electric toothbrush head

Abstract

A toothbrush head for an electric toothbrush, comprising a brush having a bristle dome joined to an annular carrier, the bristle dome comprising a support dome having a convex outer surface and bristles extending outwardly from the convex outer surface, the bristle dome being a monolithic structure with fused bristles. The brush may be substantially hemispherical, and the head may comprise one or two such brushes.

Description

[Technical Field]

[0001] The present invention relates to an improved toothbrush head for an electric toothbrush comprising a bristle tufted hemisphere or sphere, particularly a bristle tufted hemisphere or sphere of a configuration that allows for a reduced size of the toothbrush head. [Background technology]

[0002] EP 2142138 describes a toothbrush comprising a substantially spherical brush with two substantially hemispherical sections separated from each other by a channel and drive means extending through the channel, the toothbrush being adapted to impart at least an independent first brushing movement and an independent second brushing movement to the head.

[0003] Applicant has found that toothbrushes with such spherical bristles should be no larger than a certain size to allow for comfortable use and effective cleaning of all teeth. It is an object of the present invention to provide an improved electric toothbrush head having substantially spherical bristles of a sufficiently small size to allow for efficient cleaning of teeth.

[0004] It is a further object of the present invention to provide an improved electric toothbrush head having a substantially hemispherical brush.

[0005] Substantially spherical brushes with drive means have inherent disadvantages when compared to conventional toothbrushes, which typically comprise a group of bristles formed from a plurality of "bristle bundles" hammered into a support at their fixed ends, with the bristles generally projecting in the same orientation from the support to provide a generally flat brushing surface at their free ends.

[0006] A spherical or hemispherical brush (at its base diameter) has a central spherical support from which bristles project in opposite directions. As a result, for a given length of bristles, the overall dimensions of the spherical brush are twice the overall dimensions required for a one-sided configuration. Furthermore, because the bristles must be of a minimum length to provide sufficient fit for a given bristles diameter set by wear requirements, the spherical configuration sets a minimum size for a hemispherical or spherical brush, plus any intervening supports, of at least twice this minimum bristle length.

[0007] Therefore, the size of the support needs to be minimized, but at the same time, the support must provide a strong holding force for the toothbrush bristles. Furthermore, if the support is provided with a drive force receiver, such as a gear, this drive force receiver must be strong enough to transmit / receive sufficient power from the toothbrush drive mechanism to the bristle ball or bristle hemisphere so that the bristle ball or bristle hemisphere rotates even when dentifrice is being used.

[0008] Another problem is that because the bristles project generally radially from the spherical surface, the spacing between the bristles at the free ends will be more pronounced in small domes than in large domes for a fixed bristles length. Applicant has therefore recognised that it is important to maximise the "packing" of the bristles on the support surface to ensure a sufficient density of bristles on the brushing surface of the brush for efficient cleaning and to provide a visually acceptable appearance.

[0009] To this end, Applicant has recognized that the need for a separate support is reduced, and preferably eliminated, by fusing the bristle bundles (also known as tufts) at their bases to provide a monolithic support structure, i.e., a support structure formed from and integral with the bristle material. A bristle dome of reduced size can be manufactured that still retains good bristles' retention strength without a separate support and the associated hammering required to secure the bristles within the support. In another refinement, the monolithic structure is coupled to a support ring that provides a drive force receiver for the bristle dome. Preferably, the support ring is formed from the same material as the bristles and fused to the dome by plastic heating, thereby bringing the entire support ring, dome, and bristles together to form a monolithic structure. Furthermore, by optimizing the bristle bundle geometry to improve packing density at the proximal end of the bristle bundle, the amount of bristle fusing required to form the support dome is minimized. Summary of the Invention

[0010] According to the present invention, there is provided a toothbrush head for an electric toothbrush, comprising a brush comprising a bristle dome joined to an annular carrier, the bristle dome comprising a support dome having a convex outer surface and bristles extending outwardly from the convex outer surface, the bristle dome comprising fused bristles, preferably a monolithic structure consisting of fused bristles.

[0011] Preferably, the support dome formed by the fused bristle material has a radius, measured to the outer surface, of between 2mm and 4mm, preferably between 2.5mm and 3.5mm, most preferably about 6mm.

[0012] Preferably, the support dome formed by the fused bristle material has a wall thickness of between 0.5mm and 2mm, more preferably about 1mm.

[0013] Preferably, the bristles are of substantially equal length and the bristle dome is shaped so that the brush is substantially hemispherical.

[0014] Preferably, the substantially hemispherical brush has a hemispherical radius of 10 mm or less, more preferably 9 mm or less.

[0015] The toothbrush head may further include a second brush comprising a bristle dome joined to an annular carrier, each brush comprising a support dome having a convex outer surface and bristles extending outwardly from the convex outer surface, each bristle dome being a monolithic structure formed by thermal fusing the bristles, the first brush and second brush being joined about their annular carriers to provide a pair of opposite, outwardly facing bristle domes.

[0016] Preferably, the annular carrier of the first brush is bonded to the annular carrier of the second brush. The first annular carrier may be bonded to the second annular carrier using an adhesive or, more preferably, by heat fusion.

[0017] Most preferably, the first annular carrier is fused to the second annular carrier by laser welding. Preferably, the first annular carrier is doped with a material that absorbs laser energy at a predetermined laser frequency, such as carbon black, thereby making it opaque to the predetermined laser light, while the second carrier is undoped and remains substantially transparent to said predetermined laser frequency, thereby ensuring good control of melting at the interface between the first and second annular carriers.

[0018] Preferably, the first brush and the second brush are substantially hemispherical, with the pair of opposed outwardly facing bristle domes providing a substantially spherical brush assembly.

[0019] Preferably, the substantially spherical brush assembly has a spherical diameter of 20 mm or less, more preferably 18 mm or less.

[0020] Preferably, each pair of substantially hemispherical brushes presents a spherical cone with tufts of between 135° and 145°, preferably about 140°, which provides a useful cleaning area at the distal ends of the bristles while providing clearance therebetween for receiving the driving force to the associated annular carrier.

[0021] Preferably, at least one bristle dome is coupled to the annular carrier, and if more than one bristle dome is used, all of the bristle domes are coupled to their annular carriers.

[0022] Preferably, the dome is bonded to the annular carrier using adhesive and / or welding, and / or is bonded to the annular carrier using a mechanical / fusion interface such as a snap fit mechanism which is then heated to fuse the bristled dome to the annular carrier, and / or is bonded to the annular carrier by fusing the bristled dome to the annular carrier.

[0023] Most preferably, the bonding is achieved by heat fusing at least one bristle dome to its annular carrier, thereby fusing the bristle dome and the annular carrier together.

[0024] Preferably, the annular carrier of at least one brush provides the bearing surface, and if two annular carriers are used, each carrier provides at least one bearing surface.

[0025] Preferably, the annular carrier of at least one brush provides a drive force receiving body. Preferably, the drive force receiving body provides at least a portion of a drive ring for receiving drive force from an external drive device, including a gear ring or a pulley ring. More preferably, the drive ring is a gear ring for receiving drive force from a gear drive device.

[0026] When two annular carriers are used, each annular carrier can be adapted to provide a first and second quadrant of the drive ring, the first and second quadrants being equally angularly spaced about the annular carrier, such that the combined annular carriers form a complete drive ring.

[0027] More preferably, the first brush comprises a first annular carrier with a gear ring, and the second brush comprises a second annular carrier that can be coupled to the gear ring of the first gear ring.

[0028] Preferably, the at least one bristle dome and the annular carrier are formed from compatible heat-fusible materials.

[0029] Preferably, the at least one bristle dome is formed from nylon or PBT (polybutylene terephthalate), and the annular carrier is formed from a compatible material.

[0030] Preferably, when at least one bristle dome is made from nylon, the corresponding annular carrier is made from nylon or PC.

[0031] More preferably, at least one bristle dome is made from PBT and the corresponding annular carrier is made from PBT or ABS (acrylonitrile butadiene styrene) or PC (polycarbonate) or PEI (polyetherimide).

[0032] Most preferably, at least one brush comprises a bristle dome and annular carrier formed from PBT.

[0033] Preferably, at least one annular carrier is provided with an annular surface adapted to provide a keying feature for mating with the bristle dome.

[0034] Preferably, the keying feature has a non-flat surface, in particular a re-entrant surface, especially a castellated surface with an annular arrangement of upstanding fingers which may be curved.

[0035] Optionally, keying features are provided on at least one annular carrier, the annular carrier comprising etched material or a plurality of anchors around which the molten bristle material can flow and which, after solidification, can be secured to provide a mechanical bond between the bristle material and the anchors on the annular carrier.

[0036] Preferably, the bristle dome comprises a plurality of bristle bundles, each having a distal end and a proximal end, and the bristles of the bristle bundles are fused at adjacent proximal ends by application of heat to form the support dome, while the distal end of each bristle is free to form the cleaning surface.

[0037] Preferably, all of the support domes of the at least one brush are provided by fused bristle material.

[0038] Preferably, the bristle bundles have a polygonal cross section at their proximal ends to allow for close packing before fusing.

[0039] More preferably, the bristle bundles are formed to have polygonal cross sections at their proximal ends, such that the bristle bundles form loosely packed hemispherical polyhedrons that fuse together to form the support dome.

[0040] Preferably, at least one brush comprises at least a first frusto-conical array of bristle bundles and a second frusto-conical array of bristle bundles concentrically arranged on an annular carrier, the bristle bundles of the first annular array having a first polygonal cross-section and the second annular array of bristle bundles having a second polygonal cross-section, the first polygonal cross-section and the second polygonal cross-section being different from each other.

[0041] Preferably, the bristle bundles are arranged concentrically on the annular carrier in four annular arrays, with the bundles in each concentric array being provided with a different polygonal cross-section than the bundles in another concentric array.

[0042] Preferably, the bristle bundles are arranged concentrically on the annular carrier in four frustoconical arrays, the bundles in each array having a different polygonal cross-section than the bundles in another array.

[0043] Preferably, the bristle bundles are arranged concentrically on the annular carrier in four frusto-conical arrays, with a first array being the outermost array adjacent the annular carrier, a second array being intermediate and spaced further from the annular carrier but interdigitated with the first array, a third array being spaced further from the annular carrier so that the bundles are positioned above the bundles in the first array but interdigitated with the bundles in the second array, and a fourth array disposed around the periphery of the top of the dome.

[0044] More preferably, the first, second and third arrays each comprise seven bristle bundles, while the fourth array comprises three bristle bundles, all three bristle bundles being equiangularly spaced about the axis of the annular carrier in their respective arrays.

[0045] Preferably, the bristle bundles of the first array have an irregular hexagonal first cross-section, preferably comprising a substantially rectangular lower half adjacent the annular ring and a substantially trapezoidal upper half adjacent the annular ring.

[0046] Preferably, the bristle bundles of the second array have an irregular pentagonal second cross-section, which preferably comprises a substantially trapezoidal lower half and an adjacent substantially triangular upper half.

[0047] Preferably, the bristle bundles of the third array have a third shape that is an irregular hexagon.

[0048] Preferably, the bristle bundles of the fourth array have a fourth triangular cross-section, which preferably comprises an isosceles triangle with a curved base.

[0049] Preferably, the bristles of the bristle dome are between 4mm and 7mm, preferably between 5mm and 7mm, most preferably between 5.5mm and 6.5mm, even more preferably about 6mm. [Brief explanation of the drawings]

[0050] [Figure 1] 1 is an isometric view of an electric toothbrush incorporating a brush according to the present invention and a spherical brush assembly according to a second embodiment of the present invention. [Figure 2] FIG. 2 is an isometric view of the toothbrush head of the electric toothbrush of FIG. 1. [Figure 3] FIG. 3 shows a driven spherical brush assembly of the toothbrush of FIG. 2. [Figure 4] FIG. 4 is an exploded view of a portion of the driven brush assembly of FIG. 3. [Figure 5] 4 is a cross-sectional view of the annular carrier assembly of the driven brush assembly of FIG. 3. [Figure 6A] 1 shows a bristle dome according to the present invention; [Figure 6B] 6B shows a cross section of a first array of bristle bundles in the bristle dome of FIG. 6A. FIG. [Figure 6C]6B shows a cross section of a second array of bristle bundles in the bristle dome of FIG. 6A. FIG. [Figure 6D] 6B shows a cross section of a third array of bristle bundles in the bristle dome of FIG. 6A. FIG. [Figure 6E] 6B shows a cross section of a fourth array of bristle bundles in the bristle dome of FIG. 6A. FIG. [Figure 6F] 1 is a schematic diagram showing a portion of a non-closely packed hemispherical polyhedron formed by first, second, third and fourth arrays of bristle bundles. [Figure 7] FIG. 1 is an isometric view of a second toothbrush head incorporating a brush according to the present invention. [Figure 8] 8 is an exploded view showing the brush of FIG. 7 and part of the internal mechanism of the brush.

[0051] Note Figures 1 to 6E, 7 and 8 are based on technical drawings used in the development of toothbrush heads according to the present invention, and therefore the toothbrush heads and components are shown to scale and represent the geometry of toothbrushes according to the present invention.

[0052] Detailed Description of the Invention 1, there is shown an electric toothbrush 100 comprising a handle 102 and a replaceable toothbrush head 104. The handle comprises a drive system (not shown) capable of providing a first rotational drive to the head 104 to cause rotation of the brush in clockwise and counterclockwise directions about a first axis AA, and a second rotational drive to the head 104 to cause rotation of the brush in clockwise and counterclockwise directions about a second axis BB.

[0053] Referring to FIG. 2, the head 104 comprises a first housing 106 fixed in position relative to the handle and an inner second housing 108 having a bearing 110 at its free end 112 that holds a substantially spherical brush assembly 114. The second housing 108 is rotatable relative to the outer housing about axis BB to provide rotation of the brush assembly 114 about axis BB. Rotation of the brush assembly 114 about axis AA is achieved by providing a rotational drive within the second housing 108 to a drive force receiver (see bottom of FIG. 3 ) of the brush assembly 114, which rotates the brush assembly 114 within the bearing 110 about axis AA. The drive force receiver also forms part of the bearing 110 to precisely align the brush assembly 114 with the inner housing 108 and to transmit rotational loads, particularly when rotated about axis BB.

[0054] The stationary first housing 106 is provided with a protective cover or "spoon" 116 that shields a portion of the spherical brush assembly 114 from contact with soft tissue, such as the cheek, when brushing teeth, while the remaining exposed portion of the brush assembly 114 brushes the teeth.

[0055] Referring to FIG. 3, the spherical brush assembly 114 is shown removed from the toothbrush head 104 of FIGS.

[0056] The spherical brush assembly 114 includes a first bristle dome 118 joined to a second bristle dome 120 by a central drive-receiving body 122 including a ring gear 124 having an annular array of teeth 126. The teeth 126 are partially recessed between a first annular flange 128 and a second annular flange 130 such that each tooth root 132 is within the outer diameter of the flanges 128, 130.

[0057] Rotational drive about axis AA is provided by interaction of the drive system's drive gear 134, which is driven about its axis to drive the ring gear 124 of the brush assembly 114 in the opposite direction. The flanges 128, 130 and the location of the ring gear 124 between the flanges 128, 130, with the roots 132 located inside the outer diameter of the flanges 128, 130, ensure that the drive gear 134 is well aligned with the ring gear, ensuring good drive and minimal wear.

[0058] Referring now to Figure 4, there is shown in a partially exploded view the brush assembly 114 shown in Figure 3. The brush assembly 114 includes a first brush 136 and a second brush 138.

[0059] The first brush 136 includes a first bristle dome 118 coupled to a first annular carrier 140, although these components are shown separated to clarify certain features. The second brush 138 includes a second bristle dome 120 coupled to a second annular carrier 142.

[0060] 5, which shows a cross section of the assembly of first annular carrier 140 and second annular carrier 142, first annular carrier 140 includes a first annular flange 128 that provides a bearing shoulder with a curved outer edge 144 and an outwardly facing flat annular surface 146. Inboard of annular flange 128, annular carrier 140 is provided with an annular array of upstanding curved fingers 148a, 148b, 148c that define a textured ring 150 around the outwardly facing surface of first annular carrier 128. A series of alternating recesses 152a, 152b are formed between the fingers 148a, 148b, 148c, the recesses having alternating depths such that the embossed ring 150 provides an equal number of deep grooves 152a and shallow grooves 152b.

[0061] Opposite the first annular flange 128, the first annular carrier 140 includes a splined inner sleeve 154 having an outward array of axial splines. The splined inner sleeve 154 is received by a splined outer sleeve 156 extending from the second annular carrier 142. The splined inner sleeve 154 abuts against an inner shoulder of the splined outer sleeve 156 to provide a joint 158 between the two annular carriers 140, 142 suitable for bonding by adhesive or heat fusion. The splines on the inner sleeve 154 and the splines on the inner sleeve 156 cooperate to ensure good alignment of the first annular carrier 140 and the second annular carrier 142 after assembly.

[0062] The teeth 126 of the ring gear 124 are disposed on the outer curved surface of a splined outer sleeve 156 .

[0063] The second annular carrier 142, like the first annular carrier 140, presents a bearing shoulder provided by the second annular flange 130. The bearing shoulder presents a curved outer edge 160 and an outwardly facing flat annular bearing surface 162.

[0064] Spherical brush assembly bearing surfaces 144, 146, 160, and 162 cooperate with inner housing bearing 110 to locate brush assembly 114 within inner housing 108. The bearing surfaces provide bearing support on either side of ring gear 124 of brush assembly 114 to allow rotational movement of brush assembly 114 about axis AA when driven by drive gear 134, while ensuring good alignment of ring gear 124 and drive gear 134. Outer bearing surfaces 146 and 162 axially locate brush assembly 114 within inner housing 108, also ensuring good gear alignment, and are also important in transmitting rotational forces from inner housing 108 to assembly 110 when assembly 110 is rotated about axis BB.

[0065] Similar to first annular carrier 128, second annular carrier 142 is provided with an indented ring 164 that runs around the outwardly facing surface of second annular carrier 130. Additionally, a series of alternating recesses are formed between the fingers having alternating depths, thereby providing an equal number of deep and shallow grooves through ring 164.

[0066] Referring to Figures 6A and 6B-6E, which show the top of the bristle domes 118, 120, the bristle domes 118, 120 of each brush 136, 138 are formed by fusing multiple arrays of bristle bundles together and to the annular carriers 140, 142.

[0067] More specifically, a first array of seven bristle bundles 166a (and the following, i.e., bristle bundles 166b, 166c, 166d, 166e, 166f, 166g) is coaxially aligned with the axis of the annular carrier 140, 142. The array is equiangularly distributed about the axis of the annular carrier 140, 142 and is substantially frustoconical, i.e., approximating a truncated cone. The array is oriented at an angle of approximately 70° relative to the axis of the carrier 140, 142 (i.e., axis AA), such that each bristle bundle projects upwardly from the plane of the carrier 140, 142 by approximately 20°.

[0068] Each bristle tuft 166a (and below) extends from a proximal end 168 housed in a deep groove 152a in the textured rings 150,164 to a distal end 170 which forms the cleaning surface of the brushes 136,138.

[0069] 6B, bundle 166a (and below) has a hexagonal cross-section 172. The hexagonal cross-section includes a lower rectangular portion 168a and an adjacent upper trapezoidal portion 168b that tapers inwardly away from the adjacent junction with the lower rectangular portion.

[0070] The frustoconical second array of seven bristle bundles 174a (and the following, i.e., bristle bundles 174b, 174c, 174d, 174e, 174f, 174g) is coaxially aligned with the axis of the annular carriers 140, 142. Each bristle bundle is oriented at an angle of approximately 60° relative to the axis of the carriers 140, 142, such that each bristle bundle projects upwardly from the plane of the carriers 140, 142 at an angle of approximately 30°.

[0071] Each bristle tuft 174a (and below) in the second array extends from a proximal end 176 that is received in a shallow recess 152b in the textured ring 150, 164 to a distal end 178 that forms the cleaning surface of the brush 136, 138. The tuft 174a (and below) has a pentagonal cross-section 180 with a lower trapezoidal portion 180a and an adjacent isosceles triangular portion 180b.

[0072] The proximal end 176 of the second array is positioned to mate with the proximal end 176 of the first array, but is higher from the plane of the carriers 140, 142 than the first array, such that the lower trapezoidal portion of the second bristles 174a (and below) is completely between the first bundles, but the triangular portion 180b of the cross section 180 of the second bristle bundle 174a (and below) is positioned above the first array of bristle bundles 166a (and below).

[0073] The frustoconical third array of seven equiangularly spaced bristle bundles 182a (and below, i.e., bristle bundles 182b, 182c, 182d, 182e, 182f, 182g) is angled at approximately 30° with respect to the carrier axis, such that each bristle bundle projects upwardly from the plane of the carrier at approximately 60°. Each bristle bundle 182a extends from a proximal end 184 located adjacent the proximal ends of the first array 166a (and below) and the second array 174 (and below), to a distal end 186 that forms the cleaning surface of the brush 114.

[0074] The third array of bristle bundles 182a (and below) have a hexagonal cross-section 188 with a lower half shaped to roughly match the upper surface of the cross-section 172 of the first bristle bundle and to fit between the triangular portions 180b of the cross-section of the second bristle bundle.

[0075] The final, frustoconical, fourth array of bristle bundles 190a, 190b, 190c comprises three bristle bundles 190a, 190b, 190c equiangularly spaced about the axis of the carrier 140, 142. Each bundle is oriented at an angle of approximately 15° relative to the carrier axis, i.e., approximately 75° relative to the plane of the carrier 140, 142. Each bundle 190a (and below) extends from a proximal end 192 located adjacent the proximal end of the third array 182a (and below) to a distal end 194 that forms the cleaning surface of the bristle dome 118, 120.

[0076] The fourth array of bristle bundles 190a (and below) have lobe-shaped cross-sections 192 resembling an isosceles triangle with a curved base. The bundles are arranged flat-to-flat such that the curved base forms an annular line at its proximal end adjacent the upper surface of the fourth bristle bundle.

[0077] Referring now to Figure 6F, it is shown schematically that the cross-sections 172, 180, 177, 196 presented by the first, second, third, and fourth arrangements of the bristle bundle proximal ends 168, 176, 184, 192 may allow the proximal ends of the bristles to be closely packed with minimal gaps therebetween, thereby providing a loosely packed hemispherical polyhedron 198. Figure 6F shows just under half of the full hemispherical polyhedron 198 due to the limitations of presenting a three-dimensional surface as a two-dimensional view.

[0078] This fusion of the hemispherical polyhedrons by fusing the bristle bundles together at their proximal ends provides the bristle domes 118, 120 according to the present invention. Fusion at the proximal ends of the bristle bundles eliminates the need to hammer the bristle bundles into separately formed components, allowing for reduced dimensions while providing sufficient retention of the bristles through a monolithic structure.

[0079] Preferably, the formation of the bristle domes and the fusing of the bristle domes to the annular carrier formed from a compatible material occur simultaneously. This provides a strong bond between the bristle domes and the carrier for the reasons discussed above. Another advantage is that while the domes can be formed by fusing them together, features of the brushes (136, 138) that require special dimensional control, such as the bearing surfaces and any drive mechanisms, can be provided via injection molding of the annular carrier prior to fusing. The injection molding process has better dimensional control than the fusing process used to form the support domes, which facilitates much better control of bearing tolerances.

[0080] In manufacture, the bristle bundles are inserted into a mold having a substantially hemispherical cavity (not shown) so that they protrude into the cavity a predetermined distance. A heated hemispherical press, having a similar geometry to the hemispherical cavity but shaped to leave a gap of approximately 1 mm between the press and the cavity to form a dome support, is then inserted into the cavity, whereby the press contacts the proximal ends of all of the bristle bundles. The tool is heated to a temperature that fuses the bristle material together to form a monolithic bristle dome.

[0081] The gap between the press and the cavity provides a wall thickness of about 1 mm which is believed to provide good retention strength for the bristle bundle whilst allowing a suitably small support to be formed, although it may be possible to achieve the same properties with wall thicknesses ranging between 0.5 mm and 2 mm.

[0082] In one preferred step, the hemispherical cavity is recessed to accommodate the annular carrier 140, 142, which is inserted into the recess so that the first bristle array 166a (and below) and the second bristle array 174a (and below) are adjacent the recesses 152a, 152b, respectively, provided by the annular carrier's indented rings 150, 164. Curved fingers 148a, 148b surround the bristle arrays on either side and provide a mechanical lock to stabilize the bristle arrays in place.

[0083] A similar heated hemispherical press is then introduced into the cavity and positioned to contact the proximal ends of all of the bristle bundles and also the inside of the indented rings 150, 164 of the annular carrier. The press is heated to fuse the proximal ends together to form the support domes of the bristled domes (118, 120), which simultaneously, or nearly simultaneously, fuse with the indented rings of support to form the monolithic bristle dome and annular carrier.

[0084] In this embodiment, the bristles and carrier are all made from PBT (polybutylene terephthalate), which ensures good fusion between the components. Other materials can be used for the bristle dome, including nylon.

[0085] If the carrier is fused to the bristle dome, the same or a compatible material should be used, for example, for a PBT bristle dome, the carrier can be made from ABS (acrylonitrile butadiene styrene), or PC (polycarbonate), or PEI (polyetherimide). For a nylon bristle dome, the carrier can be made from nylon or PC.

[0086] In an alternative manufacturing process, the bristle dome can be joined to the carrier after the bristle ends are fused together, either by a separate fusing step to fuse the carrier to the bristle dome, or by using an adhesive to glue the bristle dome and carrier together.

[0087] After one bristle dome 118 is formed and joined to the first annular carrier 140 to provide the first brush 136, and one bristle dome is formed and joined to the second annular carrier 142 to provide the second brush 138, the bristle domes 118, 120 are bonded together by the use of a suitable adhesive at the joints 158 of the annular carriers 140, 142, thereby providing a substantially spherical brush assembly 114.

[0088] In an alternative process, one of the annular carriers 140, 142 may be doped with a suitable material, such as carbon black. After assembly of the bristled domes 118, 120, a laser is focused through the undoped carrier onto the abutment 158, causing the laser energy to be absorbed by the doped carrier. This causes localized heating at the abutment 158 and thus the two carriers 140, 142 to fuse together.

[0089] Ideally, all bristles in the bristle bundle are the same length after manufacture. In this embodiment, all bristles are approximately 6 mm long. Preferably, the dome of the bristle dome has a radius of 8 mm or less, more preferably 6 mm, ensuring that the substantially hemispherical brush is 20 mm or less in its widest dimension and more preferably 18 mm or less in its base dimension (across the first annular array of bristles).

[0090] Referring to FIG. 7, a second toothbrush head 200 including a brush 202 according to the present invention is shown in isometric view.

[0091] The second toothbrush is compatible with the toothbrush handle shown in FIG. 1, but is simply configured to rotate about the axis of brush 202, ie, axis AA.

[0092] 8, brush 202 comprises a single brush 204 having a bristle dome 206. An annular carrier 208 provides an annular bearing channel and is adapted to receive a splined drive gear 208. The drive gear is inclined to translate drive force received from a drive shaft 210 by 90° to rotate the brush about axis AA.

Claims

1. A toothbrush head for an electric toothbrush, comprising a brush having a bristle dome joined to an annular carrier; the bristle dome comprises a support dome having a convex outer surface and bristles extending outwardly from the convex outer surface; The toothbrush head is a monolithic structure in which the bristle dome comprises a plurality of bristle bundles, each having a distal end and a proximal end, and the bristles of the bristle bundles are fused at adjacent proximal ends to form the support dome.

2. 10. The toothbrush head of claim 1, wherein the bristle dome is shaped so that the brush is substantially hemispherical.

3. a second brush comprising a bristle dome joined to the annular carrier; each brush comprising a support dome having a convex outer surface and bristles extending outwardly from said convex outer surface; 10. The toothbrush head of claim 1, wherein each bristle dome is a monolithic structure formed by fused bristles, and a first brush and a second brush are joined about their annular carriers to provide a pair of opposed, outwardly facing bristle domes.

4. 4. The toothbrush head of claim 3, wherein the first brush and the second brush are substantially hemispherical, and the pair of opposed, outwardly facing bristle domes provides a substantially spherical brush assembly.

5. 5. A toothbrush head according to any preceding claim, wherein at least one bristle dome is coupled to the annular carrier.

6. 6. A toothbrush head according to any one of claims 1 to 5, wherein at least one bristle dome and the annular carrier are fused together.

7. A toothbrush head according to any preceding claim, wherein the annular carrier of at least one brush provides a bearing surface.

8. A toothbrush head according to any preceding claim, wherein the annular carrier of at least one brush provides a drive force receptor.

9. 9. A toothbrush head according to any preceding claim, wherein the bristle dome and annular carrier of at least one brush are formed from PBT.

10. 10. A toothbrush head according to any one of claims 1 to 9, wherein at least one brush comprises at least a first frustoconical array of bristle bundles and a second frustoconical array of bristle bundles concentrically mounted on the annular carrier, the bristle bundles of the first annular array having a first polygonal cross-section, and the second annular array of bristle bundles having a second polygonal cross-section, the first polygonal cross-section and the second polygonal cross-section being different from each other.

11. 11. The toothbrush head of claim 10, wherein the bristle bundles are arranged concentrically on the annular carrier in four frustoconical arrays, the bundles in each concentric array having a different polygonal cross-section than the bundles in another of the arrays.

12. 12. A toothbrush head according to claim 10 or claim 11, wherein the polygonal cross-section of the proximal end of the bristle bundle allows the formation of a non-closely packed hemispherical polyhedron.

13. An electric toothbrush comprising a toothbrush head according to any one of claims 1 to 12.

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