Abstract:
A refill head, and oral care implement incorporating the same, wherein the refill head can be uncoupled from a stem of a handle by compressing a portion of a tubular sleeve of the refill head radially inward, therby retracting a locking lug of the refill head radially outward

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application No. 61/506,986, filed on Jul. 12, 2011, the content of which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to refill heads for oral care implements, and specifically to the coupling structure of the refill head. 
       BACKGROUND OF THE INVENTION 
       [0003]    Powered toothbrushes having replaceable heads, commonly referred to as refill heads, are known in the art. Such powered toothbrushes typically include a handle and a refill head that is detachably coupled to the handle. The replaceability of the heads in such powered toothbrushes is desirous because the handle, which includes the motion-inducing circuitry and components, is expensive to manufacture and has a much longer life expectancy than do the tooth cleaning elements, such as the bristles, that are on the refill head. Consumers would not be willing to pay a premium to purchase such powered toothbrushes if they had to be discarded when the bristles or other cleaning elements wore out. Thus, it is now standard in the industry to provide refill heads that can be attached and detached from the handle so that worn out refill heads can be replaced as needed for the same handle. 
         [0004]    Existing refill heads suffer from a number of deficiencies, including complexity of manufacture, the ability to improperly load the refill head to the handle, and inadequate coupling of the refill head to the handle. Thus, a need exists for a refill head having an improved coupling structure. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present invention is directed to a refill head, and oral care implement incorporating the same, wherein the refill head can be uncoupled from a stem of a handle by compressing a portion of a tubular sleeve of the refill head radially inward, thereby retracting a locking lug of the refill head radially outward. 
         [0006]    In one embodiment, the invention can be a toothbrush comprising: a handle comprising: a gripping portion; and a stem extending from the gripping portion, the stem extending along an axis, the stem comprising first and second locking lugs extending radially outward from an outer surface of the stem, the first and second locking lugs arranged in a circumferentially spaced apart manner; and a refill head detachably coupled to the handle, the refill head comprising: a head portion comprising a plurality of tooth cleaning elements; a tubular sleeve coupled to the head portion, the tubular sleeve having a cavity in which the stem is disposed, the tubular sleeve comprising first and second resilient zones that are compressible radially inward, the first and second resilient zones circumferentially spaced apart from one another; a resilient collar located within the cavity in transverse alignment with the first and second resilient zones and coupled to the tubular sleeve, the resilient collar comprising first and second locking lugs extending radially inward from an inner surface of the resilient collar, the first and second locking lugs of the resilient collar radially aligned with the first and second locking lugs of the stem respectively; and wherein compressing the first and second resilient zones of tubular sleeve radially inward alters the resilient collar from: (1) a locked state in which the locking lugs of the resilient collar operably mate with the first and second locking lugs; to (2) an unlocked state in which the locking lugs of the resilient collar are retracted radially outward and out of operable mating with the locking lugs of the stem. 
         [0007]    In another embodiment, the invention can be a refill head comprising: a head portion; a tubular sleeve coupled to the head portion, the tubular sleeve having a cavity for receiving a stem of a handle and extending along an axis, the tubular sleeve comprising at least one resilient zone that is compressible radially inward; a resilient collar located within the cavity in transverse alignment with the resilient zone and coupled to the tubular sleeve, the resilient collar comprising at least one locking lug extending radially inward from an inner surface of the resilient collar; and wherein compressing the resilient zone of the tubular sleeve radially inward retracts the locking lug of the resilient collar radially outward from the axis. 
         [0008]    In yet another embodiment, the invention can be a refill head comprising: a head portion; a tubular sleeve coupled to the head portion, the tubular sleeve having a cavity for receiving a stem of a handle and extending along an axis; at least one locking lug extending radially inward from an inner surface of the tubular sleeve; and wherein compressing a portion of the tubular sleeve radially inward retracts the locking lug radially outward from the axis. 
         [0009]    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 
         [0010]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a front view of a refill head and a toothbrush handle in alignment for detachable coupling according to one embodiment of the present invention, wherein the refill head and the handle are shown in one-quarter longitudinal cross-section; 
           [0012]      FIG. 2  is a longitudinal one-quarter cross-sectional view of the refill head according to one embodiment of the present invention; 
           [0013]      FIG. 3  is a left-side view of a proximal portion of the tubular sleeve of  FIG. 1  illustrating one of the resilient zones; 
           [0014]      FIG. 4  is a transverse cross-sectional view of the toothbrush of  FIG. 5  taken along view IV-IV, wherein the resilient collar is in a locked state; 
           [0015]      FIG. 4A  is a transverse cross-sectional view of the toothbrush of  FIG. 5  taken along view IV-IV, wherein the resilient collar is in an un-locked state due to the resilient zones of the tubular sleeve being compressed radially inward; 
           [0016]      FIG. 5  is one-quarter longitudinal cross-sectional view of the refill head and the toothbrush handle of  FIG. 1  detachably coupled together according to one embodiment of the present invention, taken along view V-V of  FIG. 4 ; and 
           [0017]      FIG. 6  is a transverse cross-sectional view of the toothbrush of  FIG. 5  taken along view VI-VI, wherein the indexing feature of the toothbrush is exemplified. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    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. 
         [0019]    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 derivative 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. 
         [0020]    Referring to  FIGS. 1 and 5  concurrently, a powered toothbrush  1000  according to one embodiment of the present invention is illustrated. The powered toothbrush  1000  generally comprises a refill head  100  and a handle  200 . The powered toothbrush  1000  generally extends along a longitudinal axis A-A. As discussed in greater detail below, the refill head  100  and the handle  200  are designed so that the refill head  100  can be repetitively coupled to and uncoupled from the handle  200 . In  FIG. 1 , the powered toothbrush  1000  is illustrated in a state wherein the refill head  100  is not coupled to the handle  200  but is positioned in axial alignment with the handle  200  so that such coupling can be effectuated. In  FIG. 5 , the powered toothbrush  1000  is illustrated in a state wherein the refill head  100  is coupled to the handle  200  according to an embodiment of the present invention. 
         [0021]    While the invention is exemplified herein as a powered toothbrush  1000 , it is to be understood that the inventive concepts discussed herein can be applied to manual toothbrushes that utilize refill heads, or other manual or powered oral care implements, including without limitation tongue cleaners, water picks, interdental devices, tooth polishers and specially designed ansate implements having tooth engaging elements. 
         [0022]    Referring now to  FIGS. 1 ,  3  and  5  concurrently, the handle  200  will be described in greater detail. The handle  200  generally comprises a gripping portion  210  (only a small portion of which is exemplified) and a stem  220 . The stem  220  extends from the gripping portion  210  along the longitudinal axis A-A. 
         [0023]    The gripping portion  210  of the handle  200  is an elongated structure that provides the mechanism by which a user can hold and manipulate the toothbrush  1000  during use. The gripping portion  210  can take on a wide variety of shapes, contours and configurations, none of which are limiting of the present invention. Although not illustrated herein, it should be understood that included within the gripping portion  210  is a power source, a motor and electrical circuitry and components necessary to create a desired motion within the refill head  100 . In the exemplified embodiment, the desired motion is a vibratory motion. The vibratory motion is imparted to the refill head via a vibratory element, such as an eccentric  211 , that is located within the stem  220  and that is rotated via operable coupling to the motor. The gripping portion  210  also includes a user interface that controls the various operations of the toothbrush  1000 , including without limitation turning off and on, changing speeds of the motor, or other functions. The gripping portion  210 , in essence, forms a watertight housing for the aforementioned electrical circuit and mechanical components that need to be protected from moisture. 
         [0024]    In the exemplified embodiment, the motion to be transmitted to the head portion  110  of the refill head  100  is a vibratory motion. In order to generate such vibratory motion, the handle  200  comprises a vibratory element, which in the exemplified embodiment is in the form of an eccentric  211  coupled to a drive shaft  212 . A proximal portion (not illustrated) of the drive shaft  212  is operably coupled to the electric motor (not illustrated) so that the electric motor can rotate the drive shaft  212 . A distal portion  213  of the drive shaft  212  is retained by an annular bearing  214  which is mounted within the stem  220 . As the drive shaft  212  is rotated, the eccentric  211 , due to its off-center center of gravity, generates vibrations that are transmitted to the stem  220  and to the refill head  100  (discussed in greater detail below). While the eccentric  211  is exemplified as a portion of the drive shaft  212  that is radially offset from the longitudinal axis A-A, the invention is not so limited. In other embodiments, the eccentric  211  may be an offset disc or other offset weight, as is known in the art. As can be seen in  FIG. 1 , the stem  220  forms a watertight housing having an internal cavity  215  in which the drive shaft  212  and eccentric  211  are housed. Additional details of a suitable vibratory producing handle, and related structure that can be incorporated into the powered toothbrush  1000  of the present invention, can be found in U.S. Patent Application Publication No. 2010/0269275, Shimoyama et al., published Oct. 28, 2010 (filed as U.S. patent application Ser. No. 12/377,355), the entirety of which is hereby incorporated by reference. 
         [0025]    Referring to FIGS.  1  and  4 - 6 , the stem  220  of the handle  200  will be described in greater detail. The stem  220  comprises an inner surface  223  and an outer surface  224 . Furthermore, the stem  220  comprises a base portion  225  and an alignment plug  226 . The alignment plug  226  extends from a distal end  227  of the base portion  225 . As noted above, the stem  220  extends from the gripping portion  210  along the longitudinal axis A-A. The stem  220  is an elongated structure that has a coupling structure that enables the refill head  100  to be repetitively coupled to and uncoupled from the handle  200 . Specifically, the stem  220  comprises a first locking lug  221  and a second locking lug  222 . In the exemplified embodiment, the first and second locking lugs  221 ,  222  are located on the base portion  225  of the stem  220 . However, the invention is not to be so limited and the first and second locking lugs  221 ,  222  can be otherwise positioned on the stem  220  as desired. 
         [0026]    Each of the first and second locking lugs  221 ,  222  extends radially outward from the outer surface  224  of the stem  220 . Furthermore, the first and second locking lugs  221 ,  222  are arranged on the outer surface  224  of the stem  220  in a circumferentially spaced apart manner. In certain embodiments, the first and second locking lugs  221 ,  222  are spaced 180° apart. However, the invention is not to be so limited and the first and second locking lugs  221 ,  222  can be spaced apart at other angles of circumferential spacing in alternate embodiments. 
         [0027]    The stem  220  further includes a flange  230  extending from the outer surface  224 . The flange  230  comprises an axial slot  231  formed therein. The flange  230  and axial slot  231  are configured for maintaining relative rotational orientation between the handle  200  and the refill head  100  as will be described in detail below. Stated simply, it is an indexing feature. 
         [0028]    Referring now to  FIGS. 1 ,  2  and  5  concurrently, the refill head  100  will be described in greater detail. As noted above, the refill head  100  is capable of being detachably coupled to the handle  200  so that the refill head  100  can be replaced with a new refill head when it becomes worn out and/or no longer effectively cleans a user&#39;s teeth and/or other oral surfaces. By enabling the powered toothbrush  1000  to have refill heads  100  that can be detachably coupled to the handle  200 , the entire powered toothbrush  1000  does not need to be replaced when the tooth engaging elements  111  on the refill head  100  become worn out. 
         [0029]    The refill head  100  generally comprises a head portion  110  and a tubular sleeve  120  that is coupled to the head portion  110 . In the exemplified embodiment, the tubular sleeve  120  and the head portion  110  of the refill head  100  are integrally formed as a single unitary structure using a molding, milling, machining or other suitable process. However, in other embodiments the head portion  110  and the tubular sleeve  120  of the refill head  100  may be formed as separate components which are operably connected at a later stage of the manufacturing process by any suitable technique known in the art, including without limitation thermal or ultrasonic welding, a tight-fit assembly, a coupling sleeve, threaded engagement, adhesion, or fasteners. 
         [0030]    The head portion  110  of the refill head  100  comprises a collection of oral cleaning elements such as tooth cleaning elements  111  extending therefrom for cleaning and/or polishing contact with an oral surface and/or interdental spaces. In the exemplified embodiment, the tooth cleaning elements  111  are generically illustrated. While the collection of tooth cleaning elements  111  is suited for brushing teeth, the collection of tooth cleaning elements  111  can also be used to polish teeth instead of or in addition to cleaning teeth. As used herein, the term “tooth cleaning elements” is used in a generic sense to refer to any structure that can be used to clean, polish or wipe the teeth and/or soft oral tissue (e.g. tongue, cheek, gums, etc.) through relative surface contact. Common examples of “tooth cleaning elements” include, without limitation, bristle tufts, filament bristles, fiber bristles, nylon bristles, spiral bristles, rubber bristles, elastomeric protrusions, flexible polymer protrusions, combinations thereof and/or structures containing such materials or combinations. Suitable elastomeric materials include any biocompatible resilient material suitable for uses in an oral hygiene apparatus. To provide optimum comfort as well as cleaning benefits, the elastomeric material of the tooth or soft tissue engaging elements has a hardness property in the range of A8 to A25 Shore hardness. One suitable elastomeric material is styrene-ethylene/butylene-styrene block copolymer (SEBS) manufactured by GLS Corporation. Nevertheless, SEBS material from other manufacturers or other materials within and outside the noted hardness range could be used. 
         [0031]    The tooth cleaning elements  111  of the present invention can be connected to the refill head  100  in any manner known in the art. For example, staples/anchors, in-mold tufting (IMT) or anchor free tufting (AFT) could be used to mount the tooth cleaning elements. In AFT, a plate or membrane is secured to the brush head such as by ultrasonic welding. The bristles extend through the plate or membrane. The free ends of the bristles on one side of the plate or membrane perform the cleaning function. The ends of the bristles on the other side of the plate or membrane are melted together by heat to be anchored in place. Any suitable form of cleaning elements may be used in the broad practice of this invention. Alternatively, the bristles could be mounted to tuft blocks or sections by extending through suitable openings in the tuft blocks so that the base of the bristles is mounted within or below the tuft block. 
         [0032]    The tubular sleeve  120  comprises an inner surface  123  and an outer surface  124 . The inner surface  123  of the tubular sleeve  120  defines a cavity  130 . When the refill head  100  is detachably coupled to the handle  200  in accordance with the present invention, the stem  220  of the handle  200  is disposed within the cavity  130 . The cavity  130  comprises a proximal axial section  131 , a middle axial section  132  and a distal axial section  133 . The proximal axial section  131  of the cavity  130  includes an opening  150  for receiving the stem  220  of the handle  200 . Thus, the opening  150  forms a passageway into the cavity  130 . The middle axial section  132  tapers from the proximal axial section  131  to the distal axial section  133 . The distal axial section  133  has a narrowed transverse cross-sectional profile relative to the proximal and middle axial sections  131 ,  132 . 
         [0033]    The tubular sleeve  120  and the head portion  110  of the refill head  100  are generally formed of a material that is rigid, such as a moldable hard plastic. Suitable hard plastics include polymers and copolymers of ethylene, propylene, butadiene, vinyl compounds and polyesters such as polyethylene terephthalate. Of course, the invention is not to be so limited and other materials can be used to form the tubular sleeve  120  and head portion  110  of the refill head  100 . 
         [0034]    Referring to  FIGS. 1-5  concurrently, the tubular sleeve  120  further comprises a first resilient zone  135   a  and a second resilient zone  135   b.  Each of the first and second resilient zones  135   a,    135   b  is formed by sealing an aperture  129   a,    129   b  in the tubular sleeve  120  with a resilient material. The resilient material that forms the first and second resilient zones  135   a,    135   b  can be an elastomeric material, such as a suitable thermoplastic elastomer (TPE) or other similar materials used in oral care products. The elastomeric material of the first and second resilient zones  135   a,    135   b  may have a hardness durometer measurement ranging between A13 to A50 Shore hardness, although materials outside this range may be used so long as the first and second resilient zones  135   a,    135   b  can be compressed as described herein below. A suitable range of the hardness durometer rating is between A25 to A40 Shore hardness. Of course, the invention is not limited to having resilient zones  135   a,    135   b  formed as described above and in other embodiments the resilient zones  135   a,    135   b  can be formed by simply thinning out (or otherwise pre-weakening) regions of the tubular sleeve  120  so that those regions of the tubular sleeve  120  are compressible. 
         [0035]    The first and second resilient zones  135   a,    135   b  are circumferentially spaced apart from one another along the circumference of the tubular sleeve  120 . As can be seen in  FIG. 3 , in the exemplified embodiment, each of the resilient zones  135   a,    135   b  takes on a generally elliptical shape. However, the invention is not to be so limited and, in other embodiments, the resilient zones  135   a,    135   b  can take on other shapes as desired. The first and second resilient zones  135   a,    135   b  are capable of being compressed radially inwardly in order to facilitate coupling and uncoupling of the refill head  100  to the handle  200  (described in greater detail below). Due to the resilient nature of the first and second resilient zones  135   a,    135   b,  even when the first and second resilient zones  135   a,    135   b  are compressed radially inward, the first and second apertures  1291 ,  129   b  remain sealed by the resilient material. 
         [0036]    The tubular sleeve  120  comprises an axial rib  127  that protrudes inwardly from the inner surface  123  of the tubular sleeve  120 . During coupling of the refill head  100  to the handle  200 , the axial rib  127  mates with the axial slot  231  in the flange  230  of the stem  220 . As a result, the inner surface  123  of the tubular sleeve  120  and the outer surface  224  of the stem  220  are keyed in order to maintain relative rotational orientation between the stem  220  and the tubular sleeve  120 . 
         [0037]    The refill head  100  further comprises a resilient collar  140  that is positioned within the cavity  130 . More specifically, the resilient collar  140  is located within the cavity  130  in transverse alignment with the first and second resilient zones  135   a,    135   b.  The resilient collar  140  is preferably formed of a deformable thermoplastic material, such as polypropylene. While thermoplastics, such as polypropylene, are typically considered rigid or hard plastics, the thickness of the resilient collar  140  is selected so that the resilient collar  140  has the desired degree of compressibility and resiliency. In other words, by balancing the material selected and its thickness, the resilient collar  140  can be constructed so as to sufficiently rigid from a structural standpoint to axially retain the stem  220  within the cavity  130  while still allowing for the required resiliency for locking and unlocking. 
         [0038]    During assembly, the resilient collar  140  is placed into the bottom of the tubular sleeve  120  and then snap fitted therein. More specifically, the resilient collar  140  is positioned within the proximal axial section  131  of the cavity  130  of the tubular sleeve  120  of the refill head  100 . The resilient collar  140  comprises a first locking lug  141  and a second locking lug  142  extending radially inward into the cavity  130  from an inner surface  143  of the resilient collar  140 . The first and second locking lugs  141 ,  142  are circumferentially spaced apart from one another. As discussed in greater detail below, when the refill head  100  is detachably coupled to the handle  200 , the first and second locking lugs  141 ,  142  of the resilient collar  140  are radially aligned with and operably mate with the first and second locking lugs  221 ,  222  of the stem  220 , respectively. 
         [0039]    The tubular sleeve  120  comprises an annular retaining flange  128  protruding inwardly towards the cavity  130  from the inner surface  123  of the tubular sleeve  120 . The annular retaining flange  128  axially retains the resilient collar  140  in position within the tubular sleeve  120 . The annular retaining flange  128  protrudes inwardly towards the cavity  130 , thereby preventing axial removal of the resilient collar  140  from the tubular sleeve  120 . 
         [0040]    Referring to  FIGS. 4-6  concurrently, the coupling and uncoupling of the refill head  100  to the handle  200  will be described. When it is desired to attach the refill head  100  to the handle  200 , the refill head  100  is positioned above and in axial alignment with the handle  200 . The handle  200  is then axially translated so that the stem  220  begins to be inserted into the cavity  130 . If necessary, the handle  200  is then rotated relative to the refill head  100  until the axial rib  127  comes into alignment with the axial slot  231  that is formed in the flange  230  of the stem  220 . As can be seen in  FIG. 6 , upon the axial rib  127  mating with the axial slot  231 , the desired relative rotational orientation between the stem  220  and the tubular sleeve  120  is achieved and maintained. Aligning the axial rib  127  with the axial slot  231  formed in the flange  230  of the stem  220  also ensures that the first and second locking lugs  141 ,  142  of the resilient collar  140  are radially aligned with the first and second locking lugs  221 ,  222  of the stem  220  during the coupling of the refill head  100  to the handle  200 . Such radial alignment facilitates the locking of the refill head  100  to the handle  200  during assembly. 
         [0041]    After alignment of the axial rib  127  with the axial slot  231  is achieved, the stem  220  continues to be inserted into the cavity  130  by axially translating (i.e., sliding) the stem  220  into the cavity  130  of the refill head  100 . As a result, the first and second locking lugs  141 ,  142  of the resilient collar  140  are forced to flex outwardly and snap past the first and second locking lugs  221 ,  222  of the stem  220 , thereby achieving a locked state. Thus, insertion of the stem  220  into the cavity  130  automatically achieves locking engagement between the refill head  100  and the handle  200  because the resilient collar  140  is biased into the locked state.  FIG. 4  illustrates the locking engagement between the first and second locking lugs  141 ,  142  of the resilient collar  140  and the first and second locking lugs  221 ,  222  of the stem  220 . 
         [0042]    Referring to  FIGS. 1 and 5  concurrently, the structural arrangement of the powered toothbrush  1000  when the refill head  100  is detachably coupled to the handle  200  will be described. When the refill head  100  is coupled to the handle  200 , the alignment plug  226  of the stem  220  extends into the distal axial section  133  of the cavity  130 . Furthermore, when the refill head  100  is coupled to the handle  200 , only a distal section  229  of the outer surface  224  of the stem  220  is in intimate surface contact with the inner surface  123  of the tubular sleeve  120 . By having the distal section  229  in surface contact with the inner surface  123  of the tubular sleeve  120 , vibrations from the stem  220  can be transmitted directly to the refill head  100 . It is advantageous to minimize the amount of the stem  220  that is in intimate contact with the inner surface  123  of the tubular sleeve  120  in order to prevent vibration from being transmitted to the handle  200 . The loose fitting resilient collar  140  further facilities minimizing the contact between the stem  220  and the tubular sleeve  120  below the distal section  229  of the stem  220  to minimize vibration transmission to the handle  200  to maximize comfort to a user during use of the powered toothbrush  1000 . 
         [0043]    Referring to  FIGS. 4 ,  4 A and  5 , unlocking the refill head  100  from the handle  200  so that the refill head  100  can be detached from the handle  200  will be described. When it is desired to separate or detach the refill head  100  from the handle  200 , the first and second resilient zones  135   a,    135   b  are compressed radially inwardly to alter the configuration (which in the exemplified embodiment is the shape of the transverse cross-sectional profile) of the resilient collar  140 . Specifically, the biased state of the resilient collar  140  is a locked state (shown in  FIG. 4 ) in which the first and second locking lugs  141 ,  142  of the resilient collar  140  operably mate with the first and second locking lugs  221 ,  222  of the stem  220  to prevent axial separation of the refill head  100  form the handle  200 . When the first and second resilient zones  135   a,    135   b  are compressed radially inwardly, the first and second resilient zones  135   a,    135   b  press against the resilient collar  140 . Due to the resiliency of the resilient collar  140 , compressing the first and second resilient zones  135   a,    135   b  alters the resilient collar  140  into the unlocked state (shown in  FIG. 4A ) in which the first and second locking lugs  141 ,  142  of the resilient collar  140  are retracted radially outward and out of operable mating with the first and second locking lugs  121 ,  122  of the stem  120 . Once the first and second locking lugs  141 ,  142  of the resilient collar  140  are out of operable mating with the first and second locking lugs  121 ,  122  of the stem  120 , the refill head  100  can be detached from the handle  200  by pulling the refill head  100  axially away from the handle  200 . 
         [0044]    The locking/unlocking feature of the resilient collar  140  is achievable in part due to the shape of the resilient collar  140 . More specifically, the resilient collar  140  has an oval transverse cross-sectional profile in both the locked state and the unlocked state, wherein the oval transverse cross-sectional profile has a major axis A maj  and a minor axis A min . The major axis A maj  and the minor axis A min  of the oval transverse cross-sectional profile of the resilient collar  140  change or swap direction/position depending upon whether the resilient collar  140  is in the locked or unlocked state. 
         [0045]    The inner surface  123  of the tubular sleeve  120  has a circular transverse cross-sectional profile having a diameter that is substantially equal to a length of the major axis A maj  of the oval transverse cross-sectional profile of the resilient collar  140 . Thus, a portion of the inner surface  123  of the tubular sleeve  120  is in contact with a portion of the resilient collar  140 . Referring first to  FIG. 4 , in the locked state the resilient collar  140  has an oval transverse cross-sectional profile having a major axis A maj  that is in radial alignment with the first and second resilient zones  135   a,    135   b  of the tubular sleeve  120  and a minor axis A min  that is in radial alignment with the first and second locking lugs  121 ,  122  of the stem  120 , the major axis being greater than the minor axis. Thus, in the locked state ( FIG. 4 ) the portion of the inner surface  123  of the tubular sleeve  120  that is in contact with the resilient collar  140  is the first and second resilient zones  135   a,    135   b.    
         [0046]    Because the first and second resilient zones  135   a,    135   b  are in contact with the resilient collar  140  when the resilient collar  140  is in the locked state, compressing the first and second resilient zones  135   a,    135   b  also results in compression of the resilient collar  140 . More specifically, as a user compresses the first and second resilient zones  135   a,    135   b  (and thus the resilient collar  140 ), the resilient collar  140  becomes altered from the locked state to the unlocked state. Altering the resilient collar  140  form the locked state to the unlocked state results in the transverse cross-sectional profile of the resilient collar  140  changing so that the major axis A maj  and the minor axis A maj  swap with one another. In other words, in the unlocked state ( FIG. 4A ), the transverse cross-sectional profile of the resilient collar  140  is modified to comprise a minor axis A min  that is in radial alignment with the first and second resilient zones  135   a,    135   b  of the tubular sleeve  120  and a major axis A maj  that is in radial alignment with the first and second locking lugs  121 ,  122  of the stem  120  due to the inward compression of the first and second resilient zones  135   a,    135   b  of the tubular sleeve  120 . 
         [0047]    Thus, as the first and second resilient zones  135   a,    135   b  are compressed, the resilient collar  140  is modified so that the major axis A maj  is aligned with the first and second locking lugs  141 ,  142 . Changing the location of the major axis A maj  of the resilient collar  140  retracts the first and second locking lugs  141 ,  142  of the resilient collar  140  radially outward and away from the first and second locking lugs  121 ,  122  of the stem  120  in a direction transverse to the longitudinal axis A-A. This creates enough separation between the first and second locking lugs  141 ,  142  of the resilient collar  140  and the first and second locking lugs  121 ,  122  of the tubular sleeve  120 , respectively so that a first gap  136   a  exists between the first locking lug  141  of the resilient collar  140  and the first locking lug  121  of the tubular sleeve  120  and a second gap  136   b  exists between the second locking lug  142  of the resilient collar  140  and the second locking lug  122  of the tubular sleeve  120 . The first and second gaps  136   a,    136   b  are substantially equal in width. Thus, compression of the first and second resilient zones  135   a,    135   b  pulls the first and second locking lugs  141 ,  124  of the resilient collar  140  out of operable mating engagement with the first and second locking lugs  121 ,  122  of the tubular sleeve  120 . The gaps  136   a,    136   b  enable the refill head  100  to be detached from the handle  200  with an upward or axial pulling motion of the refill head  100  relative to the handle  200 . 
         [0048]    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 referenced 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. 
         [0049]    While the foregoing description and drawings represent the exemplary embodiments of the present invention, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope of the present invention as defined in the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other specific forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being defined by the appended claims, and not limited to the foregoing description or embodiments.