PATENT ABSTRACT
A toothbrush has a handle and a head part, on which bristle filaments and at least one flexible cleaning element are arranged. The at least one flexible cleaning element is arranged on a carrier element which consists of a hard material and is connected to the head part. A process for producing such a toothbrush is also disclosed.

PATENT DESCRIPTION
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. application Ser. No. 10/389,448 filed Mar. 14, 2003, incorporated herein by reference. Cross-reference is also made to U.S. patent application Ser. No. 09/526,679 filed on Mar. 16, 2000, now U.S. Pat. No. 6,553,604, and Ser. No. 09/576,590 filed on May 22, 2000, now U.S. Pat. No. 6,564,416, both of which are assigned to Gillette Canada Company. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates generally to the field of oral care, and in particular to toothbrushes. More specifically, the invention relates to a toothbrush head having one or more pivoting tufts of bristles, the head having two portions that can move independent of each other.  
       BACKGROUND OF THE INVENTION  
       [0003]     A Japanese patent document having an application number of 3-312978 discloses a toothbrush having a multiplicity of tufts of nylon bristles. In a first embodiment shown in  FIGS. 1, 2  and  3  of the document, a plurality of cylindrical recessed sections in the head are set orthogonally to the longitudinal axial direction of a shank and are formed at equal intervals. Column-shaped rotary bodies  5  are respectively contained in the recessed sections. On the peripheral surfaces of the rotary bodies  5 , along the axial direction, projected strip sections  5   a  are formed, and they are set in a state that they are positioned at the opening sections of the recessed sections. At the opening sections of the recessed sections, contact surfaces to be positioned on both the sides are formed. At both the ends of the upper surfaces of the projected strip sections  5   a , nylon bristles  6  are arranged to be vertically erected.  
         [0004]     As shown in  FIG. 3  of the document, the arrangement described above allows bristles  6  to rotate during use of the brush. A problem with this brush is that two tufts of bristles are secured to each strip section  5   a  and thus must rotate in unison. As a result, an individual tuft of bristles cannot rotate independently of its “partner” tuft. The individual tuft may thus be prevented from achieving optimal penetration between two teeth during brushing because the partner tuft might contact the teeth in a different manner and interfere with rotation of the individual tuft.  
         [0005]      FIGS. 4, 5  and  6  of the document disclose a second embodiment in which each tuft of bristles is secured to the head by a ball and socket type arrangement. While this embodiment allows each tuft of bristles to swivel independent of the other tufts, it does have disadvantages. If a tuft of bristles is tilted out towards the side of the head and that tuft is positioned near the interface between the side and top surfaces of the teeth, chances are increased that the bristle tips will not even be in contact with the teeth during brushing. Further, the random orientation in which the tufts can end up after brushing detracts from the attractiveness of the brush.  
         [0006]     The Japanese reference also discloses that the brush head is made of a unitary structure. As such, water cannot flow through any central portion of the brush head, thereby inhibiting the cleanability of the brush. Further, the unitary head structure does not allow different portions of the head to move independently of each other. Accordingly, the bristle tufts extending from the tuft cannot accommodate the varying tooth surfaces as well as a brush in which the head has two or more portions that can move or flex independent of each other.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, a toothbrush head has a tooth cleaning element extending from the head. The head is divided into at least two portions which can be moved independent of each other. The tooth cleaning element is rotatable relative to that portion of the head from which it extends.  
         [0008]     According to another aspect of the invention, a tooth cleaning element includes one or more tooth cleaners, a base support, and an anchor pivot. One end of the one or more tooth cleaners is secured to a first end of the base support. One end of the anchor pivot is secured to a second end of the base support. The anchor portion has a larger section further from the base support than a smaller section of the anchor portion.  
         [0009]     In accordance with a third aspect of the invention, a method of making a toothbrush head includes molding a plastic toothbrush head in a mold. The head has two distinct portions which are spaced a predetermined distance from each other. The head is removed from the mold. At least that part of the head where the two head portions connect is heated. The two head portions are moved towards each other. At least that part of the head where the two head portions connect is cooled such that the two head portions will now remain in positions where they will be spaced apart a distance which is less than the predetermined distance.  
         [0010]     According to a fourth aspect of the invention, a method of making a toothbrush head includes molding a plastic toothbrush head in a mold. The head has at least one hole therein which extends all the way through the head. The head is removed from the mold. A tooth cleaning element is inserted into the hole  
         [0011]     These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a perspective view of the toothbrush head of  FIG. 1 ;  
         [0013]      FIG. 2  is a top view of the head of  FIG. 1 ;  
         [0014]      FIG. 3  is a side view of the head of  FIG. 1 ;  
         [0015]      FIG. 4  is a bottom view of the head of  FIG. 1 ;  
         [0016]      FIG. 5  is a side view of the head of  FIG. 1  showing one of the head portions flexing;  
         [0017]      FIG. 6  is a top view of the head of  FIG. 1  with the two head portions separated from each other;  
         [0018]      FIG. 7  is a top view of the head of  FIG. 1  after the head portions have been positioned closer to each other;  
         [0019]      FIG. 8  is a front view of a pivoting tuft taken along the lines  8 - 8  of  FIG. 13 ;  
         [0020]      FIG. 9  is a side view of the pivoting tuft of  FIG. 8  taken along lines  9 - 9 ;  
         [0021]      FIG. 10  is a top view of one of the holes in the head for receiving the pivoting tuft (see  FIG. 6 );  
         [0022]      FIG. 11  is a sectional view of  FIG. 10  taken along lines  11 - 11 ;  
         [0023]      FIG. 12  is a sectional view of  FIG. 10  taken along lines  12 - 12 ;  
         [0024]      FIG. 13  is a side view of the head of  FIG. 1  (a portion is removed to facilitate viewing) and a pivoting tuft prior to insertion into the head;  
         [0025]      FIG. 14  is a side view of the head of  FIG. 1  (a portion is removed to facilitate viewing) and a pivoting tuft after insertion into the head;  
         [0026]      FIG. 15  is a side view of the pivoting tuft showing its motion;  
         [0027]     FIGS.  16 A-C are sectional views of  FIG. 15  taken along the lines  16 A-C- 16 A-C;  
         [0028]      FIG. 17  is a perspective view of a tooth cleaner in the form of a ribbed fin; and  
         [0029]      FIG. 18  is a side view of the ribbed fin of  FIG. 17 . 
     
    
     DETAILED DESCRIPTION  
       [0030]     Beginning with  FIGS. 1-5 , there is shown a toothbrush head  16  which extends from a neck  14  which extends from a handle (not shown) to form a toothbrush. The type of handle is not germane to the present invention. The head and handle are preferably made of polypropylene. The head has a serpentine split  18  which divides the head into two portions  20  and  22 . An end of the split  13  near neck  14  is preferably circular in shape (see  FIG. 2 ). As shown in  FIG. 5 , the split in the head allows portions  20  and  22  to flex or move independent of each other during use of the toothbrush, thus facilitating cleaning of the teeth.  
         [0031]     Split  18  can also be defined as an opening in the head between head portions  20  and  22 . This opening allows water to flow through the head, thereby enhancing cleaning of the top head surface which typically gets caked with toothpaste in spite of efforts to rinse the head clean.  
         [0032]     Head portion  20  includes a projecting part  24  which fits (at least partially) into a recess  26  (see  FIG. 6 ) defined by portion  22 . Projecting part  24  has several tufts of bristles extending from it (to be described in further detail below) and is surrounded on three sides by head portion  22 .  
         [0033]     Referring now to  FIGS. 2 and 3 , each of the tufts of bristles on head  16  will be described. A first pair of tufts  28  are located towards the free end of the head, one on each head portion  20 ,  22 . Each tuft has bristles (tooth cleaners) which preferably are each made of polybutylene-terepthalate (PBT) and have a diameter of 0.007 inches. The shortest bristles in tuft  28  have a length of 0.420 inches with the remaining bristles increasing in length steadily to a tip of the tuft. Each tuft tilts away from the handle by an angle of preferably about 12 degrees relative to that portion of the surface of the head from which it projects. As shown in  FIG. 2 , tufts  28  have a larger cross-section than any other tuft on the head.  
         [0034]     A second group of tufts are pivoting tufts  30  (the only tufts on the head which are rotatable). There are four tufts  30  on each head portion  20 ,  22  which are located towards the outside of the head. Each tuft  30  can pivot up to about 15 degrees to either side of a vertical position on the head, more preferably being able to pivot up to about 8 degrees to either side of a vertical position on the head. The pivoting of tufts  30  is roughly towards or away from neck  14 . Each tuft  30  includes a base support  32  made of polypropylene. The bristles are made of polyamid 6.12, have a diameter of 0.008 inches and extend 0.420 inches above the base support.  
         [0035]     A third group of tufts  34  extend perpendicular to the head. There are four tufts  34  on each head portion  20 ,  22  which alternate with tufts  30 . When viewed from the top ( FIG. 2 ) the tufts are oval in shape (similar to tufts  30  but larger). In other words, the tufts  34  and  30  have oval shaped cross-sections. Each tuft  34  has bristles which are made of polyamid 6.12, have a diameter of 0.006 inches and extend above the head by about 0.385 inches.  
         [0036]     A fourth group of tufts  36  are located towards the inside of the head. There are two such tufts on each head portion  20 ,  22 . Each tuft  36  extends perpendicular to the head. The bristles of tuft  36  have a diameter of 0.006 inches, are made of polyamid 6.12 and rise about 0.360 inches above the head.  
         [0037]     A fifth and final group of tufts  38  are also located towards the inside of the head (away from a perimeter  21  of the head). There are 4 pairs of tufts  38 . In each pair one tuft is closer to neck  14  than the other tuft. In each pair of tufts  38 , (a) a base of one tuft is closer to a first side of the head and this one tuft leans towards a second side of the head, and (b) a base of the other tuft is closer to the second side of the head and this other tuft leans towards the first side of the head. As such, the tufts in each pair lean across each other. The angle of tilt towards the side of the head is about five degrees. Each tuft  38  bristles which are made of PBT, have a bristle diameter of about 0.007 inches and extend about 0.460 inches above head  16 . Each tuft  38  has an oval cross-section with a long dimension of the oval being oriented in the direction of tilt.  
         [0038]     The bristles used on the head can be crimped (see U.S. Pat. No. 6,058,541) or notched (see U.S. Pat. No. 6,018,840). Other types of tooth cleaners besides bristles can be used. For example, a tuft of bristles could be replaced by an elastomeric fin. The US patents listed in this paragraph are incorporated herein by reference.  
         [0039]     Turning now to  FIG. 6 , a description will now be provided as to how the toothbrush (head) is made. In a first step, the head, neck and handle of the toothbrush are injection molded in a mold. During this injection molding step, tufts  28 ,  34 ,  36  and  38  are secured in the head by a hot-tufting process. Hot-tufting processes are notoriously well known by those skilled in the art (see e.g. U.S. Pat. Nos. 4,635,313; and 6,361,120; British patent application 2,330,791; and European patent application 676,268 A1).  
         [0040]     Briefly, hot-tufting involves presenting ends of a multiplicity of groups of plastic filaments into a mold. Each group of filament ends inside the mold is optionally melted into a blob. Each filament group is cut to a desired length (either before or after being introduced into the mold) to form a tuft of bristles. The mold is closed and molten plastic is injected into the mold. When the plastic solidifies, it locks one end of the tufts of bristles into the head of the toothbrush.  
         [0041]     It can be seen in  FIG. 6  that the opening  18  between head portions  20  and  22  is much wider at this point than in the heads final form (see  FIG. 2 ). In other words, head portions  20  and  22  are spaced a predetermined distance (preferably at least about 1 mm) from each other. Further, through holes  40  are created during the molding step for receiving pivoting tufts  30  at a later point in the manufacturing process. Holes  40  will be described in greater detail below.  
         [0042]     With reference to  FIG. 7 , after the toothbrush is removed from the mold, heat  42  is applied to the head near the neck and to part of the neck (hereinafter the neck). The heat can be applied in a number of ways including hot air, radiant heating, ultrasonic or convection (e.g. hot oil) heating. Here the heat is shown being applied to the sides of the neck. It is preferable to apply the heat to the top and bottom surface of the neck. The heat brings the plastic up to 1.0-1.12 times its glass transition temperature (when temperatures are measured in the Kelvin scale). The plastic should not be heated above 1.12 times its glass transition temperature in order to avoid damaging the plastic. More preferably, the plastic is heated to about 1.03-1.06 times its glass transition temperature (measured in degrees Kelvin). The glass transition temperature for polypropylene is about 100 degrees centigrade whereas the glass transition temperature for copolyester and polyurethane is about 65 degrees centigrade.  
         [0043]     Pressure  44  is then applied to head portions  20 ,  22  to move the portions towards each other. Once head portions  20 ,  22  are in the position shown in  FIG. 2 , the heated portion of the head/neck is cooled by, for example, exposing the heated portion to a cold gas or liquid. If room temperature air is used to cool the neck, such air should be applied for about 20-25 seconds. This has the effect of forming the two head portions into their final positions.  
         [0044]     In order to achieve short process times, the highest temperature heat source which will not damage the plastic should be used. If too hot a heat source is used and/or if the heat is applied for too long, the plastic can be damaged. If the heat source is not hot enough, the process will take too long and/or head portions  20 ,  22  will not remain in their final desired positions. If the head/neck are made of polypropylene and hot air is used to heat the neck, (a) the heated air should be at a temperature of about 170 degrees centigrade and should be applied to the neck for about 70 seconds, (b) the polypropylene should be raised to a temperature of about 140 degrees centigrade, and (c) a nozzle which applies the hot air to the neck should be about 10 mm from the neck.  
         [0045]     If copolyester or polyurethane is used as the material for the head neck, (a) the heated air should be at a temperature of 250 degrees centigrade and should be applied to the neck for about 10 seconds, (b) the material should be raised to a temperature of preferably 95-100 degrees centigrade, and (c) a nozzle which applies the hot air to the neck should be about 15-20 mm from the neck.  
         [0046]     Heating the respective materials above for the time indicated allows the material to be softened and mechanically bent into its final form. Exceeding the heating times above could cause the material to overheat and become damaged.  
         [0047]     Turning to  FIGS. 8 and 9 , each pivoting tuft  30  has a multiplicity of bristles  46 , a base support  48  and an anchor pivot  50 . The bristles are secured to and extend from a first end  52  of the base support while a first end  54  of the anchor pivot extends from a second end  56  of the base support. The base support and anchor pivot are preferably a unitary structure made of the same material. Anchor pivot  50  includes a first portion  58  near the first end  54  and a second portion  60  near a second end  62  of the anchor pivot. First portion  58  is smaller in an X an Y dimension than second portion  60 . Base support  48  is larger in an X and Y dimension than second portion  60  of the anchor support. Second portion  60  includes a pair of lips  63 . The anchor pivot defines an opening  64  therethrough.  
         [0048]     Tuft  30  can also be made by a hot-tufting type process as described above. Instead of injecting plastic into the mold to form a toothbrush handle, neck and head, the plastic is injected into a mold to form base support  48  and anchor pivot  50 , capturing bristles  46  when the injected plastic cools.  
         [0049]     With reference to  FIGS. 10-12 , through holes  40  ( FIG. 6 ) will now be described. Each hole  40  extends from a top surface  66  of the brush head through a bottom surface  68 . Hole  40  includes first and second portions  70  and  72 . Portion  72  is substantially a parallelepiped except that some of its lower section is rounded off (see  FIG. 11 ). Portion  70  is also substantially a parallelepiped except that two of its sides are flared to the sides by about 15 degrees (see  FIG. 12 ). Hole portion  72  is longer in a dimension A than hole portion  70  ( FIG. 11 ). Hole portion  70  has about the same width in a dimension B as hole portion  72  where hole portions  70  and  72  meet ( FIG. 12 ). Dimensions A and B are substantially perpendicular to each other in this embodiment. A pair of lips  73  are defined by this arrangement.  
         [0050]     Turning now to  FIGS. 13-16 , the insertion of pivoting tufts  30  into holes  40  will be described. A tuft  30  is positioned over a hole  40  with end  62  of anchor pivot  50  facing the hole ( FIG. 13 ). As shown in FIGS.  16 A-C, tuft  30  is moved towards hole  40  until end  62  starts to enter the hole ( FIG. 16A ). Tuft  30  is then pressed into the hole causing sides of hole portion  70  to squeeze second portion  60  of the anchor pivot. Accordingly, anchor pivot  50  collapses causing opening  64  to become temporarily smaller. Tuft  30  is then pushed all the way into hole  40  ( FIG. 16C ) at which point the resilient plastic anchor pivot springs back to its form shown in  FIG. 16A . This paragraph describes a snap-fit retention of tuft  30  to the head.  
         [0051]     Referring to  FIG. 16C , base support  48  is longer in the A dimension than hole portion  70  and thus prevents tuft  30  from being pressed further into hole  40 . Second portion  60  is also longer in the A dimension than hole portion  70  and so prevents tuft  30  from moving back out of hole  40 . This is due to the fact that lips  63  ( FIG. 8 ) engage lips  73  ( FIG. 11 ). This arrangement also prevents tuft  30  from rotating about the long axis of the bristles.  
         [0052]     As shown in  FIG. 15 , tuft  30  pivots when it is engaged by, for example, portions of the oral cavity during brushing. Preferably each tuft  30  can pivot up to about 15 degrees to either side of a position perpendicular to surface  66 .  
         [0053]     Turning to  FIGS. 17 and 18 , another type of tooth cleaning element in the form of a fin  80  is disclosed. Each fin is supported by a base support  48  and an anchor pivot  50  (both not shown) as described above, allowing the fin to pivot on the brush head. Alternatively, a fin can be securely affixed to the head so that it does not pivot. The fin is created of a thermoplastic elastomer (TPE) by an injection molding process. In this embodiment, a textured surface is provided by a series of ribs  82 . These ribs enhance cleaning of the oral cavity. The ribs are formed by injection molding a TPE over the fin. The ribs are preferably softer than the fin. Alternative textured surfaces (e.g. dimples) can be used in place of the ribs.  
         [0054]     As shown in  FIG. 18 , the fin has a width of preferably about 0.030 inches. The long dimension of the fin above the base support is preferably 0.420 inches. A tip  84  of fin  80  has a width of preferably 0.007 inches. The distance from the base of the ribs to tip  84  is about 0.168 inches whereas the distance from the top of the ribs to the tip is about 0.079 inches. The top of the ribs have a width of about 0.035 inches. The ribs (textured surface) preferably extend about 2-12 mil away from said fin.  
         [0055]     The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention.