Abstract:
The present invention relates to a brush, in particular a toothbrush, comprising a brush body carrying cleaning elements and a perforated plate through which the cleaning elements are projecting. A brush which is improved in terms of hygiene is created by the present invention in that the cleaning elements are arranged on a bristle carrier which is in threaded engagement with the brush body, and that the perforated plate is rotatably held on the brush body. Furthermore, the present invention suggests a bristle insert as a replacement part for said brush.

Description:
REFERENCE TO RELATED APPLICATION 
     This is a continuation application of PCT Application No. PCT/EP99/07672 filed Oct. 13, 1999, which is based on the German application No. 298 18 046.4 filed Oct. 13, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a toothbrush including a handle part, and a brush head carrying cleaning elements that project through a perforated plate. A bristle carrier supports the cleaning elements and the perforated plate, said bristle carrier having a circumference upon which thread webs are formed. 
     2. Description of the Prior Art 
     A toothbrush of the above-mentioned type in which the cleaning elements are formed by bundles or tufts of bristles is, for example, known from U.S. Pat. Nos. 4,152,806 and 4,149,293. In this prior-art toothbrush the perforated plate is pivotably supported on the brush body. The distance between the perforated plate and the brush body is varied by the pivotal movement of the perforated plate. As a result, the free length of the ends of the bristle filaments at the use side, i.e. that part of the bristle filaments that projects over the perforated plate, is also changed, so that a change in the stiffness of the bristle filaments is effected by the pivotal movement of the perforated plate relative to the brush body. When the bristle filaments project over the perforated plate with a relatively large length, the stiffness and, as a consequence, the hardness of the brush are low; with a small length, the stiffness is high. 
     The German Patent No. DE-A-39 28 919 discloses a massage device comprising a pot-shaped basic body and a base member which is also pot-shaped and provided in the basic body in engagement therewith. The base member comprises recesses through which a multitude of massage elements that are formed as bristle tufts are projecting. The ends of the massage elements at the fastening side are received in a mount which is in threaded engagement with the basic body. The distance of the ends of the massage elements at the fastening side is changed relative to the base member by rotating the mount. The base member is received with its annular edge in a correspondingly formed, surrounding annular groove of the basic body and locked to the basic body. 
     The above-mentioned toothbrushes that are already known from the prior art have the drawback that they do not meet today&#39;s hygienic demands. A wedge-shaped slot in which bacteria and dirt may get stuck is formed between the toothbrush body and the end of the perforated plate at the fastening side. A gap in which dirt may get stuck is also formed in the area of the bristle filaments between the perforated plate and the brush body, so that the brush becomes unsightly after a certain period of use. Moreover, the above-mentioned toothbrushes have the drawback that the free length of all of the bristle filaments projecting through the perforated plate is not changed in a uniform manner due to the pivotal movement of the perforated plate. Rather, the bristle filaments that are more remote from the point of pivotal movement are subjected to a greater change in length than the bristle filaments arranged in the neighborhood of the point of pivotal movement. Depending on the pivotal movement of the perforated plate, this results in a gradient of stiffness within the toothbrush tufting formed by the bristle filaments. The stiffness of the bristle filaments cannot be adjusted in a predeterminable manner with the necessary accuracy in the prior-art brushes. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a toothbrush of adjustable stiffness that satisfies today&#39;s hygienic demands and is still attractive in appearance after a long period of use, and whose stiffness can be adjusted very accurately. It is also the object of the present invention to provide a bristle insert as a replacement and wear part for the toothbrush according to the invention. 
     According to a more specific object of the invention, the toothbrush includes a handle part, and a brush head carrying cleaning elements that project through a perforated plate. A bristle carrier supports the cleaning elements and the perforated plate, said bristle carrier having a circumference upon which thread webs are formed. 
     Thanks to the perforated plate which is rotatably held on the brush body, the brush body is closed relative to the ends of the bristle filaments at the fastening side. The filaments are held in a bristle carrier which is in threaded engagement with the brush body. For changing the stiffness the bristle carrier is rotated relative to the brush body so that the bristle carrier travels relative to the brush body according to the thread pitch in the axial direction of a hole which accommodates the bristle carrier. The perforated plate just follows the rotation of the bristle carrier, thereby effecting a change in the stiffness of the cleaning elements without creating an open gap between the perforated plate and the brush body where dirt may collect. Thanks to the threaded engagement the bristle carrier changes its position relative to the perforated plate altogether, so that all of the cleaning elements held on the bristle carrier are uniformly changed with respect to their length. Thus the stiffness of all of the cleaning elements projecting beyond the perforated plate, which cleaning elements are e.g. formed by bristle filaments, is identically changed as well. Moreover, the brush of the invention has the further advantage that the desired stiffness of the bristle filaments can be adjusted accurately by rotating the bristle carrier. 
     Under hygienic aspects it is preferred that the perforated plate ends flush with the upper side of the brush body. Thanks to this measure a smooth surface is created on the surface of the brush in the area of those bristles whose stiffness can be varied. 
     Preferably, the brush body has further provided thereon an annular groove in which the perforated plate is detachably and rotatably held. Preferably, the detachable connection between perforated plate and brush body is created by a lock type connection. The perforated plate can thus be removed from the brush body and the bristle carrier can be rotated out of the brush body to replace worn bristle filaments held on the bristle carrier. If all of the bristle filaments of the toothbrush are arranged on the one or several bristle carriers, the whole toothbrush need not be replaced upon wear of all of the bristle filaments, but it is only necessary to replace the bristle carrier carrying the bristle filaments and, preferably, the perforated plate through which the bristle filaments are projecting. 
     The bristle carrier is detachably connected to the brush body, preferably together with the perforated plate. Such a detachable unit creates a bristle insert which can be inserted into the brush body as a replacement part. The detachable connection between the perforated plate and the brush body is preferably established by a lock type connection which is designed such that the bristle carrier is pressed against the perforated plate by applying pressure to said carrier, and the perforated plate can be removed together with the bristle carrier from the brush body. 
     Preferably, at least two thread webs are provided on the bristle carrier and distributed over the circumference thereof, with guide grooves being provided for the thread webs between the perforated plate arid a thread formed on the brush body. With such a configuration only the thread webs must be brought into alignment with the corresponding grooves and the bristle carriers must then be pressed together with the perforated plate into the brush body, whereby the insertion of the bristle carrier is, in particular, simplified during replacement of a bristle carrier with worn bristle filaments together with the perforated plate. 
     Bristle carrier and perforated plate are preferably removed in a simplified way in that the respective insertion grooves are in alignment with the end of the thread turns for the threaded pins. Upon rotation of the bristle carrier in such a way that said carrier moves towards the perforated plate, the thread webs in an end position will impinge on a boundary surface formed on the brush body for the thread. This boundary surface is in alignment with a respective side surface of a guide groove, so that the thread webs in the end position come to rest in the insertion grooves and the bristle carrier in said end position can be removed from the brush body by a mere axial displacement towards the perforated plate. 
     According to a further preferred development of the present invention, a hardness scale is provided on the face of the bristle carrier that faces away from the bristle filaments, so that the user of the brush is enabled to adjust a desired stiffness of the bristle filaments in a predeterminable way. 
     For the adjustment of the stiffness the bristle carrier may be connected to a knurled ring which at least in part projects over the portion of the brush body which surrounds the bristle carrier. Under hygienic aspects, however, it is preferred that, instead of such a knurled ring on the face of the bristle carrier facing away from the bristle filaments, a grip portion is provided, for instance for the fingers of a user. For an easy handling, however, it is preferred that the grip portion is designed such that a bristle carrier tool can be brought into operative communication with the bristle carrier. Such a bristle carrier tool is preferably detachably connected to the brush body, so that the bristle carrier tool can be gripped any time. Moreover, the brush body is made longer by the detachable bristle carrier tool connected thereto, so that the brush can be handled more easily on the whole. 
     Furthermore, the present invention relates to a bristle insert for a toothbrush of the above-mentioned type, comprising a bristle carrier carrying cleaning elements, the circumferential surface of which has formed thereon thread webs, as well as a perforated plate through which the cleaning elements are projecting. Such a bristle insert is suited as a replacement part for the above-mentioned toothbrush, which may also be an electrically driven toothbrush. Preferred developments of the bristle insert are indicated in the dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Further features, details and advantages of the present invention will become apparent from the following description of an embodiment taken in conjunction with the attached drawing, in which: 
     FIG. 1 is a partly sectional side view of an embodiment; 
     FIG. 2 is an enlarged sectional view taken along line II—II according to the illustration shown in FIG. 1; 
     FIG. 3 is a side view of a bristle carrier for the, embodiment shown in FIG. 1; 
     FIG. 4 is a top view on the bottom side of the bristle carrier according to the illustration shown in FIG. 3; 
     FIG. 5 is a partly sectional illustration of the brush head of the toothbrush shown in FIG. 1, in a first position of the bristle carrier; 
     FIG. 6 shows the brush head illustrated in FIG. 5, in a second position of the bristle carrier; 
     FIG. 7 is a side view showing part of a further embodiment; 
     FIG. 8 is a perspective view of a third embodiment; and 
     FIG. 9 is a top view on a bristle carrier with exemplary cross-sections of the tufts. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 is a partly sectional side view showing an embodiment of the present invention that is designed as a toothbrush. The toothbrush comprises a handle part  2  and a brush head  4 , the two members having formed therebetween a tapered neck portion  6  which provides the elasticity required between handle part  2  and brush body  4  for preventing injuries of the oral mucosae that might be caused by the brush head  4  acting within the oral region. A bristle carrier tool  8  is arranged at the end of the handle part  2  that faces away from the brush head  4 . Said bristle carrier tool  8  is connected to the handle part  2  via a lock type connection (not shown in more detail). The handle part  2  and the bristle carrier tool  8  are each provided with a cylindrical core  10  the circumference of which has arranged thereon in distributed fashion three ribs  12  extending in the longitudinal direction of the handle part  2 . The diameter of the core  10  and the ribs  12  are made identical in the transitional portion between the handle part  2  and the bristle carrier tool  10 . It is only in the area of ribs  12  that a notch  11  is provided by beveling the opposite, faces of the ribs, the notch signalizing the transition between handle part  2  and bristle carrier tool  8 . 
     The ribs  12 , on the one hand, and the core  10 , on the other hand, are made from different components on the handle part  2  and on the bristle carrier tool  8 , respectively, the ribs  12  being preferably made from a non-rigid plastic material. Alternatively, however, the ribs  12  may also be made from a more rigid material. 
     The brush head  4  is formed by a substantially annular structural member which integrally joins the neck portion  6 . A screw thread  14 , which is shown in more detail in FIG. 2, is formed on the inner cylindrical surface of a recess  13  of the annular brush head  4 . Insertion grooves  20  are formed between the screw thread  14  and the upper edge of the brush head  4  in accordance with the number of radially outwardly extending thread webs or projections  18  that are provided on a bristle carrier  16  shown in FIG. 3. A side surface  22  that laterally defines the insertion groove  20  forms a stop with respect to an upper turn of the thread  14 . 
     The upper edge of the brush head  4  has formed thereunder an annular groove  24  the radius of which is smaller than the distance between the center point of the annular brush head  4  and the circumferential boundary surface of the insertion groove  20 . A particularly compact design of the brush head  4  is created by this configuration. 
     The bristle carrier  16  shown in FIG. 3 is formed by a substantially cylindrical body on the circumference of which the thread webs  18  (here: two) are arranged in distributed fashion. A multitude of bristle filaments  26  which are combined to form bundles or tufts  25  of bristles project through the upper face of the bristle carrier  16  and are fastened thereto. The bristle filaments  26  may be fastened in the conventional way, i.e. by means of a metallic anchor. In the mounted state of the perforated disk, the bristle carrier  16  is then provided with bristles, i.e. the bristle filaments  26  are inserted through the perforated disk into the bristle carrier  16 . Alternatively, the bristle filaments may be provided by over-molding bristle tuft ends when the bristle carrier  16  is manufactured in an injection molding process. In such a manufacturing process the perforated disk is preferably injection-molded together with the bristle carrier  16 , with the mold cavity for the perforated disk being designed such that the individual bristle tufts to be connected to the bristle carrier  16  do not come into contact with plastic material. 
     The face of the bristle carrier  16  that faces away from the bristle filaments  26  has a slightly convex curvature. As can be seen in FIG. 4, this surface has formed thereon a central hole  28  into which a pin  30  formed on the bristle carrier tool  8  can be inserted with a cylindrical cross-sectional surface. The hole  28  acts together with the pin  30  as a centering means for the bristle carrier tool  8 . The face of the bristle carrier  16  that faces away from the bristle filaments  26  has formed thereon three recesses  32  that are arranged in distributed fashion on the circumference and extend in radial direction from the hole  28 . The recesses  32  are configured such that they are cut into the convex surface of the bristle carrier  16  and the ribs  12  of the bristle carrier tool  8  can be introduced in a positive manner into the recesses  32 . Finally, the face of the bristle carrier  16  that faces away from the bristle filaments  26  has mounted thereon a hardness scale  34  which is formed by optically distinguishable dots arranged on the edge portion of the circular face. This hardness scale can be read with the help of a reading web  36  which is formed on the bottom side of the brush head  4  and differs in color from the material of the neck portion  6 . 
     A bristle insert which can be inserted as a wear part into the recess  13  formed on the brush head  4  consists of the bristle carrier  16  and of a perforated plate  38  shown in FIGS. 5 and 6, which is penetrated by the bristle filaments  26  that are combined to form bristle tufts  25 . The perforated plate  38  is designed as a circular disk, with holes being provided on the perforated plate  38  to correspond to the position of the respective bristle tufts  25 . The diameter of said holes corresponds to the thickness of the respective bristle tuft  25  projecting through the corresponding hole. In the illustrated embodiment bristle tufts  25  of an identical diameter are used. However, it is also possible to fasten bristle tufts  25  of a different thickness and geometrical design to the bristle carrier  16 . In such a case the geometrical design of the holes of the perforated plate  38  corresponds to the boundary of the respective receiving means for the corresponding bristle tufts  25  in the bristle carrier  16 . 
     For inserting the bristle insert into the recess  13  the radially outwardly extending thread webs  18  are first brought into alignment with the respective insertion grooves  20 . Thereupon the bristle carrier  16  is axially pressed into the recess  13  together with a perforated plate  38  which is penetrated by the bristle tuft  25  and which rests on the upper side of the bristle carrier  16 . A surrounding bead  40  of the annular groove  24  which is convexly formed on the side surface of the perforated plate  38  thereby presses associated locking noses  42  (FIG. 2) radially outwards, with the locking noses  42  covering the annular groove on the upper side. The axial advance movement of the bristle carrier  16  together with the perforated hole  28  will be stopped when the thread webs  18  impinge on the lower edge of the upper thread turn and when the perforated plate  38  is received in the annular groove  24  and gripped from behind by the locking noses  42 . In this end position the perforated plate  38  rests on the upper face of the bristle carrier  16  so that the bristle filaments  26  project over the perforated plate  38  at a maximum length of use. 
     For changing the stiffness of the tufting formed by the bristle filaments  26  the bristle carrier tool  8  is removed in the illustrated embodiment in axial direction from the handle part  2 . The pin  30  is introduced into the hole  28  and the ribs  12  are introduced into the recesses  32  by rotating the bristle carrier tool  8  centered in this way on the bristle carrier  16 . The bristle carrier  16  is now rotated counterclockwise by operating the bristle carrier tool  8 , so that the bristle carrier  16  travels according to the pitch of the thread  14  in axial direction along the recess  13 . The perforated plate  38  which is rotatably supported in the annular groove  24  follows this rotation of the bristle carrier  16 . The rotation of the bristle carrier  16  has the effect that the bristle carrier  16  is removed from the perforated plate  38 . The ends of the bristle filaments  26  at the fastening side move in the same manner away from the perforated plate  38 , whereby the free length of the bristle filaments  26  projecting over the perforated plate  38  to the outside is reduced, and the stiffness of the tufting increases. 
     The desired stiffness can be set via the angular position of the hardness scale indicia  34  and the reading web projection  36  in an exactly predeterminable way. The engagement of the bristle carrier tool  8  permits an adjustment of the stiffness of the toothbrush that can easily be handled. In the illustrated embodiment any desired and medically reasonable stiffness of the tufting of the toothbrush can be adjusted. 
     In the embodiment shown in the drawings all of the bristle filaments  26  are arranged on the bristle carrier  16 . This has the advantage that worn bristle filaments  26  can be exchanged by replacing the bristle carrier  16 . The component formed from the handle part  2 , the brush head  4 , the neck portion  6  and the bristle carrier tool  8  can be further used, i.e., irrespective of the worn state of the bristle filaments  26 . To remove the bristle carrier  16 , said carrier must be rotated clockwise until the thread webs  18  impinge on the side surface  22  of the insertion grooves  20 . With his thumb a user can apply a force of pressure to the face of the bristle carrier  16  facing away from the bristle filaments  26  to undo the locking of the perforated plate  38  by the locking noses  42  and to press the bristle carrier  16  together with the perforated plate  38  out of the recess  13 . A new bristle carrier with unused bristle filaments is inserted in the above-described manner. 
     FIGS. 7 and 8 show two further embodiments in which in accordance with the above-explained embodiment a bristle carrier  16  is held in threaded engagement on a brush head  4 . Further bristle tufts  50  that are fastened to the brush head  4  in a manner known per se, and whose stiffness is not adjustable, are provided in the longitudinal direction of the toothbrush in front of and behind the bristle carrier  16 . 
     As can be seen in FIG. 7, the bristle tufts  52  next to the neck portion  6  are cut to length in this embodiment in the longitudinal direction such that the tufted surface comprising the ends of the bristle tufts  52  at the use side is inclined forwards whereas the bristle filaments forming the front bristle tufts  50  are cut to length such that the tufted surface comprising the ends of said bristle tufts  50  at the use side is inclined rearwards, i.e. towards the neck position  6 . The bristle tufts  25  arranged on the bristle carrier  16  are spherically cut. In the end position of the bristle carrier  16  which is shown in FIG.  7  and in which the bristle tufts  25  project over the perforated plate to a maximum degree, the bristle tufts  50 ,  52  which are arranged next to the bristle tufts  25  and are not adjustable with respect to their hardness are provided at a lower level than the adjustable bristle tufts  25 . The bristle filaments of the bristle tufts  50 ,  52  may be made from a material differing from that of the bristle filaments of the bristle tufts  25  and may in particular differ therefrom in their hardness. When the adjustable bristle tufts  25  are made longer by rotating the bristle carrier  16 , the effect of said bristle tufts  25  is enhanced during the cleaning action; when the bristle tufts  25  are shortened, the cleaning characteristics of the bristle tufts  50 ,  52  are prevailing. Thus it is possible to vary not only the stiffness of the toothbrush, but also the cleaning characteristics of the brush on the whole by rotating the bristle carrier  16 . 
     FIG. 8 shows a further embodiment of the present invention. In this embodiment the cleaning elements which are secured to the bristle carrier are not formed by bristle tufts, but by flexible rod-like massage elements  54  which in the instant case consist of a thermoplastic elastomer (TPE). In this instance, too, the free length of the rod-like massage elements  54  and thus the stiffness thereof can be varied as in the case of the above-described embodiments by rotating the bristle carrier  16  relative to the brush head  4 . By analogy with the embodiment shown in FIG. 7, bristle tufts  50 ,  52  which cannot be adjusted with respect to their length and thus hardness are provided in front of and behind the massage elements  54 . Apart from the stiffness of the massage elements  54 , the position of the ends of the rod-like massage elements  54  at the side of use relative to the ends of the bristle tufts  50 ,  52  at the side of use and thus the cleaning characteristics of the brush on the whole are varied by rotating the bristle carrier  16 . When the rod-like massage elements  54  are relatively short the effect of the bristle tufts  50 ,  52  prevails; when the rod-like massage elements  54  are relatively long, they will first contact the teeth to be cleaned and the gum, respectively, thereby exerting a predominant influence on the cleaning characteristics of the toothbrush. 
     FIG. 9 shows various cross-sections of cleaning elements that may be formed either by bristle tufts or by TPE bristles. The bristle carrier  16  may be provided, optionally or in combination, with cleaning elements of a closed cross-sectional profile which may be triangular (reference numeral  56 ), round (reference numeral  58 ), square or rectangular (reference numeral  60 ) or polygonal (reference numeral  62 ). Moreover, the cross-section may be substantially C-shaped. Reference numeral  64  refers to such an open profile of a cleaning element. Likewise, it is possible to make the cross-sectional profile of the cleaning elements its star-shaped or cruciform (reference numeral  66 ). Finally, the cleaning element may have the cross-sectional geometry of a closed hollow profile (reference numeral  68 ). The illustrated hollow profile has an irregularly shaped circumferential surface, with the wall thickness being relatively small in comparison with the diameter of the hollow profile. Such open cross-sectional shapes are particularly suited for forming a hollow rod-shaped massage element. 
     The present invention is not limited to the illustrated embodiments. Of course, it is possible to provide a plurality of bristle carriers which have assigned thereto perforated plates rotatably supported on the brush body, whereby different hardness ranges of the tufting of a toothbrush can be set. Moreover, it should be noted that instead of the thread webs formed on the bristle carrier it is possible to realize any desired type of thread-like engagement between bristle carrier and brush body. In the embodiment shown in the drawing the recess  13  provided on the brush head  4  is encapsulated by the perforated plate  38  on the one hand and by the bottom side or the circumferential surface of the bristle carrier  16  on the other hand to minimize the penetration of dirt and impurities into the recess  13 . In addition, one or several outwardly opening flushing openings may be provided on the brush body, the flushing openings communicating with the gap formed between the brush body  2 ,  4 ,  6  and the bristle carder  16 . Dirt which has been introduced between the bristle carrier  16  and the perforated plate  38  into the recess  13  can be flushed out through such flushing openings.