Patent Description:
It is known that a head for a personal care device such as a cleaning head for an electric toothbrush comprises cleaning elements and specifically can comprises cleaning elements made from injection molded plastic material.

<CIT> discloses a pore cleansing brush that comprises a plurality of projections projecting from a brush face of a base and made partially or wholly of the projections. These projections comprise a base made of elastomer and protruding from the brush face, and are equipped at the tip parts of the projections with pore cleansing hair bundles projecting further from the base.

There is a general object to provide a head for a personal care device comprising at least one cleaning element that is improved over previously known heads. There is also a general object to provide a method for making such a head.

In accordance with at least one aspect, a head for a personal care device is provided in accordance with claim <NUM>.

In accordance with at least one aspect, a method for making a head for a personal care device is provided in accordance with claim <NUM>.

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

In the context of the present description "personal care" shall mean the nurture (or care) of the skin and of its adnexa (i.e., hairs and nails) and of the teeth and the oral cavity (including the tongue, the gums etc.), where the aim is on the one hand the prevention of illnesses and the maintenance and strengthening of health and on the other hand the cosmetic treatment and improvement of the appearance of the skin and its adnexa. It shall include the maintenance and strengthening of wellbeing. This includes skin care, hair care, and oral care as well as nail care. This further includes grooming activities such as beard care, shaving, and depilation. A "personal care device" thus means any device for performing such nurturing or grooming activity, e.g. (cosmetic) skin treatment devices such as skin massage devices or skin brushes; wet razors; electric shavers or trimmers; electric epilators; and oral care devices such as manual or electric toothbrushes, (electric) flossers, (electric) irrigators, (electric) tongue cleaners, or (electric) gum massagers. This shall not exclude that the proposed personal care device may have a more pronounced benefit in one or several of these nurturing or device areas than in one or several other of these areas. In the present description, an electric toothbrush was chosen to present details of the proposed personal care device. To the extent in which the details are not specific for an electric toothbrush, the proposed technology can be used in any other personal care device.

In accordance with the present disclosure, a head for a personal care device comprises at least one cleaning element and may comprise at least one or a plurality of further cleaning elements. In the present disclosure, the cleaning elements as discussed are named "cleaning element" and "further cleaning element". They could also have been named "first cleaning element" and "second cleaning element" - there is no difference to be seen in this naming convention. A cleaning element as described herein has an embedded cleaning element portion that extends within a carrier of the head and a non-embedded cleaning element portion that extends outside of the carrier. The cleaning element is understood to be an integral cleaning element, i.e., a cleaning element that is a one-piece element. This shall not exclude that a head in accordance with the present description has other non-integral elements suitable for cleaning, e.g., tufts assembled from a plurality of individual fibers, which are generally known in the art of brushes, e.g., toothbrushes or body brushes. It shall be understood that the carrier of the head has a front surface and that the non-embedded portion of the cleaning element extends from this front surface and that the portion of the cleaning element extending up to and below the front surface is the embedded portion of the cleaning element. For ease of presentability, the front surface of the carrier shown in the figures is a planar surface, but this shall not exclude that the front surface of the carrier is non-planar, specifically non-planar in the area of the cleaning element.

The carrier may be made from a plastic material, preferably a thermoplastic, where the plastic material may have a Young' modulus of above about <NUM> GPa, preferably of above about <NUM> GPa. The plastic material may be a polypropylene, a polycarbonate, a polyethylene or any other suitable thermoplastic.

In accordance with the present disclosure, the embedded portion of the at least one cleaning element has a top end that ends on the level of the front surface of the carrier and a bottom end that typically ends somewhere inside of the carrier, even though this shall not exclude that in some embodiments the bottom end ends at a back side of the carrier or even extends beyond such a back surface. The portion of the embedded portion of the cleaning element between the top end and the bottom end may be referred to as a middle portion of the embedded portion of the cleaning element. The top end of the embedded portion of the cleaning element has a top end cross-sectional area defined on the level of the front surface and has a top end cross-sectional shape. The non-embedded portion of the cleaning element extends from the front surface of the carrier between a base end that lies on the level of the front surface of the carrier and a free end. The base end of the embedded portion of the cleaning element has a base end cross-sectional area defined on the level of the front surface and base-end cross-sectional shape.

In accordance with the present disclosure and proposed head, the top end cross-sectional area of the embedded portion of the cleaning element is larger than the base end cross-sectional area of the non-embedded portion of the cleaning element by at least <NUM>%. Preferably, the top end cross-sectional area is by at least <NUM>% or at least <NUM>% or at least <NUM>% or at least <NUM>% or at least <NUM>% or at least <NUM>% or at least <NUM>% larger than the base end cross-sectional area and on an absolute scale the larger top end cross-sectional area has a size of at least <NUM><NUM>, preferably at least <NUM><NUM> or at least <NUM><NUM> or at least <NUM><NUM> or at least <NUM><NUM> or at least <NUM><NUM> or at least <NUM><NUM> or at least <NUM><NUM>. The cleaning element as discussed here is an injection molded cleaning element and shall be secured at the carrier so that it cannot be easily removed, e.g., by biting on it while the head moves. The cleaning element shall thus have a retention force of at least 3N, preferably of at least <NUM> N or at least <NUM> N. Several measures can be used to achieve a high retention force and the concept that is used here is a large top end cross-sectional area as this increases the contact area between the outer surface of the embedded portion of the cleaning element and the contacting surface of the carrier. The materials of at least the embedded portion of the cleaning element and of the carrier may be chosen such they form a chemical and/or physical bond when the cleaning element is injection molded. The material from which at least the embedded portion of the cleaning element is made may be a thermoplastic elastomer (TPE). The TPE may have a hardness of below about <NUM> Shore A, preferably of below about <NUM> Shore A or of below about <NUM> Shore A or of about <NUM> Shore A, where the Shore A hardness is measured in accordance with DIN ISO <NUM>-<NUM>. A soft TPE material leads to a relatively long elongation of the TPE cleaning element when a force is applied to rip it out. Further measures can be added to increase the retention force, specifically an undercut between the carrier and the embedded portion of the cleaning element with respect to the extracting direction. A further measure would be an essentially laterally extending arm that is connected with the bottom end of the embedded portion of the cleaning element, which arm may preferably connect the bottom end of the embedded portion of the cleaning element with a center point of the carrier and the arm may potentially also be connected with a bottom end of an embedded portion of a further cleaning element. It is also contemplated to provide a structure of at least a portion of the outer surface of the embedded portion that is in contact with the carrier in order to increase the overall contact area between the embedded portion and the carrier. The structure may be microscopic or macroscopic.

The mentioned undercut may preferably be created by a widening of the embedded portion of the cleaning element between the top-end towards the bottom end, preferably a widening occurring in a middle portion of the embedded portion of the cleaning element. With "widening" here a continuous widening is meant, i.e., a change from one cross-sectional area and shape to another cross-sectional area and shape occurring over a certain length so the latter cross-sectional area is larger. Instead of a continuous widening, a step-like widening may be provided in the middle portion of the embedded portion of the cleaning element. Both concepts may also be combined, i.e., a continuous widening and a widening step may both be used in combination, optionally each one or both concepts also in combination with a laterally extending arm.

A method of making a head in accordance with the present disclosure comprises the steps of:.

The method may include one or several or all of the following optional steps:.

The method to measure the retention force of an integral (or TPE) cleaning element analogously applies the method to measure the tuft retention force as provided by ISO <NUM>:<NUM> + Amd <NUM>:<NUM> ("Dentistry - Manual toothbrushes - General requirements and test methods"). The force range for measuring the retention force of integral/TPE cleaning elements is to be chosen such that the lower retention forces of an integral cleaning element can be reliably measured - the sensor may have a maximum force range value of <NUM> N.

An example integral cleaning element has a base end-cross-sectional area of the not embedded portion that is slightly arc-shaped and has a length of about <NUM> and a width of about <NUM>. The top end cross-sectional area of the embedded portion is wider by <NUM> in all directions - the top end cross-section area of the embedded portion is in this example about <NUM>% larger than the base end cross-sectional area of the not embedded portion of the cleaning element. The material of the carrier was a polypropylene, specifically an unfilled polypropylene homopolymer for injection molding, and the TPE material of the integral cleaning element (a TPE-O, unfilled high performance thermoplastic elastomer with high flow rate) was having a hardness of <NUM> Shore A. The retention force of these cleaning elements was measured and a retention force of at least <NUM> N, typically of at least <NUM> N was found and most cleaning elements had a retention force of at least <NUM> N. In case the above mentioned <NUM> are reduced to <NUM> the increase area would be about <NUM>% and in case of <NUM> this increased area would be about <NUM>%. In case the not embedded portion would have a circular base end cross-sectional area having a diameter of <NUM> and the top end cross-sectional area would be by <NUM>, the increase would be <NUM>%.

<FIG> is a cross-sectional cut through an example head <NUM> in accordance with the present disclosure. The head <NUM> has a carrier <NUM>, a cleaning element <NUM> and a further cleaning element <NUM> that is of course optional and is used to discuss some aspects that are either alternative or additional aspects. The cleaning elements <NUM> and <NUM> are connected by a laterally extending arm <NUM>. Further, the head <NUM> comprises an optional connector <NUM> that may be used to connect the head with a drive unit of a personal care device (see <FIG> for an example personal care device).

The carrier <NUM> has a front surface <NUM> and a back surface <NUM>. The carrier <NUM> may be made from a front portion <NUM> and a back portion <NUM> that may be made in successive molding steps and this structure may serve to completely embed the cleaning elements <NUM> and <NUM> in the carrier <NUM> and/or to connect the carrier with the connector <NUM>. As will be explained in more detail in connection with the manufacturing method with reference to <FIG> further below, the front portion <NUM> of the carrier <NUM> has (while the back portion <NUM> is not yet made) a back surface <NUM>.

The cleaning element <NUM> shown on the left-hand side comprises a non-embedded portion <NUM> and an embedded portion <NUM>, which embedded portion <NUM> means the portion of the cleaning element <NUM> that here is located within the carrier <NUM> and that ends on the level of the here flat front surface <NUM> of the carrier <NUM>. The non-embedded portion <NUM> of the cleaning element <NUM> has a base end <NUM> that extends from the front surface, i.e., from the level of the front surface, towards a free end <NUM> of the non-embedded portion <NUM> of the cleaning element <NUM>. The base end <NUM> of the non-embedded portion <NUM> of the cleaning element <NUM> has a base end cross-sectional area and a base end cross-sectional shape in the level of the front surface <NUM>. Examples are discussed with reference to <FIG>. The embedded portion <NUM> of the cleaning element <NUM> has a top end <NUM> that lies in the front surface <NUM> of the carrier <NUM> and which top end <NUM> has a top end cross sectional area and a top end cross-sectional shape. Examples are again discussed with reference to <FIG>. In accordance with the present disclosure, the top end cross-sectional area is larger than the base end cross-sectional area for the reasons as already discussed, namely improved chemical and/physical bonding between the embedded portion <NUM> of the cleaning element <NUM> and the carrier <NUM>.

The embedded portion <NUM> of the cleaning element <NUM> has a bottom end <NUM> that is here completely embedded by the carrier <NUM>. Between the top end <NUM> and the bottom end <NUM> a middle portion <NUM> extends. For the cleaning element <NUM>, there is a widening step <NUM> provided in the middle portion <NUM>, that is an essentially spontaneous widening the embedded portion <NUM> of the cleaning element <NUM> that increases the retention force needed to rip out the cleaning element <NUM> from the carrier <NUM> or to rip apart the cleaning element <NUM>. The bottom end <NUM> of the embedded portion <NUM> of the cleaning element <NUM> may be connected, as is here shown, with a laterally extending arm <NUM> so that an arm section <NUM> extends between the bottom end <NUM> and a center section <NUM> of the laterally extending arm <NUM>. The center section <NUM> may represent an injection point for the material from which the cleaning element <NUM> is made during the manufacturing of the head <NUM>. The cleaning element <NUM> and the laterally extending arm <NUM> may thus be integral with each other. The laterally extending arm <NUM> may extend within a channel that is provided in the back side of the front portion <NUM> of the carrier <NUM>.

The further cleaning element <NUM> shown on the right-hand side comprises a non-embedded portion <NUM> and an embedded portion <NUM>, which embedded portion <NUM> means the portion of the further cleaning element <NUM> that here is located within the carrier <NUM> and that ends on the level of the here flat front surface <NUM> of the carrier <NUM>. The non-embedded portion <NUM> of the further cleaning element <NUM> has a base end <NUM> that extends from the front surface, i.e., from the level of the front surface, towards a free end <NUM> of the non-embedded portion <NUM> of the cleaning element <NUM>. As is shown by way of example, the further cleaning element <NUM> (like any other cleaning element) may have a structure <NUM> to support cleaning of a surface such as a tooth surface. The base end <NUM> of the non-embedded portion <NUM> of the further cleaning element <NUM> has a base end cross-sectional area and a base end cross-sectional shape in the level of the front surface <NUM>. Examples are again discussed with reference to <FIG>. The embedded portion <NUM> of the further cleaning element <NUM> has a top end <NUM> that lies in the front surface <NUM> of the carrier <NUM> and which top end <NUM> has a top end cross sectional area and a top end cross-sectional shape. Examples are again discussed with reference to <FIG>. In accordance with the present disclosure, the top end cross-sectional area is larger than the base end cross-sectional area for the reasons as already discussed, namely improved chemical and/physical bonding between the embedded portion <NUM> of the further cleaning element <NUM> and the carrier <NUM>.

The embedded portion <NUM> of the further cleaning element <NUM> has a bottom end <NUM> that is here completely embedded by the carrier <NUM>. Between the top end <NUM> and the bottom end <NUM> a middle portion <NUM> extends. For the further cleaning element <NUM>, there is a widening <NUM> provided in the middle portion <NUM>, that is an essentially continuous widening the embedded portion <NUM> of the further cleaning element <NUM> that increases the retention force needed to rip out the further cleaning element <NUM> from the carrier <NUM> or to rip apart the further cleaning element <NUM>. The bottom end <NUM> of the embedded portion <NUM> of the further cleaning element <NUM> may be connected with a laterally extending arm <NUM> so that an arm section <NUM> extends between the bottom end <NUM> and a center section <NUM> of the laterally extending arm <NUM>. The center section <NUM> may represent an injection point for the material from which the further cleaning element <NUM> is made during the manufacturing of the head <NUM>. The further cleaning element <NUM> and the laterally extending arm <NUM> may thus be integral with each other. The laterally extending arm <NUM> may extend within a channel that is provided in the back side of the front portion <NUM> of the carrier <NUM>. In the example shown in <FIG>, the laterally extending arm <NUM> connects the bottom end <NUM> of the embedded portion <NUM> of the cleaning element and the bottom end <NUM> of the embedded portion <NUM> of the further cleaning element <NUM>.

<FIG> is a cross-sectional cut through a first embodiment of a cleaning element 200A extending from a front surface 1010A of a carrier, where the cross-sectional cut was done in the plane of the front surface 1010A and the viewing direction is top-down as indicated by arrows in <FIG>. In this top-down view, a base end cross-sectional area 215A and a base end cross-sectional shape 216A of a non-embedded portion 210A of the cleaning element 200A are shown. Further, a top end cross-sectional area 225A and a top end cross-sectional shape 226A of an embedded portion 220A of the cleaning element 200A are shown. In this example, the top end cross-sectional area 225A is larger than the base end cross-sectional area 215A and the first fully encompasses the latter. In this example, the top end cross-sectional shape 226A is circular and the base end cross-sectional shape 216A is circular as well and both are coaxially arranged, which is merely an optional positioning and they may as well be positioned in a non-coaxial manner.

<FIG> is a cross-sectional cut through a second embodiment of a cleaning element 200B extending from a front surface 1010B of a carrier, where the cross-sectional cut was done in the plane of the front surface 1010B and the viewing direction is top-down as indicated by arrows in <FIG>. In this top-down view, a base end cross-sectional area 215B and a base end cross-sectional shape 216B of a non-embedded portion 210B of the cleaning element 200B are shown. Further, a top end cross-sectional area 225B and a top end cross-sectional shape 226B of an embedded portion 220B of the cleaning element 200B are shown. In this example, the top end cross-sectional area 225B is larger than the base end cross-sectional area 215B and the first fully encompasses the latter. In this example, the top end cross-sectional shape 226B is elliptical and the base end cross-sectional shape 216B is arc-like with a tapering towards one end (giving the impression of a Yin or Yang symbol).

The shapes shown in <FIG> are exemplary only and the skilled person will be able to contemplate various other shapes like triangular, rectangular, star-like, banana-like, kidney-like, half-moon-like, trapezoidal etc..

<FIG> are depictions of various manufacturing steps of making an example head for a personal care device in accordance with the present disclosure and of intermediate head products and of the final head.

<FIG> is a cross-sectional cut through a schematically depicted mold 600A having a first mold half 610A and a second mold half 620A that define a first cavity 601A for injection molding of a front portion of a carrier. The separation line between the two mold halves 610A and 620A s indicated to coincide with a plane defining the front surface of the to be injection molded front portion of the carrier - this position of the separation line is understood to be non-limiting. In this example, two pins 630A and 640A extend into the first cavity 601A, which pins define through-holes in the front portion of the carrier. It is indicated by a dashed line that the second mold half 620A may comprise one or several cavity portions 602A for defining a non-embedded portion of a cleaning element. Such a cavity portion would then be sealed by a pin, as is here the case for pin 640A so that no plastic material would flow into cavity portion 602A during the injection of molten plastic material into the first cavity 601A. While in this cross-sectional cut two pins are shown, it should be understood that this is a non-limiting example shown for sake of presenting the concept and in some embodiments only one pin is used, while in other embodiments two or three or four etc. pins are used - just as many as injection molded cleaning elements are planned. This shall also not exclude that further cleaning elements made from, e.g., bundles of fibers are present on the carrier together with at least one of the injection molded cleaning elements.

<FIG> is a cross-sectional cut through a front portion 101B of a carrier made by injecting molten plastic material into the first cavity 601A shown in <FIG>. The front portion 101B of the carrier has two through-holes 102B and 103B that extend between a front surface 1010B and a back surface 1011B of the front portion 101B of the carrier. A channel 104B connecting the two through holes 102B and 103B is shown in the back surface 1011B.

<FIG> is a cross-sectional cut through a schematically depicted mold 600C having a first mold half 610C and a second mold half 620C that define a second cavity 601C. A front portion 101C is inserted into the cavity 601C as an insert. It shall be understood that the front portion 101C may of course be the front portion 101B shown in <FIG>. The second cavity 601C with the inserted front portion 101C comprises several cavity portions 6011C to 6017C. A central channel cavity portion 6011C is provided on the backside of the front portion 101C of the carrier and two channel arms are defined by cavity portions 6012C and 6013C, which two arms cavity portions 6012C and 6013C connect the central channel cavity portion 6011C with through holes in the front portion 101C of the carrier, which through-holes define cavity portions 6014C and 6015C for molding of embedded portions of cleaning elements. The second mold half 620C comprises here two cavity portions 6015C and 6016C that are aligned with the cavity portions 6014C and 6015C, respectively, and that allow to mold non-embedded portions of the cleaning elements. In <FIG> a injection nozzle 611C is indicated that is positioned in alignment with the central channel cavity portion 6011C, which is to be understood as a non-limiting example.

<FIG> is a cross-sectional cut through a pre-head 105D comprising a front portion of a carrier 101D and two cleaning elements 200D and 300D that may be the result from an injection molding step into the second cavity shown in <FIG>. The cleaning elements 200D and 300D are integrally connected by a laterally extending arm 400D on the backside of the front portion 101D. As was mentioned before, the plastic materials of the front portion 101D and of the cleaning elements 200D, 300D may be chosen such that the materials form and chemical and/or physical bond.

<FIG> is a cross-sectional cut through a schematically depicted mold 600E having a first mold half 610E and a second mold half 620E that define a third cavity 601E. A pre-head 105E is inserted into the third cavity as is a connector 500E that may serve to connect the final head to be molded with a drive mechanism. The pre-head 105E may be the pre-head 105D that is shown in <FIG>. Molten plastic material that will be injected into the third cavity 601E will connect the pre-head 105D and the connector 500D by a physical and/or chemical bond and/or by a positive fit. The material to be injected into the third cavity 601E forms a back portion of the carrier and completely embeds the embedded portion of the cleaning elements 200D and 300D as well as the laterally extending arm 400D.

<FIG> is a depiction of a head 1F that may result from the final injection molding step discussed with respect to <FIG>. The head 1F comprises a carrier 100F, an array of cleaning elements 200F and a connector 500F. The connector 500F may comprise a connecting structure 501F to allow the connection with, e.g., a drive mechanism and/or with a locking mechanism (such as a locking pin) as is commonly known in the art. The array of cleaning elements 200F comprises two cleaning elements 201F shown in solid lines. It is here indicated by dashed lines that the head 1F may comprise more than the two cleaning elements that were shown and discussed in the previous <FIG>, namely additional cleaning elements 202F.

<FIG> is a depiction of a personal care device <NUM> realized as an electric toothbrush that comprises a handle section <NUM> and a replaceable attachment <NUM> at which a head <NUM> is provided, preferably a head in accordance with the present disclosure.

<FIG> is a depiction of a replaceable attachment <NUM> realized as a replacement brush head for an electric toothbrush, which replaceable attachment <NUM> comprises a head <NUM>, preferably a head in accordance with the present disclosure.

Claim 1:
A head (<NUM>) for a personal care device comprising
a carrier (<NUM>) having a front surface (<NUM>);
at least one cleaning element (<NUM>), being an integral cleaning element, partly embedded in the carrier (<NUM>) and thus having an embedded cleaning element portion (<NUM>) and a non-embedded cleaning element portion (<NUM>), the non-embedded cleaning element portion (<NUM>) extending from the front surface (<NUM>) of the carrier (<NUM>) between a base end (<NUM>) on the front surface (<NUM>) and a free end (<NUM>) and the embedded cleaning element portion (<NUM>) extending from the front surface (<NUM>) between a top end (<NUM>) on the front surface (<NUM>) and a bottom end (<NUM>),
wherein the base end (<NUM>) of the non-embedded cleaning element portion (<NUM>) has a base end cross-sectional shape and a base end cross-sectional area, and the top end (<NUM>) of the embedded cleaning element portion (<NUM>) has a top end cross-sectional shape that preferably is different to the base end cross-sectional shape and a top end cross-sectional area that is by at least <NUM>% larger than the base end cross-sectional area; and
wherein an integral arm (<NUM>) connects the bottom end (<NUM>) of the embedded cleaning element portion (<NUM>) with a center point (<NUM>) in the carrier (<NUM>), the center point (<NUM>) being laterally displaced from the bottom end (<NUM>), the integral arm (<NUM>) being completely embedded in the carrier (<NUM>).