Abstract:
A handheld toothbrush with a brush head having a forward free end and a rearward portion. Provided at the forward free end of the brush head is at least one bristle tuft of a first set. Adjoining the first set in rearward direction is a second set of tufts comprised of several bristle tufts arranged serially on a ring and extending in the circumferential direction of the ring at an angle of inclination relative to the surface of the brush head. A third set of tufts adjoins the second set of bristle tufts in the direction towards the rearward portion. The tufts of the third set are inclined in the circumferential direction in opposition to the direction of the bristle tufts of the second set. As a result, these tufts are capable of penetrating optimally between the user&#39;s teeth, hence ensuring a better cleaning result.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application claims priority to German Patent Application No. DE 103 32 872.6, filed Jul. 19, 2003, which is incorporated herein by reference in its entirety. 
   TECHNICAL FIELD 
   This invention relates to handheld toothbrushes. 
   BACKGROUND 
   In some handheld toothbrushes, tufts of bristles arranged on a ring in the mid-region of the brush head project from the surface close to the brushing side. The tufts extend in opposition to the circumferential direction in an inclined relationship to the surface of the brush head. Disposed radially inside these tufts are further tufts that are arranged on a second ring of smaller diameter and are equally inclined in the same direction as the outer tufts. 
   It is an object of the present invention to provide a handheld toothbrush in which, during brushing, a maximum possible number of bristle tufts easily penetrate between the teeth and perform a thorough cleaning operation. Preferably, this occurs not only during an up and down movement, but also during a back and forth movement of the handheld toothbrush. Furthermore it is also an object to clean during brushing the sides of the teeth particularly thoroughly. 
   SUMMARY 
   The present invention provides a handheld toothbrush which enables thorough cleaning of the interproximal spaces between teeth and their sides. This is accomplished by arranging the outer bristle tufts of a second set of bristle tufts, disposed on a ring, in an inclined position in opposition to the bristle tufts of a third set and separating the two sets locally in a longitudinal direction. This arrangement enables particularly good penetration between the user&#39;s teeth by those bristle tufts that are inclined in the direction of movement of the handheld toothbrush, while the bristle tufts that are inclined in opposition to the direction of movement of the handheld toothbrush more or less clean the surface of the tooth sides. When the toothbrush is moved in the other direction, the oppositely directed bristle tufts engage better between the teeth, yet from the other side, so that they are in a position to better clean the interproximal spaces from the other side. 
   When the handheld toothbrush is moved back and forth, those bristle tufts on the rings make particularly effective brushing engagement with the teeth as are disposed more or less in the edge region of the brush head. This is so because, on the side edges, individual tufts extend in the direction of movement of the handheld toothbrush, striking the interproximal spaces and the tooth surface transversely from above—similar to a scraper—thus particularly effectively removing plaque from the tooth surface. 
   The bristle tufts, inclined in a direction transverse to the back and forth movement of the handheld toothbrush, are arranged more or less in the inner region of the brush head. They extend in a direction transverse to the direction of movement of the toothbrush, thus producing a sliding effect on the end faces of the teeth which are easily accessible from the side. 
   When the toothbrush is moved up and down, that is, essentially parallel to the interproximal spaces, the scraping and sliding cleaning function in the interproximal spaces is performed by the bristle tufts arranged in the mid-region of the brush head on the outer ring. Thus, a better cleaning operation is accomplished in the interproximal spaces and also on the end faces of the teeth in a shorter period of time. During this up and down movement, the bristle tufts provided on the outer edge perform a sweeping movement directed at cleaning the surface of the tooth sides, because these tufts do not reach between the user&#39;s teeth as easily. Accordingly, the toothbrush of the invention cleans the interproximal spaces within a shorter time than is the case with prior-art devices. 
   Another benefit is that a first set of bristle tufts provided at the forward free end of the brush head services the rearmost molar region because this set is in the foremost position when the brush head enters an oral cavity. 
   The cleaning action performed by the outer bristle tufts provided on a ring is preferably aided by further bristle tufts supporting the outer bristle tufts from within as the bristles are pressed against the tooth surface, thus enabling them to better penetrate the interproximal areas and better clean the end faces. At the same time and additionally, the further bristle tufts are in a position to better clean the front surfaces of the teeth so that it is not necessary for the outer bristle tufts to perform the cleaning work alone. This has the added effect of extending the useful life of the handheld toothbrush. 
   By fanning out the free ends of the bristle tufts, a continuous surface of the bristle tufts of the second and third sets can be obtained to enable a still further improved cleaning operation on the user&#39;s tooth surfaces. Owing to the nearly continuous surface of the inner bristle tufts arranged within the rings of the outer bristle tufts, a particularly large area of the tooth surface is cleaned. Consequently, even in the presence of an increased application pressure, the bristles do not quickly bend away to the sides which would be of little advantage for the cleaning result and the durability. Furthermore, toothpaste is capable of adhering better to the continuous surface and cannot run down along the bristle tufts. 
   Similarly, a particularly uniformly roughened, continuous cleaning surface can be achieved on the free ends of the inner bristle tufts. In this arrangement, the fine fiber structure has the effect of causing interlacing of the free ends of the individual bristles of the tufts so as make them indistinguishable. The bristles of all the inner tufts form a joint tuft having just one common working surface that is capable of cleaning a large area of the tooth surface. In this arrangement, the fanning out of the bristle tufts can be performed by means of a rapidly rotating disk having on its surface small blades extending perpendicularly to the disk. The blades operate to break up the working ends of the inner bristle tufts and to fan them out in such manner that their fine fibers become interlaced, thereby producing a continuous, yet roughened, surface. 
   Particularly good cleaning results are obtained when the bristle tufts of the second and third sets located on the rings are inclined at an angle of inclination relative to the surface of the brush head. Owing to the small angle of inclination, the individual bristle tufts exert some resistance when pressed against the tooth surface, thus enabling a user&#39;s hand to deliver a maximum possible amount of application pressure onto the tooth surfaces. This increases the effectiveness of a toothbrush, producing a better cleaning result in a shorter period of time. The angle of inclination is preferably between about 5° and about 12° and, more preferably, between about 7.5° and 8.5°. 
   The bristle tufts located on the rings can be selected to have a first common length that is greater than a second common length of the further bristle tufts lying within the rings. This results in a soft and elastic working surface of the handheld toothbrush. Consequently, in the presence of a low application pressure, the bristle tufts formed on the ring make an initial engagement with the tooth surfaces, and when the application pressure on the tooth surface is increased, the tufts that have not entered an interproximal space bend to an extent causing the other, shorter tufts to be put to use. The user becomes aware of this condition as the handheld toothbrush becomes harder as pressure continues to be applied. It is then necessary for the application pressure on the handheld toothbrush to be significantly increased when it is desired to bend or deform all the bristle tufts on the brush head to accomplish a thorough cleaning operation. This tuft array improves the handling of the handheld toothbrush because the user receives a better feedback enabling him to react promptly to a higher or lower pressure. 
   In addition, a fourth set of bristle tufts can be added extending transversely to the longitudinal direction of the brush head so that the fourth set adjoins each of the first, second and third sets of bristle tufts. The fourth set of bristle tufts, arranged between the second and third set of bristle tufts, supports the tufts of the second and third set during their brushing movements in small fringe regions in the sense of reinforcing the sides, that is, in addition to their own brushing function they contribute to increasing the flexural resistance of these bristle sets. This provides for greater durability of the handheld toothbrush of the invention. This effect is further enhanced when the bristle tufts of the fourth set are comprised of spaced apart bristle tufts in a side-by-side array with a greater hardness than the individual bristle tufts of the first, second, and third sets, so that overall the wear of the bristle tufts of the handheld toothbrush is further reduced. 
   Wear can be reduced still further by arranging the bristle tufts of the fourth set level with the bristle tufts lying within the bristle tufts provided on a ring. The bristle tufts are put to use simultaneously, thus causing hardening of the working surface of the tufts. However, they can also be longer than the bristle tufts lying within the bristle tufts provided on the ring, while being shorter than the bristle tufts provided on the ring. Thus, the tufts are put to use with a slight delay, yet still contribute to hardening the working surface of the tufts adequately. They also have a supporting effect on the tufts of the first to third set provided between these tufts. 
   The bristle tufts of the fourth set can also be arranged to protrude upwardly substantially vertically from the surface of the brush head thus effecting a supporting action for the bristle tufts of the second set lying closest to these bristle tufts. By virtue of the vertical arrangement of the bristle tufts of the fourth set, these can be arranged on the brush head in such manner that they are particularly close to the bristle tufts provided on the ring so that the supporting effect is obtained right at the beginning of the cleaning operation. 
   When the frontal bristle tuft of the first set is inclined towards the forward end at an angle relative to the vertical on the surface of the brush head, the handheld toothbrush of the invention provides superior cleaning because the forward area of the brush head reaches deeper into the molar region. This also enables the rearmost region of the molars to be better cleaned. The first set can also be comprised of six bristle tufts whose free ends terminate on a common plane inclined at an angle relative to the surface, and that the first plane extends above a second plane formed by the free ends of the second and third sets of bristle tufts. With such a toothbrush held in conventional manner, this feature ensures that the working end of the first set of bristle tufts, which has its plane inclined, makes relatively snug engagement with the tooth surface to be cleaned, thus performing a uniform cleaning function of the molar surface without requiring a constant change in application pressure. 
   The handheld toothbrush can use bristle tufts of an essentially circular configuration. The cross sections of the bristle tufts can be essentially equal. This affords particular ease of manufacture, in that the tufts are of like cross section but yet of different bristle strength and bristle color. These features enable the tooling required for such a handheld toothbrush to be manufactured with greater ease so that the manufacturing cost of the handheld toothbrush can be reduced. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     DESCRIPTION OF DRAWINGS 
       FIG. 1  is a side view of a handheld toothbrush equipped with the bristle sets of the present invention; 
       FIG. 2  is a top plan view of the handheld toothbrush of  FIG. 1 , taken in the direction of arrow X; 
       FIG. 3  is a partial side view of the brush head showing the complete bristle sets of  FIG. 1 , yet on an enlarged scale; and 
       FIG. 4  is a partial top plan view of the brush head showing the complete bristle sets of  FIG. 3 . 
   

   Like reference symbols in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
     FIGS. 1 and 2  show a handheld toothbrush  1  that is comprised of an elongated handle  2 , a neck  3  of reduced cross section which adjoins the handle  3 , and a brush head  4  adjoining the neck  3 . The brush head  4  has a forward end  5  and a rearward end  6  between which four sets  8  to  11  of bristle tufts  21  and  24  to  30  extend upwardly from the surface  7  ( FIG. 1 ), as also illustrated in  FIGS. 3 and 4  on an enlarged scale. Provided on the upper side  12  of the handle  2  is a grip area  13  suitable for engagement with a user&#39;s thumb, the grip area slightly recessed within the surface  12  and including raised ribs  14  that extend from the end close to the rearward free end in a direction transverse to the handle  2 , are made from a thermoplastic elastomer material and bent slightly forwardly in the direction of the brush head  4 . 
   Referring now to  FIG. 1 , a further grip area  35  is provided on the lower side  15  of the handle  2  level with the grip area  13 . The further grip area  35  is formed by lamella-type ribs  16  extending in a direction transverse to the longitudinal axis of the handheld toothbrush  1 , said ribs being very narrow and accordingly of a yielding configuration similar to a cushion when individual fingers are pressed against them. The fine ribs  16  and the substrate  17  interconnecting the ribs  16  are equally fabricated from a thermoplastic elastomer material that is injection molded onto the body  18  of the handle  2  and provided only in the forward and side regions of the handle  2 . 
   As shown in  FIGS. 1 ,  2 , and  3 , the handheld toothbrush  1  is of a symmetrical configuration having an axis of symmetry or center axis  23  that extends in the longitudinal direction of the handheld toothbrush  1 . As seen in top plan view, the brush head  4  has the shape of an elongated oval having ends with a pronounced curvature, which form the forward and rearward ends  5  and  6 , respectively. The surface  7  of the brush head  4  from which the four sets  8  to  11  of bristle tufts  21  and  24  to  30  project extends at an upward inclination, forming an angle a with a depository area  19 . The depository area  19  can be any surface of a piece of furniture. When the handheld toothbrush  1  is placed down on this depository area  19  as shown in  FIG. 1 , some of its bearing areas  36 ,  37  provided on its lower side  20  take support on the depository area  19 , causing the toothbrush  1  to occupy a stable position in which the upper side  12  points substantially vertically upwardly, as shown in  FIG. 1 . The included angle a defined between the depository area  19  and the surface  7  is between 2° and 6°, preferably 4°. With such an angle a, the handling of the handheld toothbrush  1  is particularly good because it does not require a user&#39;s hand to be turned for the sets  8  to  11  of the bristle tufts  21  and  24  to  30  to engage against the user&#39;s tooth surfaces (not shown) relatively vertically. 
   According to  FIGS. 1 to 4 , adjacent to the forward end  5  is a first set  8  of bristle tufts  21  that is inclined toward the forward end, forming an angle b with the vertical on the surface  7 . The angle b is between 5° and 9°, preferably 7°. The free ends  22  of the bristle tufts  21  form a common plane sloping upwardly at an angle c relative to the surface  7 . The angle c is between 13° and 18°, preferably about 15°. The foremost point E 1  of the foremost bristle tuft  21  is at a distance L 1  of about 12 mm to the surface  7 . The rearmost point E 2  of the two rearmost bristle tufts  21  is at a distance L 2  of 10.5 mm to the surface  7 . The bristle tufts  21  of the first set protrude from the surface  7  so that they all combine to outline an essentially crescent-shaped cross section according to the top plan views of  FIGS. 2 and 4 . The first set  8  is formed by six bristle tufts  21  of which five tufts  21  extend parallel to the edge  38  and one tuft  21  is located within the five tufts  21 , so that this set  8 , when viewed from end-on, appears in an essentially crescent-shaped configuration. 
   Adjoining the first set  8  of bristle tufts  21  is a portion of a fourth set  11  of bristle tufts  24  extending in a direction transverse to the center axis  23  of the handheld toothbrush  1 , as shown in  FIGS. 2 and 4 . The portion of fourth set  11  is comprised of three tufts  24  essentially equidistantly spaced from the closest neighboring tufts  21  of the first set  8 . Accordingly, they lie on an arc of a circle and extend symmetrically to the center axis  23 , with the middle tuft  24  being centrally located directly on the center axis  23 . 
   According to  FIGS. 1 to 4 , the portion of fourth set  11  of bristle tufts  24  is adjoined by a second set  9  of bristle tufts  25  equidistantly spaced apart on a diameter D and inclined anticlockwise at an angle f to the surface  7 , as shown in  FIG. 2 . The angle f amounts to between 6° and 8°, preferably about 7°, while the diameter D is between 7 and 10 mm, preferably about 8.5 mm. The bristle tufts  25  are diametrically opposed to one another and comprised of eight to fourteen, preferably ten, tufts  25 . Four further tufts  26  extend from the surface  7  from radially within the second set  9 . These further tufts  26  are likewise diametrically opposed to one another and have their center in the same central point M as is the case for the tufts  25 . The tufts  26  extend vertically upwardly from the surface  7 . They lie on a common diameter D1 and are spaced apart by 90°, with two bristle tufts  26  extending centrally to the center axis  23 . 
   Next to this second set  9  is another portion of fourth set  11  of two tufts  27  that located transversely to the center axis  23 , are equidistantly spaced from the center axis  23  and project vertically upwardly from the surface  7 . 
   Adjacent to the bristle tufts  27  is a third set  10  of bristle tufts  28 , which is likewise comprised of ten tufts  28  equally spaced apart circumferentially. Unlike the tufts  25  which are inclined anticlockwise, the tufts  28  are inclined clockwise circumferentially at an angle g having the same inclination of 6° to 8°, preferably 7°, as previously indicated for the angle f of the second set  9 . Radially disposed within the tufts  28  are again four further tufts  29  protruding vertically upwardly from the surface  7 . Greater details regarding the third set  10  are omitted because, with the exception of the opposite direction of inclination, the bristle tufts  28 ,  29  and their arrangement on the brush head  4  have the same dimensions as previously indicated for the second set  9 . 
   Adjoining the third set  10  is again a portion of fourth set  11  of three tufts  30 , wherein the middle tuft  30  is located on the center axis  23 . The two outer tufts  30  are equidistantly spaced from the center axis  23 . 
   As shown in  FIGS. 1 and 3 , the tufts  21  of the first set  8  project farthest in upward direction. However, the tufts  25  and  28  combine to form a common plane E 4  ( FIG. 3 ) that extends parallel to the surface  7 . The relative distance L 3  of the surface  7  to the plane E 4  amounts to between 9 and 11 mm, preferably 10 mm. The relative distance d of the plane E 4  to the free ends  31  of the tufts  30 ,  27 ,  24  of the portion of fourth set  11  is equal, amounting to between 0.7 and 1.1 mm, preferably 0.9 mm. The relative distance e of the plane E 4  to the free end  32  of the bristle tufts  29  and  26  amounts to between 1.2 and 1.8 mm, preferably 1.5 mm. While the tufts  25  and  28  have a diameter i of 1.6 mm, the diameters h of the remaining tufts  21 ,  24 ,  26 ,  27 ,  29  and  30  amount to about 1.9 mm. The free ends  31 ,  32  of the tufts  30 ,  27 ,  24  and  29  and  26  extend equally parallel to the surface  7 . 
   As shown in  FIG. 4 , the bristle tufts  25  and  28  lie on imaginary rings  33  and  34 , respectively, shown as thin lines in  FIG. 4 . The inner and outer diameters of the rings  33 ,  34  touch in the worst case the side walls of the tufts  25  and  28 , respectively. Otherwise, a distance can still be maintained between the edge of the tufts  25  and  28  and, respectively, the inner and outer diameter of the rings  33 ,  34 . It is, however also possible for a bristle tuft  25  and  28  to be disposed closer to the inner radius or closer to the outer radius of the ring  33  and  34 , respectively. 
   The tufts  26  and  29  disposed within the tufts  25  and  28 , respectively, are in such close proximity to each other that their free ends  32 , in fanned out condition, form a nearly continuous surface which is, however, not shown in  FIGS. 2 and 4  for better clarity of illustration of the basic cross section of the bristle tufts  26 ,  29 . 
   The bristle tufts  24 ,  27 ,  30  of the fourth set  11  have a longitudinal dimension L 5  extending from the surface  7  up to their free ends  31 . The bristle tufts  26 ,  29  have a longitudinal dimension L 4  extending from the surface  7  up to their free ends  32 . Length L 4  is shorter than length L 5 , which in turn is shorter than length L 3 . Dimension L 4  is obtained from L 3  minus e, dimension L 5  from L 3  minus d. A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.