Abstract:
A toothbrush and toothbrush head with a bristle carrier, on which a bristle section featuring a multitude of filaments is arranged. At least one filament is provided with a taper on its free end with a shape other than a rotationally symmetrical shape to preserve a high flexural strength of the filament in one direction. The taper is a flat-pressed scarfing such that the filament has a greater flexural strength with respect to a first lateral axis than with respect to a second lateral axis perpendicular to the first lateral axis in the region of the taper. The flat-pressed scarfing at the point of the filament improves penetration into the interdental spaces, while the higher geometrical moment of inertia of the wide side reduces the bending of the filament during use.

Description:
TECHNICAL FIELD 
       [0001]    The present invention pertains to a toothbrush head with a bristle carrier, on which a bristle section is arranged that comprises a multitude of filaments, wherein at least one filament is provided with a taper toward its free end, as well as to a toothbrush with such a toothbrush head. 
       BACKGROUND 
       [0002]    It was already proposed to realize toothbrushes with bristles, the filaments of which have a smaller diameter on their free end than at their base. This usually conical or nose cone-shaped taper is intended to make it easier for the filaments to penetrate into and to better clean the interdental spaces. However, the taper of the filaments results in a reduced flexural strength that prevents or impairs this penetration. The geometrical moment of inertia of the filaments is reduced such that the filaments are excessively soft in the direction of the interdental space and can no longer penetrate therein. 
         [0003]    JP 11-075939 describes a bristle arrangement for toothbrushes, in which such elements are provided with a taper toward their point, but this bristle arrangement ultimately cannot ensure an actually improved penetration into the interdental spaces. Furthermore, US 2005/0172436 proposes to provide the bristle clusters consisting of a multitude of filaments with a sloped head, in which the individual filaments have a graduated length. However, this does not actually simplify the penetration into the interdental spaces as long as the individual filaments themselves are not provided with a sufficient point or taper on their free ends. 
       SUMMARY 
       [0004]    The present description features an improved toothbrush head able to achieve an improved penetration of the filaments into the interdental spaces. 
         [0005]    In one aspect, the invention proposes to provide the taper on the point of the at least one filament with a shape other than a rotationally symmetrical shape so as to preserve a higher flexural strength of the filament in one direction. According to various embodiments, the taper is realized in the form of a flat-pressed scarfing such that the tapered region of the filament has a greater flexural strength with respect to a first lateral axis than with respect to a second lateral axis extending perpendicular to the first lateral axis. In the region of the flat-pressed scarfing, the filament cross section has a longer lateral axis or long main axis, as well as a shorter lateral axis or a short main axis, respectively, such that the filament has different geometrical moments of inertia with respect to both aforementioned axes in the region of the scarfing. The flat-pressed scarfing at the point of the filament simplifies the penetration into the interdental spaces, wherein the higher geometrical moment of inertia of the wide (non-tapered) side(s) prevent the filament from bending. The flat-pressed scarfing or taper of the filament consequently is limited to one side or two opposite sides of the filament end. In this context, the term flat-pressed refers to a geometric shape of the filament (as described above) rather than its manufacturing method. 
         [0006]    In some implementations, the free end of the filament is scarfed in a wedge-shaped fashion. In this case, the scarfing may be realized with only one sloped surface that extends at an acute angle relative to the longitudinal filament axis. Alternatively, the wedge-shaped scarfing may be realized with two opposite sloped surfaces that are inclined relative to one another by an acute angle such that the free end of the filament has an essentially gable roof-shaped contour. 
         [0007]    In some embodiments, the at least one sloped surface forming the wedge-shaped scarfing of the filament may be planar. Alternatively, the sloped surface may also have a curvature that is preferably uniaxial. According to one advantageous embodiment of the invention, the at least one sloped surface has a convex curvature, wherein the curvature axis may extend perpendicular to the longitudinal filament axis. Alternatively or additionally, the sloped surface may also be convexly curved about an axis that lies in a plane containing the longitudinal filament axis. 
         [0008]    In some cases, the at least one sloped surface may also have a concave curvature, wherein the curvature axis may extend perpendicular to the longitudinal filament axis and/or lie in a plane containing the longitudinal filament axis as described above. 
         [0009]    On the filament end, the flat-pressed scarfing advantageously features a rounding on its edge. Along with easy penetration into interdental spaces, this makes it possible to gently clean the teeth and to prevent injuries to the gums. 
         [0010]    The scarfing may be rounded on the face side, particularly on the end of the filament and/or toward the lateral flanks. According to one advantageous embodiment of the invention, the free end of the filament may feature a blunt crest or a residual surface that transforms into the sloped surface of the scarfing via the aforementioned rounding. The thickness of the blunt crest that remains after the scarfing may, in principle, have different dimensions depending on the required or desired sharpness or the specific application. According to one advantageous embodiment of the invention, the above-described blunt crest may have a thickness of about ⅕ to ⅖ the filament diameter. 
         [0011]    The incline of the aforementioned sloped surfaces relative to one another or relative to the longitudinal filament axis, in principle, may also be chosen differently. In one additional development of the invention, a favorable compromise between a sufficiently strong design that allows the penetration into the interdental spaces and a sufficient residual strength is achieved in that the scarfing has a wedge angle of less than 40°, preferably less than 30°. According to one advantageous embodiment of the invention, the scarfing may be realized with a wedge angle in the range between 15° and 25°. 
         [0012]    The at least one filament may, in principle, have different cross-sectional shapes in its non-scarfed region. According to one advantageous embodiment of the invention, the filament has a circular cross section in the non-scarfed region. 
         [0013]    In order to prevent excessive weakening of the entire filament while still realizing a sufficient taper that improves the penetration into the interdental spaces, an implementation of the invention includes scarfing that extends over approximately ⅛ to 4/8 of the free filament length, preferably ⅜ of the free filament length. 
         [0014]    It is advantageous that the at least one filament is arranged on the bristle carrier with a special alignment, namely such that the flat-pressed scarfing can easily penetrate into the interdental spaces and the filament has a higher flexural strength during wiping movements in the interdental spaces, i.e., parallel to the tooth axis. The at least one filament may be arranged on the bristle carrier, in particular, such that the longer cross-sectional main axis of the scarfing extends parallel to the interdental spaces when the bristle head is properly oriented relative to a row of teeth, namely such that the longitudinal bristle carrier axis or the longitudinal toothbrush axis is essentially positioned tangential to the tooth arch. 
         [0015]    In this case, the filament may be aligned differently on the bristle carrier depending on the design of the toothbrush or the toothbrush head, respectively. 
         [0016]    If the toothbrush head forms part of a manual toothbrush, the filament is advantageously aligned such that the aforementioned longer cross-sectional main axis of the scarfing extends perpendicular to the longitudinal toothbrush axis. If the scarfing is realized with two sloped surfaces that are inclined relative to one another as described above, the thusly formed ridge extends perpendicular to the longitudinal toothbrush axis between the two sloped surfaces. 
         [0017]    Alternatively, the toothbrush head may also be designed for an electric toothbrush. In this case, the scarfed filaments may be arranged and aligned differently depending on the realized axis of motion. According to one advantageous embodiment of the invention, the toothbrush head with its bristle carrier can be driven in a rotatively oscillating fashion about a drive axis that extends parallel to the longitudinal toothbrush axis. In this case, the at least one filament with the flat-pressed scarfing is aligned similar to the aforementioned manual toothbrush. The longer cross-sectional main axis extends perpendicular to the longitudinal toothbrush axis. 
         [0018]    Alternatively, the toothbrush head may also feature a bristle carrier that can be driven in a rotatively oscillating fashion about a lateral axis that extends approximately perpendicular to the longitudinal toothbrush axis. In this case, the at least one filament with the flat-pressed scarfing is advantageously arranged in a sector of the bristle arrangement that is situated in the rotational center position of the bristle carrier on approximately the longitudinal toothbrush axis, wherein the aforementioned sector may extend over different angles that, however, advantageously amount to less than 45°, particularly less than 30°. If the brush head is properly positioned such that the bristle carrier is aligned about tangentially on the dental arch, the filaments arranged in these two sectors or angular sectors carry out a movement that extends at least approximately in the direction of the slot-shaped interdental spaces. In this case, it is advantageous to align the filament such that the longer cross-sectional main axis of its scarfing extends perpendicular to the longitudinal toothbrush axis. 
         [0019]    The bristle arrangement of the toothbrush head may, in principle, include several filament clusters or bristle clusters, wherein other cleaning elements such as wiping strips, plastic wipers or elastomer wipers may also be provided, if so required. At least one filament of at least one bristle cluster is realized as described above. The bristle arrangement advantageously comprises at least one bristle cluster, in which the majority of filaments are realized in the above-described fashion. The filaments within one bristle cluster preferably have an at least approximately identical alignment, i.e., the longer cross-sectional main axis of the scarfing extends in the same direction in all filaments of the bristle clusters. 
         [0020]    Various methods may be considered, in principle, for realizing the scarfing of the at least one filament. According to one preferred embodiment of the invention, the scarfing, particularly the at least one sloped surface and/or the rounding that limits this sloped surface, are produced by grinding the finished bristle carrier fitted with the bristle arrangement. 
         [0021]    These characteristics as well as other characteristics of the invention are not only disclosed in the claims, but also in the following description of preferred embodiments and the corresponding figures, wherein the features may be implemented individually or in the form of sub-combinations regardless of their combination in the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0022]    The figures show: 
           [0023]      FIG. 1 , a side view of a wedge-shaped, scarfed filament of a toothbrush according to one preferred embodiment of the invention; 
           [0024]      FIG. 2 , a side view of the filament according to  FIG. 1  that is turned relative to  FIG. 1  by 90° and shows a top view of one sloped surface of the scarfing; 
           [0025]      FIG. 3 , a side view of a filament with a wedge-shaped scarfing according to another preferred embodiment of the invention; 
           [0026]      FIG. 4 , a side view of the filament according to  FIG. 3  that is turned relative to  FIG. 3  by 90° and shows a top view of one sloped surface of the scarfing; 
           [0027]      FIG. 5 , a side view of a filament with a wedge-shaped scarfing according to another preferred embodiment of the invention; 
           [0028]      FIG. 6 , a side view of the filament according to  FIG. 5  that is turned relative to  FIG. 5  by 90° and shows a top view of one sloped surface of the scarfing; 
           [0029]      FIG. 7 , a side view of a filament with a wedge-shaped scarfing according to another preferred embodiment of the invention, 
           [0030]      FIG. 8 , a side view of the filament according to  FIG. 7  that is turned relative to  FIG. 7  by 90° and shows a top view of one sloped surface of the scarfing; 
           [0031]      FIG. 9 , a cross section through a filament according to one advantageous embodiment of the invention that is scarfed on both sides, wherein the sloped surfaces of the scarfing are convexly curved; 
           [0032]      FIG. 10 , a cross section through a filament according to one advantageous embodiment of the invention that is scarfed on both sides, wherein the sloped surfaces of the scarfing are concavely curved; 
           [0033]      FIG. 11 , a top view of a manual toothbrush with a toothbrush head according to one preferred embodiment of the invention; 
           [0034]      FIG. 12 , a top view of an electric toothbrush with a toothbrush head according to one preferred embodiment of the invention that can be a driven in a rotatively oscillating fashion about a longitudinal axis of the toothbrush, and 
           [0035]      FIG. 13 , a top view of an electric toothbrush with a toothbrush head according to one preferred embodiment of invention, the bristle section of which can be driven in a rotatively oscillating fashion about a lateral axis. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]      FIGS. 1 and 2  show a filament or toothbrush filament  1  that is inserted into a bristle carrier  2  of a toothbrush head that is not illustrated in detail in  FIGS. 1 and 2 . At its base, the filament  1  has a basically cylindrical shape that is scarfed on two sides toward the free end  3  of the filament  1 . In the embodiment according to  FIGS. 1 and 2 , the scarfing  4  on the free end  3  of the filament  1  consists of two opposite sloped surfaces  5  and  6  that are inclined relative to one another by an acute angle and are planar in the embodiment shown. The two sloped surfaces  5  and  6  of the embodiment shown include a wedge angle  7  of approximately 20° to 25°, wherein the two sloped surfaces  5  and  6  are arranged in such a way that a straight ridge results on the free end  3 . 
         [0037]    The scarfing  4  is realized in a blunt fashion at its head in the embodiment shown. The sloped surfaces  5  and  6  do not converge completely into a mathematical line at their free ends  3 , but rather are slightly spaced apart from one another such that a blunt, approximately rectangular head surface  8  is formed. 
         [0038]    According to  FIG. 1 , the edges of the sloped surfaces  5  and  6  on the face side are provided with a rounding  12  that forms the transition between the respective sloped surfaces  5  and  6  and the blunt head surface  8 . The rounding  12  follows the entire outside contour of the sloped surfaces  5 ,  6 . 
         [0039]    In this case, the scarfing  4  is realized in such a way that it extends over a length  10  that approximately amounts to ⅜ the total length  11  of the filament  1  in the embodiment shown. The thickness  9  of the blunt head surface  8  amounts to approximately ¼ the filament diameter in the embodiment shown. 
         [0040]    In an alternative variation of the embodiment shown in  FIGS. 1 and 2 , the scarfing  4  of the filament  1  may also be formed by a single sloped surface  5  that also extends at an acute angle referred to the longitudinal axis of the respective filament  1  as shown in  FIGS. 3 and 4 . The sloped surface  5  is advantageously inclined less acutely relative to the longitudinal filament axis than in a two-sided scarfing. The angle of inclination of the sloped surface  5  once again amounts to approximately 25° in the embodiment according to  FIG. 3  such that the scarfing  4  also has a total wedge angle  7  of approximately 25° in this case. The sloped surface  5  is also realized plane in the embodiment shown in  FIGS. 3 and 4  such that the elliptical shape of the sloped surface  5  shown in  FIG. 4  results in connection with the basically cylindrical shape of the filament  1 . 
         [0041]    The edge of the sloped surface  5  on the face side is also advantageously rounded in the embodiment according to  FIGS. 3 and 4 . The sloped surface  5  also transforms into a blunt head surface  8  via the rounding  12  in the embodiment shown in  FIGS. 3 and 4 . In this case, the arrangement of the sloped surface  5  is also chosen such that the scarfing  4  extends over a total length  10  that approximately amounts to ⅜ the total length  11  of the filament  1  and the thickness  9  of the blunt head surface  8  approximately amounts to ¼ the total thickness of the filament  1 . 
         [0042]    The embodiment shown in  FIGS. 5 and 6  essentially corresponds to the embodiment shown in  FIGS. 1 and 2 , wherein the sloped surfaces  5  and  6  are not planar in this case, but rather concavely curved about an axis extending perpendicular to longitudinal filament axis. According to  FIG. 5 , the wedge angle  7  between the sloped surfaces  5  and  6  decreases toward the free end  3  of the filament  1  in this case. However, it also advantageously lies below 40°, preferably between 15° and 35°. 
         [0043]    In addition, the embodiment according to  FIGS. 7 and 8  essentially also corresponds to the two-sided scarfing shown in the embodiment according to  FIGS. 1 and 2 , but the sloped surfaces  5  and  6  have a convex curvature in this case, namely about a curvature axis that extends perpendicular to the longitudinal filament axis such that the wedge angle  7  between the sloped surfaces  5  and  6  gradually increases toward the free end  3  of the filament. It advantageously also lies between 15° and 35° in this case. 
         [0044]    The sloped surfaces  5  and  6  may alternatively or additionally have a convex or concave curvature about a curvature axis that extends in a plane containing the longitudinal filament axis.  FIG. 9  shows such a convex curvature while  FIG. 10  shows a corresponding concave curvature of the sloped surfaces  5  and  6 . 
         [0045]    The scarfing  4  and the rounding  12  can be produced by grinding the filaments of the finished bristle carrier  2  fitted with the bristle arrangement. 
         [0046]    One common aspect of the filaments  1  shown in  FIGS. 1 to 10  is the essentially wedge-shaped design of the scarfing  4 , wherein the filaments  1  have different geometrical moments of inertia with respect to axes extending at a right angle or perpendicular to one another in the region of the scarfing  4 . The flexural strength of the filament  1  is greater in the direction  13  of the longer cross-sectional main axis (see  FIGS. 2 ,  4 ,  6  and  8 ) than in the direction of the shorter cross-sectional main axis of the scarfing  4 . In other words, this means that the filament  1  is more rigid when it is bent parallel to the sloped surfaces  5  and  6  of the scarfing and less rigid if it is bent perpendicular to the sloped surfaces  5  and  6 . 
         [0047]    The filaments  1  are advantageously aligned such that the direction  13  of the longer cross-sectional main axis extends parallel to the slot-shaped interdental spaces when the toothbrush is properly placed on the denture arch. According to  FIG. 11 , the filaments  1  may be combined into bristle clusters  14  and collectively form a bristle section  15  arranged on the bristle carrier  12  of a toothbrush head  17 . If the toothbrush head  17  forms part of a manual toothbrush as shown in  FIG. 11 , the filaments  1  are aligned perpendicular to the longitudinal toothbrush axis with their longer cross-sectional main axis that extends in the direction  13 . 
         [0048]    This applies similarly if the toothbrush head  17  is intended for an electric toothbrush, in which the bristle carrier  2  can be driven in a rotatively oscillating fashion about a drive axis  18  that extends parallel to the longitudinal toothbrush axis as shown in  FIG. 12 . The rotative oscillating movement about the drive axis  18  is symbolized with an arrow  19 . In this case, the filaments  1  are aligned in the direction  13  extending perpendicular to the longitudinal toothbrush axis and therefore perpendicular to the drive axis  18  with their longer cross-sectional main axis. 
         [0049]    In the electric toothbrush shown in  FIG. 13 , the bristle carrier  2  is essentially realized in a disk-shaped or, e.g., oval fashion and can be driven in a rotatively oscillating fashion about the drive axis  18 . In this case, the drive axis  18  lies approximately perpendicular to the longitudinal toothbrush axis. It is advantageous that only the filaments  1  of a few bristle clusters are scarfed in the above-described fashion in this case. This may concern, in particular, the bristle clusters  20  and  21  that lie in the angular sectors or sectors  22  and  23  of the bristle section  15  that has an approximately cylindrical or, e.g., oval overall shape, wherein said angular sectors lie on the longitudinal toothbrush axis and are arranged symmetrically thereto in the rotational center position of the bristle carrier  2 . The aforementioned sectors  22  and  23  may cover different angular ranges, e.g., of respectively about 30° in the embodiment shown. The bristle clusters  20  and  21  that lie on the edge of the bristle section  15  in the sectors  22  and  23  carry out a movement that extends approximately parallel to the slot-shaped interdental spaces. The longer cross-sectional main axes of the filaments  1  extending in the direction of the arrow  13  are advantageously also aligned perpendicular to the longitudinal toothbrush axis when the bristle carrier  2  is situated in its rotational center position. 
         [0050]    In some embodiments, the oppositely arranged sectors  24  and  25  optionally form the bristle section  15  and are specifically arranged adjacent to the sectors  22  and  23 . In the sectors  24  and  25 , the filaments  1  are arranged in bristle clusters  26  and  27  in such a way that the longer cross-sectional main axis of the scarfing  4  extends perpendicular to the longitudinal toothbrush axis in the direction of the arrow  13 . This means that the scarfing  4  of all filaments  1  in the bristle section  15  are aligned parallel to one another. When the bristle carrier  15  carries out the rotatively oscillating movement in accordance with the arrow  19 , the moving direction of the filaments  1  of the bristle clusters  26  and  27  in the sectors  24  and  25  approximately extends perpendicular to the shorter cross-sectional main axis of the scarfing  4 . This means that the filaments  1  of the bristle clusters  26  and  27  only generate little resistance to bending in the region of the scarfing  4 . The filaments  1  therefore can be easily bent in the sectors  24  and  25 , in which they contact the gums while brushing the teeth. This prevents injures to the gums. 
         [0051]    Another advantage of the parallel alignment of the scarfing  4  of all filaments  1  of a bristle section  15  can be seen in the simplified manufacture, for example, if the scarfing  4  is simultaneously ground on all filaments  1 .