Electric toothbrushes are well known in the art and typically comprise a motor element housed within the brush handle and a head, which is usually replaceable.

Most electric brushes effect cleaning by rapidly moving the brush head (hereinafter known as oscillating brushes) but some merely vibrate (hereinafter known as vibrating brushes).

There is a multitude of oscillating brushes on the market and some have particular oscillating patterns, e. g. longitudinally oscillating elements, or they may have multiple brush heads, such as that marketed by Phillips under the tradename Plaque Remover ', which comprises a rotating head and a laterally oscillating array of bristles distal to the brush handle.

An example of a vibrating brush is that sold by J&J under the tradename Powerbrush@'.

Manual brushes with flexible heads are also well known in the prior art. For example, the brush sold by Unilever under the tradename Adaptor@'comprises an array of bristle tufts mounted in boots. These boots are connected to a central skeleton by a rubbery elastomer material. In this way, the

tufts mounted in the boots are capable of effecting a toggling movement during brushing.

A disadvantage of oscillating brushes is that the electrical devices required to effect a proper brushing of the teeth comprise expensive technology. A disadvantage of the vibrating brushes, which are usually cheaper, is that they have to vibrate considerably to effect any kind of cleaning benefit. Such vibration is often uncomfortable for the user as the handle often vibrates as much as the head.

Additionally, it is not clear to the user whether to use the brush as a vibrating manual brush or as an electric toothbrush.

An object of the present invention is to provide a cheap electric toothbrush, which provides an improved cleaning benefit and is easy and comfortable to use.

We have found that an electric toothbrush can provide an improvement upon the prior art when the brush head is flexible.

Accordingly, the present invention provides an electric toothbrush comprising a handle and a head, characterised in that the head is a flexible head.

It is to be understood that the head part of an electric toothbrush comprises a bristle bearing section and a neck portion connecting the bristle bearing section to the handle.

In a particular embodiment, the head is segmented to provide flexibility. While there may be any number of segments on such a segmented brush head each segment may be unitary with any of a number of other segments or be linked to any number of other segments by a further material.

In an alternative embodiment, the head comprises a rubbery material. Such a rubbery material may link the segments of a segmented brush head.

The inclusion of a flexible head can modify the vibrational character of the brush head in such a way as to either improve the cleaning compared to an oscillating brush or to improve the action of a vibrating brush. It is also possible that the inclusion of a flexible head reduces the output required from the motor element, which in turn may make the brush more comfortable to use and reduce the power requirements, thus reducing battery changing frequency.

It is an essential feature of the invention that the brush head is flexible. A conventional brush head comprises hard materials, such as polypropylene or polyacrylonitrile and it may be that the physical dimensions of these materials provide the flexibilty of the head, e. g. the brush head comprises two or more segment which are linked by a hinge which is unitary with the segments.

It is expected, however, that the brush head also comprises a rubbery material to provide flexibility.

It is also possible for the brush head to be comprised almost entirely of the rubbery material; the more conventional harder materials, such as polypropylene or styrene acrylonitrile, being present to facilitate anchoring of the bristle tufts.

In a particularly preferred embodiment the rubbery material extends to cover a substantial portion of the neck portion of the head. Depending on the type of rubber this may reduce the incidence of damage to the users gums and lips as the rubber absorbs the vibrations of the motor.

By rubbery is meant that the material has some elastic nature. Given that electric toothbrushes vibrate at an extremely high frequency it is anticipated that a high elastic nature is not necessary and a material with a Shore A hardness of less than conventionally used polypropylene is suitable for use in the present invention.

In a preferred embodiment, the rubbery material has a Shore A hardness of less than 100, more preferably less than 80, and especially less than 55.

Particularly suitable rubbery material include elastomeric materials such as those described in W097/20484, the contents of which are incorporated by reference.

In an alternative embodiment the flexibilty in the head is achieved through the use of a hinge between the bristle bearing section and the neck.

The brush head may comprise any number of such hinges to provide flexibility. Typically the hinges will be located so as to maximise efficacy of flexing during use. As such they would, preferably, be located on the bristle-bearing portion of the head. A hinge may be located anywhere on such a bristle-bearing portion of the head. For example, it may be transverse the general longitudinal axis of the head dividing the head into two segments by being situtated anywhere, e. g. half-way or 60% towards the tip or 30% towards the tip per length of the bristle-bearing portion, between the tip and the base end of the bristle-bearing portion of the head.

It is also envisaged that the head of the brush according to the invention is replaceable.

In an alternative aspect the invention provides an electric toothbrush with improved sensory benefits. The brush according to the invention provides an improved feel in the oral cavity, especially when the brush comprises a rubbery material in the head or neck. This is particularly so when the non-bristle bearing surfaces of the head is significantly covered by a rubbery material and contacts the buccal lining. This sensory benefit is seen as an important consumer positive.

Accordingly, the invention also provides the use of an electric toothbrush comprising a handle and a head, which head comprises a rubbery material for improved sensory benefit in the oral cavity.

The electric toothbrush according to the invention provides an improvement over the prior art by the inclusion of a flexible head section. It is thought that the flexible head provides enhanced oscillation/vibration due to its flexible nature or, more specifically, due to the differences in elasticity of the materials/sections comprising the head.

Particular embodiments according to the invention will now be described with reference to the following non-limiting figures.

Figure 1 is an elevation of a brush according to the invention. It shows a brush (1) comprising a handle (2) and a head (3). The head (3) comprises a bristle bearing portion (4) and a neck portion (5). The bristle bearing portion (4) comprises two segments (6) linked by a hinge (7).

Typically, the handle (2) will comprise a motor element which vibrates or oscillates at least the brush head (3).

The gap between the segments may optionally be filled with a rubbery material.

Figure 2 illustrates a toothbrush head according to the invention which comprises a neck portion of the head (5) and a bristle-bearing portion of the head (4) and a central support (6) which bears bristles and may be made from any conventional toothbrush handle material such as polypropylene or acrylonitrile. The bristle-bearing head portion also comprises flexible boots (8) which may be made from the same material as the remainder of the head e. g. polypropylene and serve to locate individual bristle tufts.

These boots are linked to the central support (6) by way of flexible hinges (7) which are integral with both boot (8) and central support (6). As in figure 1 the handle (not shown) will comprise a motor element to provide vibration.

Figure 3 illustrates the brush according to figure 2 with elastomer material (9) incorporated around the boots (8) and the central support (6). This may be achieved using standard injection moulding technology.

Figure 4 illustrates the bristle-bearing portion of the head of an embodiment of a toothbrush according to the invention.

The head portion comprises an elastomer material (9) surrounding part of each side of the head portion and has flexible boots (8) which are comprised of the elastomer.

While the brush head is vibrating the boots will also vibrate in the elastomer (9).

Figure 5 illustrates an embodiment according to figure 4 where the tufts of the boots are embedded in the elastomer (9).

Figure 6 illustrates a similar embodiment to figure 5 but where the boot tufts are embedded in a boot (10) comprising a material such as polypropylene which may or may not be hingedly linked to the central portion (8) and surrounded with elastomer (9). Alternatively, the polypropylene boots (10) may float'in the elastomer (9).