Patent Publication Number: US-2011072603-A1

Title: Toothbrush

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of European Patent Convention Application No. 09012375.3, filed on Sep. 30, 2009, the substance of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present disclosure relates to a toothbrush having a brush section and a handle section. More particularly, the present disclosure relates to a handle section that has ergonomic handling features. 
     BACKGROUND OF THE INVENTION 
     International patent application WO 2004/060110 A1 describes an electric toothbrush that distinguishes from previous toothbrushes in that a pair of batteries are provided in a 45 degree offset configuration. It is described that this 45 degree offset configuration of the pair of batteries produces a natural shape to a handle that is advantageous for a user to hold. This offset positioning of the pair of batteries allows for a more user-friendly handle design. 
     It is a desire of the present disclosure to provide a toothbrush that can be held in an ergonomic manner and that is improved over the known toothbrushes or at least provides an alternative to the known toothbrushes. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a toothbrush includes a brush section and a handle section that longitudinally extends between a first end distal to the brush section and a second end proximal to the brush section. The handle section includes at least three longitudinally extending edges on the outer surface of the handle section defining at least three longitudinally extending surface areas that each span between two neighboring edges. The at least three edges each twist in the longitudinal direction by a total twist angle lying in the range of from about 80 degrees to about 100 degrees. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the specification concludes with claims which particularly point out and distinctly claim the subject matter that is regarded as the invention, it is believed the various embodiments will be better understood from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an electric toothbrush according to one embodiment; 
         FIG. 2  is a side view of the toothbrush of  FIG. 1 ; 
         FIG. 3  is a front view of the toothbrush of  FIG. 1 ; 
         FIG. 4A  is a cross sectional view taken along line A-A of the toothbrush of  FIG. 3 ; 
         FIG. 4B  is a cross sectional view taken along line B-B of the toothbrush of  FIG. 3 ; 
         FIG. 4C  is a cross sectional view taken along line C-C of the toothbrush of  FIG. 3 ; 
         FIG. 4D  is a cross sectional view taken along line D-D of the toothbrush of  FIG. 3 ; 
         FIG. 5A  is a schematic view of a toothbrush according to one embodiment being held by a left-handed user in a holding position in which the toothbrush is switched on or off; and 
         FIG. 5B  is a schematic view of a toothbrush according to one embodiment being held by a right-handed user in a holding position adopted during brushing operation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to the present disclosure, a toothbrush has a brush section (which can be realized as a replaceable brush section) and a handle section. The handle section extends in a longitudinal direction between a first end that is distal to the brush section and a second end that is proximal the brush section. At least three edges are present on the outer surface of the handle section. In one embodiment, four edges are present on the outer surface of the handle section. The edges extend longitudinally, but not necessarily from the first end to the second end, but the edges could smooth out, for example, towards the second end. The edges define surface areas, which surface areas each span between a pair of neighboring edges. The edges twist in the longitudinal direction by a total twist angle lying in the range of from about 80 degrees to 100 degrees, in one embodiment by a total twist angle of about 90 degrees. This twist of from about 80 degrees to about 100 degrees happens over the full longitudinal extension of the edges; hence, for sake of clarity, the twist of from about 80 degrees to about 100 degrees is the total twist angle of the edges. In the embodiment with four edges (which in turn define four surface areas spanning between each pair of neighboring edges), the rotation of the toothbrush by about 90 degrees (in order to brush the various tooth surfaces of the human denture) is effectively supported by the outer form of the handle section. 
     If the handle section has four edges that twist by about 90 degrees, the edges might be arranged at a 90 degree distance in a plane perpendicular to the longitudinal extension axis of the toothbrush. The four edges define four surface areas on the outer surface of the handle section. Four surface areas support to hold the toothbrush such that bristles extending from a brush head provided at the brush section either extend upwards, downwards or to one of the sides with respect to the user. In one embodiment, if the edges are arranged at a 90 degree distance the user can just turn the toothbrush from a given position to the next position by a 90 degree rotation. If the outer surface is symmetric with respect to these 90 degree turns, the holding feel is identical for the four holding positions. 
     In contrast to what is described by WO 2004/060110 A1, it was surprisingly found that a twist of the handle section by about 90 degrees instead of 45 degrees provides for optimal ergonomic holding comfort and supports the user in the precise orientation of the toothbrush. 
     In an embodiment of the proposed toothbrush, the handle section is longitudinally divided into a first handle section part and a second handle section part adjoining the first handle section part, where the first handle section part lies proximal to the brush section. The edges twist essentially only in the second handle section part. Thus, a first handle section part is provided that has a certain structure of the outer surface but gives the user a clear feeling about the orientation of the toothbrush as the surface areas spanning between the edges in the first handle section part do not twist. In one embodiment, a switch button for switching on or off the toothbrush (in a case in which the toothbrush is realized as an electrical toothbrush) is arranged on one of the surface areas of the first handle section part. In another embodiment, one of the surface areas in the first handle section parts is provided in alignment with the brushing orientation of a brush head provided at the brush section, i.e. the center surface normal vectors of the brush head and of the surface area being in alignment lie in a single plane. 
     In a further embodiment, the surface areas spanning between the edges are convex in the planes perpendicular to the longitudinal extension axis of the toothbrush. In a refinement of this embodiment, the convexity may vary as a function at least a parameter that is one of the longitudinal position and/or the radial distance of the surface to the longitudinal extension direction. This allows for providing an optimization of the outer surface of the handle section for ergonomic holding. 
     In yet another embodiment, the handle section has a waist section, which waist section is in particular arranged at a longitudinal position that would coincide with the position of the thenar and hypothenar of the holding hand of a user. In particular, the waist section is provided at a longitudinal distance of about 8 cm-12 cm from the second end of the handle section or from a thumb resting position. 
     In an even further embodiment, one of the surface areas spanning between the edges is realized by an attachable part. This allows providing a different material or a differently colored material for one of the surfaces, which material may enhance the holding properties or may improve the identification of the brushing direction by the user. Instead of an attachable part, one of the surface areas may be provided by an (additional) injection molding process by which the surface area is provided. 
     In another embodiment, the angular position of the edges varies as a function of the longitudinal position in a non-constant manner. In particular, the angular position of the edges changes faster towards the first end of the handle section. 
     Generally it is to be stated that even though the following description of an exemplary embodiment of a toothbrush as disclosed herein refers to a powered toothbrush, the proposed toothbrush and its respective features are independent from the toothbrush being a powered toothbrush or a manual toothbrush. Hence, it should be understood that the term “toothbrush” as used herein in general encompasses both powered toothbrushes and manual toothbrushes. 
     In the different embodiments from  FIGS. 1 to 5 , the same elements are characterized with the same reference numerals. 
       FIG. 1  is a perspective view of a powered toothbrush  1 . The toothbrush  1  includes a brush section  10  and a handle section  100 . The brush section  10  comprises a neck section  11  and a brush head  12  at which a bristle field  13  is arranged. The bristle field  13  comprises a plurality of bristle tufts that extend from a bristle carrier into a brushing direction. The handle section  100  extends from a first end  150  distal to the brush section  10  to a second end  151  proximal the brush section  10 . In one embodiment, the handle section  100  has a longitudinal length of from about 13 cm to about 20 cm, and in another embodiment from about 14 cm to about 16 cm. 
     As can be seen in  FIGS. 1-3 , the handle section  100  has an outer surface that is irregular insofar as the outer surface has four edges  101 ,  102 ,  103 , and  104  that extend generally in the longitudinal extension direction of the handle section  100 . The four edges  101 ,  102 ,  103 , and  104  can be realized as rounded edges for ease of manufacture. The four edges  101 ,  102 ,  103 , and  104  do not cross each other and are here arranged with a constant circumferential distance, i.e. the edges  101 ,  102 ,  103 , and  104  are arranged such that the first edge  101  has an angular distance in circumferential direction of 90 degrees to the second edge  102 , the second edge  102  has an angular distance in circumferential direction to the third edge  103  of 90 degrees, the third edge  103  has an angular distance in circumferential direction to the fourth edge  104  of 90 degrees, and the fourth edge  104  has an angular distance in circumferential direction to the first edge  101  of 90 degrees. As such, the four edges  101 ,  102 ,  103 , and  104  define four surface areas  110 ,  111 ,  112  (not shown in  FIG. 1 ), and  113  that each extend between two neighboring edges, i.e. the first surface area  110  spans between the first edge  101  and the second edge  102 , the second surface  111  spans between the second edge  102  and the third edge, the third surface area  112  spans between the third edge  103  and the fourth edge  104 , and the fourth surface area  113  spans between the fourth edge and the first edge  101 . 
     As shown in  FIG. 3 , the four surface areas  110 ,  111 ,  112 , and  113  are slightly convex in a plane perpendicular to the longitudinal extension axis L. The convexity may change as a function of the longitudinal position. In another embodiment, the surface areas  110 ,  111 ,  112 , and  113  may be slightly concave in at least a certain longitudinal range of the handle section  100 . A handle section  100  having four surface areas  110 ,  111 ,  112 , and  113  that are arranged at a homogeneous 90 degrees distance is optimized for holding the toothbrush  1  in four rotation positions that differ by 90 degrees and thus is optimized for brushing the teeth surfaces in the four quadrants of the human denture. 
     With respect to the embodiment shown in  FIG. 1 , the four edges  101 ,  102 ,  103 , and  104  twist around the longitudinal extension direction of the handle section  100  by 90 degrees in a counter-clockwise direction when viewed from the brush section  10  downwards onto the handle section  100 . In the shown embodiment, the 90 degree angular distance in circumferential direction is preserved in longitudinal direction. Nevertheless, it is also contemplated to change the angular distance between the four edges  101 ,  102 ,  103 , and  104  as a function of the longitudinal position in order to, for example, optimize the ergonomic holding properties of the handle section  100 . In one example, the twist of the edges could lie in a range of from about 80 degrees to about 100 degrees, in another example between from about 85 degrees and about 95 degrees. As the handle section  100  of the shown exemplary toothbrush  1  is to be held in four different orientations, a constant angular distance of 90 degrees between each pair of neighboring edges may be provided. In another embodiment, the four angular distance values between neighboring edges could be 80 degrees, 100 degrees, 80 degrees, and 100 degrees. Even though the edges  101 ,  102 ,  103 ,  104  extend in the shown embodiment from the first end  150  to the second end  151  of the handle section  100 , it is to be understood that the edges could only be present on a certain longitudinal section of the handle section, which longitudinal section in general should cover at least about 80 percent of the length of the handle section  100 . For example, the four edges  101 ,  102 ,  103 , and  104  could gradually taper off towards the second end  151  of the handle section such that the cross section perpendicular to the longitudinal extension axis would gradually change from a four-cornered cross section to a circular, oval or ellipsoidal cross section. 
     The toothbrush  1  as shown also comprises a switch  190  for switching on and off a movement of the brush section  113  (a drive mechanism and a power supply are arranged in the handle section  100  as is known in the art). Further, the handle section  100  may comprise illuminated icons  191  as is schematically shown. The icons may be used to show a certain function that is currently performed during operation of the toothbrush  1  to the user or an icon  191  may be used to indicate a charge status of a rechargeable battery used as power supply for the drive system. In the shown embodiment, the switch  190  is arranged on a surface area  110  that is in alignment with the brush head orientation. The handle section  100  may also comprise a ribbed area  192  that can be arranged longitudinally above the switch  190  to provide a resting place for the thumb of the hand of a user while holding the toothbrush  1  during brushing operation. 
     As can be seen in  FIG. 1 , the four edges  101 ,  102 ,  103 , and  104  longitudinally extend from the first end  150  of the handle section  100  that is distal to the brush section  10  to the second end  151  of the handle section  100  that is abutting the brush section  10 . In this example, the four edges do not twist in a first handle section part  100 A that is proximal the brush section  10 . Instead, the four edges  101 ,  102 ,  103  and  104  twist in a second handle section part  100 B. The switch  190  is arranged on the first handle section part  100 A, while the illuminated icons  191  are arranged in the upper part of the second handle section part  100 B that abuts the first handle section part  100 A. Thus, all the electronic parts that relate to the switch  190  and the icons  191  can be arranged on an untwisted single circuit board, which circuit board is arranged in a hollow inner cavity of the handle section  100  that also accommodates the drive system and the power source. 
       FIG. 2  is a side view of the toothbrush  1  in  FIG. 1 . It is indicated that the first handle section part  100 A corresponds to a first length L 1 , while the second handle section part  100 B corresponds to a second length L 2 . In one embodiment, the first length L 1  is about half as long as the second length L 2 . In another embodiment, the handle section  100  has a longitudinal length of about 15 cm, while the first handle section part  100 A has a length of from about 3 cm to about 5 cm and the second handle section part  100 B consequently has a length of from about 12 cm to about 10 cm. It is also indicated that the brushing orientation of the brush head  12  that may be defined by a center normal S 1  is in alignment with the orientation of the switch arranged on the surface area  110 A, which surface area  110 A has a center normal S 2  that essentially coincides with the center normal S 1  of the brush head  12 . Thus, positioning the thumb on the surface part  110 A gives the user a clear feeling about the orientation of the brush head  12 . 
     In can also be seen in  FIGS. 1-3  that the handle section  100  has a waist section  100 C that has a lower diameter (for example, measured between two opposing edges) than the parts of the handle section  100  above and below the waist section  100 C (where “above” and “below” is to be understood with respect to the longitudinal extension axis L). The waist section  100 C supports the ergonomic holding properties of the handle section  100 . In particular, as will be explained in more detail with reference to  FIGS. 5A and 5B , the waist section  100 C effectively suppresses that the handle section  100 —even if wet and slippery during operation due to a mixture of water, toothpaste and saliva covering the outer surface—slips through the holding hand of the user, as the waist section  100 C provides almost a form-fitting counterpart to the hypothenar and thenar of the hand of the user. In an embodiment, where the length of the handle section  100  is about 15 cm, the center of the waist section  100 C may be arranged at a distance of from about 4 cm to about 6 cm measured from the first end  150  of the handle section  100  that is distal to the brush section  10  to the center of the waist section  100 C. 
       FIG. 3  is a front view of the toothbrush  1  as shown in  FIG. 1  and  FIG. 2 . The longitudinal extension axis L is indicated. Further, four cutting planes A-A, B-B, C-C, and D-D that are perpendicular to the longitudinal extension axis L are indicated. Respective cross sectional cuts along the indicated planes perpendicular to the longitudinal extension axis L are shown in  FIGS. 4A-4D  and will be described in the following. The  FIGS. 4A-4D  do not show the inner features of the toothbrush, i.e. the cross sectional cuts do not show the drive shaft, drive system, circuit boards, power supply, gear section etc. for sake of simplicity and visibility of the features of the handle section. 
       FIG. 4A  shows a cross sectional cut through the toothbrush  1  shown in  FIG. 3  taken along the plane A-A which is perpendicular to the longitudinal extension axis L of the toothbrush  1 . The plane A-A cuts through the second end of the handle section that abuts the brush section. The viewing direction is from the brush section downwards to the first end of the toothbrush that is distal to the brush section. In this top-down view it can be seen that the angular positions of the four edges  101 ,  102 ,  103 , and  104  are essentially constant in the first handle section part  100 A (see  FIG. 2 ) until at least the widest section that coincides with the center of the switch  190  shown in  FIG. 3  (a cut through this widest section of the first handle section part is shown in  FIG. 4B ). Insofar as the outer surface of the second handle section part  100 B (see  FIG. 2 ) is visible in  FIG. 4A , it can be seen that the angular positions of the edges  101 ,  102 ,  103 , and  104  twist in a counter-clockwise direction. In total, the angular positions of all four edges  101 ,  102 ,  103 , and  104  twist by 90 degrees from the second end of the handle section to the first end of the handle section. The housing  130  has a certain thickness and an inner cavity  180 . The handle section may be made from a plastic material such as ASA (acrylonitrile styrene acrylate), ASB (acrylonitrile butadiene styrene) or PP (polypropylene) that has some medium thickness at the level of plane A-A. It can also be seen that in the shown embodiment that the housing  130  comprises an attachable part  131  that forms the surface area  110  that spans between the first and second edges  101  and  102 . Via this attachable part  131 , the surface area  110  spanning between the first edge  101  and the second edge  102  can be made from a different material (for example having enhanced grip properties) or from a differently colored material for easier identification of the front side of the toothbrush. 
       FIG. 4B  shows a cross sectional cut through the toothbrush shown in  FIG. 3  taken along the plane B-B which is perpendicular to the longitudinal extension axis L of the toothbrush. The plane B-B cuts through the center of the switch  190  shown in  FIG. 3 . The viewing direction is from the brush section downwards to the first end of the toothbrush that is distal to the brush section. It can be seen that the thickness of the housing  130  of the handle section is larger than in plane A-A. In case the housing is manufactured by a plastic injection molding process, the essentially cylindrical inner cavity  180  of the housing is defined by a core provided in the injection mold. In such a manufacturing process, the thickness variations of the housing  130  and thus the difference between the widest housing diameter (provided at plane B-B) and the smallest housing diameter (provided in the center of the waist section  100 C shown in  FIG. 3  with cross sectional cut shown in  FIG. 4C ) is defined by the parameters of the plastic injection molding process. In another embodiment, widened sections of the handle section could be achieved by attachable parts. 
       FIG. 4C  shows a cross sectional cut through the toothbrush  1  shown in  FIG. 3  taken along the plane C-C which is perpendicular to the longitudinal extension axis L of the toothbrush. The plane C-C cuts through the center of the waist section  100 C shown in  FIG. 3 . The viewing direction is from the brush section downwards to the first end of the toothbrush that is distal to the brush section. It can be seen that the housing  130  has a low thickness, while the inner cylindrical cavity  180  formed in the housing has essentially the same diameter as in plane B-B (a small difference may occur due to a slight conical shape of the core, which conical shape is provided for easy removal of the core from the housing at the end of the injection molding process). The four edges  101 ,  102 ,  103 , and  104  twist by about 55 degrees from the plane C-C to the first end of the handle section (plane D-D), which shows that the incremental twist per longitudinal length increases towards the first end of the handle section in order to optimally follow the anatomical contour of the hand of a user. 
       FIG. 4D  shows a cross sectional cut through the toothbrush shown in  FIG. 3  taken along the plane D-D which is perpendicular to the longitudinal extension axis L of the toothbrush. The plane D-D cuts through the first end of the handle section. The viewing direction is from the brush section downwards to the first end of the toothbrush that is distal to the brush section. It can be seen that a widened section at the first end of the toothbrush is realized by splitting the housing at a certain level into an outer shell  130 A and an inner sleeve  130 B; a further core can be provided in the injection mold to achieve this. 
       FIG. 5A  schematically shows a toothbrush  1  as proposed in accordance with the exemplary embodiment as previously discussed when being held by a user&#39;s hand  200  (here: a left-handed user) in a first holding position in which the user switches the toothbrush  1  on or off (via a switch that is here covered by the thumb  201  of the user). The thumb  201  rests on the surface area  110 A on which the switch is provided. The orientation of the surface area  110 A is arranged in alignment with the brushing orientation of the brush head  12 . The index finger  202  rests on the surface area  112 A that is opposite to the surface area  110 A. The hypothenar  210  rests against the surface area  112 B that is essentially twisted by 90 degrees in anti-clockwise direction when seen from the brush section  10  downwards. The middle finger  203  partially grips around surface area  112 A and surface area  111 A, while the ring finger  204  and the little finger  205  press against the twisted surface area  110 B in order to fix the toothbrush  1  between these two fingers and the hypothenar  210 . As can be seen, the twist of the surface areas  110 ,  111 ,  112 , and  113  thereby optimally follows the natural positions of the thumb  201 , the fingers  202 ,  203 ,  204 , and  205  and the hypothenar  210 . Thus, the toothbrush  1  as proposed provides very ergonomic holding properties. It further provides optimal guidance to the user for rotating the toothbrush  1  by 90 degree steps around the longitudinal extension axis due to the provision of four surface areas  110 ,  111 ,  112 ,  113  that are arranged with a 90 degree angular offset in circumferential direction. Additionally, as can be easily understood, the twist of the edges  101 ,  102 ,  103 , and  104  (and hence of the surface areas spanning between the edges) by 90 degrees provides optimal lying properties (i.e. in a position when a user puts the toothbrush  1  horizontally on a bathroom shelf) as, for example, the upper surface area  112 A provides a first lying surface and the surface area  111 B that is twisted by 90 degree provides a second lying surface so that the toothbrush  1  lies relative stable in the horizontal position. Hence, an additional roll stopper element is gratuitous. 
     In a somewhat tighter holding position, which is adopted during the brushing operation, in which the thumb is moved upwards (for example, onto the ribs  192  as shown in  FIG. 3 ), the thenar  211  of the left hand  200  rests against the twisted portion of surface  113 B in the waist section  100 C of the handle section  100 , while the hypothenar  210  presses against the twisted surface area  112 B at the first end of the handle section  100 . The middle finger  203 , the ring finger  204 , and the little finger  205  then press against the twisting surface  110 A. 
       FIG. 5B  shows an embodiment of a proposed toothbrush with a tight holding position as is being adopted by a right-handed user during the brushing operation. Here, the thumb  201  of the hand  200  of the right-handed user lies against the surface area  110 A, the index finger  202  embraces the toothbrush  1  and lies against the surfaces  112 A and  113 A. The middle finger  203 , the ring finger  204  and the little finger  205  follow the twist of the surface  113 B. The thenar  211  of the right hand follows the twist of the surface area  110 B essentially in the waist section  100 C of the handle section (which thus provides for an ergonomically optimal indentation of the handle section  100 ), while the hypothenar  210  presses against the lower part of the twisted surface area  111 B. The twist of 90 degrees, thus ergonomically follows the curves of the thenar  211  and the hypothenar  210  of a right-handed user and also provides for the optimal grip position of the thumb and fingers. As the thenar  211  and the hypothenar  210  closely embrace the waist section  100 C along the twisting surfaces  110 B and  111 B, the waist section  100 C effectively ensures a tight hold of the toothbrush  1  even if the outer surface of the handle section  100  is covered with a mixture of toothpaste, water, and saliva. Handle sections having a smooth cross section such as a circular cross section and/or that have no waist section tend to move through the holding hand due to the pressure applied on the toothbrush in longitudinal direction during brushing operation. 
     The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”. 
     Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.