Abstract:
A toothbrush and replaceable brush head wherein the brush head is easily and positively inserted and removed by axial motion along the axis of the handle. The handle and head have cooperating tongue and groove configurations providing parallel guides to receive and retain the members in assembled relation by virtue of handle recesses and resilient catches on the brush head, while permitting ready disassembly to remove and replace the brush head. Further, the handle and brush head have cooperating wedge formations to insure positive centering of the brush head along the axis of the handle. The assembly is snug and leaves no room for dirt, thereby enhancing hygiene during repeated use.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a toothbrush according to those having interchangeable brush heads for ready replacement when the brush head is worn or for insertion of differing brush heads for use by plural users, and to a brush head for the toothbrush. 
     Toothbrushes and brush heads of this type are known and are available on the market in a variety of designs. Illustrative of prior art constructions are seen in the U.S. patents to Hansen et al U.S. Pat. No. 4,80,924 or Arsenault et al U.S. Pat. No. 5,224,234, for example. 
     The object of the present invention is to provide a toothbrush and a brush head which, in addition to ensuring that used-up brush heads can be exchanged in a straightforward manner, also ensure that the brush head is fastened securely when the toothbrush is used. 
     BRIEF SUMMARY OF THE INVENTION 
     This object is achieved according to the invention by a toothbrush and a brush head having the unique axial insertion and removal of a brush head from the toothbrush handle which insures releasable latching of the head to the handle. 
     Preferred developments of the toothbrush according to the invention and of the brush head form the structure seen in the drawings and include the flat groove in the handle cooperating with the flat tongue spaced from the base of the brush head, including parallel resilient latches on the brush head detachably interengaging with recesses on the handle adjacent the groove therein. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     An exemplary embodiment of the toothbrush according to the invention and of the brush head according to the invention is described in more detail hereinbelow and is illustrated in the drawing, in which: 
     FIG. 1 shows a side view of a toothbrush with a handle and a brush head attached; 
     FIG. 2 shows the toothbrush according to FIG. 1 as seen in arrow direction A; 
     FIG. 3 shows a plan view of the brush head and the handle of the toothbrush according to FIG. 1 in the separated state; 
     FIG. 4 shows, on a larger scale than in FIG. 1, a side view of the brush head and the front part of the handle in the separated state; 
     FIG. 5 shows the brush head and the front part of the handle according to FIG. 4 as seen in arrow direction A; 
     FIG. 6 shows a plan view of the brush head and the front part of the handle according to FIG. 4; and 
     FIG. 7 shows the brush head according to FIG. 6 as seen in arrow direction B. 
     FIG. 8 is similar to FIG. 5 showing a modification wherein the centering protrusion and recess arrangements are in a reversed position from that of FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     According to FIGS. 1 to  3 , a toothbrush  1  has a handle  2  with an exchangeable brush head  4 , which can be attached to a front part  3  of the handle  2 . The brush head  4  comprises a bristle carrier  5  and bristles  6  which are anchored in the bristle carrier  5  and of which the free ends form a brushing surface  7  (FIG.  1 ). The bristle carrier  5  is provided with bristles up to its border, as can be seen from FIGS. 3 and 6. The longitudinal axis of the toothbrush is designated by la in FIGS. 2 and 3; it has a plane of symmetry E of the toothbrush  1  running through it. 
     The bristle carrier  5  and the brushing surface  7  are preferably of oval shape in plan view, as is illustrated in FIGS. 2 and 3; the front part  3  of the handle  2  is also adapted to this shape in plan view. A base surface of the bristle carrier  5 , from which the bristles  6  project, is designated by  9  in FIG.  1 . 
     The way in which the brush head  4  is retained in a removable manner in the front part  3  of the handle  2  can easily be seen, in particular, from FIGS. 4 to  6 , in which the brush head  4  and the handle  2  are shown in a state in which they have been separated from one another. 
     The front part  3  of the handle  2 , said front part being offset by a step from the rest of the handle  2  (cf. FIG.  4 ), has a recess  8  which is defined by a base  11 , a rear wall  10  and two side walls  12 ,  13 . The inner surfaces  12 ′,  13 ′ of the side walls  12 ,  13  are slightly inclined with respect to the plane of symmetry E and converge rearward toward the wall  10 . The inner surfaces  12 ′,  13 ′ of the side walls  12 ,  13  are each provided with a longitudinal groove  14 ,  15 , which runs in the longitudinal direction of the toothbrush (arrow direction S according to FIGS.  2  and  4 ), and with a latching groove  16 ,  17 . The latching grooves  16 ,  17  are located in the rear region, in the vicinity of the rear wall  10 . The top surface of the side walls  12 ,  13  form guide surfaces which are designated by  18 ,  19  in FIGS. 6 and 7. 
     A rounded step surface between the front part  3 , which is of spoon-like design, and the rest of the handle  2  is designated by  20  in FIGS. 4 to  6 . The step surface  20  is provided with a centering recess  22  which is parallel to the base  11  and of which the side surfaces  23 ,  24  are inclined with respect to the plane of symmetry E such that the centering recess  22  tapers rearward. 
     The bristle carrier  5  of the brush head  4  has a front part  30 , a handle-side, rear part  31  and a retaining part  32 , which is provided on the underside of the rear part  31 . The retaining part  32  is provided on both sides with a guide strip  34 ,  35  running in the longitudinal direction S of the toothbrush, the shape and width of the retaining part  32  and of the guide strips  34 ,  35  corresponding to the longitudinal grooves  14 ,  15 . 
     On the handle-side, rear, free end, the retaining part  32  is provided with two resiliently elastic latching tongues  37 ,  38  which can be deformed elastically transversely with respect to the longitudinal direction S, are arranged parallel to the base surface  9 , and to a bottom guide surface  33  of the rear part  31 , and have in each case one latching protrusion  39 ,  40  on their outsides. The latching protrusions  39 ,  40  correspond to the latching grooves  16 ,  17  in terms of shape and arrangement. 
     Provided on the rear part  31  of the bristle carrier  5  is a centering protrusion  42  which is designed to mate with the centering recess  22 , provided in the handle  2 , and has two rearwardly converging side surfaces  43 ,  44  which are inclined with respect to the plane of symmetry E. 
     The front part  30  of the bristle carrier  5  has a rounded, bottom step surface  45  at the rear (see FIGS.  4  and  5 ), and this step surface  45  is configured to mate with a rounded end surface  46  of the front handle part  3 . A rear stop surface  47  of the rear bristle-carrier part  31 , said stop surface being provided with the abovementioned centering protrusion  42 , is likewise rounded such that it corresponds to the step surface  20  of the handle  2 . 
     When a new brush head  4  is attached to the handle  2 , the bristle carrier  5  is pushed in the longitudinal direction of the toothbrush (arrow direction S according to FIG.  4 ), by way of its guide surface  33 , onto the top guide surfaces of the front handle part  3 , the retaining part  32  being introduced into the recess  8 . The guide strips  34 ,  35  pass into the mating longitudinal grooves  14 ,  15  and wedge slightly with respect to the same; at the end of this pushing movement, in an end position of the bristle carrier  5 , the latching tongues  37 ,  38  latch into the latching grooves  16 ,  17  by way of their latching protrusions  39 ,  40 . In this case, the step surface  45  of the bristle carrier  5  comes to rest against the end surface  46  of the handle  2  and the stop surface  47  comes to rest against the step surface  20 , it also being the case that the centering protrusion  42  is introduced into the centering recess  22  and wedges with respect to the same. In order to remove a used-up brush head  4 , the bristle carrier  5  is manually forced forward in the longitudinal direction of the toothbrush (direction counter to arrow S according to FIG.  4 ), for example by exerting force on the slightly upwardly projecting stop surface  47 . This overcomes the wedging action of the centering elements (centering recess  22 , centering protrusion  42 ) and the latching tongues  37 ,  38  are forced together elastically transversely with respect to the longitudinal direction S; the latching protrusions  39 ,  40  are unlatched from the latching grooves  16 ,  17 , and the brush head  4  is pushed out of the recess  8 . 
     This achieves, in a straightforward manner, a fastening for the exchangeable brush head  4  which can easily be released by hand—without using an additional tool—but is nevertheless secure. The additional locking of the two toothbrush parts, said locking being ensured by the centering protrusion  42  and the centering recess  22 , improves the hold of the brush head  4  in the handle  2  when one is cleaning one&#39;s teeth, i.e. it prevents the brush head  4  from being loose or even from being released from the handle  2  in an undesired manner. This eliminates any risk of injury when the toothbrush is being used. Moreover, in the case of the inventive design of the brush head  4  and of the handle  2 , interspaces in which water and extraneous particles could penetrate are advantageously filled well when the two toothbrush parts are joined together; deposits of dirt in the recess  8  are largely prevented, which makes it easier to maintain the toothbrush and is highly advantageous from the point of view of hygiene. 
     It would, in fact, be possible for the plug-in connection of the brush head and the handle to be such that the handle is provided with deformable latching tongues with latching protrusions and the bristle carrier is provided with latching recesses. It may, however, be more expedient for parts such as the latching tongues, which are likely to show signs of wear as time progresses, to be assigned to the toothbrush part which can be disposed of once it has been used up. A converse configuration of the additional centering means (centering protrusion on the handle, centering recess in the bristle carrier) is likewise conceivable. Such an arrangement is shown in FIG. 8, wherein the protrusion  42 ′ similar to protrusion  42  in FIG. 6 is on handle  2  extending forwardly from the arcuate surface  20 , and the receiving centering recess  22 ′ similar to recess  22  in FIG. 5 is provided on the rear part  31  of bristle carrier  4  and extending thereinto. In like manner, protrusion  42 ′ has converging tapering side surfaces  43 ′ and  44 ′ and which are complementary to like converging tapered side surfaces  23 ′ and  24 ′ of recess  22 ′ to assist centering of the bristle carrier on the handle. 
     The longitudinal guide for the exchangeable brush head, said longitudinal guide extending in the longitudinal direction S of the toothbrush, could also be formed by guide strips in the handle, in which mating longitudinal grooves in the bristle carrier engage. 
     The inventive embodiment of the toothbrush and the exchangeable brush head is advantageous not just from an aesthetic point of view but also from an ecological point of view since a comparatively small amount of material is required for the disposable parts.