Patent Description:
It is known that a drive shaft of an oral care device handle such as an electric toothbrush can be coupled to a motion transmitter disposed within an oral care device attachment such as a replacement brush head by means of magnetic attraction, specifically in case that the drive shaft provides a linear vibration. The motion transmitter may be coupled with a carrier mounted at an outer tube housing of the attachment so that the carrier is driven into an oscillating rotation around a rotation axis when the linear vibration of the drive shaft is transferred to the carrier by the motion transmitter. Such a magnetic coupling avoids wear-prone mechanical coupling components and serves to transfer the linear vibration in a low noise manner as the magnetic attraction keeps the coupling partners together. As the magnetic coupling partners only need to connect to on the axial surfaces, the distance between, e.g., the drive shaft coupling end and a housing of the oral care device handle can be realized relatively small, e.g., with a circumferential distance or gap of less than <NUM>, which renders the overall coupling area less bulky than with other designs. Such a coupling concept is, for example, described in documents <CIT>.

But the magnetic coupling requires, e.g., a magnet disposed in the coupling end of the drive shaft of the oral care device handle and a further magnet or magnetizable element in the respective coupling end of the motion transmitter disposed in the attachment. These components make the coupling relatively expensive.

Document <CIT> discloses an electric toothbrush including a brush head with bristles, an elongated main housing, a motion transmission link, motion generating means and motion transformation means, wherein said brush head includes an elongated stem for connecting said brush head to said motion generating means via said motion transmission link, said motion generating means include means for generating reciprocating motions along a longitudinal axis, said motion transmission link transmits the reciprocating motions generated by said motion generating means along said longitudinal axis to said elongated stem of said brush head, said elongated stem is rotatable about said longitudinal axis while undergoing said reciprocating motions said longitudinal axis, and said motion transformation means include means to rotate said brush head about said longitudinal axis while said elongated stem is undergoing reciprocating longitudinal motions along said longitudinal axis. Said motion transmission link includes a crank arm and a connection member, said connection member connects said elongated member to said crank arm, said crank arm includes a head portion disposed adjacent to a narrowed neck portion for coupling to said connection member, said connection member includes a hollow cylindrical body with an inwardly extending radial flange, said head portion of said crank member being retained within said hollow cylindrical body of said connection member by said inwardly extending radial flange. Said motion transformation means include a generally cylindrical collar member surrounding said elongated stem, said guiding means include a guiding track on the cylindrical surface of said collar member, said guiding track extends between the longitudinal ends of said collar member and is non parallel to said longitudinal axis, said tracking means include a tracking member which is slidably movable along said guiding track, a spring member is disposed between the cylindrical collar member of said motion transformation means and the connection member of said motion transmission link, said spring member is disposed so that it is compressed by said connection member of said motion transmission link when said connection member moves towards said collar member, said spring member pushes said elongated stem away from said collar member when connection member moves away from said collar member.

Document <CIT> discloses an interlocking device of an electric toothbrush rotating head mainly includes a Z shaped connecting rod as a power connection between a handle body and a brush disc, with one end of the connecting rod serving as a horizontal shaft and the other end serving as a vertical shaft. The transverse shaft is pivotally mounted on the clamping cover to connect the interlocking shaft rod of the handle body and the elevation shaft is connected onto the eccentric elevation hole of the brush disc to convert linear motion of the interlocking shaft rod of the handle body into reciprocating rotary motion at the brush disc. A spring of the outer cover of clamping cover is supported at its bottom by convex edge of clamping cover and supported at its top by one wall of engine unit to help clamping cover return downwards to the starting point.

Hence, there is a need to provide a less expensive coupling between an essentially cylindrical coupling end of a drive shaft of an oral care device handle and a motion transmitter of an oral care device attachment for the oral care device handle that still allows for a small circumferential gap between the coupling end of the drive shaft and a housing of the oral care device handle.

In accordance with at least one aspect an oral care device attachment is provided in accordance with claim <NUM>. Further embodiments are provided by the depending claims.

The present disclosure will be further elucidated by a detailed description of example attachments and with reference to figures. In the figures.

In accordance with the present disclosure, solutions are proposed for coupling an oral care device attachment to an oral care device handle having a drive shaft with an essentially cylindrical drive shaft coupling end. The drive shaft is arranged to provide a linear vibration, i.e., an oscillatory motion of the drive shaft along is longitudinal axis. The essentially cylindrical drive shaft coupling end may have (a) a diameter in a range of between <NUM> and <NUM>, preferably of about <NUM> such as <NUM>, (b) a relatively small circumferential distance to a portion of a housing of the handle enveloping the essentially cylindrical drive shaft coupling end, where the circumferential gap or distance may be less than about <NUM>, preferably less than about <NUM>, further preferably in the range of about <NUM> and/or (b) may have at least one indentation, a circumferential groove or may continue with a lower diameter. The circumferential may be non-constant, i.e., the housing enveloping the essentially cylindrical drive shaft coupling end may have a non-circular cross-section or may be arranged non-coaxial with respect to the essentially cylindrical drive shaft coupling end. That may mean that the circumferential gap has, e.g., a gap width of about <NUM> in at least one area and a gap width of, e.g., <NUM> in another area. The gap width shall be understood to be measured in a plane that is perpendicular to a longitudinal axis of the essentially cylindrical drive shaft coupling end. Further, the essentially cylindrical drive shaft coupling end may have a length extension in the direction of the longitudinal axis in the range of between <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>, further preferably of about <NUM> such as <NUM>.

<FIG> is a depiction of an example oral care device <NUM> that comprises an oral care device attachment <NUM> (referred to herein also simply as "attachment") and an oral care device handle <NUM> (referred to herein also simply as "handle"). The attachment <NUM> comprises an outer attachment tube or housing <NUM>, a carrier <NUM> that is mounted at the outer attachment tube <NUM> for driven oscillatory rotation as is indicated by double arrow R (even though the herein proposed attachment is not limited to comprise carriers being driven into an oscillatory rotation). Oral Care elements <NUM> are here mounted on the carrier <NUM>. The handle comprises a housing <NUM>. The attachment <NUM> is detachably attached to the handle <NUM>, preferably, the outer attachment tube <NUM> is mechanically secured at the housing <NUM> of the handle <NUM> so that in an attached state the outer attachment tube <NUM> and the housing <NUM> do not move relative to each other. As will be explained in more detail, a drive shaft of the handle <NUM> is detachably connected with a motion transmitter disposed in the outer attachment tube <NUM> so that a motion (typically a linear vibration along a longitudinal direction) provided by the drive shaft is transmitted to the carrier <NUM> in operation by the motion transmitter. The oral care device <NUM> is here shown as an electric toothbrush, the attachment <NUM> as a replaceable brush head and the oral care elements <NUM> as bristle tufts.

<FIG> is a depiction of an example attachment 10A shown in isolation. The attachment 10A comprises an outer attachment tube or housing 11A, a carrier 12A mounted at the outer attachment tube 11A for driven motion and a plurality of oral care elements 13A mounted on the carrier 12A.

<FIG> is a cross-sectional cut through a top portion of an oral care device 1B as known from prior art and comprising an attachment 10B detachably attached to a handle 20B (only partly shown) that has a housing 21B that is here only indicated. The attachment 10B and the handle 20B generally extend along a longitudinal axis L that here coincides with a central axis of a drive shaft 31B of the handle 20B. The cross-sectional cut shows an oral care device 1B as it is generally discussed, e.g., in document <CIT>. In the oral care device 1B, a motion transmitter 13B is coupled at a first end with a carrier 12B, which carrier 12B carries a plurality of oral care elements 13B and is mounted at an outer attachment tube 11B of the attachment 10B for driven rotation about an axle 15B, i.e., about a rotation axis defined by the axle 15B. The motion transmitter 13B comprises at a second end a first magnetically interacting element 14B and is releasably coupled with an essentially cylindrical drive shaft coupling end 30B. The essentially cylindrical drive shaft coupling end 30B comprises a second magnetically interacting element 32B that magnetically interacts with the first magnetically interacting element 14B so that both magnetically interacting elements 14B and 32B essentially stay in abutting contact in regular operation when the drive shaft 31B provides a linear reciprocation motion along the longitudinal axis L. The magnetic interaction is established by each of the magnetically interacting elements 14B and 32B being realized as a magnet or by one of them being realized as a magnet and the other as a magnetizable element. The first magnetically interacting element 14B is secured at the second end of the motion transmitter 13B and the second magnetically interacting element 32B is a part of the essentially cylindrical drive shaft coupling end 30B. One may prefer to realize the second magnetically interacting element 32B as a magnet and the first magnetically interacting element 14B as a magnetizable element as the attachment 10B may typically intended to be a disposable part. The essentially cylindrical drive shaft coupling end 30B is here realized by a cap 34B, e.g., a metal cap, in which the second magnetically interacting element 32B, which may be a cylindrical magnet, e.g., a cylindrical NdFeB-type magnet, is one the one hand secured to the cap 34B by means of an adhesive 33B and on the second hand secured to the drive shaft 31B by means of the adhesive 33B. The essentially cylindrical drive shaft coupling end 30B has a diameter d and a length l as is indicated in <FIG>. Potential values for the diameter d and the length l have been discussed in a previous paragraph. Underneath the essentially cylindrical drive shaft coupling end 30B, i.e., at the lower end facing the handle 20B, an undercut may be provided as the drive shaft 31B may be smaller in diameter than the essentially cylindrical drive shaft coupling end 30B. The meaning of the term "undercut" in the present application is thus of a portion underneath the essentially cylindrical drive shaft coupling end that is smaller in diameter than the essentially cylindrical drive shaft coupling end itself and it may be smaller in all directions or just in one or several circumferentially distributed areas. The attachment 10B here comprises a coupling end comprising a first mechanical connector 16B that is detachably coupled with a second mechanical connector 26B of the handle 20B so that the outer attachment tube 11B and a drive shaft housing 22B are positionally secured to each other. The first and second mechanical connectors 16B and 26B may mechanically couple to each other by means of mechanical coupling elements such as flexible snap hooks as is generally known in the art. The drive shaft 31B may be sealed against a hollow of the drive shaft housing 22B by means of a seal 35B so that liquids cannot enter the hollow.

In the following, oral care device attachments are described, where the attachment discussed with reference to <FIG> is an example attachment as covered by the claimed invention. All attachments but the example attachment of <FIG> comprise a coupling unit having a top plate and either (a) one at least partly deformable essentially cylindrical wall element that together with the top plate defines a receiver cylinder suitable to receive an essentially cylindrical drive shaft coupling end of a drive shaft from an oral care device handle or (b) at least two elastic or deflectable or pivotable wall elements that define an essentially cylindrical receiver volume or receptacle to receive said essentially cylindrical drive shaft coupling end. There are at least three additional aspects that are considered in the attachments as discussed herein, which aspects can be implemented individually or together, i.e., two of the three aspects together or all three aspects together. These three additional aspects are:.

Possible material choices for realizing the at least one at least partly deformable essentially cylindrical wall element from a thermoplastic elastomer or a natural rubber comprise, in a non-limiting manner, one of following materials: thermoplastic elastomer (TPE), nitrile rubber (NBRs), silicone rubber, EPDM rubber, styrene-butadiene rubber (SBR).

Possible material choices for realizing the at least partly deformable essentially cylindrical wall element or the at least two elastic or deflectable wall elements from a thermoplastic material comprise, in a non-limiting manner, one of following materials: polypropylene (PP), polyamide (PA), polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), thermoplastic elastomer (TPE) such as Hytrel, or polybutylene terephthalate (PBT). The same materials can be chosen for realizing the top plate if the top plate or a part thereof are to be made from a thermoplastic material.

Possible material choices for realizing the at least partly deformable essentially cylindrical wall element or the at least two elastic or deflectable wall elements from sheet metal comprise, in a non-limiting manner, one of following materials: stainless steel, e.g., having the material number <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> according to standard EN <NUM>-<NUM> and other non-corroding steels or other metals suitable for making thin foils with good elastic properties that preferably are labelled as food-grade materials. Other metal materials like molybdenum, titanium or alloys may be used as well but tend to be more expensive. The same materials can be chosen for realizing the top plate if the top plate or a part thereof are to be made from metal.

<FIG> are depictions of an attachment <NUM> not covered by the claimed invention. <FIG> is a cross-sectional cut through the attachment <NUM>, <FIG> is a perspective view onto a detail showing the second end of a motion transmitter <NUM> comprising a coupling unit <NUM>, <FIG> is a cross-sectional cut through a lower portion of the attachment <NUM> and of a drive shaft <NUM> comprising an essentially cylindrical drive shaft coupling end <NUM>, and <FIG> is a perspective and partly transparent view onto an attachment <NUM>' that further comprises a first mechanical connector <NUM> that is omitted in <FIG>. Identical features of the attachment <NUM> or <NUM>' have the same reference numerals.

The attachment <NUM> shown in <FIG> has an outer attachment tube <NUM> and a motion transmitter <NUM> arranged within a hollow of the outer attachment tube <NUM>. The motion transmitter <NUM> has a first end that is coupled with a carrier <NUM> that carries oral cleaning elements <NUM> and that is arranged for driven motion relative to the outer attachment tube <NUM>. The attachment <NUM> has a lower end comprising an opening <NUM> for allowing coupling of the attachment <NUM> to a handle of an oral care device, where specifically a drive shaft of the handle would enter into the hollow via the opening <NUM> to establish a connection with a second end or coupling end of the motion transmitter <NUM>, the coupling end of the motion transmitter <NUM> comprising a coupling unit <NUM>. The coupling unit <NUM> comprises a top plate <NUM> and an at least partly deformable essentially cylindrical wall element <NUM> that defines a virtual receiver cylinder <NUM> for receiving an essentially cylindrical drive shaft coupling end of a drive shaft of a handle of an oral care device - see <FIG>. The lower end of the attachment <NUM> typically comprises a first mechanical connector <NUM>, which is omitted in <FIG> and <FIG>, but is shown in <FIG>.

<FIG> shows the lower portion of the motion transmitter <NUM>, where "lower" relates to the second end of the motion transmitter <NUM> that comprises the coupling unit <NUM>. The motion transmitter <NUM> has a first portion <NUM> that extends towards the first end that is coupled with the carrier <NUM> (see <FIG>) and a second portion <NUM> that continues into the coupling unit <NUM>. A pivot <NUM> is provided between the first portion <NUM> and the second portion <NUM> of the motion transmitter <NUM> to compensate for an angulation between the first and second portions <NUM>, <NUM> of the motion transmitter <NUM> in operation. The pivot <NUM> is here realized as a living hinge. The coupling unit <NUM> comprises the top plate <NUM> that here is integral with the motion transmitter <NUM> and the complete integral part may be made by plastic injection molding. The at least partly deformable cylindrical wall element <NUM> comprises a slot <NUM> that extends from a lower end to the level of the top plate <NUM> to make the wall element <NUM> at least partly deformable due to its elastic properties. The at least partly deformable cylindrical wall element <NUM> may be made from thin bent metal sheet, e.g., the metal sheet may have a thickness of between <NUM> micrometer and <NUM> micrometer, preferably between <NUM> micrometer and <NUM> micrometer such as <NUM> micrometer, <NUM> micrometer, <NUM> micrometer, <NUM> micrometer, <NUM> micrometer, <NUM> micrometer, <NUM> micrometer or <NUM> micrometer. These thickness values are generally applicable to all attachments discussed herein comprising a metal sheet part. The at least partly deformable cylindrical wall element <NUM> may be connected to the top plate <NUM> by at least one, preferably at least two caulked projections <NUM> extending from the top plate <NUM>. This shall not exclude that the wall element <NUM> may be secured to the top plate <NUM> by other or additional techniques such as (laser) welding, gluing, riveting, screwing etc. Alternatively or additionally to the slot <NUM>, the wall element <NUM> may comprise a slot <NUM> that is indicated by dashed lines and that may extend along the complete length of the wall element <NUM>. The coupling unit <NUM> comprises a receiver opening <NUM> to allow the essentially cylindrical drive shaft coupling end to enter into the virtual receiver cylinder <NUM> (see <FIG>).

<FIG> shows the same cross-sectional cut as shown in <FIG> but only of a portion of the attachment <NUM> and including an upper portion of a drive shaft <NUM> having an essentially cylindrical drive shaft coupling end <NUM> that is shown here in a coupled state in which the essentially cylindrical drive shaft coupling end <NUM> is received in the virtual receiver cylinder <NUM>. As was already discussed in connection with <FIG>, the essentially cylindrical drive shaft coupling end <NUM> may comprises a magnet or magnetizable element <NUM>, a cap <NUM> and an adhesive <NUM> fixedly connection the cap <NUM>, the magnet or magnetizable element <NUM> and the drive shaft <NUM> together. But it is noted here, that the magnetically interaction capability is not of relevance as the attachments discussed herein attach mechanically to the essentially cylindrical drive shaft coupling end <NUM>. Thus, the essentially cylindrical drive shaft coupling end <NUM> may also be just a cylinder, e.g., a plastic cylinder or a metal cylinder. Underneath the essentially cylindrical drive shaft coupling end <NUM> a smaller diameter section <NUM> may extend so that an undercut in accordance with the definition of "undercut" provided in a previous paragraph is provided there. The attachments shown in <FIG> make use of the presence of such an undercut underneath the essentially cylindrical drive shaft coupling end <NUM>. It is noted that instead of a smaller diameter section realizing the undercut also a groove or individual receptacles may be provided in the essentially cylindrical drive shaft coupling end <NUM> to realize the undercut.

<FIG> is a perspective view of an attachment <NUM>' essentially identical with the attachment <NUM> shown in <FIG> and <FIG> but with the outer attachment tube <NUM> shown transparent and with a first mechanical connector <NUM> disposed in the lower end of the attachment <NUM>', where the term lower end refers to the end of the attachment <NUM>' that is intended to be coupled with a handle. The other elements shown in <FIG> have already been discussed and it is referred to the above description relating to <FIG>.

<FIG> are depictions of an attachment 100A not covered by the claimed invention. The elements of this attachment that remain essentially identical in comparison to <FIG> are not again discussed (the reference numerals change, e.g., from <NUM> to 120A or to 120B etc. in the following description) and only the differences are highlighted. This will also hold true for the following description up to and including <FIG>. Instead of a living hinge as discussed for the previous attachment, the present attachment comprises a pivot 142A realized by a swivel joint having a pivot axle 1421A. The pivot 142A allows a first portion 141A and a second portion 143A of a motion transmitter 140A to pivot relatively to each other to allow a changing angulation between the first portion 141A and the second portion 143A. The coupling unit 200A comprises a top plate 210A and an at least partly deformable essentially cylindrical wall element 220A that defines a virtual receiver cylinder 251A for receiving an essentially cylindrical drive shaft coupling end of a drive shaft. The top plate 210A and the second portion 143A of the motion transmitter 140A may be made from metal such as non-magnetic steel and the partly deformable essentially cylindrical wall element 220A may again be made from non-magnetic thin metal sheet material and may be connected to the top plate 210A by laser welding or any other metal connection technology such as gluing, screwing, riveting etc..

<FIG> are depictions of an attachment 100B not covered by the claimed invention. Here, a spring 250B is arranged between a coupling unit 200B and an outer attachment tube 110B so that the coupling unit 200B is biased towards an opening 111B provided in a lower end of the attachment 110B. The spring 250B is here at one end abutting an annular abutment surface 112B provide on the inner surface of the outer attachment tube 110B and on the other end is abutting a top abutment surface 212B of a top plate 210B of the coupling unit 200B. The spring 250B supports attaching the coupling unit 200B on an essentially cylindrical drive shaft coupling end of a drive shaft in an attachment process. The outer attachment tube 110B may comprise an essentially cylindric inner section 113B that provides a guide for the spring 250B so that the spring cannot bulge or move sidewards. The coupling unit 200B here comprises the top plate 210B and an at least partly deformable essentially cylindrical wall element 220B that may be made from plastic and that may be realized together with a motion transmitter 140B as an integral part. As was discussed with respect to the previous attachments, the at least partly deformable essentially cylindrical wall element 220B may comprise a slot or other cutout 221B that supports the deformation of the at least partly deformable essentially cylindrical wall element 220B.

<FIG> are depictions of an attachment 100C not covered by the claimed invention. The attachment 100C comprises a coupling unit 200C that has some similarities with a secondary closure for champagne bottles. The coupling unit 200C has two deflectable or pivotable wall elements 2210C and 2220C mounted at a top plate 210C of the coupling unit 200C. The two deflectable wall elements 2210C and 2220C are each deflectable or pivotable around an axle 225C, i.e., around an axis defined by the axle 225C, against a restoring spring force. In their rest position, the two deflectable wall elements 2210C and 2220C envelope a virtual receiver cylinder 251C for receiving an essentially cylindrical drive shaft coupling end of a drive shaft. Each of the two deflectable wall elements 2210C and 2220C comprises a spring extension 2211C and 2221C, respectively, that each abut an abutment surface 1431C of a second portion 143C of a motion transmitter 140C, even though this is considered non-limiting and the restoring spring force may be otherwise provided. In case that one of the two deflectable wall elements 2210C or 2220C is deflected essentially radially outwards around the axle 225C, the respective spring extension 2211C or 2221C is pushed against the second portion 143C of the motion transmitter 140C and thus elastically deforms, whereby a restoring spring force is created that pushes the deflected wall element back 2210C or 2220C into its rest position. In the shown attachment, each of the two deflectable wall elements 2210C and 2220C comprises a cut-out 2212C and 2222C, respectively, provided at a lower end and each comprises a radially inwards extending projection 2213C and 2223C, respectively. The projections 2213C and 2223C may be realized as being integral with the respective deflectable wall element 2210C and 2220C at which they are provided. , the wall elements 2210C and 2220C may be made from thin metal sheet material and the projections 2213C and 2223C may be made from a rolled or folded or bent piece of metal sheet material as is indicated in <FIG>. When an essentially cylindrical drive shaft coupling end enters into the virtual receiver cylinder 251C, the projections 2213C and 2223C push the two deflectable wall elements 2210C and 2220C radially outwards so that they pivot around the axle 225C until the projections 2213C and 2223C snap into an undercut such as a smaller diameter section underneath the essentially cylindrical drive shaft coupling end or a groove or receptacle provided in the essentially cylindrical drive shaft coupling end.

<FIG> are depictions of an attachment 100D not covered by the claimed invention. The attachment 100D comprises a coupling unit 200D that comprises two deflectable wall elements 2210D and 2220D that define a virtual receiver cylinder 251D. In contrast to the attachment shown in <FIG>, the two deflectable wall elements are not arranged to be pivotable around an axle but are arranged to be deflectable or bendable due to the elasticity of the material from which they are made, e.g., they may be made from a metal sheet material. A top plate 210D of the coupling unit 200D and a motion transmitter 140D are an integral part that may be made by plastic injection molding. The two deflectable wall elements 2210D and 2220D may be connected to the top plate 210D by means of one or several caulked projections 211D or other techniques as was already discussed with reference to <FIG>. Further, the two deflectable wall elements 2210D and 2220D each comprise a radially inwards extending projection 2213D and 2223D, respectively. The projections 2213D and 2223D may be made by stamping or bending. It is noted here for sake of clarity that while in this attachment the projections 2213D and 2223D are realized in a manner different to the projection discussed with respect to the attachment shown in <FIG>, this is not to be understood as limiting. All ways to realize the projections may be interchangeably used in all attachments where projections are used and specifically the two or more projections do not all need to be made in the same manner.

<FIG> are depictions of an attachment 100E not covered by the claimed invention. This attachment has some similarities with the attachment shown in <FIG> but here a top plate 210E and two deflectable wall elements 2210E and 2220E that define a virtual receiver cylinder 251E are together realized as an integral part, e.g., as a plastic injection molded part. The integral part may also comprise a motion transmitter 140E. The two deflectable wall elements 2210E and 2220E may again each comprise a radially inwards extending projection 2213E and 2223E, respectively, which in this attachment may then be made in the plastic injection molding process.

<FIG> are depictions of an attachment 100F not covered by the claimed invention. The attachment 100F comprises a coupling unit <NUM> that is detachably coupled with at least a portion of a motion transmitter 140F. More precisely, in the shown attachment, a first portion 141F of the motion transmitter 140F ends with a first separable coupling part 1421F, which is separably coupled with a second separable coupling part 1422F, and the first and second separable coupling parts 1421F and 1422F together form a separable joint 142F which may be realized as a separable ball joint. The first separable coupling part 1421F is here realized as a spherical end portion of the first portion 141F of the motion transmitter 140F and the second separable coupling part 1422F here comprises several flexible arms that define a spherical receiver volume that can receive the spherical end portion. The coupling unit 200F is here realized integral with the second separable coupling part 1422F and a second portion 143F of the motion transmitter 140F so that they together form a separable adaptor 400F and the adaptor 400F may be realized as a plastic injection molded part. The coupling unit 200F here comprises two deflectable wall elements 2210F and 2220F that define a virtual receiver cylinder 251F and each of the two deflectable wall elements 2210F and 2220F comprise a radially inwards extending projection 2213F and 2223F, respectively, that may be structured to only allow a one-time attachment to an essentially cylindrical drive shaft coupling end by engaging into an undercut. Once attached to the essentially cylindrical drive shaft coupling end, the coupling unit 200F may then only be removable by destroying the projections 2213F and 2223F. Alternatively, the projections 2213F and 2223F may be shaped such that the coupling unit 200F can only be removed from the essentially cylindrical drive shaft coupling end by applying a relatively high force but without destroying the projections 2213F and 2223F - such removal force may be well above usual forces acting on the adaptor 400F during regular operation, e.g. the removal force may be above <NUM> N or above <NUM> N or above <NUM> N. The removal force should in particular be set higher than the separation force needed to separate the separable joint 142F. The basic idea here is that the integral part comprising the coupling unit 200F, the second portion of the motion transmitter 143F and the second separable coupling part 1422F remains attached to the essentially cylindrical drive shaft coupling end and the remainder of the attachment 100F can then be replaced when worn out or to attach a different attachment serving a different purpose.

<FIG> are depictions of an attachment <NUM> not covered by the claimed invention. The shown attachment is a combination of the attachment discussed with reference to <FIG> and a spring <NUM> discussed with reference to <FIG>. This attachment is specifically provided as it shows that the various aspects discussed herein can be combined to the extent they are not mutually excluding.

<FIG> are depictions of an attachment <NUM> not covered by the claimed invention. This attachment is a variant of the attachment shown in <FIG> with the separable pivot joint 142F, as the present atachment also comprises a separable pivot joint <NUM>. But instead of two deflectable wall elements, a coupling section <NUM> of the present attachment comprises a deformable essentially cylindrical wall element <NUM> that defines a cylindrical receiver volume <NUM>. The deformable essentially cylindrical wall element <NUM> may be made from an elastomeric material such as an artificial or natural rubber.

<FIG> are depictions of an example attachment 100I in accordance with the claimed invention. This attachment deviates from all the previously discussed attachments insofar as it does not comprise any wall element to define a cylindrical wall element. Instead, a coupling unit 200I only comprises a top plate 210I with a flat coupling surface 215I that is structured to become biased against a flat coupling surface of an essentially cylindrical drive shaft coupling end when the attachment 100I is attached to a handle. A spring 250I serves to apply the biasing force. As was described already, the spring 250I is arranged between an annular abutment projection on an inner side of an outer attachment tube 110I and the top plate 210I. The top plate 210I may be guided by an inner cylindrical portion 113I of the outer attachment tube 110I. In addition to what is shown here, the top plate 210I may comprise one or several downwards extending alignment projections to establish a positional alignment between the flat coupling surface 215I and the coupling surface of the essentially cylindrical drive shaft coupling end. The spring 250I and the spring constant of the spring 250I should be chosen such that the flat coupling surface 215I always stays in contact with the coupling surface of the essentially cylindrical drive shaft coupling end. While a drive of the handle then needs to work against the spring 250I in the phase in which the drive shaft moves upwards and compresses the spring, this stored energy is again released when the spring support to push the drive shaft downwards. Only plastic deformations of the spring and conversion of motion into heat will then cause addition drive losses. This is also true for the other attachments with a biasing spring.

<FIG> is a perspective view onto a coupling end of an oral care device handle <NUM> comprising an essentially cylindrical drive shaft coupling end <NUM> and a drive shaft housing <NUM>. As was already explained, the drive shaft housing may serve to mechanically receive an outer attachment tube of an oral care device attachment so that the two become detachably coupled with each other. The drive shaft housing <NUM> has a somewhat elongated cross-sectional shape, e.g., an elliptical or oval shape so that also an inner hollow of the drive shaft housing <NUM> accommodating the essentially cylindrical drive shaft coupling end <NUM> has an essentially elongated cross-sectional shape. Preferably, the essentially cylindrical drive shaft coupling end <NUM> is not coaxially or not centrically arranged in the hollow of the drive shaft housing <NUM>, which leads to a gap <NUM> between the drive shaft housing <NUM> and the essentially cylindrical drive shaft coupling end <NUM> that has a non-constant width. As is visualized in <FIG>, a width of the gap <NUM> between the essentially cylindrical drive shaft coupling end <NUM> and the drive shaft housing <NUM> in a plane perpendicular to an extension axis of the drive shaft (see axis L in <FIG>) may have a minimum value w1 and a maximum value w2, where in an example the minimum width w1 may be about <NUM> and the maximum width w2 may be about <NUM>. More generally, but still without limitation, a range of the minimum width w1 may be between <NUM> and <NUM> and a range for the maximum width w2 may be between <NUM> and <NUM>. The difference between the minimum width w1 and the maximum width w2 may be at least about <NUM>, preferably at least <NUM> and further preferably at least about <NUM>. Alternatively or in addition to the eccentric arrangement between the essentially cylindrical drive shaft coupling end <NUM> and the drive shaft housing <NUM>, the drive shaft housing <NUM> may comprise one or several pockets <NUM>, <NUM>, <NUM> in its inner side wall. The at least one pocket <NUM>, <NUM>, <NUM> may have a circumferential extension of at least about <NUM> degrees, preferably at least <NUM> degrees, more preferably at least about <NUM> degrees and even more preferably at least about <NUM> degrees. In some examples, the circumferential extension may be at least <NUM> degrees. In some examples, the drive shaft housing <NUM> may have two or three or four or five such pockets. In a preferred example, the drive shaft housing <NUM> has three pockets as is visualized in <FIG>, even though the dimensions shown in <FIG> are exemplary only. A length extension of the at least one pocket <NUM>, <NUM>, <NUM> along the drive shaft extension axis (see axis L in <FIG>) may be, without limitation, at least about <NUM>, preferably at least about <NUM>, further preferably at least about <NUM> and also preferably below about <NUM>. A depth of the pockets in the width direction of the gap <NUM> may be at least about <NUM>, preferably at least about <NUM>, more preferably at least about <NUM> and even more preferably at least about <NUM>.

The just described structure of the gap <NUM> between the essentially cylindrical drive shaft coupling end <NUM> and the drive shaft housing <NUM> may be reflected in the dimensions of an at least partly deformable essentially cylindrical wall element or of at least two elastic or deflectable wall elements, which elements were described already with reference to many attachments. That means that, e.g., a width of the at least partly deformable essentially cylindrical wall element may vary in circumferential direction, using the available space provide by the gap. The at least partly deformable essentially cylindrical wall element may then have a smaller width where the width w1 of the gap <NUM> is minimal and may have a larger width where the width w2 of the gap <NUM> is maximum. The practically chosen width may depend on the tolerance of the various elements and also on the side motion of the essentially cylindrical drive shaft end <NUM> during operation. The same holds true for a width or widths of at least two elastic or deflectable wall elements, where at least one of these wall elements may have a larger width than the other. It may be beneficial for the strength of the coupling to adapt the width of the wall element(s) to the available gap width. The wall element(s) may also adapt to the geometry provided by the at least one pocket <NUM>, <NUM>, <NUM>, i.e., the wall element(s) may have respective thickenings that may then project towards or even extend into the at least one pocket <NUM>, <NUM>, <NUM>.

With reference to the description of the example attachment shown in <FIG>, the one or several downwards extending alignment projections to establish a positional alignment between the flat coupling surface 215I and the coupling surface of the essentially cylindrical drive shaft coupling end may be dimensioned such that they extend into the space provided by the at least one pocket <NUM>, <NUM>, <NUM> or such that they are at least in positional alignment with the at least one pocket <NUM>, <NUM>, <NUM> so that the increased width of the gap avoids a collision between the projections and the inner side wall of the drive shaft housing <NUM>. In an example, the drive shaft housing <NUM> comprises three pockets <NUM>, <NUM>, <NUM> that are preferably evenly distributed in circumferential direction and the oral care device attachment comprises in circumferential direction three evenly distributed downwards extending alignment projections to establish a positional alignment between the flat coupling surface and the coupling surface of the essentially cylindrical drive shaft coupling end.

Claim 1:
An oral care device attachment (100I) for being coupled to a drive shaft of an oral care device handle (<NUM>) having an essentially cylindrical drive shaft coupling end (<NUM>; <NUM>), the attachment (100I) comprising:
an outer attachment tube (110I) having a coupling end that is intended for being secured at the oral care device handle (<NUM>);
a carrier (120I) mounted for driven motion at the outer attachment tube (110I);
a motion transmitter (140I) disposed inside of the outer attachment tube (110I), the motion transmitter (140I) has a first end coupled with the carrier (120I) and a second end arranged for being coupled with the essentially cylindrical drive shaft coupling end (<NUM>), the second end comprising a coupling unit (200I) having a top plate (210I);
wherein a spring (250I) is arranged between the outer attachment tube (110I) and the motion transmitter (140I) so that the motion transmitter (140I) is biased into a position towards the coupling end of the outer attachment tube (110I), wherein the spring (250I) is a coil spring that encircles a portion of the motion transmitter (140I),
wherein the top plate (210I) is guided by an inner cylindrical portion (113I) of the outer attachment tube (110I),
characterized in that the coupling unit (200I) comprising the top plate (210I) is integral with the motion transmitter (140I).