Patent Description:
Personal care implements, like toothbrushes, are well known in the art. Generally, tufts of bristles for cleaning teeth are attached to a bristle carrier or mounting surface of a brush head intended for insertion into a user's oral cavity. A handle is usually attached to the head, which handle is held by the user during brushing. Usually, heads of manual toothbrushes are permanently connected to the handle, e.g. by injection molding the bristle carrier, the handle, a neck connecting the head and the handle, in one injection molding step. After the usual lifetime of a toothbrush, i.e. after about three months of usage, the toothbrush is discarded. In order to provide environmentally friendly/sustainable toothbrushes generating less waste when the brushes are discarded, manual and electrically operated toothbrushes are known comprising heads or head refills being exchangeable, i.e. repeatedly attachable to and detachable from the handle. Instead of buying a completely new toothbrush, consumers can re-use the handle and buy a new head refill only.

Electrically operated toothbrushes exhibit the advantage that they assist users during brushing and may facilitate improved cleansing of the teeth and gums, in particular in hard to reach areas in the mouth. Typically, handles for electrical, handheld devices comprise a housing made from plastic materials to accommodate an energy source, e.g. a battery. While the housing itself is usually molded out of a hard-plastic material, like PP (polypropylene) or ABS (acrylonitrile butadiene styrene), a switch area for operating the electrical device is molded out of a soft elastomeric material, like TPE (thermoplastic elastomer), thereby forming a substantially waterproof membrane that allows actuation of a switch located within the housing. However, in order to allow for a substantially waterproof sealing and sufficient bonding between the switch and the housing by overmolding of a soft component (that forms the switch) on the hard-plastic housing, specific material combinations and geometries of the bonding area have to be selected.

<CIT> discloses an electrical appliance for personal care. The appliance includes a handle with a longitudinal axis, and a plug-on part which can be attached to the handle. A vibration unit has an electric motor and an eccentric element arranged in the handle. A switch for actuating the appliance is made from a soft material.

<CIT> discloses a body care device comprising a basic body having a handle and a treatment head which is hingedly mechanically connected with the handle. A discrete flexible zone for enabling an elastic deflection of the treatment head with respect to the handle during normal use of the body care device and a deflection sensor which is capable of producing an electrical signal as a function of the elastic deflection. is provided.

However, it has been found out that for premium personal care products it is a special consumer delight, if the outer housing is not made from plastic material but from real metal. Beside higher value impression of metal vs. plastic, a metal housing has the advantage that a much thinner wall of the housing can be provided, while still ensuring high durability and stability of the housing. Further, the overall product design can be provided with slimmer appearance.

It has been found out that such metal housings bring new challenge in creating a waterproof switch area. Due to the relatively thin wall thickness and reduced freedom in designing the housing (the metal housing is not freeformed as usual plastic parts, but have the form of a simple metal tube), the bonding area between the components is limited and a switch area/element cannot be simply overmolded onto the housing. The bonding force between the switch area/element and the metal tube is not sufficient to withstand regular stress occurring during use of the switch. Peel stress in the bonding area weakens the bonding connection which may result in gaps allowing water entering the inner part of the housing. A durable waterproof handle housing cannot be provided by such design.

It is an object of the present disclosure to provide a handle for an electrically operated personal care implement, e.g. a handle for a toothbrush, which overcomes at least one of the above-mentioned drawbacks, in particular which comprises a waterproof switch area on a metal tube housing. It is also an object of the present disclosure to provide a personal care implement comprising such handle.

In accordance with one aspect, a handle for an electrically operated personal care implement is provided, the handle comprising a metal tube housing, the housing having a metal wall with an opening and an inner surface, the inner surface defining an inner cavity of the housing for accommodating an energy source, the handle further comprising a switch assembly for activating the energy source, the switch assembly being accommodated in the opening and sealing the opening from the inner surface, the switch assembly comprising a hard switch component and a soft switch component, the hard switch component comprising a frame with a recess, the frame being attached to the inner surface of the metal wall thereby surrounding the opening and providing an undercut between the recess and the inner surface, the undercut being open to the opening, wherein the soft switch component is positioned in the undercut and covers at least partially the opening.

In accordance with one aspect a personal care implement is provided, the personal care implement comprising such handle and a head.

The scope of the invention is as defined in the appended claims.

The handle suitable to be used in connection with an electrically operated personal care implement comprises a metal tube housing. The housing is made of a metal material thereby providing a metal wall with an inner surface. Said inner surface defines an inner cavity of the housing to accommodate an energy source for operating the personal care implement. The wall of the housing comprises an opening, e.g. a cut-out, to accommodate a switch assembly for activating the energy source, e.g. switching the electronically operated personal care implement to an ON/OFF status. The switch assembly is attached to the inner surface of the wall thereby sealing the opening provided in the metal wall.

For example, the personal care implement may be battery-operated and may comprise a battery located in the inner cavity of the handle housing. The electrically operated personal care implement comprising such handle and a head may be an electrically operated toothbrush. The head may be repeatedly attachable to and detachable from the handle. The head may be attachable to the handle via a snap-fit locking mechanism. For example, the handle may comprise a connector which may be insertable into a hollow portion in the head, or the head may comprise a connector inserable into a hollow portion in the handle. Alternatively, a connector may be provided as a further, i.e. separate part of the oral care implement. Such connector may be insertable into a hollow portion in the handle and into a hollow portion the head, respectively, thereby providing sufficiently strong connection and stability between the head and the handle to enable a user to perform a brushing action.

While the high-quality handle of the personal care implement is adapted for use over a longer period of time as compared to common implements, like manual toothbrushes which are discarded after about three months of use, the relatively cheap head/brush refill can be exchanged on a regular basis, e.g. after about three months. This provides a cost-efficient and environmentally sustainable personal care implement providing both, high quality handle solutions as well as cost saving opportunities as only the head has to be exchanged/re-purchased and not the handle.

The switch assembly for operating the implement comprises a hard switch component and a soft switch component; the hard switch component comprises a frame with a recess. The frame of the hard switch component is attached to the inner surface of the metal wall and surrounds the opening, while the recess of the frame provides/creates an undercut being open towards the opening to accommodate a portion of the soft switch component. The soft switch component is positioned in the undercut provided by the recess and is arranged in a manner that it covers at least partially the opening.

The metal tube housing may provide for a electrically operated personal care product with improved premium consumer delight in contrast to housings made from plastic materials. Beside higher value impression and comfortable haptic, the use of metal material also allows for relatively low wall thicknesses of the housing to enable an overall slim product design. Such slim product design drives premium consumer perception and improved handling properties. A wall thickness of about <NUM> to about <NUM> may create a durable metal wall handle, while ensuring high product perception. The thickness of the metal wall may be about <NUM> to about <NUM>, preferably of about <NUM> to about <NUM>.

For example, the metal tube housing may be made from stainless steel and/or aluminum. Such materials are highly durable and allow for slim product designs.

Typical housings for electrical, handheld devices according to the art are usually made from plastic materials. While the housing itself is molded out of hard-plastic material, like PP or ABS, such devices often comprise a switch area molded out of soft elastomeric material, like TPE to form a membrane that allows the actuation of a switch located inside the housing. By overmolding the soft component on the hard-plastic housing a waterproof housing assembly can only be achieved, if the right material combination and geometry is selected; sufficient bonding properties between the hard and the soft component are crucial.

However, if a slim overall product design with a housing made from metal having small wall dimensions is to be provided, a waterproof assembly cannot be ensured by simply overmolding the soft component onto the metal housing as the bonding area is not sufficiently large (due to the low wall thickness and reduced freedom to design such metal tube housing vs. freeformed plastic parts).

To enable the provision of a waterproof switch assembly (i.e. a durable and waterproof sealing/bonding between the switch assembly and the metal material) in connection with a metal tube housing having small wall dimensions (e.g. between <NUM> and about <NUM>) without the need of using separate sealing elements, the present disclosure suggests a switch assembly comprising a hard switch component and a soft switch component. The hard switch component comprises a frame with a recess which in turn creates an undercut when attached to the inner surface of the housing. The frame surrounds the opening while the undercut provided between the recess and the inner wall surface is open towards the opening. The soft switch component is positioned in said undercut thereby being supported by the opposing walls of the recess and inner wall surface, respectively. The soft switch component is arranged in a manner that it covers at least partially the opening. The hard switch component may be fixed within the housing by means of gluing and/or by other means, including but not limited to substance-to-substance bonds, mechanically interlocking or frictional connections. The soft switch component may be provided by overmolding. The hard switch component can be further supported by a chassis inserted into the inner cavity of the housing. The chassis may comprise a carrier holding components for electrically operating the personal care implement, e.g. a motor, electronics and an energy source, for example a battery.

The recess of the frame of the hard switch component forming the undercut allows for solid anchoring of the soft switch component. The undercut can be filled with the soft component, e.g. during an overmolding process. Such undercut allows for bonding of the soft switch component on at least two opposite sides (see <FIG> and description provided below). Neither a force applied from the outside of the housing onto the switch component, nor a force applied from the inside of the housing results in significant peel stress on the bonding area as the frame provides a counterforce and holds the soft switch component in place. A switch assembly according to the present disclosure can be seamlessly integrated into the opening in the metal tube housing and can seal the opening in a substantially waterproof manner. Such design prevents water, toothpaste and saliva from entering the housing; a hygienic electrically operated toothbrush can be provided.

The handle according to the present disclosure enables the provision of a slim and sleek housing of an electrically operated personal care implement. While the use of metal material drives premium consumer perception and high durability, the handle can be sustainably used over a long period of time. Further, the slim housing enables users to perform a well-coordinated brushing technique and also improves the sensory feeling during brushing.

In contrast to the present disclosure, simply overmolding the soft switch component onto the metal tube housing cannot provide a durable waterproof handle housing as the bonding force between the soft switch component and the metal tube housing is not sufficiently strong; the bonding area between the two components (soft switch component and metal tube housing) is not sufficiently large and no counterforce is provided to hold the soft switch component in place. If a force is applied onto the switch component to activate the electrically operated implement, peel stress occurs in the bonding area which significantly weakens the bonding connection. A weakened bonding connection may cause fine cracks or crevices allowing water to enter the inner cavity of the handle metal tube housing.

The hard switch component of the present disclosure may be made from hard-plastic material, e.g. from acrylonitrile butadiene styrene (ABS) and/or acrylonitrile styrene acrylate (ASA), while the soft switch component may be made from soft elastomeric material, e.g. from thermoplastic elastomers (TPE). TPE adheres well to metal and to hard plastic materials, like ABS and/or ASA.

The opening accommodating the switch assembly in the housing may be, e.g. a cut-out provided in the metal wall by laser cutting. The metal wall circumferencing the opening may define an angle α between its outer surface and the neighboring surface/side wall of <NUM>° or less. If angle α is less than <NUM>°, the bonding area between the metal wall and the soft switch component is slightly increases which results in even better bonding properties.

The frame of the hard switch component may comprise at least two protrusions for precisely positioning/centering the hard switch component onto the inner surface of the metal wall during assembling. Such protrusions may help to define the position of the hard switch component in respect to the metal tube housing thereby facilitating manufacturing.

The hard switch component may also comprise a lever arm which may extend into the opening provided in the metal wall. The lever arm may comprise a button element, also positioned within the opening. At least a portion of the button element may not be covered by the soft switch component, e.g. when injection molded over the hard switch component. The material of the hard switch component may be provided in a color different from the color of the soft switch component to precisely indicate where the user shall put/rest his finger to activate the switch assembly of the personal care implement.

The handle may comprise magnetic/ferromagnetic material which may allow for hygienic storage of the oral care implement by magnetically attaching the handle to a magnetic holder, e.g. provided at a wall. If the personal care implement is a toothbrush, remaining water, toothpaste slurry and saliva can drain off from the brush. The oral care implement can dry relatively quickly. Consequently, bacteria growth can significantly be reduced, thereby rendering the oral care implement more hygienic. In contrast to a common toothbrush being stored in a toothbrush beaker where drained fluids get collected and accumulated at the bottom of the beaker, the brush according to the present disclosure is exposed to wet conditions over a significantly shorter period of time.

The magnetic holder may have the form of a flat disk attachable to a wall. Such flat disk may represent an easy to clean surface. Further, a user just needs to bring the oral care implement in close proximity to the magnetic holder, and then the oral care implement gets attached automatically. No precise positioning or threading as with common toothbrush holders is required. If the magnetic properties are merely provided in the handle, and not in the head, the head portion cannot accidentally be attached to the magnetic holder, thereby reducing the risk that the magnetic holder gets soiled.

The handle or part of the handle may be electroplated to add improved appearance and a pleasant feel. Thermoplastic elastomers are well suited for electroplating as they allow for the creation of both hard and soft composite components to be electroplated selectively in one operation.

For example, the handle may comprise a thumb rest being made from a thermoplastic elastomer material and/or from a polypropylene material. These materials can be easily injection molded over the metal tube housing. Such thumb rest may provide the handle with improved handling properties, e.g. with anti-slip properties to improve maneuverability of the personal care implement under wet conditions, e.g. when the user brushes his teeth. The thumb rest may be made from thermoplastic elastomer material having a Shore A hardness from about <NUM> to about <NUM>, or about <NUM> to prevent the oral care implement from being too slippery when used in wet conditions. At least a portion of the thumb rest may have a concave shape with an angle α with respect to the area of the remaining portion of the thumb rest from about <NUM>° to about <NUM>°, or about <NUM>°. The thumb rest or a gripping region may be attached onto the front surface of the handle in the region close to the proximal end, i.e. closest to the head. The thumb rest may comprise a plurality of ribs, e.g. extending substantially perpendicular, parallel or diagonal to the longitudinal axis of the oral care implement. Such ribs may allow users/consumers to use the oral care implement with even more control. The user/consumer can better grasp and manipulate the handle of the oral care implement during brushing. Such handle may provide further improved control and greater comfort during brushing, in particular under wet conditions.

Thermoplastic elastomer material may form the thumb rest on the front surface of the oral care implement and/or a palm grip on the back surface being opposite the front surface to be gripped by the user's/consumer's fingers and thumb. Such handle configuration may even further resist slippage during use.

If the personal care implement is a toothbrush, tooth cleaning elements, e.g. bundle of filaments forming one or a plurality of tufts, may be attached to the toothbrush head by means of a hot tufting process. One method of manufacturing the head with tufts of filaments embedded in the head may comprise the following steps: In a first step, tufts are formed by providing a desired amount of filaments. In a second step, the tufts are placed into a mold cavity so that ends of the filaments which are supposed to be attached to the head extend into said cavity. The opposite ends of the filaments not extending into said cavity may be either end-rounded or non-end-rounded. For example, the filaments may be not end-rounded in case the filaments are tapered filaments having a pointed tip. In a third step the head is formed around the ends of the filaments extending into the mold cavity by an injection molding process, thereby anchoring the tufts in the head. Alternatively, the tufts may be anchored by forming a first part of the head - a so called "sealplate" - around the ends of the filaments extending into the mold cavity by an injection molding process before the remaining part of the oral care implement is formed. Before starting the injection molding process the ends of the tufts extending into the mold cavity may be optionally melted or fusion-bonded to join the filaments together in a fused mass or ball so that the fused masses or balls are located within the cavity. The tufts may be held in the mold cavity by a mold bar having blind holes that correspond to the desired position of the tufts on the finished head of the oral care implement. In other words, the tufts attached to the head by means of a hot tufting process are not doubled over a middle portion along their length and are not mounted in the head by using an anchor/staple. The tufts are mounted on the head by means of an anchor-free tufting process.

The following is a non-limiting discussion of example embodiments of oral care implements and parts thereof in accordance with the present disclosure, where reference to the Figures is made.

<FIG> shows a personal care implement <NUM>, in this specific embodiment an electrically operated oral care implement, i.e. toothbrush <NUM>. Toothbrush <NUM> comprises a handle <NUM> and a head <NUM>, the head <NUM> being repeatedly attachable to and detachable from the handle <NUM>, e.g. by means of connector <NUM>. The connector <NUM> may be made from stainless steel and/or plastic material with or without glass-fibers. The connector <NUM> may comprise a spring-loaded ball element comprising a ball and a spring, the spring applying a radial force onto the ball in a direction towards an outer lateral surface of the connector. The connector may be inserted into in the inner cavity of the handle and fixed therein e.g. by gluing, welding and/or press-fitting. Alternatively, the connector <NUM> may be inserted into the inner cavity mounted to the handle thereby providing some degree of movement of the connector in relation to the housing to allow the use of a pressure sensor.

The handle comprises a switch assembly <NUM> located in the housing for activating an energy source accommodated within the handle <NUM> so that the electrical toothbrush <NUM> is operational. Electrical toothbrush <NUM> can be switched in an ON/OFF status by actuating the switch assembly <NUM>.

The housing of the handle <NUM> comprises substantially three parts as shown in <FIG> and <FIG>, respectively: a metal tube housing <NUM> (<FIG>), a hard switch component <NUM> (<FIG>), and a soft switch component <NUM> (<FIG> shows the metal tube housing <NUM>, the hard and the soft switch component <NUM>, <NUM> in an assembled state.

As derivable from <FIG>, the metal tube housing <NUM> is made from a metal wall <NUM> provided with an opening <NUM> for receiving the switch assembly <NUM>. The metal wall <NUM> has an inner surface <NUM> which defines an inner cavity <NUM> for accommodating the energy source, e.g. a battery. The metal tube housing <NUM> may be made from stainless steel and/or aluminum to provide high durability as well as high quality perception and appearance of the overall product. The metal wall <NUM> may have a thickness <NUM> (extending between the inner surface <NUM> and an outer surface <NUM>) of about <NUM> to about <NUM>, or of about <NUM> to about <NUM> to provide an overall slim product design.

The switch assembly <NUM> for activating the energy source comprises hard switch component <NUM> (<FIG>) and soft switch component <NUM> (<FIG>). Both, the hard and the soft switch components <NUM>, <NUM> are located within the opening <NUM> provided in the metal wall <NUM> of the housing <NUM>. The hard and soft switch components <NUM>, <NUM> are arranged in a manner that the switch assembly <NUM> seals the opening <NUM> in a substantially waterproof manner.

While hard switch component <NUM> may be molded from hard-plastic material, e.g. from acrylonitrile butadiene styrene (ABS) and/or acrylonitrile styrene acrylate (ASA), soft switch component <NUM> may be made from soft elastomeric material, e.g. from thermoplastic elastomers (TPE). TPE adheres well to metal material as well as to ABS and ASA. As shown in <FIG>, the hard switch component <NUM> comprises a frame <NUM> with a recess <NUM>, the frame <NUM> being attached to the inner surface <NUM> of the metal wall <NUM> thereby surrounding/circumferencing the opening <NUM> in the metal tube housing <NUM> (see <FIG> and <FIG>). The recess <NUM> creates an undercut <NUM> in which the soft switch component <NUM> is positioned and securely fixed (see <FIG>). The hard switch component <NUM> may be connected to the inner surface <NUM> of the housing <NUM> by gluing, i.e. glue may be applied onto area <NUM> of the frame <NUM>, and then the frame gets connected to the inner surface <NUM> of housing <NUM>. Fixation of the hard switch component <NUM> on the inner surface may alternatively be provided by means of substance-to-substance bonds, mechanically interlocking or frictional connections. The frame <NUM> of the hard switch component <NUM> may comprise at least two protrusions <NUM>, <NUM> that help positioning the hard switch component <NUM> onto the inner surface <NUM> of the metal wall <NUM>; to this end the inner surface <NUM> may comprise respective recesses to receive said protrusions <NUM>, <NUM>.

The hard switch component <NUM> may further comprise a lever arm <NUM> comprising a button element <NUM> at the distal end of the lever arm <NUM>. The lever arm <NUM> and the button element <NUM> may extend into the opening <NUM> of the metal wall <NUM>.

The material forming the softs witch component <NUM> may be overmolded over the lever arm <NUM> and partially over the button element <NUM> thereby keeping a portion of the button element <NUM> exposed to provide an indication where a user should place his finger to activate switch assembly <NUM>. To this end, the color of the material of the hard switch component <NUM> and the color of the material of the soft switch component <NUM> may be different to provide a clear and easily visible indication. The material of the soft switch component <NUM> covers any remaining open area of the opening <NUM> and is fixed in the undercut <NUM> provided between recess <NUM> and inner surface <NUM> of metal wall <NUM>.

To further strengthen the bonding properties between the material of the soft switch component <NUM> and the metal wall <NUM> by slightly increasing the bonding area, the metal wall <NUM> surrounding the opening <NUM> may define an angle α between the outer surface <NUM> and the neighboring surface <NUM> of <NUM>° or less.

The housing assembly comprising the metal tube housing <NUM>, the hard and soft switch components <NUM>, <NUM> allows for solid anchoring of the soft switch component <NUM>. The recess <NUM> of the hard switch component <NUM> together with the inner surface <NUM> creates a defined undercut, i.e. cavity that can be filled with the material of the soft switch component <NUM> during a molding process. The recess faciliates bonding of the soft switch component <NUM> on three sides <NUM>, <NUM>, <NUM>. Neither a force applied from the outside of the handle, nor a force applied from the inside onto the soft switch component <NUM> results in peel stress as the frame of the hard switch component <NUM> holds the softs witch component <NUM> in place. By overmolding the soft switch component <NUM>, a substantially waterproof and durable seal can be provided which may prevent water, toothpaste and/or saliva from entering the inside/inner cavity <NUM> of the housing <NUM>.

Claim 1:
A handle (<NUM>) for an electrically operated personal care implement (<NUM>), characterized in that the handle (<NUM>) comprises a metal tube housing (<NUM>), the housing (<NUM>) having a metal wall (<NUM>) with an opening (<NUM>) and an inner surface (<NUM>), the inner surface (<NUM>) defining an inner cavity (<NUM>) of the housing (<NUM>) for accommodating an energy source, the handle (<NUM>) further comprising a switch assembly (<NUM>) for activating the energy source, the switch assembly (<NUM>) being accommodated in the opening (<NUM>) and sealing the opening (<NUM>) from the inner surface (<NUM>) of the metal wall (<NUM>), the switch assembly (<NUM>) comprising a hard switch component (<NUM>) and a soft switch component (<NUM>), the hard switch component (<NUM>) comprising a frame (<NUM>) with a recess (<NUM>), the frame (<NUM>) being attached to the inner surface (<NUM>) of the metal wall (<NUM>) thereby surrounding the opening (<NUM>) and providing an undercut (<NUM>) between the recess (<NUM>) and the inner surface (<NUM>), the undercut (<NUM>) being open to the opening (<NUM>), wherein the soft switch component (<NUM>) is positioned in the undercut (<NUM>) and covers at least partially the opening (<NUM>).