the arrow P. Because the stem  250  of the rocker unit  400  is fit snugly within the connection cavity  236  of the oral care refill head  300 , the pivoting of the oral care refill head  300  in the direction of the arrow P causes the stem  250  to also pivot in the direction of the arrow P. As the stem  250  pivots in the direction of the arrow P, so too does the motor  140  because it is coupled to the stem  250 . As the motor pivots  140 , the upper portion  410  of the motor chassis  402  rocks about the protrusion  412 , which forms the fulcrum of the rocker unit  400  as described herein. 
     As the motor  140  and the upper portion  410  of the motor chassis  402  pivot, the bottom portion  142  of the motor  140  pivots to the right in the view shown in  FIGS.  17  and  18    in the direction of the arrow labeled X. As the bottom portion  142  of the motor  140  pivots, the first section  452  of the lower portion  450  of the motor chassis  401  which surrounds the bottom portion  142  of the motor  140  also pivots or flexes or bends or rocks in the direction of the arrow X, which is a direction opposite the direction of the force F. 
     As discussed above, the second section  453  of the lower portion  450  of the motor chassis  401  does not pivot because it is fixedly coupled to the housing  210  (directly or indirectly via the support chassis  402 ). Thus, the first section  452  of the lower portion  450  of the motor chassis  401  pivots relative to the second section  453  of the lower portion  450  of the motor chassis  401  and also relative to the housing  215  of the handle  200 . In that regard, the pressure being applied onto the tooth cleaning elements  314  must have a force (i.e., the force F) with a strength or magnitude that is sufficient to cause the first section  452  of the lower portion  450  of the motor chassis  401  to pivot relative to the second section  453  of the lower portion  450  of the motor chassis  401 . As discussed above, the lower portion  450  of the motor chassis  450  is an integral, monolithic component and thus the first section  452  of the motor chassis  401  will not pivot relative to the second section  453  of the motor chassis  401  without a particular magnitude of force being applied. The lower portion  450  of the motor chassis  410  is formed from plastic such as polypropylene in the exemplified embodiment but it may be formed from other plastics or even thin metals in other embodiments without detracting from the function described herein. 
     In the exemplified embodiment, as the force F is applied onto the tooth cleaning elements  314 , the first section  452  of the lower portion  450  of the motor chassis  401  pivots so that the contact element  456  on the actuator arm  455  contacts the pressure actuator element  155 . In the exemplified embodiment, upon the contact element  456  contacting the pressure actuator element  155 , the pressure actuator element  155  is actuated. As noted above, in other embodiments the force F may cause the contact element  456  on the actuator arm  455  to actuate the pressure actuator element  155  by depressing it rather than simply closing a gap and coming into contact with it. Either way, the force F applied to the tooth cleaning elements  314  causes the rocker unit  400  to alter from the normal state shown in  FIGS.  15  and  16    into the excessive-pressure state shown in  FIGS.  17  and  18   . In the excessive-pressure state shown in  FIGS.  17  and  18   , the contact element  156  of the rocker unit  400  actuates the pressure actuator element  155  of the control unit  150 . 
     As seen in  FIG.  18   , the fulcrum upon which the rocker unit  400  rocks is the protrusion  412  on the upper portion  410  of the motor chassis  401 . Thus, the fulcrum is located above a top edge of the motor  140  and between the motor  140  and the distal end  211  of the gripping portion  210  of the handle  200 . The contact element  456  of the rocker unit  400  which actuates the pressure actuator element  155  is located below a bottom end of the motor  140 , or between the bottom end of the motor  140  and the power source  130 . Thus, the entire motor  140  is located axially between the contact element  456  of the rocker unit  400  and the fulcrum (i.e., the protrusion  412 ) of the rocker unit  400 . The motor  140  forms a part of the rocker unit  400  such that the motor  140  actually rocks or pivots as the rocker unit  400  is being altered between the normal and excessive-pressure positions. 
     When the contact element  156  of the rocker unit  400  actuates the pressure actuator element  155  of the control unit  150 , the control unit initiates generation of a user perceptible signal. In the exemplified embodiment, the user perceptible signal is the activation of the light source  380  to generate and emit light. In the exemplified embodiment, a lower annular ring portion  290  of the handle  200  is transparent or translucent or otherwise light transmissive so that light emitted by the light source  380  is emitted through the lower annular ring portion  290  of the handle  200  where it can be seen by a user of the oral care implement. Thus, upon seeing light emitted through the lower annular ring portion  290  of the handle  200 , the user will know that he/she is brushing with too much force and that he/she should adjust his/her brushing technique. In other embodiments, the light source may be positioned at other locations within the handle  200 . For example, activation of the pressure actuator element  155  may cause the control unit  150  to activate a light source located along a rear of the handle  200  to emit light through the rear of the handle  200 . In other embodiments, activation of the pressure actuator element  155  may cause the control unit  150  to activate a light source located along a front of the handle  200  or at any other location along the oral care implement  100  to emit light therefrom that can be seen by a user. The activation of the light source  380  provides an indication to a user of excessive brushing pressure that can then be remedied by the user. 
     Although activation of the pressure actuator element  155  causes the control unit  150  to activate a light source in the exemplified embodiment, in other embodiments different user perceptible signals may be generated upon activation of the pressure actuator element  155 . For example, the oral care implement may comprise a sound emission device (such as a speaker) and activation of the pressure actuator element  155  may cause the control unit  150  to activate the sound emission device to generate a sound that can be heard by the user. In still other embodiments, upon activation of the pressure actuator element  155 , the control unit  150  may alter an operating characteristic of the motor  140  by either abruptly stopping operation of the motor  140 , slowing down the speed of the motor  140 , increasing the speed of the motor  140 , pulsing the motor  140 , or the like. Thus, this may form a haptic user perceptible indicator or signal. In some embodiments, activation of the pressure actuator element  155  may cause the control unit  150  to both activate the light source  380  and alter an operating characteristic of the motor  140 . 
     Upon a user reducing the force F being applied onto the tooth cleaning elements  314  to a magnitude that is below the predetermined threshold, the rocker unit  400  will be altered back from the excessive-pressure position into the normal position. This is because, as noted above, the rocker unit  400  is biased into the normal position. Thus, user force is required to alter the rocker unit  400  from the normal position into the excessive-pressure position, and upon cessation of the force the rocker unit  400  will automatically alter from the excessive-pressure position back to the normal position. In altering from the excessive-pressure position to the normal position, the rocker unit  400  will no longer actuate the pressure actuator element  155  and the control unit  150  will stop the generation of the user perceptible signal. The strength of the connection between the first and second sections  452 ,  453  of the lower portion  450  of the motor chassis  402  will dictate the predetermined threshold. This can be achieved by altering the thickness of the first and second struts  457 ,  458 , altering the material of construction for the lower portion  450  of the motor chassis  402 , or the like. 
     As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls. 
     While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. Thus, the spirit and scope of the invention should be construed broadly as set forth in the appended claims.